Showing papers in "Annals of Microbiology in 2008"
TL;DR: It is found that drying process has eliminated the active principles in the seaweeds and methanol:toluene (3∶1) was found to be the best solvent for extracting the antimicrobial principles from fresh algae.
Abstract: Fourteen seaweeds collected from the intertidal zone of Southwest coast of India were tested against ten human pathogen bacteria and one human pathogen fungus using the well diffusion test in the casitone agar medium. The species used in the present study include five Chlorophyta (Bryopsis plumosa, Ulva fasciata, Acrosiphonia orientalis, Chaetomorpha antennina, Grateloupia filicina), five Rhodophyta (Hypnea pannosa, Gracilaria corticata, Centroceras clavulatum, Portieria hornemannii, Cheilosporum spectabile) and four Phaeophyta (Padina tetrastromatica, Sargassum wightii, Stocheospermum marginatum, Chnoospora bicanaliculata). Of these, seven species were determined to be highly bioactive and screened on the multiresistant pathogens. We found that drying process has eliminated the active principles in the seaweeds. In the present study, methanol:toluene (3∶1) was found to be the best solvent for extracting the antimicrobial principles from fresh algae. However, the ethanolic extract showed no antibacterial activity.Acrosiphonia orientalis showed activity against 70% of the tested organisms.Stocheospermum marginatum was the only seaweed that showed activity againstKlebsiella pneumoniae. The extract fromGracilaria corticata was highly active againstProteus mirabilis, a Gram negative pathogenic bacterium. The present findings revealed that the tested seaweeds were highly active against Gram negative bacteria than Gram positive bacteria. The antimicrobial principle from seaweed was found to be a lipophilic compound. The compound was stable over a wide range of temperature (30–60 °C). The active principles of highly active seaweedsAcrosiphonia orientalis andStocheospermum marginatum were bactericidal.
139 citations
TL;DR: The present study describes the isolation of bacteria from soil with the ability to degrade plastic polyurethane (PU) and the results of the Sturm test for degradability and Scanning Electron Microscopy and Fourier Transform Infrared Spectroscopy showed certain changes on the surface of PU film and formation of some new intermediate products after polymer breakdown.
Abstract: The present study describes the isolation of bacteria from soil with the ability to degrade plastic polyurethane (PU). Bacterial strains attached on the polyurethane film, after soil burial for 6 months, were isolated and identified asBacillus sp. AF8,Pseudomonas sp AF9,Micrococcus sp. 10,Arthrobacter sp. AF11, andCorynebacterium sp. AF12. In plate assay, zones of hydrolysis were visualised around the bacterial colonies on mineral salt agar plates containing polyurethane as a sole carbon source. The results of the Sturm test for degradability showed more CO2 production in the test than in control. The production of esterase was detected in the presence of polyurethane as a substrate. The Scanning Electron Microscopy and Fourier Transform Infrared Spectroscopy showed certain changes on the surface of PU film and formation of some new intermediate products after polymer breakdown.
100 citations
TL;DR: An understanding of persistence, fate and phytotoxicity of allelochemicals in the natural environment is developed, and the possible solution of the problems due to microbial interventions in the soil is pointed out.
Abstract: Soil microorganisms interact with plants in diversified manner ranging from mobilising nutrients and enhancing their growth, to inducing diseases. They also produce allelochemicals directly or indirectly through conversion from other compounds. In order to hamper plant growth, allelochemicals must accumulate and persist at phytotoxic levels in the rhizosphere soil. However, after their entry into environment, persistence, availability and biological activities of allelochemicals are influenced by microorganisms. Transformation of allelochemicals by soil microbes may result into the compounds with modified biological properties. Such bio-transformations affect the overall allelopathic capability of the producer plant in a direct manner. Several reports describe the allelopathic significance of microbial metabolism products. For instance, a bacteriumActinetobacter calcoaceticus, can convert 2 (3H)-benzoxazolinone (BOA) to 2,2′-oxo-l,l′-azobenzene (AZOB) which is more inhibitory to some plants. On the contrary, bacteriumPseudomonas putida catabolises juglone in soils beneath walnut trees; otherwise, juglone accumulates at phytotoxic levels. This review article describes the nature of microbially produced allelochemicals, and the ways to mediate microbial degradation of putative allelochemicals. The given information develops an understanding of persistence, fate and phytotoxicity of allelochemicals in the natural environment, and also points out the possible solution of the problems due to microbial interventions in the soil.
97 citations
TL;DR: A psychrotolerant, Gram negative, rod shaped, plant growth promoting bacterium (PGPB) was isolated from high altitude of North Western Indian Himalayas and the identity of the bacterium was confirmed by morphological, biochemical and sequencing of the 16S rRNA gene.
