title: Metabolic engineering of Corynebacterium glutamicum for trehalose overproduction: role of the TreYZ trehalose biosynthetic pathway.
abstract: Trehalose has many potential applications in biotechnology and the food industry due to its protective effect against environmental stress. Our work explores microbiological production methods based on the capacity of Corynebacterium glutamicum to excrete trehalose. We address here raising trehalose productivity through homologous overexpression of maltooligosyltrehalose synthase and the maltooligosyltrehalose trehalohydrolase genes. In addition, heterologous expression of the UDP-glucose pyrophosphorylase gene from Escherichia coli improved the supply of glycogen. Gene expression effects were tested on enzymatic activities and intracellular glycogen content, as well as on accumulated and excreted trehalose. Overexpression of the treY gene and the treY/treZ synthetic operon significantly increased maltooligosyltrehalose synthase activity, the rate-limiting step, and improved the specific productivity and the final titer of trehalose. Furthermore, a strong decrease was noted in glycogen accumulation. Expression of galU/treY and galU/treYZ synthetic operons showed a partial recovery in the intracellular glycogen levels and a significant improvement in both intra- and extracellular trehalose content.
authors.affiliation: Departamento de Ingeniería Química y Bioprocesos, Pontificia Universidad Católica de Chile, Casilla 306 Correo 22, Santiago, Chile.
authors.forename: Jorge
authors.initials: J
authors.lastname: Carpinelli
authors.forename: Reinhard
authors.initials: R
authors.lastname: Krämer
authors.forename: Eduardo
authors.initials: E
authors.lastname: Agosin
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D001709:Biotechnology / Q000379:methods; D048230:Corynebacterium glutamicum / Q000201:enzymology / Q000235:genetics* / Q000254:growth & development; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D005818:Genetic Engineering / Q000379:methods*; D005936:Glucans / Q000378:metabolism; D006003:Glycogen / Q000378:metabolism; D009876:Operon; D014199:Trehalose / Q000096:biosynthesis*; D005957:UTP-Glucose-1-Phosphate Uridylyltransferase / Q000235:genetics / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D005936:Glucans; C031146:maltoheptaose; D006003:Glycogen; D014199:Trehalose; D005957:UTP-Glucose-1-Phosphate Uridylyltransferase; C121039:galU protein, E coli