Showing papers in "African Journal of Microbiology Research in 2011"

Aflatoxin control and prevention strategies in key crops of Sub-Saharan Africa

Abstract: Aflatoxins are secondary fungal metabolites that contaminate agricultural commodities and can cause sickness or death in humans and animals. Risk of aflatoxin contamination of food and feed in Africa is increased due to environmental, agronomic and socio-economic factors. Environmental conditions especially high humidity and temperature favour fungal proliferation, but also drought conditions increase risk of aflatoxin contamination. Low-input farming practices compound fungal and aflatoxin contamination of crops. The socio-economic and food security status of the majority of inhabitants of sub-Saharan Africa leaves them few options for choosing low-risk and high quality products. Several technologies have been tested in Africa to reduce aflatoxin risk. Field management practices that increase yields can reduce the risk of aflatoxin development. They include use of resistant varieties, crop rotation, well-timed planting, weed control, pest control especially control of insect pests and avoiding drought and nutritional stress through fertilization and irrigation. Measures to stop the infection process by controlling the aflatoxin causing fungi in the field are achieved through use of pesticides and atoxigenic fungi to competitively displace toxigenic fungi, and timely harvest. Post-harvest interventions that reduce aflatoxin include rapid and proper drying, proper transportation and packaging, sorting, cleaning, drying, smoking, post harvest insect control, and the use of botanicals or synthetic pesticides as storage protectants. Another approach is to reduce the frequent consumption of ‘high risk’ foods (especially maize and groundnut) by consuming a more varied diet, and diversifying the diet into less risky staples like sorghum and millet. Chemo-preventive measures that can reduce aflatoxin effect include daily consumption of chlorophyllin or oltipraz and incorporating hydrated sodium calcium alumino-silicates into the diet. Reduction and detoxification of aflatoxin is often achieved physically (sorting, physical segregation, flotation etc.), chemically (e.g. calcium hydroxide, ammonia) and microbiologically by incorporating pro-biotics or lactic acid bacteria into the diet. Millers can use blending of less and more contaminated products to reduce the overall risk. There is need for efficient monitoring and surveillance with cost-effective sampling and analytical methods to reduce risk in Africa. Public education and awareness can sensitize the population on aflatoxin risk and its management. Key words: Aflatoxin, Sub-Saharan Africa, control measures.

Isolation and identification of some fruit spoilage fungi: Screening of plant cell wall degrading enzymes

Abstract: This study investigates the current spoilage fruit fungi and their plant cell wall degrading enzymes of various fresh postharvest fruits sold in Jeddah city and share in establishment of a fungal profile of fruits. Ten fruit spoilage fungi were isolated and identified as follows Fusarium oxysporum (banana and grape), Aspergillus japonicus (pokhara and apricot), Aspergillus oryzae (orange), Aspergillus awamori (lemon), Aspergillus phoenicis (tomato), Aspergillus tubingensis (peach), Aspergillus niger (apple), Aspergillus flavus (mango), Aspergillus foetidus (kiwi) and Rhizopus stolonifer (date). The plant cell wall degrading enzymes xylanase, polygalacturonase, cellulase and α-amylase were screened in the cell-free broth of all tested fungi cultured on their fruit peels and potato dextrose broth (PDB) as media. Xylanase and polygalacturonase had the highest level contents as compared to the cellulase and α-amylase. In conclusion, Aspergillus spp. are widespread and the fungal polygalacturonases and xylanses are the main enzymes responsible for the spoilage of fruits.

An overview of honey: Therapeutic properties and contribution in nutrition and human health

Abstract: Honey, a natural product of very high nutritive value is made when the nectar (floral) and sweet deposits from plants (non floral) are gathered, modified and stored in the honeycombs by honeybees of the genera Apis and Meliponini. Its composition and quality vary greatly with the botanical source of nectar as well as environmental and climatic conditions. Depending on its quality, honey can contribute to the health and nutritional status of humans. These beneficial actions have been ascribed to its antimicrobial, anti-inflammatory and anti-oxidant potential. Interestingly, honey is gradually receiving attention as a complementary and or an alternative source of treatment in modern medicines. It is active against antibiotic-sensitive and antibiotic-resistant strains of micro-organisms and has the potential not to select for further resistant strains. Key words: Honey, natural product, drug, food.

Biodegradation of low density polyethylene (LDPE) by fungi isolated from marine water a SEM analysis

Abstract: Fungi, isolated from sea water, were subjected to growth in a medium containing low density polyethylene (LDPE) as the sole carbon source with and without yeast extract. Increasing fresh weight of the fungi in the medium supplemented with LDPE after regular time intervals gave the evidence that the fungi were utilizing LDPE as the carbon source. Further confirmation of LDPE utilization was carried out by the Sturm test where the degradation was attributed to the amount of carbon dioxide evolved during the growth period. The two fungi that showed good growth in medium supplemented with LDPE proved to degrade LDPE with higher efficiency in earlier reported results Scanning Electron Microscopy analysis of the fungal treated LDPE films provided a solid evidence of biodegradation. Fungi were identified as Aspergillus spp. LDPE degradation is a severe environmental crisis in the world and we have proved that microorganisms can be used for bioremediation in this line. Key words: Biodegradation, low density polyethylene (LDPE), Aspergillus, marine fungi, Sturm test.

