Isolation of an organic solvent‐tolerant bacterium Bacillus licheniformis PAL05 that is able to secrete solvent‐stable lipase

Abstract

In this study, seven lipase-producing bacterial strains were isolated from salt-enriched and cattle farm soil samples after incubation in toluene- and benzene-enriched media. One strain (PAL05) showed significantly greater lipase activity on spirit blue agar medium and stability in organic solvents. The positive strain (PAL05) was identified as Bacillus licheniformis by 16S rRNA gene sequencing. Lipase production was optimized in a medium containing glycerol as the carbon source and Tween 80 as an inducer (0.5% glycerol+0.5% Tween 80) at pH 8.0 and a temperature of 30 °C. In addition, the enzyme was moderately halotolerant as it exhibited increased activity in the presence of 2.5% NaCl. Optimized conditions increased the lipase production threefold. Crude lipase retained its activity for 14 days of incubation in the presence of various organic solvents at a level of 25% and 50%. The enzyme was stable at 25% in most solvents; some of the solvents such as hexane, benzene, and ethanol actually stimulated enzyme activity. The organic solvent stability of the lipase produced by the strain PAL05 enables the enzyme to be used as a potential biocatalyst for ester synthesis and other applications in nonaqueous conditions.

Process optimization for production and purification of a thermostable, organic solvent tolerant lipase from Acinetobacter sp. AU07

“… 30 Solvents with high log p values cause less inactivation of enzyme than solvents with low log p values. 31 Many researchers have previously reported the solvent stable nature of lipases, 24 , 32 , 33 , 34 thus the stability of Acinetobacter sp. AU07 lipase in different solvents was studied ( Table 5 ).…”

Lipase catalysis in organic solvents: advantages and applications

“…These enzymes are not only stable in these toxic solvents but also capable of catalyzing many synthetic reactions and considered to be most favorable tools for synthetic reactions in non-aqueous systems [ 23 – 26 ]. The microorganisms belonging to Bacillus , Rhodococcus , Staphylococcus and Arthrobacter species are tolerant to very toxic organic solvents [ 16 , 27 – 29 ]. The enzymes, which can work optimally in harsh conditions such as wide pH range, high temperature, varying salt conditions and in the presence of toxic organic solvents without losing the activities are needed to be explored.…”

Inducible cellulase production from an organic solvent tolerant Bacillus sp. SV1 and evolutionary divergence of endoglucanase in different species of the genus Bacillus

“…Besides showing tolerance, the strain SV1 also had enhanced growth in the presence of the solvents n -hexane, isooctane and benzene, which suggests of its ability to either utilize or degrade these solvents. Similarly, the tolerance to organic solvents with higher log P ow values has also been found in several species of Bacillus used for enzyme productions, some of which are Bacillus aquimaris (benzene, heptane), 22 Bacillus sphaericus ( n -benzene, toluene, ethyl benzene and p -xylene), 48 Bacillus licheniformis PAL05 (benzene and toluene), 49 B. licheniformis YP1A (tetradecane and decane), 50 and Bacillus cereus BG1 (hexane). 51 Thus, the strain SV1 could be valuable for the bioremediation of multi-metal or organic solvent polluted areas.…”