A thermophilic bacterium (TP-2) was isolated from the Tatta Pani hot spring in Azad Kashmir and was characterized using phenotypic and genotypic characters. The strain developed cream colored, round, smooth, flat and slimy colonies while the cells were Gram positive rods that ranged in size from about 2.1-3.6 μm to 0.2-0.3 μm in width. Sequence analysis of its 16S rRNA gene showed that isolate TP-2 had 89% homology with Geobacillus debilis. It grew within pH range of 5.5 to 8.5 with optimum growth at pH 7.0. The isolate showed optimum growth at 65ºC and gave positive results for gelatin hydrolysis (GEL), ortho nitrophenyl-β-D-galactopyranosidase (ONPG), and nitrate production and produced acid from sucrose, glucose and maltose. It utilized glucose, fructose, maltose, lactose, sucrose, xylan, starch, filter paper and carboxymethylcellulose as sole carbon source. Isolate TP-2 produced significant amount of industrially important enzymes i.e. extracellular α-amylase, CMCase, FPase, Xylanase, Protease and Lipase and intracellular CMCase and FPase.
The production of an extracellular β-glucosidase by Aspergillus niger NRRL 599 was optimized using submerged fermentation technique. Effect of different media, different carbon sources, initial pH of the fermentation medium, temperature, incubation period and inoculum size on the production of β-glucosidase enzyme was investigated. A. niger NRRL 599 produced maximum extracellular β-glucosidase (4.48 U/mg) in Eggins and Pugh medium with 1% wheat bran (w/v) at pH 5.5 inoculated with 4% conidial suspension after 96 h of incubation at 30°C. Purified β-glucosidase gave K m and V max values of 3.11 mM and 20.83 U/mg respectively for pNPG hydrolysis. The enzyme was optimally active at pH 4.8 and at temperature of 60°C. Thermodynamic parameters, E a , ∆H and ∆S were found to be 52.17 KJ/mol, 49.90 J/mol.K and -71.69 KJ/mol, respectively. The pKa 1 and pKa 2 of ionizable groups of active site residues involved in V max were calculated to be 4.1 and 6.0 respectively.
A 1.4 Kb fragment of Bacillus licheniformis ATCC 14580 encoding β-glucosidase was cloned and expressed in Escherichia coli. β-Glucosidase expressed by E. coli harboring cloned gene was located entirely in the intracellular fraction. Recombinant β-glucosidase protein was purified to homogeneity level and the molecular weight was found to be 53 kDa using sodium dodecyl sulfate polyacrylamide gel electrophoresis analysis. It gave maximum activity at 50• C and pH 6. Km and Vmax were 0.206 mM and 1.26 U/mg, respectively, with p-nitrophenyl-β-D-glucopyranoside, while activation energy Ea, enthalpy of activation ∆H and entropy of activation ∆S were found to be 66.31 kJ/mol, 64.04 kJ/mol and 48.28 J/mol/K, respectively. The pKa1 and pKa2 of the ionizable groups of active site residues involved in Vmax were found to be 5.5 and 7.0, respectively. When the recombinant β-glucosidase protein was used as a member of consortium with endoglucanase and exoglucanase for the saccharification of wheat straw, 123% increase in saccharification was observed.
Yeast extract is extensively applied in various food industries as a food additive to enhance to flavor of food products or as a vitamin supplement. It is also considered as a crucial component of microbiological media. The current study was conducted to optimize a process for the production of yeast extract by using Baker’s yeast (Saccharomyces cerevisiae). The cultivation of yeast biomass was performed in a stirred fermenter. The influence of numerous physical and chemical parameters such as carbon and nitrogen sources, temperature, pH and agitation were evaluated on the production of yeast cells by employing one factor at a time approach and optimum conditions for the production of maximum yeast biomass was determined. The maximum growth was attained using molasses as a substrate at 30ºC supplemented with urea at 150 rpm with pH 4.5. After fermentation, cells were separated by centrifugation and were ruptured by adopting different techniques and autolysis was found the most viable method. Various techniques were applied to dry the yeast extract and the spray dryer was appeared as most effective one. Yeast extract acquired after drying was subjected to various analysis including protein and solid content estimation and amino acid profiling and compared with commercial yeast extract. The dried yeast extract was incorporated in media preparations to grow various microorganisms including yeast, fungi and bacteria and considerable growth was observed. These promising results indicated that the developed process is a cost effective alternative approach for the production of yeast extract.
Microbial fuel cell (MFC) technology is an emerging area for alternative renewable energy generation and it offers additional opportunities for environmental bioremediation. Recent scientific studies have focused on MFC reactor design as well as reactor operations to increase energy output. The advancement in alternative MFC models and their performance in recent years reflect the interests of scientific community to exploit this technology for wider practical applications and environmental benefit. This is reflected in the diversity of the substrates available for use in MFCs at an economically viable level. This review provides an overview of the commonly used MFC designs and materials along with the basic operating parameters that have been developed in recent years. Still, many limitations and challenges exist for MFC development that needs to be further addressed to make them economically feasible for general use. These include continued improvements in fuel cell design and efficiency as well scale-up with economically practical applications tailored to local needs.
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