Aerobic Exposure Induced Viable but Nonculturable (VBNC) State in Campylobacter jejuni

Abstract:

Campylobacter jejuni is a leading foodborne bacterial pathogen in the United States and developed countries. C. jejuni is considered a microaerophilic bacterium. However, under aerobic stresses, it can enter into a viable but non culturable state (VBNC), which makes C. jejuni persist in environments, and difficult to detect and control. To study development of the VBNC state, C. jejuni strain NCTC 11168 was incubated in MH broth in a shaking incubator (100 rpm) at 25°C (aerobic condition). At different time points, samples were collected for culturability assessment using the plating method (on days 0, 1, 2, 5, 12, and 19) and live/dead cell ratio measurement using the BacLightTM Bacterial Viability Kit on days 1, 5, 12, and 19. It’s observed that the culturability continued to decrease and no colonies formed after day 5, while the live/dead cell ratio decreased but stayed at a relatively high level, indicating a significant portion of C. jejuni cells were in VBNC state. A chicken study was performed to explore the possible resuscitation under in vivo conditions. Different doses (108, 109 , and 1010 cells/mL) of VBNC C. jejuni 11168 were inoculated into 3-day old chicks by oral gavage. However, no culturable C. jejuni 11168 cells were detected in the cloacal swabs of chickens during the whole experiment period. In summary, aerobic exposure promotes C. jejuni to enter VBNC state. Understanding the persistence and resuscitation of VBNC C. jejuni is critical for improving detection methods, ensuring food safety, and mitigating public health risks.

Acknowledgements:

I would like to thank Dr. Jun Lin and Dr. Ximin Zeng for all of their guidance and assistance as advisors while working through this project. I would also like to thank Wei Wang and Xinge Hu for taking care of the chickens that were used for the in vivo experiments.