Production and purification of a hyperthermostable chitinase from Brevibacillus formosus BISR-1 isolated from the Great Indian Desert soils.

A strain of Brevibacillus formosus, capable of producing a high level of chitinase, was isolated and characterized for the first time from the Great Indian Desert soils. The production of extracellularly secreted chitinase was analyzed for its biocontrol potential and optimized by varying media pH, temperature, incubation period, substrate concentrations, carbon and nitrogen sources, etc. A twofold increase in chitinase production (798 IU/mL) was achieved in optimized media containing (g l(-1)) chitin 2.0, malt extract 1.5, glycerol 1.0, ammonium nitrate 0.3%, T-20 (0.1%) and media pH 7.0 at 37 °C. The produced enzyme was purified using a three-step purification procedure involving ultra-filtration, ammonium sulphate precipitation and adsorption chromatography. The estimated molecular weight of the purified enzyme was 37.6 kDa. The enzyme was found thermostable at higher temperatures and showed a t ½ of more than 5 h at 100 °C. Our results show that the chitinase produced by B. formosus BISR-1 is thermostable at higher temperatures.

Evaluation of various ions and compounds on nitrilase produced from Streptomyces sp.

The nitrilase produced from a new isolate is evaluated for its activity in presence of a number of different ions and compounds at optimal conditions. It was found that the activity of nitrilase increased up to 10-20% in presence of most of the divalent ions at a concentration of 5 mM relative to the control. Silver, mercury, tin, DTT, ascorbic acid and thiourea, respectively, were observed as potential inhibitors of the enzyme catalysis. The investigation on storage stability of whole cells in presence of a number of stabilizers showed that the enzyme is stable (relative activity 50%) for more than 120 days at various temperatures.

Xanthan production in a plunging jet reactor.

A plunging jet reactor (0.04-0.08 m(3)) was used for the production of the exopolysaccharide xanthan with Xanthomonas campestris. The microorganism was not affected by the pump shear force. Similar specific growth rates and xanthan space-time yields to those in other reactor types were achieved at much lower specific power input. The better oxygen sorption efficiency in the jet reactor overcompensated for the effect of poor mixing in the wall region at high xanthan concentrations.

Bioethanol in India: recent past and emerging future.

There is renewed interest in bioethanol technology in view of its large potential as a transportation fuel. Bioethanol production based on lignocellulosic biomass, being the technology of the future, has been examined. The major issue is the production of ethanol at a competitive price. Biomass-based ethanol technologies are still evolving and the commercialization of this technology has to overcome various bottlenecks. Keeping this perspective in view, bioethanol technologies are analyzed in terms of feedstock availability, pretreatment strategies, efficient hydrolytic agents, availability of recombinant ethanologens and process economics with a focus on Indian research efforts. It provides indicators for research priorities to achieve these objectives.

Effect of citric acid on the biosynthesis and composition of xanthan.

The effect of citric acid metabolism by Xanthomonas campestris on composition of xanthan has been studied. Citric acid consumption in fed-batch and continuous fermentation increased the pyruvic acid content of xanthan. An increase in pyruvic acid content in xanthan has been explained with the help of energy balance in xanthan biosynthesis.

Influence of medium constituents on the biosynthesis of cephalosporin-C

Acremonium chrysogenum NCIM 1069 was used for the biosynthesis of cephalosporin-C (CPC) in batch mode of cultivation. The effect of different medium constituents for better yield of CPC was thoroughly investigated. From the results of the fermentation, it was found that ammonium sulphate as inorganic nitrogen source and methionine at the concentration of 0.4 percent are most suitable for higher yield of antibiotic. The variation in the C/N ratio on the biosynthesis of CPC showed that a C/N ratio of 8.0 is most suitable for maximum production of CPC

Extraction of bulk DNA from Thar Desert soils for optimization of PCR-DGGE based microbial community analysis

A reliable method for characterizing microbial communities on the basis of their differences in the 16S ribosomal RNA (rRNA) gene sequences in the hot arid zone sandy soils has been optimized. A desert plant (Calligonum polygonoides) was chosen to provide the rhizospheric soil samples, collected from three different agro-ecological locations. Total community DNA was efficiently extracted at small-scale level using direct lysis with hot sodium dodecyl sulphate (SDS), glass bead beating and finally subjecting the sandy soil to liquid nitrogen freeze-thaw cycles. To amplify V3 region of bacterial 16S rRNA gene, universal conserved primers were used. Second round polymerase chain reaction (PCR) was attempted to increase product concentration and to minimize the effect of inhibitory substances. To enhance the detection sensitivity of the denaturing gradient gel electrophoresis (DGGE), the effect of change in template DNA concentration was studied. The separation of bands were greatly enhanced in the fingerprints obtained after the second round of PCR representing low abundant species which were not differentiated at single optimized concentration of DNA.