Production of lipase from Pseudozyma aphidis and determination of the activity and stability of the crude lipase preparation in polar organic solvents

Abstract

The production of lipase from Pseudozyma aphidis (DSM 70725) was determined in six different media. The highest lipase production was observed in a medium with glucose as the sole carbon source, and yeast extract and sodium nitrate as the nitrogen sources. The time course studies of growth and lipase production in the optimal medium revealed that the highest lipase production was achieved at the end of the log phase of growth, reaching the value of 35.0 U cm-3 in the fifth day of cultivation. The effects of various polar, water-miscible, organic solvents on the activity and stability of the crude lipase produced by P. aphidis were evaluated. The hydrolytic activity of the crude lipase towards p-nitrophenyl palmitate (p-NPP) in aqueous media and in organic solvents was determined, using the same spectrophotometric assay in both the aqueous and organic media. The crude lipase preparation exhibited activity towards p-NPP only in acetone and acetonitrile, while the lipase was stable only in acetone, with 23% residual activity after 24 h of incubation. These results suggested that lipase from P. aphidis can be used as a biocatalyst for potential applications in such organic solvents.

Proizvodnja lipaze iz Pseudozyma aphidis utvrđena je u šest različitih medijuma. Najviša proizvodnja uočena je u medijumu gde je glukoza bila izvor ugljenika, a ekstrakt kvasca i natrijum-nitrat izvori azota. Praćenjem dinamike rasta i proizvodnje lipaze u optimalnom medijumu, uočeno je da se najviša proizvodnja lipaze dostiže pred kraj logaritamske faze rasta, i dostiže vrednost od 35 U cm-3 u petom danu kultivacije, što je četri puta veća proizvodnja od one do sada prijavljene u literaturi. Utvrđen je efekat različitih polarnih organskih rastvarača, mešljivih sa vodom, na aktivnost i stabilnost lipaze iz P. aphidis. Hidrolitička aktivnost lipaze prema para-nitrofenil-palmitatu (p-NPP-u) u vo- denoj sredini i organskim rastvaračima utvrđena je upotrebom istog spektrofotometrijskog testa. Pokazano je da lipaza ima aktivnost prema p-NPP-u samo u acetonu i acetonitrilu, dok je enzim stabilan jedino u acetonu i zadržava 23% aktivnosti nakon 24 časa inkubacije. Dobijeni rezultati ukazuju da lipaza iz P. aphidis može biti korišćena kao biokatalizator za potencijalne primene u acetonu kao medijumu.