Biofilm formation on structural materials in deep sea environments

Abstract

Biofilm formation on structural materials in deep-sea environment after long duration of exposure is reported here for the first time. Some structural material specimens such as steel, steel with zinc and aluminum anodes and carbon fibre-reinforced composite were exposed at depths of 500, 1200, 3500 and 5100 m for 174 days. The bacterial colony formation

on these specimens was studied after their retrieval from the ocean. Macrofouling was not found in any of these materials. Carbon fibre-reinforced composite did not support bacterial colony formation at all the tested depths. Steel supported bacterial colonies at all depths. Aluminium and zinc anodes did not support bacterial colonies at 3500 and 5100 m depths.

This could be related to lower temperatures prevailing at these depths. Also, all the identified bacterial colonies were aerobic as dissolved oxygen was present even at 5100 m depth. Hence, anaerobic conditions did not exist during exposure under these structural conditions. Dissolved oxygen data at the experimental site is also presented and discussed.