Abstract:
Biofilms are microbial communities encased with self-producing extracellular matrix, composed with
polysaccharide, DNA and protein. Persistent survival capability of these biofilms in food contact
surfaces cause contamination of food batches and pose health risk among the public. The biofilm
formation is affected by several environmental factors such as temperature and humidity etc. This
study was conducted to investigate the effect of temperature on biofilms formed by Salmonella, E.
coli and Proteus spp. when they are present as mono species and in combinations. Organisms were
incubated at two different temperatures (280C and 370C) for 120 hr and biofilm formation was
quantified using microtiter plate method at different time points as 24 hr, 48 hr, 72 hr, 96 hr and 120
hr. Biofilm formation at 24 hr by Proteus spp. with Salmonella and E. coli (i.e. Proteus with E. coli
and Proteus with Salmonella) were higher in the temperature of 280C compared to 370C. There was
no significant effect of temperature on mono species biofilm at 24hr incubation period. At 48 hr,
biofilm formation by Salmonella together with Proteus and E. coli (Salmonella with E. coli and
Proteus with Salmonella) and by Salmonella alone was higher at 280C than that of at 370C. At 48 hr,
Proteus and E. coli alone did not exhibit significant (p > 0.05) difference in biofilm formation at
280C and 370C. At 72 and 96 hr, the biofilm formation by Proteus and Salmonella alone and
Salmonella together with Proteus (Proteus with Salmonella) showed higher biofilm formation at
280C than at 370C. But Proteus with E. coli, Salmonella with E. coli or E. coli alone did not exhibit
any significant (p > 0.05) effect of temperature. At 120 hr, all the organisms alone and their
combinations showed significantly higher biofilm formation at 280C than at 370C. This study
concluded that temperature and time significantly (p < 0.05) affect on biofilm formation by
Salmonella, E. coli and Proteus spp. individually and as combinations. This study revealed that
biofilm formation at 280C is higher than their optimal growth temperature (370C).
Keywords: Biofilm; E. coli; Proteus; Salmonella; Temperature