Antioxidative activity of lactic acid bacteria in yogurt

Abstract: The antioxidative effect of intact cells and cell-free extract of Lactobacillus casei subsp.casei SY13 and Lactobacillus delbrueckii subsp. bulgaricus LJJ, isolated from the traditional yogurt, was evaluated by various antioxidant assays. The results showed that two Lactobacillus strains had good antioxidant capacity, inhibiting the peroxidation of linoleic acid by 62.95% and 66.16%. The cell-free extract showed excellent scavenging superoxide anion and hydroxyl radicals activity. The intact cells on 1,1-Diphenyl-2-Picrylhydrazyl (DPPH) radical scavenging ability and chelating ferrous ion capacity were superior to cell-free extract. The highest reducing activity was equivalent to 305 and 294 μM L-cysteine. This study suggests that two strains are high antioxidative bacterial strains. Antioxidative property of lactobacilli would be useful in the dairy manufacturing industry. They could beneficially affect the consumer by providing dietary source of antioxidants. Key words: Lactobacillus, reactive oxygen species, antioxidative.

Screening for antibacterial activities in some marine algae from the red sea (Hurghada, Egypt)

Abstract: Methanolic and ethyl acetate extracts from eight different seaweeds collected from the red sea Hurghada, Egypt (June, 2009) were screened for their antibacterial activities against both gram positive bacteria (Staphylococcus aureus NCIMB 50080 and Bacillus cereus) and gram negative bacteria (Escherichia coli NCIMB 50034, Enterococcus feacalisNCIMB 50030, Salmonella sp. and Pseudomonase aeruginosa). The antibacterial activities were expressed as zone of inhibition and minimum inhibitory concentrations (MIC). The seaweeds belong to Phaeophyaceae (Cystoesira myrica, Cystoesira trinodis, Padina gymnospora, Sargassum dentifolium and Sargassum hystrix); Rhodophaceae (Actinotrichia fragilis) and Chlorophyceae (Caulerpa racemosa and Codium fragile). Ethyl acetate extracts of C. racemosa, C. fragile and P. gymnospora; methanolic extracts of P. gymnospora and C. fragile showed higher antibacterial activities than other members of the tested algae. The most resistant bacteria was E. feacalis against both solvents extracts of S. dentifolium, C. myrica and A. fragilis while, Salmonella sp. and P. aeruginosa were resistant to methanolic extracts of C. racemosa, S. dentifolium and A. fragilis. On the other hand, B. cereus, S. aureus and E. coli were the most sensitive to all seaweed extracts. Our conclusion confirmed that susceptibility of gram positive bacteria to the algal extracts (zone of inhibition up to 19 mm) was more than those of gram negative bacteria (zone of inhibition up to 14 mm). The activities of ethyl acetate extracts were higher than those of methanolic extracts and the most powerful inhibitory extract was ethyl acetate extract of C. racemosa. Key word: Antibacterial, ethyl acetate extracts, marine algae, methanolic extracts, minimum inhibitory concentration, seaweeds.

The effects of nutritional restriction on neutral lipid accumulation in Chlamydomonas and Chlorella

Abstract: Under nutrient starvation conditions, many microalgae are known to accumulate triacylglycerols (TAG) that can be used for biodiesel production. However, few studies have been performed to analyze the effect of deficiency in nutrient elements such as sulfur, phosphorus, potassium, iron, magnesium and calcium on oil production, particularly in Chlamydomonas and Chlorella. In this study, we investigated lipid content of Chlamydomonas reinhaditti CC124 and Chlorella vulgaris Y-019 grown in TAP, HSM, BG11, SE lacking optimal concentrations of these elements. Our results showed that, in high carbon HSM and TAP media, N and S starvation led to significant increase in cellular lipid content in both microalgae species. In addition, C. reinhaditti grown in TAP media without P, Fe, K, Ca or Mg or in HSM media without K, Ca or Mg also accumulated detectably higher neutral lipids. In contrast, in C. vulgaris, such accumulation was observed only in Mg-free and Fe-free HSM media. In low carbon SE and BG11 media, N starvation resulted in a moderate increase in the lipids content both in C. reinhaditti and C. vulgaris. On the other hand, P, S, K, Ca or Mg deficiency promoted neutral lipids accumulation in C. vulgaris. Finally, we analyzed and discussed the relationships among cell growth rate, lipid accumulation and nitrogen concentrations in C. reinhaditti. Key words: Nutrient limitation, lipid accumulation, nitrogen, sulfur, phosphorus, potassium, iron, magnesium, calcium.

Fungi and mycotoxins in stored foods

Abstract: This review focused on the worldwide contamination of foods and feeds with mycotoxins as a significant problem. Mycotoxins are secondary metabolites of molds that have adverse effects on humans, animals, and crops that result in illnesses and economic losses. Aflatoxins, ochratoxins, trichothecenes, zearelenone, fumonisins, tremorgenic toxins, and ergot alkaloids are the mycotoxins of greatest agro-economic importance. Factors influencing the presence of mycotoxins in foods or feeds include environmental conditions related to storage that can be controlled. Other extrinsic factors such as climate or intrinsic factors such as fungal strain specificity, strain variation, and instability of toxigenic properties are more difficult to control. The economic impact of mycotoxins include loss of human and animal life, increased health care and veterinary care costs, reduced livestock production, disposal of contaminated foods and feeds, and investment in research and applications to reduce severity of the mycotoxin problem. Although efforts have continued internationally to set guidelines to control mycotoxins, practical measures have not been adequately implemented. Key words: Fungi, mycotoxins, aflatoxins, contamination, relative humidity, safe moisture content.

