Lipase “whole-cell” de Streptomyces clavuligerus : produção, caracterização e aplicação em meio orgânico
Abstract
Cell-associated lipases have been considered biocatalysts economically advantageous because
they are produced at low cost, avoiding further recovery or purification steps. Few studies
regarding Streptomyces clavuligerus lipase have reported the production of extracellular
enzyme, although at first this had been considered a cell-associated enzyme. In this context,
the aim of this work was the production of the cell-associated lipase from Streptomyces
clavuligerus (whole-cell lipase, Sc-WCL) by submerged fermentation, the biochemical
characterization of the enzyme and its use in the synthesis of butyl butyrate, an aroma ester
with industrial importance. The culture conditions on rotary shaker and the operational
parameters for cultivation in bioreactor were evaluated in order to establish a protocol for Sc-
WCL production. The conditions for S. clavuligerus cultivation in rotary shaker that resulted
in maximal hydrolytic activity of Sc-WCL (3,000 U.L-1) were: baffled flask, free-glycerol
production medium, pH 6.8 and 28 °C. The operational parameters in bench reactor that
resulted in maximal volumetric productivity of Sc-WCL (54 U.L-1.h-1) were agitation of 400
rpm and aeration of 1 vvm. The maximal volumetric productivity in bioreactor operated under
selected conditions (52.5 U.L-1.h-1) was reached after 24 h, while similar productivity in rotary
shaker (54.8 U.L-1.h -1) was achieved only after 48 h fermentation. The catalytic potential of
Sc-WCL in hydrolysis reactions was comparable to the commercial lipase preparations. Sc-
WCL was more active at 60 °C and pH 10.7, and stable at 30-40 °C after 1 h incubation at pH
10. For butyl butyrate synthesis catalyzed by Sc-WCL, the reaction conditions that resulted in
higher ester conversion (85%) were: 5 g of Sc-WCL/ L, molar ratio of fatty acid: alcohol 1:1
in heptane and 8 h reaction. The stability at alkaline pH and organic medium (leastwise in
heptane and butanol), associated with the low cost, make Sc-WCL attractive in industrial
applications, such as flavors synthesis, detergent formulations, hydrolysis of vegetable oils,
among others.