Abstract:

Adhesion of probiotics to the gastrointestinal tract is prerequisite for its beneficial function. This study aims to
investigate the adhesion ability of biofilm-like cells of Lactobacillus paraplantarum L-ZS9 and determine factors influencing
the biofilm formation of this strain. The adhesion ability to HT-29 of biofilm cells of L-ZS9 was compared with its planktonic
cells. In addition, the effects of culture time, temperature, nutrition, low pH, high bile salt, proteases and quorum sensing
signal (autoinducer-2, AI-2) on biofilm formation were investigated by crystal violet staining method. The results showed
that the adhesion ratio of biofilm cells of L-ZS9 to HT-29 was 1.5 times higher than that of its planktonic cells. The genes
fbb, ropN and rrf2 were up-regulated in biofilm cells. The strain produced the largest number of biofilm cells when cultured
at 37 ℃for 36 h. Sufficient nutrition promoted biofilm formation. Low pH and high bile salt destroyed the formed biofilm. Pepsin
and trypsin inhibited biofilm formation and destroyed the formed biofilm as well. AI-2 (0.5%, V/V) had the strongest beneficial
effect on biofilm formation and weakened the inhibition and destruction of pepsin and trypsin. This work can lay a foundation for
producing functional foods containing biofilm probiotics with better adhesion to the gastrointestinal tract.

Key words: Lactobacillus paraplantarum L-ZS9, adhesion, biofilm, influencing factors, signal AI-2