Abstract: A psychrotolerant, Gram negative, rod shaped, plant growth promoting bacterium (PGPB) was isolated from high altitude of North Western Indian Himalayas. The identity of the bacterium was confirmed by morphological, biochemical and sequencing of the 16S rRNA gene. The sequence analysis revealed maximum similarity withPseudomonas vancouverensis. It exhibited tolerance to a wide pH range (5–12; optimum 7.0) and salt concentrations up to 5% (w/v). The isolate produced 8.33 and 1.38 μg/ml of IAA at 15°C and 4°C respectively, on the third day after incubation. It solubilised 42.3, 66.3 and 74.1 μg/ml of tricalcium phosphate at 4, 15 and 28°C respectively after seven days of incubation. The strain also possessed HCN and siderophore production abilities at 4°C. It exhibited inhibitory activity against several phytopathogenic fungi in three different bioassays. The maximum relative growth inhibition was recorded againstSclerotium rolfsii andRhizoctonia solani (100%), followed byPythium sp. (73.1%) andFusarium oxysporum (19.7%), in volatile compound assays. Seed bacterization with the isolate enhanced the germination of wheat seedlings grown at 18±1°C by 20.3%. Bacterized seeds also recorded 30.2 and 27.5% higher root and shoot length respectively, compared to uninoculated controls.
95 citations
TL;DR: One strain of lactic acid bacteria isolated frompaocai samples in various areas of China exhibited high ability to convert sodium glutamate to γ-aminobutyric acid, and was identified as lactobacillus brevis according to its phenotypic and phylogenetic characteristics.
Abstract: To find a high γ-aminobutyric acid-producing lactic acid bacterium, more than 1000 strains of lactic acid bacteria isolated frompaocai samples in various areas of China were screened by the ability in production of γ-aminobutyric acid, analysed with paper chromatography, HPLC and HPLC-MS. Among them, one strain NCL912 exhibited high ability to convert sodium glutamate to γ-aminobutyric acid. The strain accumulated 149.05 mM of γ-aminobutyric acid in a modified MRS medium containing 3% sodium glutamate after 48 h of static cultivation at 30 °C. This strain was identified asLactobacillus brevis according to its phenotypic and phylogenetic characteristics.
81 citations
TL;DR: The results showed that the essential oil of Mentha longifolia ssp.longifolia had great potential of antimicrobial activity against all 8 bacteria and 8 yeast species tested.
Abstract: This study was conceived to evaluate the difference in the chemical composition of the essential oil ofMentha longifolia ssp.longifolia from two ecotypes (Sidi Bouzid and Gabes) as well as the difference of the composition of the oils extracted from the leaves and stems. The antimicrobial activity was also tested against 16 human pathogenic microorganisms. The chemical composition of the hydrodistilled essential oils ofMentha longifolia ssp.longifolia were analysed by GC and GC/MS system. Remarkable differences were recorded between the percentages of the few constituents from leaves and stems and between plants from the two geographical provinces. The chemical analysis of the essential oil obtained from leaves and stems showed the presence of 34 compounds. The most important ones were consecutively: 1,8-cineole (5.6–10.8%), menthone (20.7–28.8%), terpineol-4 (3.1–4.9%), menthol (19.4–32.5%), pulegone (7.8–17.8%) and piperitone (2.2–3.3%). These major components occur in different amounts depending on the organs (leaves or stems) and the geographical origin of the plant. The antimicrobial activity of the essential oil was tested using the disc-diffusion assay and minimal inhibition concentration (MIC) values were estimated according to the microdilution method. The results showed that the essential oil ofMentha longifolia ssp.longifolia had great potential of antimicrobial activity against all 8 bacteria and 8 yeast species tested. The (MIC) for bacteria was ranging from 0.195 to 3.12 × 103 μg/ml.
76 citations
TL;DR: Screening results in thirteen strains having more than one PGP trait showed that B. thuringiensis harbours and expresses several PGP determinants that could be very interesting in field application to enhance the plant growth.
Abstract: This study aimed to evaluate the plant growth promoting (PGP) potential ofBacillus thuringiensis. In this context, several genetic determinants of factors implicated in PGP potential were investigated by polymerase chain reaction (PCR) in 16B. thuringiensis strains of different origin and belonging to different subspecies. PCR screening was performed on acid phosphatase, phytase, siderophore biosynthesis protein, 1-aminocyclopropane-1-carboxylate (ACC) deaminase and indolpyruvate decarboxylase (ipdC). Production of indol acetic acid (IAA)-like compounds and of ACC deaminase, and capability of solubilising mineral phosphate were investigated by phenotypic tests. All the strains were PCR positive for the presence of the siderophore biosynthesis protein, ACC deaminase and acid phosphatase genes. Five and seven strains gave an amplicon with the expected length for the phytase andipdC genes respectively. All the strains produced IAA compounds and seven had a high capacity to solubilise inorganic phosphorous. Qualitative phenotypic test for ACC deaminase activity showed that seven strains are able to grow on salt minimal medium containing ACC as sole nitrogen source, indicating the expression of theaccd genes. Our screening results in thirteen strains having more than one PGP trait and showed thatB. thuringiensis harbours and expresses several PGP determinants that could be very interesting in field application to enhance the plant growth. To our knowledge, this is the first report on the multiple plant growth promoting potential ofB. thuringiensis.
