Biofilm formation by lactobacilli and resistance to stress treatments

Abstract

Summary We investigated biofilm formation by six lactobacilli isolates and tested the resistance of biofilm and planktonic Lactobacillus plantarum B1 and Lactobacillus paracasei W1 to ethanol (ET) and acetic acid (AA). The viability of both isolates was considerably affected by ET, with a higher reduction observed in the planktonic cells, whereas AA was harmful only to L. paracasei W1. Cells that had intact (Syto® 9+PI−) and compromised (Syto® 9−PI+) membranes, and adopted intermediate states with different concentrations of the probes, i.e., Syto® 9+PI+ and Syto® 9−PI−, were identified following flow cytometry. We linked Syto® 9+PI+ to the planktonic cells and clarified on Syto® 9−PI− cells, which after being sorted could regain growth better in biofilm cells. Based on confocal laser scanning microscopy, numerous cells had damaged membranes in the ET‐treated biofilm, while half the cells in the AA‐treated biofilm maintained their membrane integrity.

Effect of Biofilm Formation by Lactobacillus plantarum on the Malolactic Fermentation in Model Wine

“…In agreement with other studies [ 25 , 29 ], the results obtained showed that the survival of L. plantarum is strongly affected by a high ethanol level (12%) combined with a low pH (both pH 3.2 and pH 3.5). Conversely, biofilm life-style is widely recognized as a suitable tool to protect bacteria from harsh environmental conditions [ 31 , 63 ]. In agreement with these findings, in our work, the levels of culturable cells attached to biofilm were not significantly affected ( p > 0.05) in MW at pH 3.5 and pH 3.2, highlighting that cells of L. plantarum in biofilm form were much more resistant than planktonic ones.…”

Biosynthesis of high antibacterial silver chloride nanoparticles against Ralstonia solanacearum using spent mushroom substrate extract

“…SYTO ® 9 is highly permeable and can penetrate both living and dead cells, but PI does not readily pass through cell membranes and can only stain dead cells. In addition, due to the high molecular weight of PI, the green fluorescence caused by SYTO ® 9 is inhibited, and the red fluorescence is enhanced under a CLSM observation [51]. As a result, living cells show green fluorescence, while dead cells show red fluorescence.…”