Abstract The gene encoding a hypothetical YqiA/YcfP family α/β-fold hydrolase from Pseudomonas sivasensis R11S16 was cloned, heterologously expressed in Escherichia coli , and purified as a histidine-tagged recombinant enzyme (PsEst yfh ). The enzyme, with a molecular weight of about 23 kDa, exhibited typical esterase activity against short-chain p -nitrophenyl esters (C 4 > C 8 > C 2 > C 10 ). PsEst yfh exhibited the highest activity at 20 °C and pH 9, indicating its cold-active and alkaline-tolerant nature. The half-life of PsEst yfh at 30 °C and 40 °C was nearly 6 h and 2 h, respectively. The enzyme retained about 70–95% of its activity after 1 h of incubation over the pH range of 5–10 and remained remarkably stable, with ~ 50% relative activity even in the presence of 16% NaCl. In the presence of 1 mM Ni²⁺, Cu²⁺, and Ca²⁺, the enzyme activity increased by 26.74%, 24.20%, and 20.84%, respectively. The enzyme retained more than 80% of its activity in the presence of 10% (v/v) methanol, acetone, chloroform, and butanol. The Michaelis constant ( K m ) and the maximum velocity ( V max ) of PsEst yfh were determined from a Lineweaver-Burk plot to be 129.97 µM and 33.3 µmol/min, respectively, with p -NPB as the substrate. Importantly, PsEstyfh achieved over 95% reduction in azithromycin’s antimicrobial activity. Furthermore, ecotoxicological assessment indicated that the resulting transformation products did not exert significant toxic effects on Lemna minor . To our knowledge, this study represents the first report describing the recombinant production, functional characterization, and biotechnological potential of an esterolytic enzyme encoded by a hypothetical YqiA/YcfP family α/β-fold hydrolase gene from P. sivasensis .
Çon et al. (Mon,) studied this question.