MODIFICATION OF RHAMNOSE CONTAINING GLYCANS (RWPS) IN CELL-WALL POLYMERS OF Lactobacillus casei GROWN IN HIGH SALT CONDITION

MALONE LUCÍA; ALLIEVI MARIANA C; FINA MARTIN, JOAQUINA; PALOMINO MARÍA MERCEDES; RUZAL, SANDRA M

Congreso; XI Congreso Argentino de Microbiología General; 2015

Sociedad Argentina de Microbiología General

The bacterial cell envelopes have an important role in the maintenance of the shape, integrity and survival of the species as well as communicating with the environment and bacteriophage interaction. In Lactobacillus species we have found that growth in high salt condition results in profound changes to deal with osmotic stress adaptation. We have characterized the sugar composition of rhamnose containing glycans (RWPS), a non-proteinaceous compound of cell envelope, responsible of the phage adsorption when assayed for its inhibition. Biochemical analysis showed that no difference in composition is observed, however a different quantity of RWPS is obtained when growth in 0.7 M NaCl.Since those differences could be attributed to two possible facts: 1) loosely bind RWPS due to modified envelope structure or 2) a differential level of expression of the biosynthesis pathways.To determine which fact is responsible for the lower level of RPWS recovery we verified gene expression by qRT-PCR of probable functions encoded in the genome of L. casei BL23.The coding functions related to the synthesis of RWPs wall and neutral sugars are isgC, epsC, wze, cps1A-J, rmlA-D2. We found differential expression, however it was not enough to attribute de decrease in RPWS found in high salt condition. We have analyzed growth supernatants and found an increased release of RPWS in high salt. Therefore we concluded that a mix of genotypic and phenotypic effects is the responsible of the differences observed. These findings open new insight in the developing strategies to avoid infections with phages during dairy fermentation processes if starters are pre-grown in high salt. These will be evaluated further.