Optimization of culture conditions for production of lipase by a newly isolated bacterium Stenotrophomonas maltophilia

The production of an extracellular lipase from the newly isolated Stenotrophomonas maltophilia was optimized via the statistical design method. During a screening program, the microorganism was isolated from soil samples, according to lipolytic activity on nutrient agar medium supplemented with Rhodamine B. It was identified using morphological and biochemical properties as well as 16S rDNA sequencing analysis. After the initial screening of 10 factors of the medium components, using Plackett–Burman design, results showed that four of them, included olive oil, peptone, yeast extract, and ferrous sulfate, exhibited significant effects on the lipase production by S. maltophilia. The level of each factor was subjected to optimization by using the Box–Behnken technique, and a 9.1-fold enhancement of lipase productivity (from 500 U/ml to 4559 U/ml) was achieved overall in the presence of optimum levels of the effective factors. Forty-three percent of capsaicin (initial concentration of 500 mg/L) was converted to vanillylamine after treatment with the optimized medium (lipase activity 4559 U/ml) for 18 h.