67 citations
TL;DR: It is shown that organic fungicides applied on wine grapes during ripening cause a drastic reduction in the yeast flora and a shift in yeast populations towards A. pullulans.
Abstract: In this work, the effects of fungicide treatments on the distribution and presence of the yeast flora that colonise the surfaces of grapes were investigated. Samples were collected from three vineyards treated with different fungicide applications using two methodologies to detect the yeast flora. Our results show that organic fungicides applied on wine grapes during ripening cause a drastic reduction in the yeast flora. In the absence of fungicide treatments,Hanseniaspora uvarum was the dominant species, followed byMetschnikowia pulcherrima. Results of inorganic fungicide treatment trials confirmed the dominance of these wine fermenting yeasts together with a significant presence ofAureobasidium pullulans andCryptococcus spp. The use of organic fungicides (in addition to inorganic fungicide application) showedA. pullulans as the predominant yeast species, followed by theCryptococcus species, while wine fermenting yeasts were scarcely represented. The dominance ofA. pullulans on grape surface treated with organic fungicides was confirmed in two consecutive vintages. In conclusion, organic fungicides directly applied on grape surfaces result in a dramatic reduction of yeast population and a shift in yeast populations towardsA. pullulans.
59 citations
TL;DR: Growth of the eight strains was inhibited by several antibiotics and anti-inflammatory medicaments containing ibuprofen, hydrochlorothiaziden and thioridazine hydrochlorid.
Abstract: A combination of eight strains comprising ofLactobacillus plantarum, Enterococcus faecium andLeuconostoc mesenteroides subsp.mesenteroides isolated from molasses, olives, beer and kefir were studied for growth at low pH and ox-bile resistance. pH neutralised cell-free supernatants from 24-h-old cultures inhibited the growth ofEnterococcus faecium, Lactobacillus sakei, Lactococcus lactis subsp.lactis, Listeria innocua andListeria ivanovii subsp.ivanovii. Good growth was recorded in MRS broth supplemented with 0.3% (w/v) ox-bile.Lactobacillus plantarum ST28MS and ST26MS,Enterococcus faecium ST311LD andLeuconostoc mesenteroides subsp.mesenteroides ST33LD grew well in the presence of 0.6% (w/v) ox-bile. All eight strains grew well in MRS broth, adjusted to pH 7.0. Good growth ofEnterococcus faecium ST311LD,Leuconostoc mesenteroides subsp.mesenteroides ST33LD andLactobacillus plantarum 423 was recorded in MRS broth with an initial pH of 4.0. Auto cell-aggregation ranged from 74.3% forLactobacillus plantarum ST23LD to 95.4% forLactobacillus plantarum ST28MS. Different levels of co-aggregation were recorded between the eight strains andEnterococcus faecium HKLHS,Lactobacillus sakei DSM 20017,Lactococcus lactis subsp.lactis HV219,Listeria innocua LMG 13568 and UWC N27, andListeria ivanovii subsp.ivanovii ATCC 19119. Growth of the eight strains was inhibited by several antibiotics and anti-inflammatory medicaments containing ibuprofen, hydrochlorothiaziden and thioridazine hydrochlorid. Sodium diclofenac inhibited the growth ofLactobacillus plantarum ST8KF and ST341LD,Enterococcus faecium ST311LD andLeuconostoc mesenteroides subsp.mesenteroides ST33LD. Dimenhydrinate inhibited the growth of onlyLactobacillus plantarum ST8KF. Adherence to Caco-2 cells ranged from 8.0 to 1.3%. All eight strains contain theMub, MapA andEF-Tu genes, as determined by amplification with gene-specific primers.
55 citations
TL;DR: In this paper, dilute-acid pretreatment followed by cellulase digestion was evaluated as a substrates for ethanol fermentation by Saccharomyces cerevisiae, and three agricultural wastes were found to consist of 37, 39 and 34% cellulose and 24, 41 and 22% hemicellulose, respectively, on a dry solid basis.
Abstract: Bagasse, corn cob, and rice straw agricultural wastes were found to consist of 37, 39 and 34% cellulose and 24, 41 and 22% hemicellulose, respectively, on a dry solid (w/w) basis and thus have the potential to serve as a low cost foodstock for ethanol production. Hydrolysates produced by dilute-acid pretreatment followed by cellulase digestion were evaluated as substrates for ethanol fermentation bySaccharomyces cerevisiae. After pretreatment by 141 mM sulphuric acid, bagasse waste released glucose (134 mg/g) at a higher level than that from corn cob (75 mg/g) and rice straw (8 mg/g). Hydroxymethylfurfural (HMF) levels derived from acid pretreatment of bagasse (1.5 g/l), but not corn cob (0.8 g/l) or rice straw (0.1 g/l) attained levels likely to be toxic (1.5 g/l) forS. cerevisiae growth and ethanol fermentation rates. All three agricultural wastes released likely non-toxic levels of furfural (<0.5 g/l) and lactic acid (negligible for bagasse and rice straw and 0.7 g/l for corn cob). After cellulase saccharification of the dilute-acid pretreated agricultural wastes, the glucose content of corn cob hydrolysates (13 ± 0.17 g/l) was marginally higher than that of bagasse (12 ±0.27 g/l) or rice straw (11 ± 0.07 g/l), yet the ethanol conversion yield byS. cerevisiae on corn cob hydrolysate (0.45 ± 0.006 g/g) was lower than that attained with bagasse hydrolysate (0.49 ± 0.007 g/g). Synergistic adverse effects between furfural and HMF with weak acids, or other lignin derived products in the corn cob hydrolysate are proposed as the effective inhibitor (s) for ethanol fermentation byS. cerevisiae.
