Screening of a thermostable alkaline lipase producing strain and optimization of fermentation condition for Lipase production

Using the plate assay method with Tween 80 as substrate of lipase,122 soil samples collected from Hebei province were screened and a bacterial strain Lipa1318 with high lipase activity was obtained. The results of morphological features,the physiological and biochemical characteristics and 16 S r DNA sequence alignment analysis demonstrated that the isolate was Serratia marcescens. The optimal temperature and p H of the extracellular lipase were 60℃ and 8.0,which indicated that the lipase was a thermostable alkaline lipase. The optimal fermentation condition for high lipase production in flask were as follows: glucose 1.0%,beef extract 1.0%,Triton X-100 1.5%,olive oil 0.50%,Ca Cl20.50 mmol / L,the initial p H( 8.0) and temperature( 30℃),culture time( 96h).Under these conditions,the lipase activity was increased by 3.6 times.