Isolation and characterization of bacteriophages from soil against food spoilage and foodborne pathogenic bacteria

Abstract

Microbial food spoilage and foodborne disease are the main challenges in the food industry regarding food shelf life. Current preservation methods are frequently associated with changes in organoleptic characteristics and loss of nutrients. For this reason, bacteriophage offers an alternative natural method as a biocontrol agent that can reduce bacterial contamination in food without altering the organoleptic properties. This study was conducted to isolate and characterize bacteriophage from soil to control food spoilage bacteria, such as Bacillus cereus and Bacillus subtilis, and foodborne pathogenic bacteria, such as enterotoxigenic Escherichia coli (ETEC) and enterohemorrhagic E. coli (EHEC). Isolation was done by agar overlay assay method, and phages BC-S1, BS-S2, ETEC-S3, and EHEC-S4 were recovered. The host range of all isolated phages tended to be narrow and had high specificity towards the specific bacteria. The phage efficiency were measured where ETEC-S3 showed no effectivity against B. cereus and EHEC-S4 showed low efficiency against Enteropathogenic E. coli (EPEC). Morphology analysis was conducted for phage BC-S1 and ETEC-S3 with Transmission Electron Microscopy (TEM), and it is shown to belong to the Caudovirales order. Phages BC-S1 and BS-S2 significantly reduced the host bacteria when applied to the cooked rice and pasteurized milk samples with miMOI of 0.1. While phage ETEC-S3 at miMOI of 0.001 and phage EHEC-S4 at miMOI of 1 also showed a significant reduction when applied to chicken meat and lettuce samples at storage temperatures of 4 °C and 28 °C. The highest bacterial reduction of 100% was shown by phage BC-S1 on pasteurized milk samples and reduction up to 96.06% by phage ETEC-S3 on chicken meat samples at 28 °C incubation.