52 citations
TL;DR: The view that increased antioxidant enzyme activities could be involved at least in part, in the beneficial effects of plant growth-promoting rhizobacteria strains on the performance of vegetable grown under the pathogen infection conditions is supported.
Abstract: Bacterial wilt, caused byRalstonia solanacearum (Smith) Yabuuchiet al., is an economically important disease on tomato in many provinces of China. Antagonistic bacteriumBacillus subtilis strain AR12 was used to control bacteria wilt of tomato (Lycopersicon esculentum Miller) in the greenhouse. The biocontrol efficiency was as high as 90.18%. Superoxide anion and hydrogen peroxide generation rates and changes in phenylalanine ammonia lyase (PAL), polyphenoloxidase (PPO), peroxidase (POD), superoxide dismutase (SOD), ascorbate peroxidase (APX), and catalase (CAT) activities were studied in tomato plants. Antagonist AR12 advanced and increased significantly activities of PAL, PPO, POD and SOD. As comparison, the activities of these four enzymes increased less and later in tomato only treated withR. solanacearum TM15 (control 2), and kept lowest level with few change in tomato with sterilised water (control 1). The maximum activities of these four enzymes in tomato treated with AR12 occurred in different stages: activity of PAL, PPO, POD, and SOD increased to the top level at 48, 48, 12 and 12 h, respectively, after pathogen inoculation and kept high level for some time. H2O2 is associated with hypersensitive response (HR) during systemic acquired resistance. H2O2 content increased significantly in tomato treated with AR12, but HR response was not seen. CAT and APX are the key H2O2 detoxifying enzymes. Activities of APX in tomato treated with AR12 were increased significantly, while CAT was degraded until 80 h after pathogen inoculation. This work support the view that increased antioxidant enzyme activities could be involved at least in part, in the beneficial effects of plant growth-promoting rhizobacteria strains on the performance of vegetable grown under the pathogen infection conditions.
TL;DR: The ERIC-PCR profiles among the isolated bacteria were generally heterogeneous, showing a high polymorphism and suggesting independent circulation with some evidence of cross-transmission.
Abstract: This study characterises 43Vibrio alginolyticus strains associated with diseased juveniles and older fish ofSparus aurata reared in a marine hatchery installed along the seacoasts of Monastir (Centre of Tunisia).Vibrio alginolyticus strains were isolated using the TCBS modified agar plates and the biochemical activities were tested using the API 20 E strips. The exoenzymes production and antibiotics susceptibility were also investigated. The ERIC-PCR was used to evaluate the genetic diversity of these strains.Vibrio alginolyticus was isolated from seawater (n=16), juveniles with white nodular skin lesions (n=9) and from all the internal organs of the older fish presenting a large and deep lesions in the muscle and with a necrotic eyes (n=18). Most of the studiedV. alginolyticus strains were β-haemolytic, hydrolyze the DNA and produce many exoenzymes such as lecithinase, caseinase, amylase and lipase. All tested strains were resistant to at least three antimicrobial agents. The ERIC-PCR profiles among the isolated bacteria were generally heterogeneous, showing a high polymorphism and suggesting independent circulation with some evidence of cross-transmission.
TL;DR: Consistent viability and high proteolytic activity of probiotics in tofufa during storage suggested that tofUFa is a suitable carrier for live probiotics with bioactive potential.
Abstract: Lactobacillus acidophilus FTCC 0291,Lactobacillus bulgaricus FTCC 0411Lactobacillus casei FTCC 0442,Lactobacillus fermentum FTD 13 andBifidobacterium bifidum BB 12 were screened for their α-galactosidase activity over 24 h.Lactobacillus bulgaricus FTCC 0411 andL. fermentum FTD 13 showed highest α-galactosidase specific activity and were selected to be incorporated into tofufa for a storage study of 9 days at 25 and 4 °C. The viability of both probiotics in tofufa exceeded 106 CFU/g and was maintained over storage, mainly contributed by their ability to hydrolyse oligosaccharides and to utilise the reducing sugars produced. The presence of probiotics in tofufa showed an increase in the concentrations of organic acids which led to a decrease in pH levels. This exhibited a preservative effect, where total aerobes and total anaerobes were 2 log10 CFU/g lower than the control. Probiotics in tofufa also liberated peptides with angiotensin-converting enzyme (ACE) inhibitory properties. Consistent viability and high proteolytic activity of probiotics in tofufa during storage suggested that tofufa is a suitable carrier for live probiotics with bioactive potential.
