Impact of Bacterial Injury and Repair in Food Microbiology: its Past, Present and Future

Abstract

Studies done during the past 25 years revealed that microorganisms present in semipreserved foods can be injured by sub-lethal treatments. The injured cells, irrespective of differences in sublethal treatments, have similarities in their manifestation of injury and their repair. A simple resuscitation step incorporated into currently recommended isolation procedures would enable detection of these cells. In the future, microbial cell injury studies should be directed to include not only effective detection of index and pathogenic bacteria from foods, but also growth inhibition of spoilage microorganisms and preservation of lactic cultures. In 1959, Straka and Stokes (35) reported that some cells of Escherichia coli and Pseudomonas spp. that survived freezing and thawing were metabolically injured. They also demonstrated that the injury was reversible and injured cells were able to repair when supplemented with several types of peptides. Their work exposed a new research area of interest to food microbiologists for the next two decades. Interestingly, other researchers (7,9,10,17,20) reported reversible bacterial injury caused by different sublethal physical and chemical treatments before Straka and Stokes (35). Some also emphasized the implications and importance of injured bacteria in developing methods for proper microbiological evaluation of semipreserved foods (7,9,10). However, these early studies apparently failed to generate much interest among researchers.