Bacterial colonization of artificial substrate in the vicinity of deep-sea hydrothermal vents

Abstract

Artificial substrata of different material composition were deployed at deep-sea hydrothermal areas on the Mid-Atlantic Ridge for exposure times ranging from 1 to 12 days. After 4 days of exposure, a very thick but loosely-bound biofilm formed on all surfaces. Two bacterial morphotypes dominated the attached microbial community: rod-shaped bacteria sometimes several cell layers thick and large filamentous forms attached to the substratum at one end of the filament. Quantitative extraction of biofilm lipids associated with the substratum surface indicated the accumulation of a large amount of bacterial biomass after 4 days of exposure for all substrata. Microbial biomass accumulated at different rates on the different substrata. The greatest biomass was associated with 316L stainless steel and titanium substrata. Polar lipid fatty acid (PLFA) analysis of lipid extracts contained signatures of sulfate reducing bacteria and fatty acids (FA) previously reported in filamentous sulfur-oxidizing bacteria. The results demonstrate rapid in situ colonization of artificial substrata by hydrothermal vent microbial populations irrespective of the nature of the substratum.