Vibrio sp. bacterium has long earned a reputation as being harmful. In our tanks, it has been frequently speculated that Vibrio is an instigating factor in numerous cases of RTN. Researchers have shown that the Hawaiian Bobtail squid (Euprymna scolopes) will regularly utilize Vibrio fisheri within its body to create bioluminescence for protection from predators. The squid are not born with these cultures, but will “gather” them from surrounding waters
As aquarists, we have “cultured” ourselves (pun intended) to understand that bacteria is not always bad. For example, we cherish our beloved nitrosomas and nitrobacter flourishing within our aquarium. Yet, if a bacterium does not fall into one of these mineralizing functions, can it possibly be good? In a short answer, yes. In fact, bacteria can play an enormously influential, beneficial, and synergistic role in many marine creatures. Even bacteria which have been vilified as evil incarnate, such as Vibrio sp.
Vibrio sp. bacterium has long earned a reputation as being harmful. In our tanks, it has been frequently speculated that Vibrio is an instigating factor in numerous cases of RTN. Furthermore, it is regularly implicated in causing severe health issue in humans (typically in conjunction with ingestion of an aquatic or marine organism or water).
Well, cheer up Vibrio, you’re finally getting some of the accolades you deserve! Spencer Nyholm, of the University of Connecticut’s Molecular and Cell Biology Department, has shown that the Hawaiian Bobtail squid (Euprymna scolopes) will regularly utilize Vibrio fisheri within its body to create bioluminescence for protection from predators. The young squid are not born with these cultures, but will actually “gather” them from surrounding waters, and residing within their bodies to provide countershading from potential predators. Being a nocturnal species, this is displayed on the underside of their body, to mimic the lighter water surface. However, once dawn breaks, the squids will settle into the sand, and actively “eject” up to 95% of the Vibrio bacteria out of their bodies. Why? Theories abound, but, all things considered, the existing +5% within the squid replicates quickly, and by nightfall, the bacterial culture has “recharged” completely, ready to benefit their host yet again. Not the “toxic villain” it is too often painted as.
As a thought-provoking biomedical note, this relationship has some interesting possibilities within other organisms as well. As mentioned earlier, Vibrio cholerae is a notoriously nefarious fellow- the causative agent for cholera in humans. But, is it possible that this Vibrio may share a similar pathway in humans? This instinctual genetic relationship may indeed be at play in humans, and only become problematic when the equilibrium is upset. To investigate, turn sights back to the Bobtail squid. While humans have an enormous variety of gut organisms, these squid form a relationship with one- Vibrio fisheri. How does the squid’s immune system detect that one species of bacteria, in relation the bombardment of other bacteria it is surely exposed to? Nyholm is now investigating this relationship. He states, “Understanding how the squid immune system reacts to Vibrio bacteria can help us understand how other animals interact with both beneficial and disease-causing microbes. The genes of communication appear to be similar for good and bad associations, but the mechanisms of implementation are likely different.