Microbial Biofilm Formation under the Influence of Various Physical-Chemical Factors

ABSTRACT

The study presents the biofilm formation capacity for Lactobacillus rhamnosus IL 1 and IL 4.2 strains, in abiotic conditions. The biofilm formation depends directly on the chemical composition of the culture medium, on the presence of various chemical substances (mucin, lactulose, NaCl), as well as on the influence of other physical-chemical factors (pH, temperature). The first phase of the study consisted of identifying the two strains by using BIOLOG MicroLog System release 4.2. The second phase was represented by the supplementation of the culture medium with various chemical substances. Thus, for the tested strains, the supplementation with 2.5 g/l mucin determines a growth of approximately 50% of the biofilm formation capacity. The supplementation with lactulose increases significantly the biofilm formation capacity, up to 4–5 times, according to the chemical composition of the culture medium. Low pH and NaCl 0.3M inhibits the biofilm formation capacity. An increase of more than 0.5% of the biliary acids lowers the biofilm formation capacity.

Keywords:

• Lactobacillus
• exopolysaccharides
• glucose
• dendrogram