Induction of Escherichia coli and Salmonella typhimurium into the viable but nonculturable state following chlorination of wastewater

Abstract

We examined the effects of chlorine disinfection on Escherichia coli and Salmonella typhimurium in secondary-treated wastewater to determine whether such treatment might induce these bacteria into the viable but nonculturable (VBNC) state. In this state, cells lose culturability but retain viability and the potential to revert to the metabolically active and infectious state.To examine the effects of chlorination on cells in different physiological states, cells from the logarithmic and stationary phases, or nutrient starved, or grown in natural wastewater, were studied. Isogenic cells with and without plasmids were also examined. Whereas a mixture of free and combined chlorine, as occurs under typical wastewater disinfection, was found to be rapidly lethal to most cells, regardless of their physiological state or plasmid content, c. 10 4 of the original 10 6 cells ml 21 did survive in the VBNC state. While we were not successful in resuscitating these cells to the culturable state, the presence of such nonculturable cells in treated wastewater offers a potential public health hazard.

Stress resistance in naturalised waste water E. coli strains

“…PMA binds to DNA, preventing PCR amplification of target sequences, but can penetrate only cells in which the cellular membrane of the bacteria has been compromised (Nocker et al, 2006). It is conceivable that although similar survival outcomes were observed between the human H54 strain and the naturalised waste water E. coli strains based on cell culture, that significant differences in overall survival may have existed if VBNC was also are accounted for in the authors' studies, similar to that observed by Oliver et al (2005).…”

“…In addition to possessing alternative chlorine stress-adaptive mechanisms, E. coli can also enter into a viable but nonculturable state (VBNC) -a common survival strategy used by E. coli to deal with adverse environmental conditions (Trevors, 2011) such as chlorine treatment (Oliver et al, 2005). During transition into a VBNC state, bacteria condense cellular material, often becoming much smaller, yet their cellular structures remain intact, and they become more resistant to inactivation or treatment (E et al, 2015; Zhang et al, 2015).…”

Molecular viability testing of viable but non‐culturable bacteria induced by antibiotic exposure

“…Also, the step of having a 7 day starvation before the stimulation could induce VBNC cells because they have intact cell membranes, low metabolic activity and continued mRNA synthesis (Lleo et al ., 2000). It has been known that many species of bacteria enter VBNC state when they are subjected to various environmental stressors, such as UV disinfection, osmotic pressures, high/low temperature and starvation (Colwell et al ., 1985; Byrd et al ., 1991; Oliver et al ., 2005; Pawlowski et al ., 2011). Interestingly, it has been demonstrated that VBNC and persister cells coexist after antibiotic treatment and can be resuscitated back to culturable cells when the existing stress is removed (Ayrapetyan et al ., 2015b).…”

“…Two well‐defined dormancy states, the viable but non‐culturable (VBNC) state and persister cells (persisters), have been described in non‐sporulating bacteria, where they often exhibit strong antibiotic tolerances than culturable cells (viable) (Li et al ., 2014; Maisonneuve and Gerdes, 2014). In the VBNC state, bacteria maintain a low metabolic activity and do not divide, which help them cope with chemical stressors such as chlorination (Oliver et al ., 2005) and antibiotic treatments (Ayrapetyan et al ., 2015a). Even so, they could resuscitate and regrow later when the environmental conditions are favourable.…”

Distribution of Vibrio species in Shellfish and Water Samples Collected from the Atlantic Coastline of South-East Nigeria

“…This is buttressed by the culture of direct defaecation into the sea-water, a culture that prevails among fishing communities in the five islands sampled (Eyisi, personal observation). It was, however, later observed that V. cholerae exhibited a capacity of entering a rest-period during adverse environmental conditions (15)(16)(17). This changed all the earlier hypotheses; V. cholerae can apparently survive in marine waters, frequently associated with phytoor zoo-plankton, for several months.…”