Antagonistic activity of Bacillus amyloliquefaciens subsp. amyloliquefaciens against multidrug resistant Serratia rubidaea

Abstract

Serratia rubidaea a member of the Enterobacteriaceae family, is a Gram-negative opportunistic pathogen, known to survive harsh environmental conditions and responsible for hospital associated infections. Specifically, S. rubidaea can withstand desiccation and survive on hospital surfaces and equipments as well as have acquired antimicrobial resistance determinants for different commercial antibiotics. The expansion of this multidrug resistant pattern suggests that the treatment of S. rubidaea infections will become increasingly difficult in near future. Although some measures were taken to control this species, an inhibition mechanism is remaining unknown. To design effective means to control the dissemination of S. rubidaea, an in-depth analysis is required. In the present study, one possible candidate was isolated from the soil of Sundarban Mangroove Forest (Bangladesh) that has important physiological effects to inhibit this pathogenic bacterium. The bacterial isolate was initially identified as Bacillus amyloliquefaciens subsp. amyloliquefaciens using BIOLOG identification system and confirmed to be B. amyloliquefaciens strain through 16S rDNA sequence analysis. The growth and antagonistic activity of this potential strain was shown to be stable under wide range of pH, temperature and salinity (NaCl). Moreover, the novel B. amyloliquefaciens isolate can also inhibit Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and other pathogenic bacteria. These results suggest that B. amyloliquefaciens might have potential antimicrobial properties and further research is required for future use of this bacterium as biological controls of S. rubidaea or development as new drugs for pathogenic bacteria.