Microbial dormancy evolution in the environments: Environmental adaptation and health risks of small colony variants

Abstract

Natural environmental conditions fluctuate randomly, with various factors influencing multiple aspects of the microorganisms that live in them. In adverse environmental conditions, microorganisms can enter dormant states with low metabolic activities, which is a survival strategy for them to adapt to deleterious environmental changes. Small colony variant (SCV) state is one of the dormant states; the size of SCV colonies is nearly one-tenth that of those of wild-type (WT) parental bacteria. This review used scientometric analysis to summarize relevant publications on SCVs. SCV physiological characteristics modified by changes in cell size, as well as induction conditions and mechanisms, detection technologies, and elimination methods in natural environments, were systematically reviewed. Interactions between SCVs and other coexisting microorganisms are also discussed. The emergence of SCVs ensures the survival of bacterial communities by providing metabolic and competitive protection; however, they also pose a potential threat to ecosystems and human health. For example, pathogens may enter the SCV state and move across geographical space along with their host’s geographical movements. Future research directions related to the transmission and control of SCVs in the natural environment are also highlighted. This review expands the understanding of the living states of microorganisms in natural environments and reveals the effects of SCVs on the evolution and persistence of both individual microorganisms and microbial populations.