Showing papers in "World Journal of Microbiology & Biotechnology in 2005"
TL;DR: In this paper, a bacterial consortium RVM11.1 was selected on the basis of rapid dye decolourization ability within 37 h under a wide pH range from 6.5 to 8.5 and temperature ranging from 25 to 40 °C.
Abstract: Soil samples collected from contaminated sites of Vatva, Gujarat, India were studied for screening and isolation of organisms capable of decolourizing textile dyes. A bacterial consortium RVM 11.1 was selected on the basis of rapid dye decolourization. Reactive Violet 5 (RV 5) was used as model dye. The consortium exhibited 94% decolourization ability within 37 h under a wide pH range from 6.5 to 8.5 and temperature ranging from 25 to 40 °C. The bacterial consortium was able to grow and decolourize RV5 under static conditions in the presence of glucose and yeast extract and also showed an ability to decolourize in the presence of starch in place of glucose. Maximum decolourization efficiency was observed at 200 ppm (mg/l) concentration of RV 5. Bacterial consortium RVM11.1 had the ability to decolourize 10 different dyes tested. The transformation and degradation products after decolourization were examined by HPTLC.
292 citations
TL;DR: In this paper, three species of oyster mushrooms, namely P. columbinus, P. sajor-caju and P. ostreatus, were experimentally evaluated on untreated organic wastes including chopped office papers, cardboard, sawdust and plant fibres.
Abstract: Cultivation of speciality mushrooms on lignocellulosic wastes represents one of the most economically and cost-effective organic recycling processes. Three species of Pleurotus, namely P. columbinus, P. sajor-caju and P. ostreatus were experimentally evaluated on untreated organic wastes including chopped office papers, cardboard, sawdust and plant fibres. Production studies were carried out in polyethylene bags of about 1 kg wet weight with 5% spawning rates of substrate fresh weight in a custom-made growth room especially designed for spawn run and cropping. The conversion percentage from dry substrate weight to fresh mushroom weight (biological efficiency) was determined. The highest biological efficiency was noted with P. columbinuson cardboard (134.5%) and paper (100.8%), whereas P. ostreatus produced maximum yield on cardboard (117.5%) followed by paper (112.4%). The overall yield of P. sajor-cajuwas comparatively low (range 47–78.4%). The average number of sporophore flushings ranged between 5 and 6 times. The findings that P. columbinus and P. ostreatus are superior to P. sajor-caju are consistent with previous reports elsewhere. Further evaluation of P. columbinus alone on different bagging systems containing partially pasteurized office papers as a growing substrate revealed that polyethylene bags resulted in 109.4% biological efficiency in contrast to pottery (86%), plastic trays (72%) or polyester net (56%). The above findings reveal an opportunity for commercial implication of oyster mushroom especially P. columbinus for utilization of different feasible and cheap recyclable residues.
178 citations
TL;DR: This microorganism seems to be potentially effective for bioremediation of textile-dyeing industry effluents after decolorization of sulfonated azo dyes by an unidentified bacterium.
Abstract: Kodam et al. reported a 100% decolorization of the sulfonated azo dyes Reactive Red 2, Reactive Red 141, Reactive Orange 4, Reactive Orange 7 and Reactive Violet 5 by an unidentified bacterium, KMK 48. High effectiveness was attained within 36 h of incubation at room temperature and neutral pH. Optimum decolorization took place strictly under aerobic conditions, which is contrary to other well-documented reports. Thus, this microorganism seems to be potentially effective for bioremediation of textile-dyeing industry effluents.
162 citations
TL;DR: In this article, various medium components (carbon and nitrogen sources, iron, inoculum size) and environmental factors (initial pH and the agitation speed) were evaluated for their effects on the rate and the yield of hydrogen production by Clostridium saccharoperbutylacetonicum.
Abstract: Various medium components (carbon and nitrogen sources, iron, inoculum size) and environmental factors (initial pH and the agitation speed) were evaluated for their effects on the rate and the yield of hydrogen production by Clostridium saccharoperbutylacetonicum. Among the carbon sources assessed, cells grown on disaccharides (lactose, sucrose and maltose) produced on the average more than twice (2.81 mol-H2/mol sugar) as much hydrogen as monosaccharides (1.29 mol-H2/mol sugar), but there was no correlation between the carbon source and the production rate. The highest yield (2.83 mol/mol) was obtained in lactose and sucrose but the highest production rate (1.75 mmol/h) in sucrose. Using glucose as carbon source, yeast extract was the best nitrogen source. A parallel increase between the production rate and the yield was obtained by increasing glucose concentration up to 40 g/l (1.76 mol-H2/mol, 3.39 mmol/h), total nitrogen as yeast extract up to 0.1% (1.41 mol/mol, 1.91 mmol/h) and agitation up to 100 rev/min (1.66 mol-H2/mol, 1.86 mmol/h). On the other hand, higher production rates were favoured in preference to the yield at a neutral initial pH 7 (2.27 mmol/h), 1000 mg iron/l or more (1.99 mmol/h), and a larger inoculum size, 10%, (2.36 mmol/h) whereas an initial alkaline pH of 8.5 (1.72 mol/mol), a lower iron concentration of 25 mg/l (1.74 mol/mol) and smaller inoculum size, 1%, (1.85 mol/mol) promoted higher yield over
production rate.