Antibacterial activity of Moringa oleifera and Moringa stenopetala methanol and n-hexane seed extracts on bacteria implicated in water borne diseases

Abstract: The anti-bacterial activity of methanol and n-hexane extracts of Moringa oleifera andMoringa stenopetala seeds was conducted on 3 bacterial species (Salmonella typhii, Vibrio cholerae and Escherichia coli) which normally cause water borne diseases. The paper disc diffusion method was used with treatments arranged in a completely randomized design and replicated four times. The highest inhibitions were observed at dilutions of 20, 5 and 40% for M. oleifera and M. stenopetala methanol extracts on E. coli,S. typhi and V. cholerae respectively. The n-hexane extract of both M. oleifera and M. stenopetala had a higher inhibition on S. typhii than V. cholerae and E. coli. The results of this study showed that M. oleifera and M. stenopetala had a degree of antibacterial properties especially in low doses. Key words: Moringa oleifera, Moringa stenopetala, methanol and n-hexane extracts, inhibition, Salmonella typhii, Vibrio cholera, Escherichia coli, Kenya.

An epidemiological survey on investigation of tick infestation in cattle at Chittagong District, Bangladesh

Abstract: management of cattle, seasons of the year, topography of the area and different body parts of the host. A total number of 380 cattle were examined, of which 138 (36.31%) cattle were found infested. Three species of ticks were identified namely Boophilus microplus, Rhipicephalus sanguineus and Haemaphysalis bispinosa. The range of tick burden was 1 to 7 per four square inch of heavily infested area of Chittagong District. Mean tick burden was also high in case of B. microplus (2.77 ± 0.18) followed by H. bispinosa (1.03 ± 0.12) and R. sanguineus (0.83 ± 0.10). Prevalence was significantly (p 1.5 years of age (27.80%). Infestation of tick was significantly higher (p<0.01) in female (59.37%) than the male (35.83%) cattle. Tick infestation was more prevalent in local (43.82%) cattle than the cross-bred (24.13%) cattle. Field grazing (41.96%) cattle were more susceptible (p<0.01) to tick infestation than the stall-feeding (24.8%) animals. Prevalence of tick infestation was significantly (p<0.01) higher in summer (41.66%) season followed by winter (31.5%) season. Ticks were widely distributed in different parts of the host body such as ear, neck, tail, mammary gland, udder, groin and perianal region of which groin (48.75%) was most affected parts of animal body and face and neck (30%) was the least. Prevalence of tick infestation was significantly (p<0.01) higher in hilly area (44.44%) followed by plain area (30.27%). It is concluded that B. microplus is the main tick species identified and threatening to the cattle population in Chittagong District irrespective of age, sex, breed of the animal, seasons of the year and topography of the study area.

Utility and importance of walnut, Juglans regia Linn: A review

Abstract: Juglans regia Linn is a medicinal plant that has been widely used in traditional medicine for a wide array of ailments that include helminthiasis, diarrhea, sinusitis, stomachache, arthritis, asthma, eczema, scrofula, skin disorders, and various endocrine diseases such as diabetes mellitus, anorexia, thyroid dysfunctions, cancer and infectious diseases. The present review, attempts to provide comprehensive information on the ethnobotanical use, pharmacology, nutritional value, preclinical and clinical studies, toxicity, other uses and current research prospects of the Juglans regia L. Currently, there is a renewed interest in walnut, and several investigations aimed at scientific validation of its traditional uses and a humble scientific investigation aimed at isolation and identification of active constituents of crude extracts. Key words: Juglans regia, nutritional value, bioactivity, clinical trial, traditional use, toxicity

Identification of bacterial agents and antimicrobial susceptibility of neonatal sepsis: A 54-month study in a tertiary hospital

Abstract: The spectrum of bacteria which cause neonatal sepsis varies in different parts of the world. Antibiotic resistance is an increasing problem of these bacteria. The aim of this study was to detect the most common bacterial causes of neonatal sepsis and determination of their sensitivity to antibiotics. In a descriptive cross-sectional study, records of the neonates suspicious to neonatal sepsis who were admitted to Neonatal Intensive Care Unit (NICU) were assessed. Neonates with positive blood culture along with clinical signs of sepsis were entered in the study. Evaluated data included: age, sex, birth weight, type of infection, type of isolated pathogen, antibiotic sensitivity and disease outcome. Of 3700 screened blood cultures, 153 (4.1%) reported as positive, 76.5% of the evaluated neonates were preterm, 142 (92.8%) had gram negative sepsis and 11 (7.2%) had gram positive sepsis. The most common isolated gram negative bacteria were Klebsiella pneumoniae (46.4%), enterobacter spp. (17.6%) and Escherishia coli (14.4%). Coagulase negative staphylococci (CONS) were the most prevalent gram positive bacteria (5.9%) in this study. All of the klebsiella and enterobacter strains were resistant to ampicillin and gentamicin. The sensitivity of K. pneumoniae and enterobacter to imipenem was: 90 and 92.5%, respectively. Prevalence of early and late-onset sepsis was 64.7 and 35.3% respectively. Mortality rate of sepsis in this study was reported as 53.5%. In conclusion, the most common cause of bacterial sepsis in this study was K. pneumoniae which was completely resistant to ampicillin and gentamicin. So empirical treatment of sepsis with ampicillin and gentamicin in Imam Khomeini NICU must be reconsidered.

