Trichococcus species as catalysts for biotechnological production of 1,3-propanediol

Abstract

Nowadays, large amounts of waste glycerol are generated as a major byproduct from biodiesel industry. Glycerol can be converted to 1,3-propanediol (1,3-PDO), a building block for the synthesis of polyester and biodegradable plastic fibers. We have previously isolated a novel Trichococcus species, strain ES5, which is capable to anaerobically produce 1,3-PDO from glycerol, an ability it shares with Trichococcus pasteurii. In this work, we analyzed and compared the genomes of these two bacteria and studied the production of 1,3-PDO by cultures of T. pasteurii and strain ES5 under different conditions. A continuous bioreactor system was established for achieving production of 1,3-PDO. A complete operon structure composed by 16 genes related to 1,3-PDO metabolism could be identified in the genomes of T. pasteurii and strain ES5. This genomic synteny contains the two essential genes for glycerol conversion to 1,3-PDO, glycerol dehydratase and 1,3-propanediol dehydrogenase, and additional genes for glycerol uptake and regulation factors of glycerol metabolism. The metabolic trait of 1,3-production was in silico analysed for the complete bacterial kingdom and genes were identified with an essential or accessory influence for the trait. Bacteria with fewer genes were underperforming when tested in vitro for production 1,3-PDO. Furthermore, both Trichococcus strains could grow on glycerol in a broad range of temperatures, from 4 to 40oC and strain ES5 achieved growth in 0oC. Such physiological properties may be advantageous for biotechnological production. Tolerance to high salinity may be an additional strength of Trichococcus species as a candidate for the biotechnological production of 1,3-PDO.