146 citations
TL;DR: Because of its chemical inertness and low cost, trehalose could be easily utilized as excellent bacterial preservative, both to improve the viability of starter cultures and to obtain probiotic formulations more resistant to a variety of stressful conditions.
Abstract: In the present paper, the effect of cryo-protective sugars on the survival rate of different strains of Lactic Acid Bacteria (LAB, Lactobacillus acidophilus, Lactobacillus delbrueckii subspbulgaricus, Streptococcus salivarius subsp.thermophilus), after freezing or freeze-drying procedures, was compared. The cells were incubated at 4 °C in 32% final concentration sugar solutions (trehalose, maltose, sucrose, glucose and lactose), and viability was evaluated by the enumeration of colony-forming units. All sugars tested showed a protective effect on cell viability as compared to isotonic solution, especially after freeze-drying procedures (log c.f.u./ml ranging between 1.16 and 2.08, P < 0.001). Furthermore, the resistance to different stress agents (lysozyme, pepsin, bile salts) was estimated. Trehalose was the most effective sugar in preserving bacterial viability [% (log c.f.u. trehalose/log c.f.u. isotonic solution) ranging between 124 and 175, P < 0.001] although each strain showed a different sensitivity. Finally, the protective effect of immobilization of LAB in Ca-alginate beads was compared to that exercised by trehalose. The immobilization induced a good survival rate but lower as compared to the trehalose effect, mainly after freeze-drying in the presence of the selective agents [% (log c.f.u. alginate/log c.f.u. trehalose ranging between 81.1 and 94.5, P < 0.0001]. The protective effect of trehalose was evident in particular for Lactobacillus delbrueckii subsp. bulgaricus in presence of lysozyme. Therefore, because of its chemical inertness and low cost, trehalose could be easily utilized as excellent bacterial preservative, both to improve the viability of starter cultures and to obtain probiotic formulations more resistant to a variety of stressful conditions.
139 citations
TL;DR: The results have shown the potential of using selected strains of B. subtilis in the biological control of seed pathogens, as well as in promoting soybean growth.
Abstract: Bacteria belonging to the genus Bacillus were isolated from soil samples of Parana State, Brazil, with the aim of evaluating their potential biological control of soybean seed pathogens Strain PRBS-1 was selected, showing similar effectiveness to that of the strain AP-3, used as a reference due to its known antibiotic potential The sequencing of the ribosomal 16S rRNA gene confirmed that both strains belong to the species B subtilis, although showing high genetic diversity in relation to this species Both strains inhibited five soybean seed pathogenic fungi in vitro, Rhizoctonia solani, Colletotrichum truncatum, Sclerotinia sclerotiorum, Macrophomina phaseolina and Phomopsis sp Furthermore, the metabolites of AP-3 increased production of root hairs, while the metabolites of PRBS-1 stimulated outgrowth of lateral roots in soybean The antibiotic effect of both strains seemed to be related to compounds of the iturin group, while the root growth promotion by PRBS-1 was at least partially related to the production of indoleacetic acid The results have shown the potential of using selected strains of B subtilis in the biological control of seed pathogens, as well as in promoting soybean growth
136 citations
TL;DR: The results indicate that the endophytic fungi of Chinese traditional medicinal plants are promising sources of novel bioactive compounds.
Abstract: One hundred and thirty endophytic fungi isolated from 12 Chinese traditional medicinal plants collected at Yuanmou county and Dawei Mountain, Yunnan province, southwest China, were tested for antitumour and antifungal activities by MTT assay on human gastric tumour cell line BGC-823 and the growth inhibition test against 7 phytopathogenic fungi. The results showed that fermentation broths from 9.2% of the isolates exhibited antitumour activity and 30% exhibited antifungal activity, moreover, some of them exhibited broad-spectrum antifungal activity. The active isolates were identified to 32 taxa. The results indicate that the endophytic fungi of Chinese traditional medicinal plants are promising sources of novel bioactive compounds.
