Biofilm-related interspecies interactions of Stenotrophomonas maltophilia and enterohemorrhagic Escherichia coli, and the control of biofilm using bacteriophage

抄録

Purpose

Stenotrophomonas maltophilia is a challenge in food industry for being a resilient spoilage bacteria due to its biofilm forming capabilities. The purpose of this research is to investigate its cross-species interactions with enterohemorrhagic Escherichia coli (EHEC) in biofilm formation, and to evaluate bacteriophage as a controlling agent.

Methods

S. maltophilia and EHEC were incubated at 30℃ for 24 h, and biofilm formation was measured using crystal violet method in 96-well plate. The composition of bacterial species in biofilms was determined by plating on both LB agar and CHROMagar selective agar. Biofilm was harvested by swabbing.

Bacteriophage was isolated from various sources, propagated, and high titer stocks were prepared. The phage was then characterized by whole genomic DNA sequencing and pH stability test.

Results

S. maltophilia showed strong ability of forming biofilm complex than that of EHEC. The biofilm amount formed corresponded to the initial ratio of S. maltophilia in the mixed biofilm with EHEC.

In the biofilm, the ratio of EHEC was low (0.2%-7%) regardless of initial inoculum. In the case of S. maltophilia and EHEC, the biofilm formation process was independent, with no mutual effects.

Two phages have been isolated from commercially-available chicken fillet (Sasami) and tail (Bonjiri). Currently the sequencing data are being analyzed. The phage isolated from Bonjiri was stable at pH ranging from 5-10, while the phage from Sasami was stable at pH ranging from 5-9.