Mannheimia succiniciproducens phosphotransferase system for sucrose utilization

Abstract

The succinic acid producer Mannheimia succiniciproducens can efficiently utilize sucrose as a carbon source, but its metabolism has not been understood. This study revealed that M. succiniciproducens uses a sucrose phosphotransferase system (PTS), sucrose 6-phosphate hydrolase, and a fructose PTS for the transport and utilization of sucrose.

FIG. 1.

Genetic organization of different sucrose utilization systems in bacteria and a proposed sucrose utilization system in M. succiniciproducens. Arrows indicate genes, and the numbers below the arrows are the locus number or protein number in the NCBI (http://www.ncbi.nlm.nih.gov/) and KEGG (http://www.genome.jp/kegg/) databases. The successive numbers of the sucrose utilization genes indicate that they are clustered and often are cotranscribed. The serial three dots between the arrows imply that gene cluster for the sucrose utilization is separated by other genes. (A) Several different PTSs in Gram-positive and -negative bacteria. Clostridium beijerinckii contains scrA for PTS, scrR for the LacI family sucrose regulator, scrB for sucrose 6-phosphate hydrolase, and scrK for fructokinase. Clostridium acetobutylicum contains scrT for the transcriptional regulator, scrA, scrK, and scrB. Bacillus subtilis contains sacA, sucrose 6-phosphate hydrolase, sacP for PTS, and sacT for the transcriptional regulator. Streptococcus mutans contains scrK, scrA, scrB, and scrR. Klebsiella pneumoniae contains scrK, scrY for sucrose-specific outer membrane porin, scrA, scrB, and scrR. (B) Permease with phosphorylase system in Bifidobacterium lactis, which contains scrT for sucrose-specific permease, scrP for sucrose phosphorylase, and scrR. (C) Permease with sucrase system in Escherichia coli UMN026, which contains cscB for sucrose permease, cscK for fructokinase, cscA for sucrose 6-phosphate hydrolase, and cscR for the LacI family sucrose regulator. (D) Deduced sucrose utilization system in M. succiniciproducens. MS0784 was found to encode the sucrose PTS, with MS0909 coding for sucrose 6-phosphate hydrolase, while fructokinase is not present (see text).

FIG. 2.

Schematic diagram of sucrose utilization systems. (A) Three kinds of sucrose utilization systems in bacteria. From the left are shown a permease with sucrase system, a sucrose PTS, and a permease with phosphorylase system. (B) Sucrose utilization system in M. succiniciproducens identified in this study. SUC, sucrose; FRU, fructose; GLU, glucose; P, phosphate; BP, bisphosphate.

FIG. 3.

Growth profiles of the wild-type M. succiniciproducens strain and its mutant strains in MH5S medium. (A) Cell growth (▪) and sucrose consumption (•) profiles of M. succiniciproducens MBEL55E cultured in MH5S medium. OD₆₀₀, optical density at 600 nm. (B) Nondiauxic growth of M. succiniciproducens MBEL55E (▪) in the presence of sucrose (•) and glucose (○). In this experiment, 5 g liter⁻¹ sucrose and 5 g liter⁻¹ glucose were used instead of 10 g liter⁻¹ sucrose in MH5S medium. (C) Cell growth profiles of MBEL55EΔ0784 (▴), MBEL55EΔ1237 (□), MBEL55EΔ0909 (▵), MBEL55EΔ1233 (⧫), and MBEL55EΔ2178 (⋄) in MH5S medium. (D) Nondiauxic growth of M. succiniciproducens MBEL55E (▪) in the presence of sucrose (•) and fructose (▿). In this experiment, 5 g liter⁻¹ sucrose and 5 g liter⁻¹ fructose were used instead of 10 g liter⁻¹ sucrose in MH5S medium.