Organic solvent tolerant metallo protease of novel isolate Serratia marcescens PPB-26: production and characterization.

Proteases are a class of enzymes that catalyze hydrolysis of peptide bonds of proteins. In this study, 221 proteolytic bacterial isolates were obtained by enrichment culture method from soils of various regions of Himachal Pradesh, India. From these a hyper producer of protease was screened and identified by morphological and physiological testing and by 16S rDNA sequence as Serratia marcescens PPB-26. Statistical optimization of physiochemical parameters enhanced the protease production by 75 %. Protease of S. marcescens PPB-26 was classified as a metalloprotease. It showed optimal activity at 30 °C, pH 7.5 (0.15 M Tris-HCl buffer) and with 0.8 % substrate concentration. It had K m = 0.3 %, V max = 34.5 μmol min-1 mg-1 protein and a half life of 2 days at 30 °C. The enzyme was stable in most metal ions but showed increased activity with Fe2+ and Cu2+ while strong inhibition with Co2+ and Zn2+. Further investigation showed that the enzyme could not only retain its activity in various organic solvents but also showed increased activity with methanol and ethanol. The reported metalloprotease is thus a potential candidate for carrying out industrial peptide synthesis.