Evaluation of currently employed food preservation conditions to tackle biofilm forming food pathogens

Controlling biofilm forming, pathogenic bacteria is an emerging challenge in the food industry, and the present study aims to test the efficacy of existing food preservation methods against these bacteria. We isolated 10 different biofilm forming pathogenic bacteria viz. Klebsiella quasipneumoniae, Bacillus cereus, Bacillus amyloliquefaciens, Bacillus anthracis, and Myroides odoratimimus from spoiled milk, biscuits, and cakes. K. quasipneumonia and B. amyloliquifaciens formed strong biofilm (OD₅₅₀ > 0.85), whereas B. cereus, B. anthracis, and M. odoratimimus made moderate biofilm (OD₅₅₀₅ > 0.6) in 72 hr. The isolates, B. amyloliquifaciencs, B. anthracis, and M. odoratimimus were found positive for protease activity. The isolates showed significant tolerance to preservation conditions: pH (4–10), salt (up to 5%), temperature (up to 50°C) and sodium benzoate (up to 0.1%). The isolates also exhibited high antibiotic resistance, maximum by M. odoratimimus (MIC ≤ 256 µg/ml) against chloramphenicol which can have serious implications especially in tackling food borne illness caused by the biofilm forming food pathogens.

Practical applications

The present study discloses the presence of biofilm forming pathogenic bacterial strains in common food stuff and their tolerance of preservation conditions and resistance to antibiotics. The occurrence of pathogens tolerant to common preservation conditions and their resistance to antibiotic should be addressed very cautiously. The significant findings of this study warrant the need for more stringent preservation methods to control food pathogens, especially the biofilm forming type. Moreover, findings of the present study will help to design novel preservation techniques such as incorporating antibiofilm coatings in food processing units and packaging materials, which will ensure food safety and public health.