Modification of the cell wall polymers of Lactobacillus casei grown in high salt condition

MALONE, LUCÍA; ALLIEVI, MARIANA CLAUDIA; DIETERLE, MARÍA EUGENIA; FINA MARTIN, JOAQUINA; PIURI, MARIANA; RUZAL, SANDRA M

Córdoba

Congreso; XI Congreso Argentino de Microbiología General-SAMIGE; 2015

Sociedad Argentina de Microbiologia General

The bacterial cell envelopes have an important role in the maintenance of the shape, integrity and survival of the species as wellas communicating with the environment and bacteriophage interaction. In Lactobacillus species we have found that growth inhigh salt condition results in profound changes to deal with osmotic stress adaptation. We have characterized a TCA solublefraction obtained from cell walls (CW) as the responsible of the phage interaction when assayed for its adsorption inhibition.Polymers of non-proteinaceous composition are found in this purified fraction of the cell envelope visualized by PAGE and TLC.Biochemical analysis showed that differences are obtained when growth in 0.7M NaCl. Putative components of the fraction arewall teichoic acids (WTA) and rhamnose containing glycans (RWPS). Those differences could be attributed to two possiblereasons: loosely bind polymers due to modified envelope structure or a differential level of expression of the biosynthesispathways. To determine which factor is responsible for the lower level of polymers recovery we verified gene expression byqRT-PCR of probable functions encoded in the genome of L. casei BL23. The coding functions related to the synthesis of RWPswall and neutral sugars are isgC, epsC, wze, cps1A-J, rmlA-D2. We have analyzed growth supernatants to address increasedrelease of wall polymers in high salt. Therefore we concluded that a mix of genotypic and phenotypic effects is the responsibleof the differences observed. These findings open new insight in the developing strategies to avoid infections with phages duringdairy fermentation processes by pre-growing starters in high salt, which will be further evaluated.