Screening and induction of laccase activity in fungal species and its application in dye decolorization

Abstract: A great deal of works has been carried out assessing dye-decolorization capabilities of fungi, but only few species were investigated. In this present study, ten fungal species were screened for laccase activity by indicator plate method, of which five species were found to be laccase-positive. Laccase activity varied during growth and maximal laccase activity was observed during the 9th day, except for Agaricus bisporus. Pleurotus ostreatus gave the highest laccase activities, showing average value around 570 U/L, which were higher than other strains. Addition of 1 mM copper sulphate induced the laccase production efficiently by 60 to 80%, while veratryl and benzyl alcohol induced laccase production in all the laccase positive species except for A. bisporus. Constitutive expression of laccase was observed in F. solani in the presence of copper sulphate. In addition, the extracellular laccase from the P. ostreatus could decolorize reactive dyes, which suggests the potential application of laccase in textile effluent treatment. Key words: Dyes, decolorization, inducer, laccase, Pleurotus, textile.

Detection of metallo-beta-lactamase (MBL) producing Pseudomonas aeruginosa at a tertiary care hospital in Kashmir

Abstract: Metallo-beta-lactamases (MBL) producing Pseudomonas aeruginosa strains are responsible for several nosocomial outbreaks in tertiary care centers across the world. It is well known that poor outcome occurs when patients with serious infections due to MBL producing organisms are treated with antibiotics to which the organism is completely resistant. Therefore, detection of these MBL producing P. aeruginosa is crucial for optimal treatment of critically ill patient’s and to prevent the spread of resistance. Current study was undertaken with the aim of optimizing the choice, dose and duration in MBL producingP. aeruginosa infections in a tertiary care center in Kashmir for various types of treatment modalities. Aims and objectives are now specific and not like introduction. Various clinical samples were obtained from patients admitted in hospital or attending the OPD between January 2007 to June 2008. Antimicrobial sensitivity was performed by Kirby-Bauer disk diffusion method. Minimum inhibitory concentration (MIC) of Imipenem resistant isolates was done by agar dilution method. Metallo-beta-lactamase production was detected by combined disk method, MIC reduction of imipenem in presence of EDTA and by Epsilometer test (E-test). The intergroup comparison and risk estimation was performed by using Fisher’s exact test and Odd’s ratio. Out of 283 P. aeruginosa isolates, 38 (13.42%) were resistant to Imipenem. Thirty three (11.66%) were found to be MBL producers by combined disk test and all of them showed reduction in MIC in the presence of imipenem-EDTA in E-test. The number of MBL positive isolates from ICU was statistically significant (p=0.027). The hospital stay was significantly longer (p=0.000) among patients infected with MBL producers than MBL non producers. Statistically significant association of antineoplastic chemotherapy, urinary catherization with MBL production was found. All MBL producers were resistant to commonly used antibiotics. However, they were sensitive to polymyxin B(100%), piperacillin/tazobactum (18.2%), amikacin and ciprofloxacin (9.1%). MIC reduction is a cumbersome, laborious method and given the cost constraints of E-test a simple screening test like combined disk test may be used. In absence of therapeutic MBL inhibitors, polymyxins, aminoglycoside or fluoroquinolone molecule that may have retained some activity against the isolate may be used for the treatment of MDR P. aeruginosa infections. Key words: Pseudomonas aeruginosa, combined disc test, Epsilometer test, Metallo-beta-lactamase.

Eco-friendly role of biodegradation against agricultural pesticides hazards

Abstract: This review aims to elaborate the potential applications of various biological agents in decontamination of agricultural soils, which have been polluted with continuous and higher doses of pesticides through process of biodegradation. Biodegradation is an eco friendly, cost effective, highly efficient approach and can be considered as a superior alternative to physical and chemical methods which are not only technically laborious and costly; also are not sufficient to completely degrade organic toxins. Development of experimental conditions in which all congruent biological agents are applied concurrently may be a promising strategy to enhance biodegradation and subsequently biodegradation. Much work remains to be done in carrying out field studies based on laboratory-scale results/experiments using plant-associated endophytic and rhizospheric bacteria to degrade a wide range of toxic organic compounds of concern in environmental soil before commercially viable systems. Key words: Biodegradation, pesticides, fungi, bacteria, phytodegradation.

