Expression and characterization of a thermostable monoacylglycerol lipase from thermophilic Geobacillus kaustophilus.

Thermophilic Geobacillus kaustophilus HTA426 genome possesses a monoacylglycerol lipase (MAGL) gene. MAGLs can synthesize emulsifiers for use in the food and pharmaceutical industries from fatty acids and glycerol. They can also be used to analyze monoacylglycerol (MAG) levels in serum and food. The MAGL gene from strain HTA426 was artificially synthesized and heterologously expressed in Escherichia coli BL21(DE3). The recombinant His-tag fused MAGL (GkMAGL) was purified using a Ni²⁺-affinity column. The purified enzyme showed a temperature optimum at 65 °C and was stable up to 75 °C after 30 min incubation. In addition, the enzyme exhibited a pH optimum of 7.5 and was stable from pH 5.0 to 11.0. The enzyme hydrolyzed monoacylglycerols and showed the highest activity toward 1-monolauroylglycerol. The enzyme was stable in the presence of various organic solvents and detergents. The addition of Triton X-100 significantly increased GkMAGL activity. The thermal stability of the enzyme was higher than that of thermostable MAGL from Geobacillus sp. 12AMOR1 (12AMOR1_MAGL). Circular dichroism spectral analysis showed that the conformational stability of the GkMAGL was higher than that of 12AMOR1_MAGL at higher temperatures. These results indicate that the GkMAGL has useful features that can be used for various biotechnological applications.