Isolation of lactic acid bacteria bound to the porcine intestinal mucosa and an analysis of their moonlighting adhesins

The adhesion of lactic acid bacteria (LAB) to the intestinal mucosa is one of the criteria in selecting for probiotics. Eighteen LAB were isolated from porcine intestinal mucin (PIM): ten strains of Lactobacillus, six strains of Weissella, and two strains of Streptococcus. Using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) for phosphate-buffered saline (PBS) extracts from the LAB, many bands were detected in half of the samples, while a few and/or no clear bands were detected in the other half. All six of the selected LAB showed adhesion to PIM. L. johnsonii MYU 214 and MYU 221 showed adhesion at more than 10%. W. viridescens MYU 208, L. reuteri MYU 213, L. mucosae MYU 225, and L. agilis MYU 227 showed medium levels of adhesion at 5.9-8.3%. In a comprehensive analysis for the adhesins in the PBS extracts using a receptor overlay analysis, many moonlighting proteins were detected and identified as candidates for adhesins: GroEL, enolase, and elongation factor Tu in MYU 208; peptidase C1, enolase, formyl-CoA transferase, phosphoglyceromutase, triosephosphate isomerase, and phosphofructokinase in MYU 221; and DnaK, enolase, and phosphoglycerate kinase in MYU 227. These proteins in the PBS extracts, which included such things as molecular chaperones and glycolytic enzymes, may play important roles as adhesins.