TL;DR: It was found that multiple subcultured strains were significantly more susceptible to monochloramine and not capable of entering to VBNC state in comparison with freshly opened/isolated strains.
Abstract: The aim of the study was to evaluate the response of two differentLegionella pneumophila strains with their 20 times subcultured passages, regarding VBNC induction and to test the effect of multiple subculturing on cell vulnerability in the presence of monochloramine. A freshly opened ofL. pneumophila ATCC 33152, a first subculture of environmental isolate ofL. pneumophila and the 20th subcultures of both strains were tested for survival in the presence of different doses of monochloramine (24 hours). Besides culture method, live-dead cells were visualised. It was found that multiple subcultured strains were significantly more susceptible to monochloramine and not capable of entering to VBNC state in comparison with freshly opened/isolated strains. Environmental isolate was survived at 2 ppm dose of monochloramine after 24 h, whereas 20th subculture of this strain failed to survive. Multiple subculturedL. pneumophila strains were lost their culturability and viability significantly. This phenomenon should be considered while working with laboratory strains. After monochloramine disinfection,L. pneumophila bacteria can completely lose their cultivability but do not lose viability, which remains responsible for serious outbreaks worldwide. Even after completely loosing cultivability, it is possible to find live cells in network water in the VBNC state.
TL;DR: It can be concluded that RFLP typing has more discriminatory power and this method is a useful instrument for the better understanding of transmission and the occurrence of micro-epidemics and source tracing.
Abstract: In recent years in spite of medical advancement, tuberculosis remains as a worldwide health problem. Therefore, identifying the source of transmission of infection is necessary for decreasing of tuberculosis (TB), also determining the varieties of TB strains by DNA fingerprinting helps to achieve this objective. The aim of present study was to determine tuberculosis transmission dynamics in Northwest of Iran with MIRU-VNTR and IS6110-RFLP methods. MIRU-VNTR performed for analysis of 125 strains and restriction fragment length polymorphism (RFLP) typing was performed on 119 culture-positive specimens during a period of September 2002 to March 2003 in tuberculosis centres of the region. We found 93 distinct MIRU-VNTR patterns, including in 21 clustered patterns and 72 unique patterns from isolated strains. The discriminatory power of MIRU-VNTR typing in our study was high (Hunter-Gaston discriminatory index, HGDI=0.9932) for isolates. Ninety-three distinct IS6110 patterns were revealed. Twelve clusters were found among total of 38 strains. The clusters included 26 patients who infected by 12 another’s. HGDI for our IS6110-RFLP method was 0.9928. The minimum estimate for the proportion of tuberculosis that was due to transmission with IS6110-RFLP was 21.9% and with MIRU-VNTR was 26.4%. In clusters the same patterns of Nakhichevanees patients and Iranian patients were revealed in three clusters with MIRU-VNTR and one cluster in IS6110 which showed that Nakhichevanees patients referred to tuberculosis centres of province could be a source of tuberculosis transmission. RFLP typing has more discriminatory power and it can be concluded that this method is a useful instrument for the better understanding of transmission and the occurrence of micro-epidemics and source tracing.
TL;DR: The present study focused on cloning and expression of theansA gene, encoding putative asparaginase I of Bacillus subtilis in Escherichia coli, and investigation of the basic properties of the recombinant enzyme for application in food processing industry.
Abstract: The present study focused on cloning and expression of theansA gene, encoding putative asparaginase I ofBacillus subtilis inEscherichia coli, and investigation of the basic properties of the recombinant enzyme for application in food processing industry. TheansA gene ofB. subtilis was cloned by polymerase chain reaction and expressed inE. coli Rosseta Gami B. It consisted of an open reading frame of 987 nucleotides encoding a protein of 329 amino acids with a calculated molecular mass of 36441 Da. The recombinant enzyme showed increased expression (21.7 U mg−1) and was purified to homogeneity by a two-step procedure that included L-asparagine affinity column chromatography. Based on the kinetic properties and primary structure of the native enzyme, the product of theansA gene was classified as L-asparaginase I. The enzyme showed a high specific activity compared with that of L-asparaginase II fromE. coli. Results of this study will allow us to apply the enzyme to food industry.
TL;DR: Pantoea dispersa was proven superior to Trichoderma Monitor WP and Bavistin; which are used as commercialFusarium wilt control agents.
