Question

What are VBNC bacteria and why do they exist? How have they impacted our identification of microbial life on our planet? What strategies and approaches would you follow to attempt to successfully culture bacteria (that were shown to be present through bacterial DNA extraction, PCR and gel electrophoresis) from a soil sample that would be described as “sandy”? Include some rationale behind your plans. For example, how does an understanding of the physiological state of the bacteria factor into your plan? By physiological state, I mean, states of stress, nutrient depletion, etc. Why is this important in terms of basic and applied environmental microbiology?

Answer 1

The viable but non-culturable (VBNC) state is a unique survival strategy adopted by many bacteria in response to adverse environmental conditions. Under stress conditions, many species of bacteria enter into starvation mode of metabolism or a physiologically viable but non-culturable (VBNC) state. Several human pathogenic bacteria have been reported to enter into the VBNC state under these conditions. The pathogenic VBNC bacteria cannot be grown using conventional culture media, although they continue to retain their viability and express their virulence. Several molecular studies have shown that not only can the VBNC state be induced under in vitro conditions but also that resuscitation from this state is possible under appropriate conditions. The most notable advance in resuscitating VBNC bacteria is the discovery of resuscitation-promoting factor (Rpf), which is a bacterial cytokines found in both Gram-positive and Gram-negative organisms.