Mark O. Martin, guest blogger on Small Things Considered, has written an interesting piece on Chlorochromatium aggregatum. "With apologies to the old Turtle’s song (which knocked the Beatle’s “Penny Lane” off the Billboard charts in the spring of 1967), there are many ways that microbes interact with one another. Some intermicrobial interactions can be negative, ranging from competition for resources to predation. Others can be essentially indifferent toward one member, as in commensalism. Some of the most interesting associations, though, are the ones in which both members benefit: mutualism. Being an enthusiastic fan of the microbiologically offbeat, I have been delighted in recent years to see how modern tools (and some very hard work) have begun to reveal the details of microbe-microbe interactions within each of these categories."