Ethnobotanical survey of medicinal plants used in treating viral infections among Yoruba tribe of South Western Nigeria

Abstract: Ethnobotanical survey of plants used to treat some common viral diseases, such aschicken pox, poliomyelitis, influenza, hepatitis, measles and jaundice was carried out in Ekiti, Ondo, Osun and Oyo States in South Western Nigeria. Questionnaires were distributed among the participants and oral discussions were employed. Two hundred and eight (208) data were collected and tabulated. The Yoruba names, botanical names, methods of preparation and mode of administration of the plants were considered. The research work showed that members of the family Annonaceae (10.3%) were most frequently used, followed by members of Leguminosae (9.9%), and Zingiberaceae (7.9%), for treating chickenpox and measles infections, although all other plants play prominent roles in peoples` health care. Also, knowledge of medicinal herbs was being left in the hands of the elders between the age range of 51-70 years and 71-80 years. The leaves of the plants (45.5%) were mostly used in treating viral infections, followed by the use of stem bark (13.5%). All other parts were less commonly used to treat viral diseases. Mono-prescription was rare in the data collected. Oral application had the highest mode of administration (83.7%), while the combination of both oral and external applications (12.5%) closely followed. Decoction (90.4%) was the most frequently used method of anti-viral herbal preparation, while concoction (0.9%) was least used. Herb sellers (72.6%) constituted the major source of information about the use of anti-viral medicinal herbs, followed by traders, civil servants and herbalists with 17.31, 6.25 and 3.85 respectively. Many plants in the studied area may be a good source of lead molecules needed in viral chemotherapy after extraction of the bioactive components as well as removal of toxic residue following toxicological studies. Key words: Leguminosae, mono-prescription, chickenpox, decoction.

A simple double-layered chrome azurol S agar (SD- CASA) plate assay to optimize the production of siderophores by a potential biocontrol agent Bacillus

Abstract: Siderophores, a high-affinity chelating agents for ferric iron, is one of the mechanisms by which biocontrol agents’ act in inhibiting the growth of phytopathogens. Bacillus subtilisQM3, a siderophore producer, is a potential biocontrol agent. In this study, a simple double-layered chrome azurol S agar (SD-CASA) plate assay was developed. We further studied optimal conditions for detection siderophore production by B. subtilis QM3 using various history cultures, pH value, amino acid, and different carbon-nitrogen ratio as four variables. After incubating different history cultures we found out that the LB medium presented strong significant CAS reaction even for 12 h, and with the help of changingvariables on SD-CASA plate assisting paper-disc diffusion, strain QM3 from LB medium with Fe3+ (10 μmol/L) showed difference interestingly. In addition, CAS reaction and growth reaction also increased with pH 7.0, tryptophan 10 μmol/L and carbon-nitrogen ratio 5:1. The findings on solid medium were similar as that in liquid medium. The SD-CASA assay should be a useful tool for screening potential biocontrol microorganisms by siderophore production. Key words: A simple double-layered CAS agar assay, paper-disc diffusion, siderophores,Bacillus subtilis QM3.

Effect of prebiotic oligosaccharides on growth of Lactobacillus strains used as a probiotic for chickens

Abstract: In the present study, the effect of 10 commercially available oligosaccharides on the growth of 11 Lactobacillus strains, which were isolated from the gastrointestinal tract of chickens and have been used as a multistrain probiotic for chickens, was evaluated in vitro. The utilization of oligosaccharides was highly variable among the 11 Lactobacillus strains and considerable strains differences (P < 0.05) were observed. Isomaltooligosaccharides (IMO) supported good growth for all the 11 Lactobacillus strains, followed by galactooligosaccharides (GOS), gentiooligosaccharides (GTO) and fructooligosaccharides (FOS). Oligosaccharides such as Raftilose L60, Raftilose P95, Raftiline LS, and mannanoligosaccharides (MOS) were poorly utilized by all the Lactobacillus strains. Growth kinetics study also showed variations in the specific growth rates and growth patterns of four representative Lactobacillus species on four selected oligosaccharides. The highest specific growth rate was demonstrated by Lactobacillus salivarius I 24 on FOS. The results showed that the ability of the 11 probiotic Lactobacillus strains to utilize oligosaccharides could be both strain and substrate specific, which demonstrates the importance of selecting suitable prebiotic oligosaccharides for the preparation of synbiotics.

Carvacrol and thymol components inhibiting Pseudomonas aeruginosa adherence and biofilm formation

Abstract: Pseudomonas aeruginosa has a high propensity to develop biofilms that are resistant to exogenous deleterious agents. The aim of this study was to investigate whether carvacrol and thymol can interfere with adherence phenomena as well as acting on biofilm formation. Tests of P. aeruginosa strains showed that carvacrol and thymol interferes with the starting phases of adherence as well as with P. aeruginosa biofilms. Carvacrol and thymol (2MIC) inhibition was 97±8.5 and 89±6.3% for P. aeruginosa (ATCC 27853)and 72±4.6 and 69±6.8% for P. aeruginosa (CIP A22) adherence respectively. Carvacrol (2MIC) inhibition exceeds 90% for P. aeruginosa (ATCC 27853) and P. aeruginosa (IL5)biofilm. Thymol (2MIC) inhibition is 86±2.1, 54±5.9 and 70±4.3% for P. aeruginosa (ATCC 27853) P. aeruginosa (CIP A22), P. aeruginosa (IL5), respectively. Key words: Biofilm, adherence, carvacrol, thymol, Pseudomonas aeruginosa.

