Effects of carbon sources on extracellular lipase production and lipA transcription in Acinetobacter calcoaceticus

Abstract

The effects of lactic acid, oleic acid, gum arabic and their mutual interactions, on the production of extracellular lipase and the regulation of the expression of the lipase encoding gene (lipA) in Acinetobacter calcoaceticus were investigated. Formation of extracellular lipase was measured in culture supernatants of wild-type strain BD413 and expression of the lipa gene was monitored in vivo with a chromosomal fusion of lipa to lacZ. At the level of lipa expression only oleic acid had a significant effect; it lowered expression. Neither gum arabic nor lactic acid had any effect on lipa expression. On the other hand, the yield of extracellular lipase increased 2-5 times by the addition of gum arabic, possibly due to the release of cell surface-bound lipase. An interaction between oleic acid and lactic acid was also detected.