An organic solvent‐stable lipase from a newly isolated Staphylococcus aureus ALA1 strain with potential for use as an industrial biocatalyst

Abstract

In this study, a new strain, ALA1, was identified as Staphylococcus aureus by biochemical tests, and its 16S ribosomal DNA sequence was isolated from dromedary milk. ALA1 lipase production was optimized in shake flask experiments and measured with varying pH (3-11), temperature (20-55 °C) and substrate concentrations. The maximum lipase production was recorded at pH 8 and 30 °C for up to 30 H of culture period for the S. aureus ALA1 strain. Among the substrates tested, selected carbon sources, xylose, nitrogen source, yeast extract, and olive oil (1%) were suitable for maximizing lipase production. The effects of surfactants were investigated and showed that Tween 20, Tween 80, and Triton X-100 prevented lipase production. Interestingly, isolate ALA1 was able to grow in high concentrations of benzene or toluene (up to 50% (v/v)). Moreover, the lipolytic activity of the S. aureus ALA1 lipase was stimulated by diethyl ether, whereas almost 100% of S. aureus ALA1 lipase activity was retained in 25% acetone, acetonitrile, benzene, 2-propanol, ethanol, methanol, or toluene. Because of its stability in organic solvent, the S. aureus ALA1 lipase was used as a biocatalyst to synthesize high levels of added value molecules. S. aureus ALA1 lipase could be considered as an ideal choice for applications in detergent formulations because of its high stability and compatibility with various surfactants, oxidizing agents, and commercial detergents.

Evaluation of a novel thermo-alkaline Staphylococcus aureus lipase for application in detergent formulations

“…In a previous study, we have isolated an alkaline lipase-producing strain ALA1 from dromedary milk which has been identified as S. aureus from the microscopic appearance, biochemical tests and 16S rDNA sequence analysis (Ben Bacha et al, 2015). After the optimization of various factors like incubation time, culture conditions (temperature and pH) and medium composition (nitrogen, carbon, surfactants and lipid compounds) the lipase production by S. aureus strain ALA1 (128 U/mL) was around 4 and 40-times higher than the previously isolated ones produced by the S. aureus strains (Ben Bacha et al, 2015, Daoud et al, 2013, Horchani et al, 2009).…”

“…These findings have given a structural basis of the interfacial activation compared to nearly forty years ago (Rosenstein and Gotz, 2000, Brzozowsky et al, 1991). In addition to their carboxylic ester bond hydrolysis, lipases also catalyze the reverse esterification, amidation or transesterification processes in aqueous and anhydrous organic solvents (Bornscheuer and Kazlauskas, 1999).…”

Realm of Thermoalkaline Lipases in Bioprocess Commodities

“…However, TA lipase from G. stearothermophilus is stable in acetone (ACE), acetonitrile (MeCN), methanol (MeOH), ethanol (EtOH), propanol (PROH), hexane (HEX), heptane (HEP), and cyclohexane (CY) up to more than 85% relative activity [ 26 ]. On the other hand, lipolytic activity of the S. aureus ALA1 lipase was enhanced by diethyl ether (Et2O), whereas nearly 100% of its catalytic activity was retained in 25% (v/v) organic solvents such as ACE, benzene, MeOH, MeCN, PROH, ETOH, or toluene (TOL) [ 24 , 51 ]. Polar solvents in particular can penetrate into the active site of lipase where the unfolding of proteins occurs due to disturbances to electrostatic charge interactions, hydrophobic interactions, hydrogen bonding, van der Waals forces, and disulfide linkages [ 2 , 27 ].…”

Hydrolysis of oils in the Wadi Hanifah River in Saudi Arabia by free and immobilized Staphylococcus aureus ALA1 lipase

“…The lipolytic S. aureus ALA1 strain (Access number: KF 678862) was isolated and produced from camel milk as previously described . After 30 h of culture, cells were removed by centrifugation and the crude enzyme solution was precipitated by the addition of ammonium sulfate to 65% saturation.…”