Paenibacillus sabina strain JD2, a chitinolytic marine bacterium, was isolated from sea dumps collected at Sultanpur near Bhavnagar, India and its nutritional requirement for chitinase production was defined using statistical optimisation method. Effect of 8 different medium components on chitinase production by Paenibacillus sabina strain JD2 was screened by Plackett-Burman design. The screened medium components were further used in central composite design where chitinase production, pH and biomass responses were used in different models to evaluate fit ones. After performing power transformation, quadratic model was found to be fit for chitinase response and 2F1 model was found to be fit for biomass response. Whilst for pH response, quadratic model was found to be fit without any requirement of power transformation. In multiresponse analysis, medium formulation consisting of (g/l): chitin 18, yeast extract 0.50, and CaCl 2 0.08, was found to predict 82.93 U/ml of chitinase with overall highest desirability of 0.842 as compared to other formulations. The selection of model was done on basis of high adjusted R 2 value and lowered p-value for each model in individual analysis of each response. Through desirability analysis, it was found that biomass and pH played an important role in increasing the chitinase production by Paenibacillus sabina strain JD2. Through statistical optimisation method, 2.74-fold increase in chitinase production was achieved as compared to unoptimised medium.

A halotolerant fungal isolate Aspergillus tubingensis GR1 was isolated from the man-made solar saltern located at Khambhat, Gujarat, India, and identified using 28S rDNA partial genome sequencing. This isolate was studied for β-galactosidase production under solid state fermentation using wheat bran and deproteinized acid cheese whey. The influence of various agro-industrial wastes, nitrogen source and other growth conditions on β-galactosidase production was investigated using ‘one-factor-at-a-time’ approach. Among various variables screened along with wheat bran and deproteinized acid cheese whey as major growth substrate, corn steep liquor and MgSO4 were found to be most significant. The optimum concentrations of these significant parameters were determined employing the response surface central composite design, revealing corn steep liquor concentration (2 mL) and magnesium sulphate (50 mg) per 5 g of wheat bran and 20 mL of deproteinized acid cheese whey for highest enzyme production (15,936 U/gds). These results suggest the feasibility of industrial large-scale production of β-galactosidase known to be valuable in whey hydrolysis and removal of galactosyl residue from polysaccharide.

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β-Galactosidase from halotolerant Aspergillus tubingensis GR1 was purified by two-step purification process comprising ammonium sulfate precipitation followed by size exclusion chromatography (SEC). The recovery of β-galactosidase after SEC was found to be 1.40% with 58.55-fold increase in specific activity. The molecular weight of β-galactosidase protein was found to be 93 kDa by SDS-PAGE. Activation energy for O-nitrophenol β-D-galactopyranoside (ONPG) hydrolysis was 32.88 kJ mol(-1), while temperature quotient (Q(10)) was found to be 1.375. The enzyme was found to be stable over wide pH range and thermally stable at 60-65°C up to 60 min of incubation while exhibited maximum activity at 65°C with pH 3.0. V(max), K(m), and K(cat) for ONPG were found to be 2000 U ml(-1), 8.33 mM (ONPG), and 101454 s(-1), respectively. Activation energy for irreversible inactivation Ea(d) of β-galactosidase was 100.017 kJ mol(-1). Thermodynamic parameters of irreversible inactivation of β-galactosidase and ONPG hydrolysis were also determined. However, β-galactosidase enzyme activity was activated significantly in the presence of 15% NaCl and hence shows activity up to 30% NaCl concentration.

Streptomycin-resistant bacteria were recovered from the root-free soils under sugarcane plants. Nitrosomonas species and Azotobacter chrococcum were also present in greater numbers in rhizosphere soils as compared to root-free soils up to 30 cm deep.