Evaluation of a novel halophilic lipase secrection by Marinobacter litoratis SW-45 for butyl esters synthesis from palm-based oils
Abstract
Fatty acid esters are currently synthesized by esterification via chemical technologies involving the use of toxic mineral acids as catalysts, and requiring high energy consumption. The alternative enzyme technology which is a greener process involves the
use of microbial lipase as catalysts, and holds enormous advantages of moderate reaction conditions, process simplification, and product quality over the conventional chemical process. The current trend of adopting a greener approach towards the synthesis of high value oleochemicals has prompted the need to consistently explore and improve extremozymes with novel qualities as a stable biocatalyst to function in biotechnological processes. Hence, in this study, a total of 56 halophilic bacteria and 9 halophilic fungal strains were isolated from various saline environments and screened for lipase secretion on tributyrin solid agar. The halophilic bacterial strain SW-45 which secreted the highest lipase (0.603 U/mL) in SMF under agitation condition was chosen for further optimization studies. This highest lipase-secreting strain was outsourced for molecular identification and was designated as Marinobacter litoralis SW-45. A combinatorial nonstatistical one-factor-at-a-time (OFAT) method and statistical optimization of Plackett-Burman (PB) and face-centered central composite design (FCCCD) approaches were adopted to improve halophilic lipase production by the strain. The optimum level halophilic lipase production was obtained with 3.0 g/L maltose, 1% (v/v) olive oil, 30 °C growth temperature, and 4% inoculum volume (v/v), and the optimization by FCCCD revealed 1.7-fold improvement in the halophilic lipase production from 0.603 U/mL to 1.0307 U/mL.