124 citations
TL;DR: The postulate of Cu2+-mediated antagonism of salt stress can be explained by a conceivable reversion of Na+-induced disturbance of cellular homeostasis by redox active Cu2+.
Abstract: This study provides first-hand information on the salinity and copper-induced oxidative damage and its protection in Anabaena doliolum by the antioxidant defence system. Oxidative damage measured in terms of lipid peroxidation, electrolyte leakage and H2O2 production was induced by different concentrations of NaCl and Cu2+. A greater electrolyte leakage by NaCl than Cu2+ supported the hypothesis of salinity being more injurious than copper. To explore the survival strategies of A. doliolum under NaCl and Cu stress, enzymatic antioxidant activities e.g. superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), and glutathione reductase (GR) and nonenzymatic antioxidant contents such as glutathione reduced (GSH), ascorbate, α-tocopherol, and carotenoid were measured. A general induction in SOD and APX activities as well as ascorbate and α-tocopherol contents was found under NaCl and Cu2+ stress. In contrast to this, an appreciable decline in GR activity, GSH pool and carotenoid content under Cu2+ and an increase under NaCl stress were observed. CAT activity was completely inhibited at high doses of NaCl but stimulated following Cu2+ treatment. The above results suggest the involvement of APX and CAT in the scavenging of H2O2 under Cu2+ stress. In contrast to this, only APX was involved in H2O2 scavenging under salt stress. Our postulate of Cu2+-mediated antagonism of salt stress can be explained by a conceivable reversion of Na+-induced disturbance of cellular homeostasis by redox active Cu2+.
123 citations
TL;DR: The bacterial isolate DM1 can be exploited for bioremediation of Hexavalent chromium containing wastes, since it seems to have the potential to reduce the toxic hexavalent form of chromium to its nontoxic trivalent form.
Abstract: With advances in biotechnology, bioremediation has become one of the most rapidly developing fields in environmental restoration, utilizing microorganism to reduce the concentration and toxicity of heavy metals. Hexavalent chromium reducing bacterial culture (DM1) was isolated from the contaminated sites of chemical industries and its ability to reduce hexavalent chromium to trivalent chromium, a detoxification process in cell suspension and cell extract was examined. Based on the biochemical analysis DM1 was identified as Ochrobactrum sp. It could tolerate chromium upto a maximum concentration of 300 ppm, optimum temperature and pH being 35 °C and 7 respectively for maximum chromium reduction. Assay with the permeabilized cells (treated with toluene and Triton X-100) and cell free extract demonstrated that the hexavalent chromium reduction is mainly associated with the soluble fraction of the cell. The chromium reducing activity is inducible. The presence of an induced protein having molecular weight around 30 kDa in the presence of chromium and absence in cells without chromium points out a possible role of this protein in chromium reduction. The bacterial isolate DM1 can be exploited for bioremediation of hexavalent chromium containing wastes, since it seems to have the potential to reduce the toxic hexavalent form of chromium to its nontoxic trivalent form.
108 citations
TL;DR: The results showed that streptomycetes could be a promising source for biocontrol agents in aquaculture and against the pathogenic Vibrio spp.
Abstract: A total of 94 actinomycete strains were isolated from the marine sediments of a shrimp farm, 87.2% belonged to the genus Streptomyces, others were Micromonospora spp. Fifty-one percent of the actinomycete strains showed activity against the pathogenic Vibrio spp. strains. Thirty-eight percent of marine Streptomyces strains produced siderophores on chrome azurol S (CAS) agar plates. Seven strains of Streptomyces were found to produce siderophores and to inhibit the growth of Vibrio spp. in vitro. Two of them belonged to the Cinerogriseus group, the most frequently isolated group of Streptomyces. The results showed that streptomycetes could be a promising source for biocontrol agents in aquaculture.
105 citations
TL;DR: In this paper, six varieties of mango, which are abundantly available in the region were selected for wine production and the conditions for juice extraction were optimized, and it was found that the mango juices were similar to grape juice in terms of sugar and acidity.
Abstract: Mango (Mangifera indica L) is the most popular and the choicest fruit of India. A major portion (nearly 60–70%) of the total quantity produced is locally consumed and a sizable portion is exported to other countries. In the present study, six varieties of mango, which are abundantly available in the region were selected for wine production and the conditions for juice extraction were optimized. It was found that the mango juices were similar to grape juice in terms of sugar and acidity. After fermentation, the ethanol concentration was 7–8.5% w/v, the methanol concentration was slightly higher than that of grape wines and other volatile compounds were present in comparable amounts. From the physicochemical characteristics of the mango wine produced, it was observed that aromatic components were comparable in concentration to those of grape wine.