Abstract: Fusarium wilt is one of the major yield and growth-limiting factors of pigeonpea (Cajanus cajan). For an ecofriendly and sustainable management of such a disease, a novel mycolytic strainPantoea dispersa was evaluated against fungal pathogenFusarium udum that is known to be infecting the susceptible variety of pigeonpea (T-15-15), commonly prevalent in India. To study the efficacy ofP. dispersa as a biocontrol agent in comparison with chemical fungicide Bavistin and antifungal biocontrol agentTrichoderma Monitor WP was studied in both pot and field experiments.In vitro, P. dispersa inhibits the growth ofF. udum. In the pot experiment,P. dispersa the treated pigeon pea (T-15-15) seeds showed higher percentage of seed germination and decreased wilt incidence as compared to chemical fungicide; Bavistin and antifungal biocontrol agentTrichoderma Monitor WP treatments. Moreover, the root, shoot lengths and growth were also found to be higher. Due to high impact ofP. dispersa inin vitro condition on controlling theF. udum growth, further study was conducted in field in a wilt-stricken plot. These studies were repeated for three cropping seasons (2004/2007). The seed dressing byP. dispersa reduced wilt incidence (47%) during field trials, which is greater than Bavistin (41%) andTrichoderma Monitor WP (36%) treatments. HenceP. dispersa was proven superior toTrichoderma Monitor WP and Bavistin; which are used as commercialFusarium wilt control agents.
TL;DR: The present work indicates that endophytes not only duplicate the secondary metabolite composition of host plant but can also serve as important tool for the preservation of biodiversity.
Abstract: A total of fifty-four endophytic fungi were isolated from living symptomless leaves, stem and petals ofRosa damascaena Mill. (Rose). Rose is commercially exploited for the essential oil which is used in flavour and fragrances. Methyl eugenol [1,2-dimethoxy 4-(2-propenyl) benzene] constitutes about 1.9% composition of the rose oil and also acts as a precursor for the synthesis of methyl DOPA an important vasodilator. Besides this, it is an important bioactive compound with wide range of applications in pharmaceutical and flavouring industries. So far, methyl eugenol has been extracted either from rose oil or synthesized. During the present investigation GC-MS revealed the production of methyl eugenol by anAlternaria species isolated as an endophyte of cultivated and wild rose. The present work indicates that endophytes not only duplicate the secondary metabolite composition of host plant but can also serve as important tool for the preservation of biodiversity.
TL;DR: In this paper, the authors compared four analytical methods including drop collapse, oil spreading, surface tension (SFT) measurements, and blood agar lysis tests for detection of biosurfactant-producing bacteria.
Abstract: The current study was undertaken to compare four analytical methods including drop collapse, oil spreading, surface tension (SFT) measurements, and blood agar lysis tests for detection of biosurfactant-producing bacteria. Among 32 biosurfactant-producing bacteria isolated from Ahvaz oil fields, in south of Iran, 16 isolates (50%) exhibited highest biosurfactant production. Eleven isolates (MASH.1 to MASH.11) demonstrated a reduction in surface tension from 65 mN/m to less than 41 mN/m. The results showed that about 91% of these highly biosurfactant producers had the same response levels of “++++” and “+++” in the case of both SFT and oil spreading methods. Among these, seven isolates had the haemolysis diameter less than 1 cm or between 1 and 2 cm on blood agar. As 64% of the best biosurfactant producers did not completely lyses blood, the ability of biosurfactant-producers for haemolysis may not always be trustworthy. According to our data, there is a good consistency between oil spreading technique and surface tension. As a conclusion, oil spreading method is the fastest, simplest and most consistent analytical method to be suggested for accurate measurements of biosurfactant producers.
TL;DR: Results showed that the molecular method is the good tool to discriminate F. verticillioides into two different major groups.
Abstract: Fusarium verticillioides causes a wide range of diseases in maize and also produces important mycotoxins like fumonisins which are the major threats to animals and humans In the present study 14 different isolates ofF verticillioides were collected from maize seeds represented from different parts of Southern India and the morphological identity was further confirmed by PCR The isolates were subjected to morphological, biochemical and molecular characterisation Results showed that the molecular method is the good tool to discriminateF verticillioides into two different major groups
TL;DR: Based on bioassay-guided fractionation, a nematicidal metabolite (R)-(−)-2-ethylhexan-1-ol was obtained from LCB-3 and was identified as Brevundimonas diminuta, which exhibited the strongest Nematicidal activity against both two nematodes.
Abstract: Two hundred and six bacterial isolates were obtained from leaf, flower and stem of three healthy plants,Euphorbia pulcherrima Willd,Pyrethrum cinerariifolium Trev. andHeracleum candicans Wall. The nematicidal activity experiment showed that a total of 92 isolates displayed activity againstCaenorhabditis elegans (Maupas) Dougherty, and 70 isolates resulted active againstBursaphelenchus xylophilus (Steiner & Buhrer) Nickle. Strain LCB-3 exhibited the strongest nematicidal activity against both two nematodes. According to the 16S rDNA, the strain LCB-3 was identified asBrevundimonas diminuta. Based on bioassay-guided fractionation, a nematicidal metabolite (R)-(−)-2-ethylhexan-1-ol was obtained from LCB-3. The median lethal concentrations (LC50) of the compound were 542.0 mg l−1 againstC. elegans and 168.1 mg l−1 againstB. xylophilus 48 h after treatment.
