Relation between cell-bound exopolysaccharide production via plasmid-encoded genes and rugose colony morphology in the probiotic Lactobacillus brevis KB290

Masanori Fukao, Takeshi Zendo, Takuro Inoue, Nobuo Fuke, Tomoo Moriuchi, Yasuhiro Yamane, Jiro Nakayama, Kenji Sonomoto, Tetsuya Fukaya

Research output: Contribution to journalArticlepeer-review

Abstract

The probiotic Lactobacillus brevis KB290 is a natural producer of cell-bound exopolysaccharide (EPS), and the plasmid-encoded glycosyltransferase genes are responsible for this EPS production. KB290 forms unique rugose colonies inside an agar medium; this characteristic is useful for detecting and enumerating KB290 in the gut or feces. However, the genetic elements associated with this morphology remain unclear. Here, we aimed to investigate the relation between the plasmid eps genes and rugose colony morphology in KB290. The plasmid-cured mutants formed smooth colonies, and the rugose colony morphology was restored after complementation with the eps genes. The eps genes were successfully cloned and expressed in other L. brevis and L. plantarum strains. In these transformant strains, the presence of the EPS, consisting of glucose and N-acetylglucosamine, correlated with rugose colonies, indicating that EPS is responsible for rugose colony formation. To the best of our knowledge, this is the first report identifying the genetic factors influencing rugose colonies in Lactobacillus strains. This rugose colony formation may serve as a useful selective marker for KB290 in routine laboratory and research settings and can be used to detect the spontaneous loss of plasmids in this strain.

Original languageEnglish
Pages (from-to)1575-1580
Number of pages6
JournalAnimal Science Journal
Volume90
Issue number12
DOIs
Publication statusPublished - Dec 1 2019

All Science Journal Classification (ASJC) codes

  • Agricultural and Biological Sciences(all)

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