Studies on biochemical aspects of bile salt hydrolase from the thermophile, brevibacillus borstelensis

Abstract

Chapter 1: Introduction. The first chapter is general introduction of the THESIS and it gives brief review of literature on bile salt hydrolases and bile salt hydrolase producing microorganisms. This chapter deals with Ntn hydrolase super family members, their structural similarities, catalytic behavior and mechanism. Characteristics of bile salt hydrolases, produced by various microorganisms and the bile salt tolerance mechanism are discussed in this chapter. Chapter 2: Isolation, identification of the thermophile, Brevibacillus borstelensis and optimization of fermentation conditions for the production of bile salt hydrolase. The second chapter describes the isolation of bile salt hydrolase producing thermophile from hot water springs in Maharashtra, India. Based on phenotypic analysis and 16S rDNA sequencing, the isolate was identified as Brevibacillus borstelensis. Standardization of fermentation conditions for the optimum production of bile salt hydrolase from Brevibacillus borstelensis was studied. Optimization of fermentation conditions resulted in 2.9-fold enhancement in the enzyme production. The enzyme production was enhanced when sodium glutamate medium was used as growth medium. Peak in enzyme production was attained after 12 h fermentation period with this medium. Cell bound bile salt hydrolase activity was optimum when the initial pH of the medium was 6.0 and incubated at temperature (55°C). Chapter 3: Purification and characterization of bile salt hydrolase from Brevibacillus borstelensis. The third chapter gives details about the purification of intracellular bile salt hydrolase from newly identified thermophilic source, Brevibacillus borstelensis. The enzyme was purified to homogeneity from this thermophilic source by Q-Sepharose chromatography and its enzymatic properties were characterized. The sub-unit molecular mass of the purified enzyme was estimated to be 28 kDa by SDS- PAGE and, 28.2 kDa by MALDI-TOF analysis. The native molecular mass was estimated to be 56 kDa by gel filtration