TL;DR: Based upon morphological, physiological and biochemical analysis, 33 strains of lactic acid bacteria were isolated and identified from 11 samples of traditional natural fermented goat milk collected from different individual households in Haixi region of Qinghai.
Abstract: Based upon morphological, physiological and biochemical analysis, 33 strains of lactic acid bacteria were isolated and identified from 11 samples of traditional natural fermented goat milk collected from different individual households in Haixi region of Qinghai. The counts of lactic acid bacteria were 2.5×108}3.0×109 CFU/mL, while yeasts were 2.6×106}1.6×108 CFU/mL. Strains were identified as follows: 7 strains ofLactobacillus delbrueckii susp.lactis, 4 strains ofLactobacillus delbrueckii subsp.bulgaricus, 3 strains ofLactobacillus acidophilus, 1 strain ofLactobacillus coryniformis subsp.coryniformis, 12 strains ofStreptococcus thermophilus, 1 strain ofLeuconostoc mesenteroides subsp.mesenteroides, 3 strains ofPediococcus acidilactici, and 2 strains ofAerococcus urinaeequi comb. nov.
TL;DR: In tested concentrations, the prepared extract showed positive antibacterial values, but no antifungal activity was detected, andLimonene, the terpenoid compound, was found to be the major component in the tested extract.
Abstract: Trichoderma species are common soil-inhabiting fungi that have been developed as effective biocontrol agents against various phytopathogenic microorganisms. The chemical composition of butanolic extract prepared from cultivatedTrichoderma sp. was analysed using GC-FID and GC-MS. Six components were identified. Limonene, the terpenoid compound, was found to be the major component in the tested extract (92.6%). Antibacterial and antifungal activities were also investigated against five pathogenic Gram positive and Gram negative bacterial strains and five pathogenic fungi. In tested concentrations, the prepared extract showed positive antibacterial values, but no antifungal activity was detected.
TL;DR: The effect of frozen storage ofL.
Abstract: The effects of freezing at −20 °C were examined on surviving ofListeria monocytogenes contaminating food during freezing. Slices of fresh salmon were inoculated with three strains ofListeria monocytogenes (108 CFU/g). The inoculated pieces of fish were dried for 1 h at 24 °C and then stored in closed containers at −20 °C for ten months. The identification of atypical cells found after freezing was achieved by PCR. This technique was based on the amplification of two specific genes ofL. monocytogenes hlyA andiap. The results showed that after ten months of frozen storage, the concentration ofL. monocytogenes determined on Trypticase Soya agar-Yeast Extract had declined by 2.39±0.01 log CFU/g and 2.22±0.01 log CFU/g for the strains isolated from meat, S1 and S2 respectively, and by 3.69±0.03 log CFU/g for the reference strain. The effect of frozen storage ofL. monocytogenes in salmon did not decrease the potential survival of food-borne pathogens’ over a period of ten months.
TL;DR: Analysis of 16S rRNA gene sequences demonstrated that the strains were most closely related to representatives of the generaStreptomyces andMicromonospora among actinobacteria, indicating considerable genetic diversity among the isolates.
Abstract: The genetic diversity of 41 endophytic actinobacteria isolated from 13 native medicinal plants growing in diverse ecoclimatic zones in Sichuan, China, was investigated by using PCR-RFLP of the ribosomal 16S rRNA gene and the intergenic spacer (IGS) region between the 16S rRNA and 23S rRNA genes, BOX fingerprinting and full sequence analysis of the 16S rRNA gene. The results revealed 29 and 40 genotypes from 16S and 16S–23S rRNA IGS genes PCR-RFLP data, respectively, which indicated considerable genetic diversity among the isolates. Analysis of 16S rRNA gene sequences demonstrated that the strains were most closely related to representatives of the generaStreptomyces andMicromonospora among actinobacteria. Native medicinal plants are thus important resources for endophytic actinobacteria.
TL;DR: A high thermostable extracellular protease was purified to homogeneity and characterised from Bacillus thermantarcticus, strain M1, suggesting that the enzyme belonged to the serine protease family.
Abstract: A high thermostable extracellular protease was purified to homogeneity and characterised fromBacillus thermantarcticus, strain M1. The molecular mass was about 42 kDa. Almost total inhibition of protease by phenyl methyl sulphonylfluoride (PMSF), suggested that the enzyme belonged to the serine protease family. The enzyme was active and stable in a broad range of pH with an optimum at pH 7.0. The protease showed the highest activity at 70°C and was stable for 24 h at 70°C, with an increase of the enzymatic activity of about 4 times, in the presence of CaCl2. The protease retained about 50% activity after 3 h of incubation in the presence of CaCl2 with various commercial detergents. Purified protease was found to be stable, for one week, in presence of DMSO, methanol, ethanol, acetonitrile, isopropanol.
