Enhanced halophilic lipase secretion by Marinobacter litoralis SW-45 and its potential fatty acid esters release

An approach was made to enhance the halophilic lipase secretion by a newly isolated moderate halophilic Marinobacter litoralis SW-45, through the statistical optimization of Plackett-Burman (PB) experimental design and the Face Centered Central Composite Design (FCCCD). Initially, PB statistical design was used to screen the medium components and process parameters, while the One-factor-at-a-time technique was availed to find the optimum level of significant parameters. It was found that MgSO₄  · 7H₂ O, NaCl, agitation speed, FeSO₄  · 7H₂ O, yeast extract and KCl positively influence the halophilic lipase production, whereas temperature, carbon source (maltose), inducer (olive oil), inoculum size, and casein-peptone had a negative effect on enzyme production. The optimum level of halophilic lipase production was obtained at 3.0 g L^-1 maltose, 1% (v/v) olive oil, 30 °C growth temperature and 4% inoculum volume (v/v). Further optimization by FCCCD was revealed 1.7 folds improvement in the halophilic lipase production from 0.603 U ml^-1 to 1.0307 U ml^-1 . Functional and biochemical characterizations displayed that the lipase was significantly active and stable in the pH ranges of 7.0-9.5, temperature (30-50 °C), and NaCl concentration (0-21%). The lipase was maximally active at pH 8.0, 12% (w/v) NaCl, and 50 °C temperature. Besides, M. litoralis SW-45 lipase was found to possess the promising industrial potential to be utilized as a biocatalyst for the esterification.