The use of gamma irradiation in agriculture

Abstract: Lately, radiation technology is widely used to produce changes in the product characteristics leading to the development of new products. Gamma irradiation is capable of hydrolyzing chemical bonds, thereby cleaving large molecules of starch into smaller fragments of dextrin that may be either electrically charged or uncharged as free radicals. These changes may affect the physical and rheological properties of irradiated foods, resulting in increased solubility of starch, decreased swelling power, and decreased viscosity of starch paste. Irradiation of gamma rays on bud wood can produce higher frequencies of mutation, leading to the creation of new variants compared to the control. Macronutrients (carbohydrates, proteins and lipids) content are relatively stable against irradiation doses up to 10 kGy, on the other hand, gamma irradiation affects proteins by causing conformational changes, oxidation of amino acids, rupturing of covalent bonds and formation of protein free radicals. Radiation mediated morphological, structural and functional changes in a plant are governed by the intensity and duration of the gamma irradiation. Key words: Irradiation, Foods sterilized, Mutation, Biochemical change, Agriculture.

Osmoadaptation and plant growth promotion by salt tolerant bacteria under salt stress

Abstract: Establishment of biofilm, production of exopolysacharides (EPS) and accumulation of endogenous osmolytes under varying stress conditions are significant strategies adopted by bacterial strains for their successful survival in plant rhizosphere. Our studies focus on determining the osmoadaptation strategies used by two native salt-tolerant strainsOceanobacillus profundus (Pmt2) and Staphylococcus saprophyticus (ST1) and their plant growth promoting abilities. The ability of these strains to be used as inoculants forLens esculenta Var. masoor 93 under salt stress was tested in the laboratory. We found that unlike the bacterial growth, biofilm formation, exopolysaccharide production and endogenous osmolyte (proline and glycine betaine) accumulation increased at higher salt stress. Biofilm formation and endogenous osmolytes increased with increasing salt concentrations. The maximum increase in EPS accumulation was observed at maximum NaCl stress for ST1. Bacterial inoculation improved growth parameters and endogenous osmolytes accumulation of plants under salt stress compared to noninoculated control plants. The ST1 strain in this work efficiently produced biofilm and exopolysacharide and accumulated osmolytes in response to NaCl stress. It could be speculated that these strategies reverse the detrimental effects of high osmolarity in soil and helpful for improving crop under salt stress. Key words: Biofilm, exopolysaccharide, endogenous osmolytes, Lens esculenta, salinity.

Arbuscular mycorrhizal fungi and heavy metal contaminated soils

Abstract: Arbuscular mycorrhizal fungi (AMF) associations are integral, functioning parts of plant roots and are widely recognized as enhancing plant growth on severely disturbed sites, including those contaminated with heavy metals (HMs). They are reported to be present on the roots of plants growing on HM-contaminated soils and play an important role in metal tolerance and accumulation. Isolation of the indigenous and presumably stress-adapted AMF can be a potential biotechnological tool for inoculation of plants for successful restoration of degraded ecosystems. Plants grown in metal contaminated sites harbour unique metal tolerant and resistant microbial communities in their rhizosphere. These rhizo-microi¬‚ora secrete plant growth-promoting substances, siderophores, phytochelators to alleviate metal toxicity, enhance the bioavailability of metals (phytoremediation) and complexation of metals (phytostabilisation). Most studies of HM toxicity to soil microorganisms have concentrated on effect where loss of microbial function can be observed and the effects on biodiversity within microbial populations and communities have not significantly been evaluated. This review highlights the interaction between HM-contaminated soils and AMF. Key words: Activity, arbuscular mycorrhizal fungi, biodiversity, functionality, heavy metal, soil contamination.

Antibacterial activity of quercetin on oral infectious pathogens

Abstract: The aim of this study was to evaluate the antimicrobial activity of quercetin against pathogens of the main oral infectious diseases which include caries, periodontitis and oral mucosa infectious diseases associated microorganisms. Agar diffusion assay was adopted to observe the effects of quercetin on the growth of 11 main oral pathogenic microorganisms, including Streptococcus mutans, Streptococcus sanguis, Streptococcus sobrinus, Actinomyces viscosus, Actinomyces naeslundii, Lactobacillus acidophilu, Porphyromonas gingivalis, Fusobacterium nucleatum, Actinobacillus actinomycetemocomitans, Prevotella intermedia and Candia albicans. The antibacterial activity of quercetin was determined in form of minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC) using agar dilution assay. In all experiments, results obtained indicated that quercetin had inhibitory effects on S. mutans with MIC of 2 mg/ml and MBC of 8 mg/ml, S. sobrinus with MIC of 1 mg/ml and MBC of 8 mg/ml, L. acidophilu with MIC of 2 mg/ml and MBC of 16 mg/ml, S. sanguis with MIC of 2 mg/ml and MBC of 16 mg/ml, A. actinomycetemocomitans with MIC of 1 mg/ml and MBC of 8 mg/ml,P. intermedia with MIC of 4 mg/ml and MBC of 16 mg/ml, respectively. Thus, it could be concluded that quercetin had different antibacterial activities against oral bacteria, in which the quecetin showed better antibacterial effect on caries-related bacteria, and could be encouraged for further development in caries prevention and treatment. Key words: oral bacteria, quercetin, antibacterial, minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC).

