Induction, detection, formation, and resuscitation of viable but non-culturable state microorganisms

The viable but nonculturable (VBNC) state has been recognized as a strategy for bacteria to cope with stressful environments; in this state, bacteria fail to grow on routine culture medium but are actually alive and can resuscitate into a culturable state under favorable conditions. The VBNC state may pose a great threat to food safety and public health. To date, more than 100 VBNC microorganism species have been proven to exist in fields of food safety, environmental application, and agricultural diseases. Most harsh conditions can induce these microorganisms into the VBNC state, including food processing and preservation methods, adverse environmental conditions, and plant-disease controlling means. The characteristics of VBNC state cells differ from those of normally growing cells and dead cells, based on which of the various detection methods are developed, and they are of great significance for potential risk assessment. To provide molecular level insights into this state, many studies on induction and resuscitation mechanisms have emerged over the past three decades, including research on omics, specific genes, or proteins involved in VBNC state formation and the roles of promoters in resuscitation from the VBNC state. In this review, microorganism species, induction and resuscitation factors, detection methods, and formation and resuscitation mechanisms of the VBNC state are comprehensively and systematically summarized.