TL;DR: Chitosan is an amino-polysaccharide with highly efficient properties for the binding of metal ions and anionic dyes and has been used for the recovery of mercury from dilute solutions at initial pH 5 and Reactive Black 5 (RB5, anionic dye) at pH 3 as discussed by the authors.
Abstract: Chitosan is an amino-polysaccharide with highly efficient properties for the binding of metal ions and anionic dyes. Uptake may occur through chelation on free amino functions (at near-neutral pH) or by electrostatic attraction on protonated amino groups (in acidic solutions). The polymer is soluble in acidic solutions and its binding properties can be used in both solid form (sorption) and liquid form (ultrafiltration coupled with chelation, coagulation–flocculation). These properties have been used for the recovery of mercury from dilute solutions at initial pH 5 (which reveals the most efficient pH in the range pH 4–6) and for the recovery of Reactive Black 5 (RB5, anionic dye) at pH 3. While in the case of mercury binding saturation of the biopolymer is only slightly higher when chitosan is used in the liquid form compared to solid-state adsorption, in the case of the coagulation–flocculation of RB5 (using the liquid-form of chitosan) the saturation of the polymer (calculated on the basis of molar ratio of dye vs. amino groups of the polymer) is reached at a significantly greater value than when the polymer is used for the solid-state binding of the dye. There is a much more efficient use of amino groups when chitosan is used in the liquid-form due to a better availability of amino groups (less hydrogen bonds between the chains of the polymer) and to a better accessibility to internal sorption sites (lower diffusion control).
TL;DR: The bacterial inoculants in all the formulations were found to enhance the growth parameters of the test plant species; best results were obtained in case of alginate-based formulations.
Abstract: Carrier-based preparations of two plant growth-promoting rhizobacteria (PGPR) viz. Bacillus subtilis and Pseudomonas corrugata, developed in five formulations were evaluated for their growth promotion, rhizosphere colonization, and viability under storage. The effect of these formulations as fresh preparations, and after 6 months of storage at 4 °C and room temperature, was also determined. The bacterial inoculants in all the formulations were found to enhance the growth parameters of the test plant species; best results were obtained in case of alginate-based formulations. Maximum numbers of inoculated bacteria were recovered from the rhizosphere of alginate-based formulation-treated plants after 6 weeks of growth. Viability of bacterial inoculants was maximal in alginate beads, and alginate beads supplemented with skim milk formulations, after 180 days of storage at 4 °C.
TL;DR: A rapid method, ’drop-collapse’, was used for screening biosurfactant production by Pseudomonas aeruginosa, Bacillus subtilis, Candida albicans and Phanerochaete chrysosporium liquid cultures, which showed spreading movement, meaning that they produced biosurfacts.
Abstract: A rapid method, ’drop-collapse’, was used for screening biosurfactant production by Pseudomonas aeruginosa, Bacillus subtilis, Candida albicans and Phanerochaete chrysosporium liquid cultures. Before measuring the total biosurfactant, the drop-collapse method was used in order to detect rhamnolipid presence in the culture broths. The method was performed in a microwell plate; the polystyrene platform with small wells. If the culture broth contained biosurfactant, the droplets of the broth in the oil-coated wells collapsed. If not, there was no change in the shape of the droplets. Pseudomonas aeruginosa and Bacillus subtilis culture supernatants showed spreading movement, meaning that they produced biosurfactants. However, Candida albicans and Phanerochaete chrysosporium supernatants remained beaded, meaning they did not produce any type of microbial surfactant.
TL;DR: The major antimicrobial metabolite, isolated through bioassay-guide fractionation of TLC bioautography overlay assay, was identified as norharman (a beta-carboline alkaloid) by EI-MS and NMR.
Abstract: Twenty-nine marine bacterial strains were isolated from the sponge Hymeniacidon perleve at Nanji island, and antimicrobial screening showed that eight strains inhibited the growth of terrestrial microorganisms. The strain NJ6-3-1 with wide antimicrobial spectrum was identified as Pseudoalteromonas piscicida based on its 16S rRNA sequence analysis. The major antimicrobial metabolite, isolated through bioassay-guide fractionation of TLC bioautography overlay assay, was identified as norharman (a beta-carboline alkaloid) by EI-MS and NMR.
TL;DR: Fungal endophytes reside in healthy tissues of all terrestrial plant taxa studied to date and are diverse and abundant in tropical woody angiosperms.
