Studies on the Antagonistic Effect of Serretia rubidaea for Biofilm Development Capability

Abstract

This study was performed to compare the growth dynamics of Serretia in single and co-culture biofilms condition and also evaluated its antagonistic effect against pathogenic bacteria. One preserved isolated subculture was identified on the basis of their morphological, cultural and biochemical characteristics. The isolate was belonged to the genus Serretia and provisionally identified as Serretia rubidaea. This isolate was exposed to different environmental condition. The experiments were carried out in Luria Bertani (LB) broth. The growth rate in different environmental parameter was measured by crystal violet staining of bacteria in Spectrophotometer. It was studied the ability of selected microorganism to generate biofilm on the test tube surfaces at different temperatures, pH values, NaCl concentrations and medium content. It was found that Serretia grew well at 27℃ after 48 h and co-culture grew well at 37℃ after 24 h. The 0.5% NaCl concentration was optimum for both. The results indicated that high concentration of NaCl clearly inhibited the adherence of the cells to the tube surfaces. Other analysis suggested that pH 7 was required for Serretia but pH 5 was suitable for co-culture. An attempt was also made to detect the inhibitory effects of Ciprofloxacin on the selected isolate and co-culture. It was found that, at 10 μg/mlantibiotic concentration, the Serretia single culture was more resistant than co-culture. The antagonistic effect of Serretia against pathogen showed that Serretia produced a small zone of inhibition.