This work evaluated a wild-type Streptomyces clavuligerus strain as a whole-cell lipase (Sc-WCL) producer by submerged fermentation. In an orbital shaker, lipase hydrolytic activity of 3000 U L-1, measured at pH 9.0 and 37 °C by using p-nitrophenyl palmitate as substrate, was achieved after 36 h fermentation using glycerol-free production medium in a baffled Erlenmeyer flask at 28 °C and pH 6.8. Maximum productivity of 52.5 U L-1 h-1 was achieved after 24 h in bioreactor using glycerol-free production medium at pH 6.8 and 28 °C, with agitation at 400 rpm and aeration at 1 vvm. Sc-WCL was shown to be more active at 60 °C and pH 10.7, while higher activity retention was observed at 30-40 °C after 1 h incubation at pH 10. Sc-WCL showed to have potential to be used as biocatalyst in hydrolysis and esterification reactions. In the hydrolysis of p-nitrophenyl palmitate, lyophilized Sc-WCL expressed a hydrolytic activity (330 units g-1 solid, measured at 37 °C and pH 9.0) around 100-fold higher than the ones declared by a supplier of lyophilized powders of mixtures of intracellular lipases from Thermus thermophiles and Thermus flavus (≥3.0 units g-1 solid, measured at 65 °C and pH 8.0). In the synthesis of butyl butyrate in anhydrous medium, 85% ester conversion was achieved at 37 °C after 8 h reaction. Thus, Sc-WCL showed to be a promising biocatalyst because it is cheaper than the isolated and purified lipases.
Keywords: Biochemical properties; Butyl butyrate; Esterification activity; Hydrolytic activity; Streptomyces clavuligerus; Submerged cultivation; Whole-cell lipase.