Trehalose Production Using Recombinant Trehalose Synthase in <i>Bacillus subtilis</i> by Integrating Fermentation and Biocatalysis

Abstract

Trehalose, a stable nonreducing disaccharide, protects biomolecules against environmental stress. However, trehalose production using secretory trehalose synthase (TreS) by <i>Bacillus subtilis</i> has not been well studied. In this study, a mutant TreS was successfully secreted and expressed in <i>B. subtilis</i> WB800N. The extracellular enzyme activity of TreS regulated by the P₄₃ promoter and SP_PhoD signal peptide in recombinant <i>B. subtilis</i> WB800N reached 23080.6 ± 1119.4 U/L in a 5-L fermenter after optimizing the culture medium, while <i>xpF</i>, <i>skfA</i>, <i>lytC</i>, and <i>sdpC</i> were knocked out. To reduce maltose consumption, <i>malP</i> and <i>amyE</i> corresponding to maltose transporters were further deleted. To simplify the trehalose production process, we invented a fermentation-coupling biocatalysis process involving recombinant bacteria fermentation to secrete TreS and simultaneous conversion of maltose to trehalose by TreS and found that the conversion rate of maltose to trehalose reached 75.5%, suggesting that this is an efficient strategy for large-scale trehalose production using recombinant <i>B. subtilis</i>.