High level production of extracellular β-galactosidase from Bacillus licheniformis ATCC 12759 in submerged fermentation

Abstract: Alpha amylase (E.C. 3.2.1.1) of Bacillus licheniformis ATCC 12759 was shown to produce extracellular α-amylase in submerged fermentation.Various nutrients belonging to three categories, carbon, nitrogen and amino acid sources, were investigated in terms of their effect on the production of extracellular α-amylase by Bacillus licheniformis ATCC 12759. Amongst carbon sources sugars, arabinose, sucrose, corn flour and corn starch supported maximum amylase production. Casein, sodium nitrate, ammonium sulphate, ammonium chloride, and ammonium nitrate where the best organic sources and inorganic sources respectively. Among the amino acid sources tested, L-cysteine, L-tryptophane, Lvaline, L-phenylalanine, L-methionine and L-lysine were favored the production respectively. FeSO4, ZnSO4 and CuSO4 inhibited α-amylase production. Maximum α-amylase production (1074.8±35.0 U/mg) was obtained in a medium containing 0.01% L-cysteine in 72 h at 37 o C.

Isolation, characterization and fingerprinting of some chlorpyrifos- degrading bacterial strains isolated from Egyptian pesticides-polluted soils

Abstract: Five bacterial isolates (B-CP5- B-CP6 - B-CP7- B-CP8- B-CP9) were isolated from pesticides- contaminated soil in Egypt. The capability of these isolates to degrade chlorpyrifos was investigated using enrichment mineral salt (MS) medium containing chlorpyrifos. Two different PCR-based techniques, RAPD-PCR and PCR-RFLP for amplified16S rRNA fragment were used to conduct genetic fingerprinting and obtain specific molecular markers for the studied isolates. The isolates exhibited substantial growth in mineral salt medium supplemented with 100-300 mg/L chlorpyrifos as a sole source of carbon and energy. Based on their morphological, cultural and biochemical characters, the isolates have been identified as Pseudomonas stuzeri, Enterobacter aerogenes, Pseudomonas pseudoalcaligenes, Pseudomonas maltophila andPseudomonas vesicularis respectively. Pseudomonas stuzeri was the most potent degrader strain. Five specific markers for this strain were determined. The highest genetic similarity was observed between CP8 and CP7 (66%), while the lowest genetic similarity was detected between CP8 and CP6 (37%). All isolates had the same pattern after digestion of 16S rRNA amplified fragment with two restriction enzymes (EcoRI and AluI) except Enterobacter aerogenes, which generate two monomorphic bands at 420 and 130 bp, respectively. In conclusion, the strain Pseudomonas stuzeri could be used to clean up the areas contaminated with Chlorpyrifos. Obtained molecular markers might be used for identifying and tracking the most potent bacterial isolate. The used PCR techniques represent a powerful tool and could be used for rapid typing of this strain. Key words: Pesticide, chlorpyrifos, biodegradation, 16S rRNA, RAPD-PCR,Pseudomonas sp.

Street foods: Handling, hygiene and client expectations in a World Heritage Site Town, Cape Coast, Ghana

Abstract: Handling, vending and hygienic quality of street foods available to local residents, internal and foreign tourists to Cape Coast, the most important tourism hub in Ghana, were investigated. Questionnaires assessed stakeholder commitment to and expectations of food hygiene. Laboratory analysis evaluated microbial contamination levels of the street foods. Patronised by both local residents and tourists, foreign tourists put the hygienic safety as the principal criterion over curiosity and price to patronise street foods. Although licences had been given to 27 (54%) of the 50 investigated food vendors, only 15 (55.5%) of the licensed vendors had had medical examination (8 only once and 7 annually). Food vending premises visibly needed improvement in sanitation. The foods had the following bacterial contamination levels in colony forming units per gram (cfu/g): meat pie (1.3 × 105), khebab (5 × 104), rice with stew (4.1 × 105), fried fish (8 × 104), pepper sauce (1.4 × 105), etsew or banku (3 × 105), beans with gari (2 × 104), fufu (1.6 × 105) wakye (6.6 × 105) and dakua (2.3 × 105). Presence of Escherichia coli of faecal origin was detected in all investigated food samples. Khebab, fried fish and beans with gari had acceptable bacterial contamination levels of <5 log10 cfu/g. The following major fungi were identified in the street foods: Aspergilus flavus, Aspergillus niger, Aspergillus candidus, Cladosporium herbarum, Necrospora crassa, Penicillium citrinum, Fusarium, Mucor and Rhizopusspecies. Yeasts were found in all investigated food items. The street foods were, therefore, found to have threatening unacceptable microbial contamination levels. Stakeholder education, legislation, verifiable microbiological standards, inspections and environmental sanitation improvement are necessary. Key words: Tourism, street foods, Cape Coast, Ghana.

