Soni Tiwari

Decolorization of a recalcitrant organic compound (Melanoidin) by a novel thermotolerant yeast, Candida tropicalis RG-9

BackgroundSugarcane distilleries use molasses for ethanol production and generate large volume of effluent containing high biological oxygen demand (BOD) and chemical oxygen demand (COD) along with melanoidin pigment. Melanoidin is a recalcitrant compound that causes several toxic effects on living system, therefore, may be treated before disposal. The aim of this study was to isolate a potential thermotolerant melanoidin decolorizing yeast from natural resources, and optimized different physico-chemical and nutritional parameters.ResultsTotal 24 yeasts were isolated from the soil samples of near by distillery site, in which isolate Y-9 showed maximum decolorization and identified as Candida tropicalis by Microbial Type Culture Collection (MTCC) Chandigarh, India. The decolorization yield was expressed as the decrease in the absorbance at 475 nm against initial absorbance at the same wavelength. Uninoculated medium served as control. Yeast showed maximum decolorization (75%) at 45°C using 0.2%, glucose; 0.2%, peptone; 0.05%, MgSO4; 0.01%, KH2PO4; pH-5.5 within 24 h of incubation under static condition. Decolorizing ability of yeast was also confirmed by high performance liquid chromatography (HPLC) analysis.ConclusionThe yeast strain efficiently decolorized melanoidin pigment of distillery effluent at higher temperature than the other earlier reported strains of yeast, therefore, this strain could also be used at industrial level for melanoidin decolorization as it tolerated a wide range of temperature and pH with very small amount of carbon and nitrogen sources.

Production of pullulan by a thermotolerant Aureobasidium pullulans strain in non-stirred fed batch fermentation process

Total 95 isolates of Aureobasidium pullulans were isolated from different flowers and leaves samples, out of which 11 thermotolerant strains produced pullulan. One thermotolerant non-melanin pullulan producing strain, designated as RG-5, produced highest pullulan (37.1±1.0 g/l) at 42oC, pH 5.5 in 48h of incubation with 3% sucrose and 0.5% ammonium sulphate in a non-stirred fed batch fermentor of 6 liters capacity. The two liters of initial volume of fermentation medium was further fed with the 2 liters in two successive batches at 5 h interval into the fermentor. The sterile air was supplied only for 10h at the rate of 0.5 vvm.

Isolation, Production, and Characterization of Thermotolerant Xylanase from Solvent Tolerant Bacillus vallismortis RSPP-15

Sixty bacterial strains isolated from the soils sample in the presence of organic solvent were screened for xylanase production. Among them, strain RSPP-15 showed the highest xylanase activity which was identified as Bacillus vallismortis. The isolate showed maximum xylanase production (3768 U/mL) in the presence of birch wood xylan and beef extract at 55°C pH 7.0 within 48 h of incubation. The enzyme activity and stability were increased 181.5, 153.7, 147.2, 133.6, and 127.9% and 138.2, 119.3, 113.9, 109, and 104.5% in the presence of Co2

Enhanced production and characterization of a solvent stable amylase from solvent tolerant Bacillus tequilensis RG-01: thermostable and surfactant resistant.

Ten bacterial strains isolated from the soil samples in the presence of cyclohexane were screened for amylase production. Among them, culture RG-01 was adjudged as the best amylase producer and was identified as Bacillus tequilensis from MTCC, Chandigarh. The isolate showed maximum amylase production (8100 U/mL) in the presence of starch, peptone, and Ca2+ ions at 55°C pH 7.0 within 24 h of incubation. The enzyme was stable in the presence of n-dodecane, isooctane, n-decane, xylene, toluene, n-hexane, n-butanol, and cyclohexane, respectively. The presence of benzene, methanol, and ethanol marginally reduced the amylase stability, respectively. The enzyme was showed it 100% activity at 55°C and pH 7.0 with 119% and 127% stability at 55°C and pH 7.0, respectively. The enzyme was also stable in the presence of SDS, Tween-40, Tween-60, and Tween-80 (1%) and was found stimulatory effect, respectively. Only Triton-X-100 showed a moderate inhibitory effect (5%) on amylase activity. This isolate (Bacillus tequilensis RG-01) may be useful in several industrial applications owing to its thermotolerant and organic solvents and surfactants resistance characteristics.