Abstract: Fungal endophytes reside in healthy tissues of all terrestrial plant taxa studied to date and are diverse and abundant in tropical woody angiosperms. Endophytic fungi were isolated from Terminalia arjuna, an important ethno pharmacological plant extensively used in ayurvedic medicines to treat heart ailments. Isolations were made from symptomless fresh inner bark as well as twig samples of five plants collected from three locations of riparian vegetation during two seasons (monsoon and winter) of 2003 and 2004. Two hundred and seventy eight isolates, representing 22 genera, were obtained from both seasons. Monsoon seasonal isolations representing 22 genera showed greater diversity. Coelomycetes were more numerous during the winter season than hyphomycetes and ascomycetes. Among the endophytes, the genus Pestalotiopsis dominated the endophyte assemblage of T. arjuna collected from different locations, dominance was greater during the winter season than the monsoon season. Endophytic colonization frequency was greater in inner bark (18.5%) than twigs (4.6%). The genera Pestalotiopsis (54.5%), Chaetomium (10.5%) and Myrothecium (9%) were the most predominant endophytes. Rarefaction indices indicated the highest expected number of species for bark samples, monsoon isolations and location 1 (Mysore).
TL;DR: In this study, 29 strains of the genus Bacillus were isolated from different soil samples which were taken from grasslands of Ankara, Turkey and it was found that poly-β-hydroxybutyrate (PHB) production ranged from 1.06–41.67% (w/v) depending on the dry cell weight.
Abstract: In this study, 29 strains of the genus Bacillus were isolated from different soil samples which were taken from grasslands of Ankara, Turkey and were identified as B. brevis, B. sphaericus, B. cereus, B. megaterium, B. circulans, B. subtilis, B. licheniformis and B. coagulans. Two strains, B. sphaericus ATCC 14577 and B. subtilis ATCC 6633 were also included in this study. Poly-β-hydroxybutyrate (PHB) production by these strains was determined by the spectrophotometric method, and it was found that PHB production ranged from 1.06–41.67% (w/v) depending on the dry cell weight. The highest PHB production and productivity percentage was found in B. brevis M6 (41.67% w/v).
TL;DR: In this article, room temperature, heat reflux, Soxhlet, ultrasound assisted and microwave assisted extractions were employed to extract flavonoids from dry cell cultures of Saussurea medusa Maxim.
Abstract: Room temperature, heat reflux, Soxhlet, ultrasound-assisted and microwave-assisted extractions were employed to extract flavonoids from dry cell cultures of Saussurea medusa Maxim. 24, 20, 6, 0.5 and 0.1 h exposures were necessary for room temperature, Soxhlet, heat reflux, ultrasound-assisted and microwave-assisted extractions to obtain the maximum yield of flavonoids of 3.0%, 4.1%, 3.9%, 3.5% and 4.1%, respectively. Microwave-assisted extraction showed obvious advantages in short duration and high efficiency to extract flavonoids from S. medusa cultured cells.
TL;DR: A locally isolated strain of Aspergillus foetidus MTCC 4898 was studied for xylanase production using lignocellulosic substrates under solid state fermentation, and corncobs were found as the best substrates for high yield of xylanases with poor cellulase production.
Abstract: A locally isolated strain of Aspergillus foetidus MTCC 4898 was studied for xylanase (EC 3.2.1.8) production using lignocellulosic substrates under solid state fermentation. Corncobs were found as the best substrates for high yield of xylanases with poor cellulase production. The influence of various parameters such as temperature, pH, moistening agents, moisture level, nitrogen sources and pretreatment of substrates were evaluated with respect to xylanase yield, specific activity and cellulase production. Influence of nitrogen sources on protease secretion was also examined. Maximum xylanase production (3065 U/g) was obtained on untreated corncobs moistened with modified Mandels and Strenberg medium, pH 5.0 at 1 5 moisture levels at 30 °C in 4 days of cultivation. Submerged fermentation under the same conditions gave higher yield (3300 U/g) in 5 days of cultivation, but productivity was less. Ammonium sulphate fractionation yielded 3.56-fold purified xylanase with 76% recovery. Optimum pH and temperature for xylanase activity were found to be 5.3 and 50 °C respectively. Kinetic parameters like K
m
and V
max
were found to be 3.58 mg/ml and 570 μmol/mg/min. Activity of the enzyme was found to be enhanced by cystiene hydrochloride, CoCl2, xylose and Tween 80, while significantly inhibited by Hg++, Cu++ and glucose. The enzyme was found to be stable at 40 °C. The half life at 50 °C was 57.53 min. However thermostability was enhanced by glycerol, trehalose and Ca++. The crude enzyme was stable during lyophilization and could be stored at less than 0 °C.
TL;DR: Screening of 26 marine sediment samples near 9 islands of the Andaman Coast of the Bay of Bengal resulted in the isolation of 88 isolates of actinomycetes, and three isolates showed very promising antagonistic activities against multi-drug resistant pathogens.