TL;DR: An acidic pectin lyase produced by Aspergillus ficuum MTCC 7591 was purified to apparent homogeneity by ion exchange and gel filtration chromatography and has been found to be very effective in the clarification of sweet lime and orange juices.
Abstract: An acidic pectin lyase (E.C. 4.2.2.10) produced byAspergillus ficuum MTCC 7591 of molecular weight 31.6 kD was purified to apparent homogeneity by ion exchange and gel filtration chromatography. Eighty-six fold purification with 60% yield and a specific activity of 7.8 U/mg protein was obtained. The Km and calculated turnover number (kcat) of the purified enzyme were found to be 0.60 mg/ml and 74 s−1 respectively using citrus pectin as the substrate. The pH and temperature optima were 5.0 and 50°C respectively. Exposed to 24 hours at a particular pH the enzyme was found to be relatively stable in the pH range 2.0–9.0. Exposed to a particular temperature for 1 hour, the enzyme retains full activity up to 40°C. Metal ions and protein inhibitors did not have significant effects on the activity of the enzyme. The enzyme has been found to be very effective in the clarification of sweet lime and orange juices.
TL;DR: It is proposed that the lack of glucose repression on maltase activity is the most critical criterion in the development of non-lagging strains of baker’s yeast, rather than the maltose permease, in lean dough leavening.
Abstract: Baker’s yeast,Saccharomyces cerevisiae, is a key microorganism used in the baking industry. While the preferred substrate for baker’s yeast is generally glucose, the predominant carbohydrate in lean dough is maltose. Therefore, in order to improve the leavening properties of lean dough, it is essential to improve maltose metabolism by the yeast. The objective of this study was to gain better insight into the regulation of the yeast maltose-transporter, maltose permease, and the maltose-cleaving enzyme, maltase, by glucose in lagging and non-lagging strains of baker’s yeast. Gas evolution in a low sugar model liquid dough (LSMLD) medium was used to select five out of ten industrial baker’s yeast strains for further investigation on the basis of varying metabolic characteristics. In all four of the lagging strains tested, both maltose permease and maltase were inhibited by glucose to some extent. In the relative non-lagging strain, which demonstrated the highest performance in LSMLD, it was shown that maltase was not inhibited by glucose. Based on our findings, it indicated that in lean dough leavening, it is the maltase that plays the essential role in maltose metabolism, rather than the maltose permease. Therefore, we propose that the lack of glucose repression on maltase activity is the most critical criterion in the development of non-lagging strains of baker’s yeast.
TL;DR: The degree of activity varied with the fungal species, length of exposure time, and media composition, but all four metabolites showed noticeable biological activity against B. xylophilus nematode.
Abstract: Sixty crude cultural filtrates of thirty fresh water fungi individually grown in both Potato Dextrose broth and GPC broth were assayedin vitro for antinematodal activity againstBursaphelenchus xylophilus (Steiner et Buhrer) Nickle using immersion test. Filtrates fromCamposporium quercicola YMF1.01300,Periconia digitata YMF1.00948,Caryospora callicarpa YMF1.01026 grown in both PDB and GPC broth, and the cultural filtrate ofMelanospora zamiae YMF1.00948 grown in PDB were found to be pathogenic to the tested nematodes. The degree of activity varied with the fungal species, length of exposure time, and media composition. From a nematicidal cultural extract ofCaryospora callicarpa YMF1.01026, four known naphthalenones were isolated and identified as 4,8-dihydroxy-3,4-dihydronaphthalen-1(2H)-one (1), 4,6-dihydroxy-3,4-dihydronaphthalen-1(2H)-one (2), 4,6,8-trihydroxy-3,4-dihydronaphthalen-1(2H)-one) (3), 3,4,6,8-tetrahydroxy-3,4-dihydronaphthalen-1(2H)-one (cis-4-hydroxyscytalone) (4) by NMR and MS analysis. All four metabolites showed noticeable biological activity againstB. xylophilus nematode. This is the first published report of these compounds affecting plant-parasitic nematodes.
TL;DR: In this paper, chemical and microbiological properties of organic and conventional date pastes produced from the Deglet Nour cultivar were investigated, and significant differences were observed in water content, sugar profiles, and pH among the two dates.
Abstract: Chemical and microbiological properties of organic and conventional date pastes produced from the Deglet Nour cultivar were investigated. Significant differences were observed in water content, sugar profiles, and pH among the date pastes. The low moisture and the high acidity of organic date paste were two important positive attributes for its storage and potential manufacturing uses. Before pasteurisation, moulds CFU’s of the organic paste was significantly (P <0.01) lower than those of the conventional one but no significant differences were observed for yeasts, coliforms and the total aerobic flora among the two date pastes. Considerable interest has developed on the preservation of conventional date paste by the use of natural additives such asJuniperus phoenicea and olive oil (conditioned paste). At a given mixture ofJuniperus and olive oil and after pasteurisation, mould CFU’s were reduced by 95% (P <0.01) whereas the reduction was only 84% for the yeast populations, after 45 days at 25 °C.