Bioremediation of Plant Refuges and Xenobiotics

Industrialization, urbanization, and agricultural practices have created noxiousity of xenobiotics compounds in the atmosphere, seriously affecting the health of all living systems. The hazards created by such compounds are alarming and must be controlled/treated through bioremediation, a safe, economical, and rapid method for the treatment of almost all types of xenobiotic compounds. Microbial systems mainly bacteria, fungi, yeast, actinomycetes, and algae have diversified enzyme system for metabolizing such compounds into nontoxic forms and mineralizing up to the level of plant nutrients. The knowledge of such xenobiotics compounds, their existence and persistence in natural ecosystem, risk created by such compounds, biomagnifications, and biodegradation/bioremediation are essential for its effective control from different ecosystems. A very comprehensive classification of compounds and their degrading/metabolizing microbial enzymes along with the list of microorganisms has been discussed which is very essential for the environmental scientists, microbiologist, biochemist as well as agricultural scientist for their awareness and adopting remedial measures. Several new xenobiotic compounds are being synthesized in the natural ecosystem through polymerization and other organic reactions which must be identified and treated with specific suitable microbial consortia of different tolerance capabilities to temperature, pH, O2, etc. The current scenario of bioremediation of xenobiotics compounds is greatly facilitated by the consortia of competent strain of various groups of microorganisms having the ability to coexist for longer periods without affecting their growth and metabolism, resulting in better remediation from natural ecosystem. The industrial effluents and solid waste treatment as well as field application of such microorganisms are showing effective results; therefore, large-scale cultivation and long-term preservation of these microorganisms either alone or in consortium are another area of research for safe and effective applications.

Treatment and Recycling of Wastewater from Distillery

Indian distilleries are using sugarcane molasses for ethanol production and generate large bulk of effluent containing high biological oxygen demand (BOD) and chemical oxygen demand (COD) along with melanoidin pigment. Melanoidin is a dark brown recalcitrant high molecular weight colour compound that causes several toxic effects on living system, therefore, must be treated before disposal. Detoxification/decolourization of different industrial wastewater is gaining importance for environmental safty and aesthetic values. Studies dealing with pure culture of bacteria, fungi, and yeast and their oxidative enzymes (peroxidase, laccase) in decolourization of industrial wastewater to develop a better understanding of the phenomenon of microbial decolourization. This chapter presents an overview of the characteristics of the distillery wastewater in terms of its toxicity and its biological treatment using microbial consortia system.

Integrated Effect of Rhizobium and Azotobacter Cultures on theLeguminous Crop Black Gram (Vigna mungo)

A pot experiment was performed to evaluate the integrated effect of Rhizobium and Azotobacter sp. on the plant growth, nodule appearance, no of leaf, shoot length, root length, chlorophyll contents and carbohydrate content in black gram during 2016 growing period at the Department of Microbiology, Dr. Ram Manohar Lohia Avadh University Faizabad, UP, India. Different treatments viz., T1: Control (Sterile soil+Seeds without culture treatment), T2: Sterile Soil and Seeds both are treated with Azotobacter sp., T3: Sterile Soil and Seeds both are treated with Rhizobium sp., T4: Sterile Soil and Seeds both are treated with mixed culture of Azotobacter sp. and Rhizobium sp., T5: Sterile Soil+Seeds treated with Azotobacter sp., T6: Sterile Soil + Seeds treated with Rhizobium sp., T7: Sterile Soil+Seeds treated with mixed culture of Azotobacter sp. and Rhizobium sp. All experiments were carried out in triplicate set. The T4 treatment showed maximum shoot length (51.6 cm), root length (17.3 cm), fresh and dry shoot biomass (12.99 and 3.21 g), fresh and dry root biomass (3.54 and 0.99 g), no. of leafs (20.4), root nodules per plant (18.2) and chlorophyll content (1.3 mg/g) and reducing (867.4 μg/g) and non-reducing sugar (1905.5 μg/g) content per plant biomass respectively. The Azotobacter and Rhizobium sp. have friendly associations and they have different physiology and habitat. Therefore, they help plant growth promotion by them own system. Therefore, such combination can be recommended for field application for sustainable agriculture. Excessive application of chemical fertilizers causes environmental and economic problems; hence the use of PGPR and Rhizobium bacteria can be acceptable due to cut contribution expenditure, increase in grain yield and environmental friendly.