Biodiesel and flavor compound production using a novel promiscuous cold-adapted SGNH-type lipase (HaSGNH1) from the psychrophilic bacterium Halocynthiibacter arcticus

Abstract

Background: Biodiesel and flavor compound production using enzymatic transesterification by microbial lipases provides mild reaction conditions and low energy cost compared to the chemical process. SGNH-type lipases are very effective catalysts for enzymatic transesterification due to their high reaction rate, great stability, relatively small size for convenient genetic manipulations, and ease of immobilization. Hence, it is highly important to identify novel SGNH-type lipases with high catalytic efficiencies and good stabilities. Results: A promiscuous cold-adapted SGNH-type lipase (HaSGNH1) from Halocynthiibacter arcticus was catalytically characterized and functionally explored. HaSGNH1 displayed broad substrate specificity that included tert-butyl acetate, glucose pentaacetate, and p-nitrophenyl esters with excellent stability and high efficiency. Important amino acids (N83, M86, R87, F131, and I173F) around the substrate-binding pocket were shown to be responsible for catalytic activity, substrate specificity, and reaction kinetics. Moreover, immobilized HaSGNH1 was used to produce high yields of butyl and oleic esters. Conclusions: This work provides a molecular understanding of substrate specificities, catalytic regulation, immobilization, and industrial applications of a promiscuous cold-adapted SGNH-type lipase (HaSGNH1) from H. arcticus. This is the first analysis on biodiesel and flavor synthesis using a cold-adapted halophilic SGNH-type lipase from a Halocynthiibacter species.

Active site architecture of an acetyl xylan esterase indicates a novel cold adaptation strategy

“…Most cold-adapted enzymes are highly flexible in their overall structures, leading to their high catalytic activity at low temperatures but low thermostability ( 21 ). However, a few cold-adapted enzymes are also reported to be locally flexible without compromising the global stability of proteins ( 23 , 24 , 37 , 38 , 39 ). Biochemical and structural analyses suggested that Al AXEase has high overall stability but is flexible in the loop containing the catalytic residues Asp200 and His203 because of the reduced stabilizing hydrophobic interactions and increased destabilizing residues asparagine and lysine ( Figs.…”

A cold‐active esterase enhances mesophilic properties through Mn2+ binding

“…Unlike other cold-active enzymes characterized by broad substrate specificity [12], M-Est is active on pNPA only, among tested substrates. High selectivity for short-chain esters was observed in other cold-active GDSx esterases [19,58,59] and could be due to a peculiar conformation of the entrance of the substrate binding pocket [60,61]. Although the physiological role of marine GDSx esterases is still unclear, their high specificity for acetate groups suggests that they might be involved in the deacetylation of compounds (e.g.…”

A Valuable Product of Microbial Cell Factories: Microbial Lipase

“…For example, a psychrophilic lipase from Bacillus F19L strain exhibited peak enzyme activity at 10 • C; it maintained 80% of its peak when the temperature shifted to 5 (Goomber et al, 2016). Similarly, a lipase derived from Halocynthiibacter arcticus displayed a temperature optimum of 20 • C. And, HaSGNH1 exhibited high relative activities at low temperatures, retaining ∼ 70% of its maximum activity even at 0 • C (Le et al, 2020). A sn-1,3 extracellular lipase derived from A. niger GZUF36 has an optimal reaction temperature of 35 • C and the enzyme activity dropped when the reaction temperature was beyond 50 • C (Xing et al, 2020).…”