Functional characterization of sucrose phosphorylase and scrR, a regulator of sucrose metabolism in Lactobacillus reuteri

• Published in: Food microbiology Vol. 36; no. 2; pp. 432 - 439
• Main Authors: Teixeira, Januana S., Abdi, Reihaneh, Su, Marcia Shu-Wei, Schwab, Clarissa, Gänzle, Michael G.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.12.2013; Elsevier
• Subjects: Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Biological and medical sciences; carbon; exopolysaccharides; Food industries; Food microbiology; Fructans - metabolism; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation, Bacterial; Gene Expression Regulation, Enzymologic; glucose; Glucosyltransferases - genetics; Glucosyltransferases - metabolism; hydrolysis; Lactobacillus; Lactobacillus reuteri; Lactobacillus reuteri - enzymology; Lactobacillus reuteri - genetics; Lactobacillus reuteri - metabolism; levan; levansucrase; metabolism; metabolites; mutagenesis; mutants; phosphorylase; raffinose; Raffinose - metabolism; Repressor Proteins - genetics; Repressor Proteins - metabolism; Sourdough; Sucrose; Sucrose - metabolism; Sucrose phosphorylase; HPAEC–PAD; GI; Sucrose; FtfA; ScrP; FOS; LAB; PTS; MRS; Sucrose phosphorylase; LevS; Lactobacillus reuteri; LB; ScrR; qPCR; Sourdough; HPLC; Lactobacillus; Lactic acid bacteria; Enzyme; Transferases; Glycosyltransferases; Regulator; Metabolism; Phosphorylase; Characterization; Sour dough; Bacteria; Lactobacillaceae; Carbohydrate; Hexosyltransferases; levansucrase; Luria–Bertani; fructo-oligosaccharides; sucrose regulator; high performance anion exchange chromatography with integrated pulsed amperometric detection; lactic acid bacteria; gastrointestinal; high performance liquid chromatography; fructosyltransferase A; quantitative real time polymerase chain reaction; phosphotransferase system; deMan–Rogosa–Sharpe medium
• ISSN: 0740-0020; 1095-9998
• DOI: 10.1016/j.fm.2013.07.011

Lactobacillus reuteri harbours alternative enzymes for sucrose metabolism, sucrose phosphorylase, fructansucrases, and glucansucrases. Sucrose phosphorylase and fructansucrases additionally contribute to raffinose metabolism. Glucansucrases and fructansucrases produce exopolysaccharides as alternative to sucrose hydrolysis. L. reuteri LTH5448 expresses a levansucrase (ftfA) and sucrose phosphorylase (scrP), both are inducible by sucrose. This study determined the contribution of scrP to sucrose and raffinose metabolism in L. reuteri LTH5448, and elucidated the role of scrR in regulation sucrose metabolism. Disruption of scrP and scrR was achieved by double crossover mutagenesis. L. reuteri LTH5448, LTH5448ΔscrP and LTH5448ΔscrR were characterized with respect to growth and metabolite formation with glucose, sucrose, or raffinose as sole carbon source. Inactivation of scrR led to constitutive transcription of scrP and ftfA, demonstrating that scrR is negative regulator. L. reuteri LTH5448 and the LTH5448ΔscrP or LTH5448ΔscrR mutant strains did not differ with respect to glucose, sucrose or raffinose utilization. However, L. reuteri LTH5448ΔscrP produced more levan, indicating that the lack of sucrose phosphorylase is compensated by an increased metabolic flux through levansucrase. In conclusion, the presence of alternate pathways for sucrose and raffinose metabolism and their regulation indicate that these substrates, which are abundant in plants, are preferred carbohydrate sources for L. reuteri. •Lactobacillus reuteri LTH5448 metabolizes sucrose by levansucrase and sucrose phosphorylase.•ScrP and the sucrose regulator scrR were disrupted by double crossover mutagenesis.•ScrR is negative regulator repressing ftfA and scrP in the absence of sucrose.•Sucrose metabolism in L. reuteri is not subject to carbon catabolite repression.•Sucrose is a preferred carbohydrate source for L. reuteri.