Researchers say that some ocean mircobes wield chemical weapons that are deadly to outsiders but leave their own group unharmed.
The weapons are natural antibiotics produced by a few individuals whose closest relatives carry genes that make them resistant. MIT researchers believe that the few antibiotic producers are acting as protectors of the many.
Microbes having a rather sophisticated social structure that promotes cooperation among their own, rather than cut throat competition for scare resources, suprised researchers, the journal Science reported.
"It's easy to imagine bacteria in the environment as selfish creatures capable only of reproducing as fast as conditions allow, without any social organization," said Otto Cordero, MIT postdoctoral student, who led the study, according to an MIT statement.
"But that is the mind-blowing part: Bacterial wars are organised along the lines of populations, which are groups of closely related individuals with similar ecological activities," added Cordero.
"We can't know what the environmental interactions really are, because microbes are too small for us to observe them in action," said Martin Polz, professor of civil and environmental engineering (CEE) at the MIT, lead study investigator.
"But we think the antibiotics play a role in fending off competitors. Of course, those competitors could also produce antibiotics. It's a potential arms race out there," added Polz.
MIT researchers tested about 35,000 interactions among pairs of 185 strains of Vibrionaceae bacteria populations taken from the ocean.
They found that 44 percent of the strains were able to inhibit the growth of at least one other strain and 86 percent were inhibited by at least one other strain. They then used genomic analysis to determine genetic kinship.
The study also uncovers an untapped source of antibiotics that could have the potential to aid in the fight against human bacterial pathogens, which are rapidly developing resistance to the few antibiotics in use -- nearly all of which are produced by soil-living bacteria.