Molecular cloning and expression of a novel trehalose synthase gene from Enterobacter hormaechei

Trehalose synthase (TreS) which converts maltose to trehalose is considered to be a potential biocatalyst for trehalose production. This enzymatic process has the advantage of simple reaction and employs an inexpensive substrate. Therefore, new TreS producing bacteria with suitable enzyme properties are expected to be isolated from extreme environment.

Six TreS producing strains were isolated from a specimen obtained from soil of the Tibetan Plateau using degenerate PCR. A novel treS gene from Enterobacter hormaechei was amplified using thermal asymmetric interlaced PCR. The gene contained a 1626 bp open reading frame encoding 541 amino acids. The gene was expressed in Escherichia coli, and the recombinant TreS was purified and characterized. The purified TreS had a molecular mass of 65 kDa and an activity of 18.5 U/mg. The optimum temperature and pH for the converting reaction were 37 degrees C and 6, respectively. Hg2+, Zn2+, Cu2+and SDS inhibited the enzyme activity at different levels whereas Mn2+ showed an enhancing effect by 10%.

In this study, several TreS producing strains were screened from a source of soil bacteria. The characterization of the recombinant TreS of Enterobacter hormaechei suggested its potential application. Consequently, a strategy for isolation of TreS producing strains and cloning of novel treS genes from natural sources was demonstrated.