Impact of Environmental Conditions on the Biofilm Formation of Pseudomonas lundensis

In order to investigate the influence of environmental conditions on biofilm formation ability of food spoilage strain Pseudomonas lundensis (PL), the biofilm amount was measured by microplate crystal violet method under different nutritional conditions, inoculation concentration, pH, NaCl and Mg²⁺ concentration conditions. The adhesion and structural characteristics of PL on stainless steel surface were investigated by laser scanning confocal microscope. The results showed that nutritional stress formed by dilute tryptone soy broth reduced the amount of PL biofilm formation, and the nutrient stress caused by 50-fold dilution of TSB medium reduced the amount of biofilm from 1.75±0.35 to 0.24±0.17. There was no significant difference in biofilm formation when PL inoculation amount decreased from 1.3×10⁷ CFU/ mL to 2.5×10⁴ CFU/mL (P>0.05). The highest biofilm production was observed at pH 8.0. The biofilm formation was significantly inhibited respectively when the addition of glucose exceeded 1.25%, NaCl exceeded 4% and Mg²⁺ exceeded 0.5%. The observation results of laser scanning confocal microscopy showed that the PL had the ability to form typical biofilm on stainless steel surface at a certain concentration. The ability of PL biofilm formation was influenced by environmental factors such as nutrient stress, glucose concentration, pH, NaCl and Mg²⁺ concentration.