Current Trends in Biotechnology and Pharmacy

Lipase producing strains play key role in the enzymological remediation of oil polluted soils. Diversity of cultivable lipase producing bacteria in the industrial localities of Hyderabad was studied with samples collected from different areas. Among isolated bacterial strains, the highest lipase producing strain was identified both biochemically and 16S rRNA ribotyping. The 16S rRNA studies revealed that the strain belongs to Xanthomonadaceae family and identified as Stenotrophomonas maltophilia. An overall 3-fold enhanced lipase production (175μmoles/ml) was achieved after improved conditions of production medium. Among used nutrient sources sesame oil and tryptone were found to be the most suitable substrates for maximum enzyme production. The maximum enzyme production was observed at pH 8.0 and at rotation speed of 150 rpm. Na⁺ ions induced the enzyme production where as Hg²⁺ ions inhibited the enzyme production. 80% Ammonium Sulphate precipitation showed maximum lipase activity and the molecular weight of produced lipase was identified 45 kDa based on SDS-PAGE. Optimum enzyme activity was noticed at pH (6.0) and at 50°C. The observed Km for this enzyme is 0.727 and showed V_max of 156.6μmoles/ml indicating lower Km than reported lipases that confirmed higher affinity of the enzyme for its substrate tributyrin. Arrhenius plot analysis for energy of activation denoted 11.07 Kjmol⁻¹ K⁻¹ for this lipase.