Isolation and characterization of a Klebsiella pneumoniae strain from mangrove sediment for efficient biosynthesis of 1,3-propanediol

Abstract

1,3-Propanediol (PDO) is an important bulk industrial material. It can be produced by microbial fermentation. In this study, the microbial flora of mangrove sediment was screened to identify strains with high production of PDO by fermentation of glycerol. The PDO productivities of the isolated strains were tested, and the strain with highest PDO productivity was characterized using the API20E and 16-s rRNA sequence analysis. The physiological and phylogenetic analysis indicated that the strain was closed related to K. pneumoniae species and was named as K. pneumoniae HSL4. The structure of the dha cluster which was responsible for the biosynthesis of PDO was analyzed. It is observed that K. pneumoniae HSL4 was tolerant to salt and partly tolerant to acetate and lactate, which will favor industrial applications. Fed-batch fermentation experiments revealed K. pneumoniae HSL4 exhibited an excellent ability to produce PDO with high concentration (80.08g L−1), productivity (2.22g L−1h−1) and conversion (0.435g g−1 or 0.53mol mol−1). The metabolic flux profile illuminated that glycerol was consumed rapidly and PDO was accumulated quickly to a high level during the exponential growth phase. This study provided important information for further fermentation and metabolic engineering of PDO production by K. pneumoniae HSL4.