Serological survey of brucellosis in livestock animals in Sarab City (East Azarbayjan province), Iran

Abstract: Brucellosis is an infectious and zoonotic disease of worldwide distribution. Despite its control program, the disease is endemic in Iran and remains one of the most important public health problems. The aim of this survey was to determine the seroprovalence of brucellosis in livestock animals in Sarab City, Iran. A total of 1500 animals (600 cattle, 740 sheep and 160 goats) were examined for brucellosis from February 2007 to September 2008. The examined animals were divided into two sex groups (male and female). Moreover cattle were divided into four breed groups (Holstein, Brown Swiss, Native and Mixed). Serological examinations including Rose Bengal plate test (RBPT), serum agglutination test (SAT) and 2-mercaptoethanol test (2ME) were performed on serum samples obtained from examined animals. In overall, out of 1500 blood samples 61 (4.06%) were positive for brucellosis. The prevalence of brucellosis in cattle, sheep and goats were found 3.66, 4.18 and 5%, respectively. The prevalence rates of brucellosis in different breeds of cattle, Holstein, Brown Swiss, native and mixed breeds were determined as: 4.72, 2.22, 2.50 and 3.75%, respectively. The prevalence rates of the disease in male and female animals were determined as follows: Male cattle, 1.53%, female cattle, 3.92%, male sheep, 2.8%, female sheep, 4.89%, male goats, 2.22%, and female goats, 6.08%. There were differences in the prevalences of brucellosis in different breeds and sexes of examined animals however statistically were not significant (P>0.05, X 2 <3.84). The results of the present study indicated that the prevalence of brucellosis in livestock animals in Sarab City is relatively high and effective control program of the disease should be recommended. Key words: Brucellosis, Sarab, prevalence, livestock.

Poly--hydroxybutyrate (PHB) production from domestic wastewater using Enterobacter aerogenes 12Bi strain

Abstract: A strain of poly-β-hydroxybutyrate (PHB)-accumulating bacterium was isolated and identified as Enterobacter aerogenes (designated E. aerogenes 12Bi) by using biochemical and phylogenetic characterization. The accumulation of a large amount of granules in its cells cultured in the domestic wastewater medium (DWWM) were showed by transmission electron microscopy (TEM). When PHB production by our strain was determined by Hypochlorite method, it was found that PHB production ranged from 16.66 to 96.25% (w/w). The highest PHB yield by our microorganism was up to 96.25% within 18 h in DWWM 5 (supplemented with 100% DWW). This is the first report of the use of DWW for production of PHB by E. aerogenes. The results obtained in the study demonstrated that PHB could be efficiently produced to a high concentration with high productivity by using DWWM as an inexpensive substrate. Thus, it can contribute to the reduction of high production cost of PHB. Key words: Poly-β-hydroxybutyrate (PHB), bioplastics, domestic wastewater,Enterobacter aerogenes, biochemical identification, phylogenetic identification.

Application of an improved loop-mediated isothermal amplification detection of Vibrio parahaemolyticus from various seafood samples

Abstract: The specificity and sensitivity of an improved loop-mediated isothermal amplification (LAMP) method for rapid detection of Vibrio parahaemolyticus strains from various seafood samples had been developed and evaluated in this study. Six primers, including outer primers and inner primers, were specially designed for recognizing six distinct sequences on the target gene of tlh. The optimal reaction condition was found to be 65°C for 45 min, with the detection limit as 10 CFU/ml. Application of LAMP assays was performed on 416 food borne V. parahaemolyticus strains isolated from various seafood samples, and the total detection rate for LAMP and polymerase chain reaction (PCR) assay was found to be 96.2% (400/416) and 85.6% (356/416). This is the first report of an improved and simple LAMP detection assay on V. parahaemolyticus employed procedures of simple template deoxyribonucleic acid (DNA) preparation, equipment for LAMP reaction (water bath) and direct result determination via observation of color change. In addition, this is also the first application of LAMP detection on this considerable amount of V. parahaemolyticus isolates (416 strains for application together with 105 reference strains for establishment) with the total identification rate as 96.2%, as well as its extensive application to marine fish, shrimp, oyster, mussel, jellyfish, cuttlefish and seaweed samples, with detection rate ranging from 89.5 to 100%. Key words: Loop-mediated isothermal amplification (LAMP), Vibrio parahaemolyticus, seafood samples.

Development and application of a novel multiplex polymerase chain reaction (PCR) assay for rapid detection of various types of staphylococci strains

Abstract: In this study, a novel multiplex- polymerase chain reaction (PCR) for rapid detection of various staphylococci strains, including methicillin-resistant Staphylococcus aureus (MRSA), methicillin-sensitive Staphylococcus aureus, (MSSA) methicillin-resistant coagulase-negative staphylococci (MRCNS), methicillin-sensitive coagulase-negative staphylococci (MSCNS) and non-staphylococci strains, had been developed and applied. Six primers were specially designed on three target genes, which were mecA, 16S Ribosomal ribonucleic acid (rRNA) and femA. The specific amplification generated 3 bands on agarose gel, with sizes 374 bp for mecA, 542 bp for 16S rRNA and 823 bp for femA, respectively. The PCR product showed highest levels of resolution of DNA when 250 �M of dNTP, primer concentration of mecA, 16S rRNA and femA reaching 1, 1 and 3 �M respectively. No false positive amplification was observed, indicating the high specificity of the established multiplex PCR assay. Application of this multiplex-PCR had been further performed on detection for 262 MRSA and MRCNS strains with primers pairs M1 with M2 and F1 and F2. According to the results, multiplex-PCR results showed expected products for either MRSA or MRCNS strains, demonstrating the multiplex-PCR assays established in this study to be useful and powerful methods for differentiation of MRSA, MSSA, MRCNS, MSCNS and non-staphylococci strains.