The effect of some disinfectants in inducing the viable but nonculturable (VBNC) state of some pathogenic bacteria

Abstract

Cells that are physiologically viable but cannot be cultivated on traditional culture media are referred to as viable and non-culturable cells (VBNC), because it cannot grow or divided. Those bacteria enter the (VBNC) state under stressed conditions, as a survival strategy. Although the bacteria that fail to grow on conventional culture media, but are actually alive and can be resuscitated from the VBNC state under suitable conditions. The VBNC state may pose a great threat to food safety and public health. The bacteria such as Salmonella enterica, Listeria monocytogenes, and Escherichia coli O157:H7 was entered the VBNC state when exposed to harsh conditions like the addition of preservatives, disinfectants, and food processing steps. In this paper, some bacteria (Salmonella enterica, Listeria monocytogenes, and Escherichia coli O157:H7 are all pathogens) were induced to enter the VBNC state by using sodium hypochlorite and hydrogen peroxide at different contact times. Culturable methods, which include (enrichment and resuscitation methods and the ATPase method, were used for detecting the bacteria used in this study. The result showed that Salmonella enterica, Listeria monocytogenes, and Escherichia coli O157:H7 was lost culturability and were not detected when treated with 0.01% sodium hypochlorite and 5% hydrogen peroxide for 50 minutes when detected by the enrichment method , whereas were detected by the ATPase method. However, the H₂O₂ and NaClO -treated bacteria recovered from a non-culturable to a culturable state in M9 minimal medium with the presence of 30 mM sodium pyruvate, Thus, the results suggested that conventional methods of detection the pathogenic bacteria, like enrichment methods, can not be used and could be caused big problems for health. While, the best method for detecting VBNC bacteria was the ATPase method in terms of speed, accuracy, and ease.