Nakajima-Kambe_2012_Polym.Degrad.Stab_97_139

A lipase from Aspergillus niger MTCC 2594 was purified 53.8-fold to homogeneity by hydrophobic interaction chromatography using octyl sepharose and the enzyme showed two protein bands with apparent molecular mass of 35 and 37kDa respectively. The lipase exhibited maximum activity at pH 7.0 and 37C and was stable between pH 4.0 and 10.0 and temperatures up to 50C. The values of Km and Vmax were 3.83mM and 32.21micromol/min/mg respectively, using olive oil as substrate. Lipase encoding gene, lipA, coded for 297 amino acid residues with conserved pentapeptide sequence, G-H-S-L-G, was cloned and expressed in Pichia pastoris. Although lipA showed high homology with the known Aspergillus lipases, it exhibited differences in putative lid domain. Both native and recombinant lipases have potential for degradation of poly(lactic acid) and poly(e-caprolactone), and the present study will serve as a baseline of initial studies for its exploitation in polymer degradation.