Vol.:(0123456789) 1 3 Extremophiles https://doi.org/10.1007/s00792-018-0996-9 ORIGINAL PAPER Cloning, expression and characterization of the esterase estUT1 from Ureibacillus thermosphaericus which belongs to a new lipase family XVIII Yuliya V. Samoylova 1  · Ksenia N. Sorokina 1,2  · Margarita V. Romanenko 2  · Valentin N. Parmon 1,2 Received: 13 June 2017 / Accepted: 23 December 2017 © Springer Japan KK, part of Springer Nature 2018 Abstract A new esterase gene from thermophilic bacteria Ureibacillus thermosphaericus was cloned into the pET32b vector and expressed in Escherichia coli BL21(DE3). Alignment of the estUT1 amino acid sequence revealed the presence of a novel canonical pentapeptide (GVSLG) and 41–47% identity to the closest family of the bacterial lipases XIII. Thus the esterase estUT1 from U. thermosphaericus was assigned as a member of the novel family XVIII. It also showed a strong activity toward short-chain esters (C2–C8), with the highest activity for C2. When p-nitrophenyl butyrate is used as a substrate, the temperature and pH optimum of the enzyme were 70–80 °C and 8.0, respectively. EstUT1 showed high thermostability and 68.9 ± 2.5% residual activity after incubation at 70 °C for 6 h. Homology modeling of the enzyme structure showed the pres- ence of a putative catalytic triad Ser93, Asp192, and His222. The activity of estUT1 was inhibited by PMSF, suggesting that the serine residue is involved in the catalytic activity of the enzyme. The purified enzyme exhibited high stability in organic solvents. EstUT1 retained 85.8 ± 2.4% residual activity in 30% methanol at 50 °C for 6 h. Stability at high temperature and tolerance to organic solvents make estUT1 a promising enzyme for biotechnology application. Keywords Esterase · Bacteria · Ureibacillus thermosphaericus · Solvent tolerance · Thermostability Introduction Thermostable enzymes especially lipases and esterases, are widely used in food, oil and pharmaceutical industries (Samoylova et al. 2016a, b). A key parameter for evaluation of their industrial applicability is the stability under process conditions. Thermostability of some esterases allows their application in the reactions at high temperatures (50–70 °C) with a significantly increased half-life (Haki and Rakshit 2003). High solvent tolerance is also important, as some processes including chemical synthesis and transesterifica- tion take place in the presence of organic solvents (DMSO, methanol, n-hexane) (Wang et al. 2016). Lipases and ester- ases are commonly used in these reactions as they catalyze cleavage of ester bonds in a triglyceride molecule (Zhu et al. 2013; Samoylova et al. 2017). Compared to lipases, esterases exhibit higher substrate specificity for short and medium fatty acid residues (≤ C12) and can be used for esterifica- tion at an industrial scale (Panda and Gowrishankar 2005). Bacterial thermostable esterases are of a great importance to the chemical industry due to their high substrate specific- ity, regio- and stereospecificity, stability at high temperatures and in organic solvents (Bornscheuer 2002; Panda and Gow- rishankar 2005). It was shown that esterases from thermo- philic microorganisms exhibit higher thermostability in the temperature range of 60–90 °C (Eichler 2001). They also possess high tolerance for various organic solvents (alcohols, DMSO, n-hexane, etc.) as well as during exposure to the dena- turing and inhibitory conditions (pH, metal ions, detergents) (Bornscheuer 2002; Panda and Gowrishankar 2005). Ester- ases that are stable at high temperatures and in solvents have Communicated by A. Driessen. Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00792-018-0996-9) contains supplementary material, which is available to authorized users. * Yuliya V. Samoylova samoylova.jv@catalysis.ru 1 Boreskov Institute of Catalysis (BIC), Lavrentieva ave. 5, Novosibirsk 630090, Russian Federation 2 Novosibirsk State University (NSU), Pirogova str. 2, Novosibirsk 630090, Russian Federation