Abstract: Screening of 26 marine sediment samples near 9 islands of the Andaman Coast of the Bay of Bengal resulted in the isolation of 88 isolates of actinomycetes. On the basis of sporophore morphology and structure of the spore chain, 64 isolates were assigned to the genus Streptomyces, 8 isolates to the genus Micromonospora, 5 to the genus Nocardia, 7 to the genus Streptoverticilium and 4 to the genus Saccharopolyspora. Among 64 Streptomyces spp., 44 isolates showed antibacterial activity and 17 isolates showed antifungal activity. Three isolates showed very promising antagonistic activities against multi-drug resistant pathogens.
TL;DR: Chromobacterium violaceum, Cladosporium resinae, Bacillus submarinus, Micrococcus varians, Pseudomonas aeruginosa, Candida marina and Saccharomyces estuari were the most efficient utilizers and biodegraders while Corynebacterium glutamicum, Nocardia marina, and Cryptococcus albidus exhibited moderate growth in TMSM.
Abstract: The growth profile and hydrocarbonoclastic potential of microorganisms isolated from tarballs harvested from Ibeno beach in the Bight of Bonny were examined to determine their role in the degradation of the aquatic pollutants (tarballs). The results of the analysis revealed that the mean heterotrophic bacterial count ranged from 3 (±0.01) × 103 to 3.18 (±0.2) × 105 c.f.u./g. The mycological count ranged from 1 (±0.3) × 102 to 2 (±0.4) × 104 c.f.u./g while the mean count of biodegraders on tarball mineral salt medium (TMSM) ranged from 1 (±0.3) × 102 to 2 (±0.4) × 104 c.f.u./g. The ability of the microbial isolates to utilize the tarballs as their sole source of carbon and energy was examined and noticed to vary in growth profiles between the isolates. Chromobacterium violaceum, Cladosporium resinae, Bacillus submarinus, Micrococcus varians, Pseudomonas aeruginosa, Candida marina and Saccharomyces estuari were the most efficient utilizers and biodegraders while Corynebacterium glutamicum, Nocardia marina, and Cryptococcus albidus exhibited moderate growth in TMSM. Vibrio parahaemolyticus and Escherichia coli were opportunistic inhabitants, as they could neither grow nor degrade the balls in TMSM. The results imply that the efficient biodegraders like Chromobacterium violaceum could extensively degrade the balls with time.
TL;DR: The results indicated that Bt toxin was not the direct factor causing decrease of the numbers of bacteria in the rhizosphere, and other factors may be involved.
Abstract: The concentrations of Bacillus thuringensis (Bt) toxin released from root exudation of Bt cotton were measured by an enzyme-linked immunosorbent assay (ELISA), and its impacts on the numbers of culturable functional bacteria in the rhizosphere were determined by cultivation. No Bt toxin was found in the rhizosphere of non-Bt cotton (SHIYUAN321), but varying levels of Bt toxin were present in the rhizosphere of two Bt cotton varieties (NuCOTN99B and SGK321) during the entire growth period. The levels of Bt toxin in the rhizosphere of NuCOTN99B were significantly higher (p<0.05) than those of SGK321 within all sampling dates except on June 17th in the whole growth season. Significant differences (p<0.05) were found in the numbers of the three functional bacteria between SHIYUAN321 and NuCOTN99B within each sampling day from May 27th to October 27th. No significant differences were found in the numbers of functional bacteria among three cultivars after growth season. Fortification of pure Bt toxin into rhizospheric soil did not result in significant changes in the numbers of culturable functional bacteria, except the nitrogen-fixing bacteria when the concentration of Bt toxin was higher than 500 ng/g. The results indicated that Bt toxin was not the direct factor causing decrease of the numbers of bacteria in the rhizosphere, and other factors may be involved.
TL;DR: The identification results showed fungal genera such as Oxyporus, Stereum and Trichoderma which have been only rarely reported as ligninolytic enzyme producers in the literature which were attributed to the most closely related species using PCR amplification and sequencing of the internal transcribed spacer ‘ITS’ regions of the ribosomal DNA.
Abstract: This work represents the first report on the ability of autochthonous fungi from Tunisia to produce ligninolytic enzymes. Three hundred and fifteen fungal strains were isolated from different Tunisian biotopes. These fungal strains were firstly screened on solid media containing Poly R-478 or ABTS as indicator compounds that enabled the detection of lignin-modifying enzymes as specific color reactions. Of the 315 tested strains, 49 exhibited significant ABTS-oxidation activity expressed within the first week of incubation and only 18 strains decolorized the Poly R-478. Liquid cultivations and laccase, manganese peroxidase and lignin peroxidase activity assays of positive strains confirmed that eight efficient enzyme producers were found in the screening. These strains were attributed to the most closely related species using PCR amplification and sequencing of the internal transcribed spacer ‘ITS’ regions of the ribosomal DNA. The identification results showed fungal genera such as Oxyporus, Stereum and Trichoderma which have been only rarely reported as ligninolytic enzyme producers in the literature. Culture conditions and medium composition were optimized for the laccase producer Trametes trogii CTM 10156. This optimization resulted in high laccase production, 367 times more than in non-optimized conditions and which reached 110 U ml-1 within 15 days of incubation.
