Chapter 39 : Commuting to Work

Abstract:

An underwater microbial mat has been found in fairly shallow waters off the coast of Chile and, according to headlines, it’s the size of Greece, or about 132,000 km2 (or for us norteamericanos, about the size of Alabama). These communities of sulfide-oxidizing bacteria have been known for some time, but their attention has been highlighted by the recent version of the Census of Marine Life. In fact, they were discovered in 1963 by the oceanographer and microbiologist Victor Gallardo of Chile’s University of Concepción. Scientists may not have known much about these huge mats much earlier on, but the local fishermen sure did and called them estopa, Spanish for burlap or unwashed wool or flax. Aficionados of the giant sulfide-oxidizing bacterium Thiomargarita namibiensis and other bacterial gargantuas likely include Thioploca, the occupants of these mats, in their catalog of microbial marvels. This is a genus of gliding, filamentous bacteria that live in aquatic sediments where they face the same problem as Thiomargarita, namely, how to hook up their fuel (sulfides) with their final electron acceptors (nitrates). (For details of their metabolism, see a recent paper [1.usa.gov/1RAhxrq].)