TL;DR: Antibiotic susceptibility studies revealed that seafood from India contains multiple antibiotic resistant strains of E. coli which may serve as a reservoir for antibiotic resistance genes in the aquatic environment.
Abstract: The occurrence and antibiotic resistance of Escherichia coli in tropical seafood was studied. A 3-tube MPN method was used for determining the level of faecal contamination of fresh and processed seafood. Of the 188 samples tested which included finfish, shellfish, water and ice, 155 were positive for the presence of faecal coliforms following incubation at 44.5 °C. However, E. coli was isolated from only 47% of the samples positive for faecal coliforms. The antibiotic resistance of 116 strains isolated from seafood was tested using 14 different antibiotics including ampicillin, cephalothin, chloramphenicol, ciprofloxacin, gentamycin, nalidixic acid, streptomycin and vancomycin. Seven strains were resistant to more than five antibiotics of which one was resistant to eight antibiotics. The multiple drug resistant strains harboured plasmids of varying sizes. Antibiotic susceptibility studies revealed that seafood from India contains multiple antibiotic resistant strains of E. coli which may serve as a reservoir for antibiotic resistance genes in the aquatic environment. All the strains used in this study did not harbour any virulence genes commonly associated with pathogenic E. coli, when tested by polymerase chain reaction (PCR).
TL;DR: A chitinase produced by Bacillus licheniformis MB-2 isolated from Tompaso geothermal springs, Indonesia, was purified and characterized, and the first 13 N-terminal amino acids of the enzyme were determined as SGKNYKIIGYYPS, which is identical to those in chit inases from B. lichensiformis and B. circulans.
Abstract: A chitinase produced by Bacillus licheniformis MB-2 isolated from Tompaso geothermal springs, Indonesia, was purified and characterized. The extracellular enzyme was isolated by successive hydrophobic interaction, anion exchange, and gel filtration chromatographies. The purified enzyme was a monomer with an apparent molecular weight of 67 kDa. The optimal temperature and pH of the enzyme were 70 °C and 6.0, respectively. It was stable below 60 °C for 2 h and over a broad pH range of 4.0–11.0 for 4 h. The enzyme was resistant to denaturation by urea (1 M), Tween-20 (1%) and Triton-X (1%), but unstable toward organic solvents such as dimethyl sulphoxide, DMSO, (5%) and polyethylene glycol, PEG, (5%) for 30 min. The enzyme hydrolysed colloidal chitin, glycol chitin, chitosan, and glycol chitosan. The first 13 N-terminal amino acids of the enzyme were determined as SGKNYKIIGYYPS, which is identical to those in chitinases from B. licheniformis and B. circulans.
TL;DR: In this paper, a mixture of hydrated gellan and xanthan gums was used for encapsulation of Bifidobacterium lactis, for incorporation into soft foods/beverages.
Abstract: Micro-encapsulation of the probiotic micro-organism Bifidobacterium lactis isolated from a bio-yoghurt starter culture, was carried out using a mixture of hydrated gellan and xanthan gums Rheological studies showed that the gum mix was suitable for encapsulation of B lactis, for incorporation into soft foods/beverages The gel behaved as a non-Newtonian material, and the flow curve fitted well to the Herschel–Bulkley model The average yield stress of the gum was 1515 Pa, indicating gum stability, and the yield stress range was 1 Pa over a temperature range of 35–50 °C Almost constant minimum gum viscosity occurred between 46 and 61 °C Oval/round capsules were synthesized manually using a monoaxial gum flow through a 275 G bevelled needle, together with a superposed air stream (air knife technique) The diameter of the capsules, measured using laser diffractometry, varied from 20 to 2200μm, with 50% of the capsules having a diameter of ≤637 μm Numbers of viable B lactis in the capsules were estimated using high power ultrasound (20 kHz) By using a concentrated inoculum of B lactis, microcapsules containing log10 11–12 cfu g−1 were synthesized Apart from the anaerobic culturing of B lactis, all other work was done in the presence of atmospheric oxygen The organism exhibited a high degree of oxygen tolerance A 21-day survival study of immobilized cells in 1 M sodium phosphate buffer (pH 7) stored at either 4 or 22 °C indicated that B lactis survived in excess of log10 11 cfu g−1 microcapsule This technique represents a suitable means of supplying viable probiotics to the food and/or pharmaceutical industries
TL;DR: Biosorption of heavy metals by gram-positive, non-pathogenic and non-toxicogenic Paenibacillus polymyxa P13 was evaluated and the maximum biosorption value of 1602 mg g−1 observed with purified EPS at 0.1 mg-ml−1 was particularly promising for use in field applications.
Abstract: Biosorption of heavy metals by gram-positive, non-pathogenic and non-toxicogenic Paenibacillus polymyxa P13 was evaluated. Copper was chosen as a model element because it is a pollutant originated from several industries. An EPS (exopolysaccharide)-producing phenotype exhibited significant Cu(II) biosorption capacity. Under optimal assay conditions (pH 6 and 25 °C), the adsorption isotherm for Cu(II) in aqueous solutions obeyed the Langmuir model. A high q value (biosorption capacity) was observed with whole cells (qmax=112 mgCu g−1). EPS production was associated with hyperosmotic stress by high salt (1 M NaCl), which led to a significant increase in the biosorption capacity of whole cells (qmax=150 mgCu g−1). Biosorption capacity for Cu(II) of the purified EPS was investigated. The maximum biosorption value (q) of 1602 mg g−1 observed with purified EPS at 0.1 mg ml−1 was particularly promising for use in field applications.
TL;DR: The isolated thermotolerant feather-degrading bacterial strain from Thai soil as well as purification and properties of its keratinase could improve the nutritional value of meat- and poultry-processing wastes containing keratins, collagen and gelatin.
Abstract: Isolation and identification of a thermotolerant feather-degrading bacterial strain from Thai soil as well as purification and properties of its keratinase were investigated. The thermotolerant bacterium was identified as Bacillus licheniformis. The keratinase was purified to homogeneity by three-step chromatography. The purified enzyme exhibited a high specific activity (218 U mg−1) with 86-fold purification and 25% yield. The enzyme was monomeric and had a molecular mass of 35 kDa. The optimum pH and temperature for the enzyme were 8.5 and 60 °C, respectively. The enzyme activity was significantly inhibited by PMSF and partly inhibited by EDTA and iodoacetamide, but was stimulated by metal ions. It hydrolysed soluble proteins with a relative activity of 4–100% and insoluble proteins, including keratins, with a relative activity of 3–35%. Therefore, the enzyme could improve the nutritional value of meat- and poultry-processing wastes containing keratins, collagen and gelatin.
TL;DR: The purified chitinase inhibited hyphal extension of Fusarium moniliforme, Aspergillus niger, Mucor rouxi and Rhizopus nigricans, and was effective in release of protoplasts from Trichoderma ressei, Pleurotus florida, Agaricus bisporus and Aspergell niger.
Abstract: In this study flake chitin, crab shell chitin, mushroom stalk, fungal cell wall, wheat bran and rice bran were used as substrate for chitinase production by Enterobacter sp. NRG4 under submerged and solid state fermentation (SSF) conditions. Enterobacter sp. NRG4 produced 72 and 49.7 U/ml of chitinase in presence of cell walls of Candida albicans and Fusarium moniliforme in submerged fermentation. Under SSF, maximum chitinase production was 965 U/g solid substrate with flake chitin and wheat bran (1:3 ratio) at 75% moisture level after 144 h. The purified chitinase inhibited hyphal extension of Fusarium moniliforme, Aspergillus niger, Mucor rouxi and Rhizopus nigricans. The chitinase was effective in release of protoplasts from Trichoderma ressei, Pleurotus florida, Agaricus bisporus and Aspergillus niger. Protoplasts yield was maximum with 60 mg of 24 h old fungal mycelium incubated with 60 U of chitinase and 60 U of cellulase.
TL;DR: It was shown that the biodegradation of an aromatic acid is tightly dependent on both the type and the position of the radical substituted on the aromatic ring.
Abstract: Enterobacteria growing on wastewater from olive oil extraction were selected. Among this microflora, strains of Klebsiella oxytoca and Citrobacter diversus able to degrade simple monomeric aromatic compounds were isolated by enrichment culture of the effluent lacking simple sugars. In this preliminary investigation, the phenolic acids tested on solid and liquid media were gentisic, protocatechuic, p-hydroxybenzoic, benzoic, vanillic and ferulic. It was shown that the biodegradation of an aromatic acid is tightly dependent on both the type and the position of the radical substituted on the aromatic ring. Citrobacter was the most efficient strain in metabolizing ferulic acid in liquid medium at a concentration of 1.5 g/l. The substrate biodegradation yield achieved exceeded 86%.