Microbial Induced Corrosion (MIC) is developed under a complex biological matrix on the liquid-metal interface, known as biofilm. During MIC, this biofilm generates microenvironments that locally change water chemistry (i.e. pH, ions concentration, redox potential) that influence the electrochemical processes taking place at the metal surface. MIC in marine environments is exacerbated because surfaces are exposed to a changing fluid in both its physicochemicaland biological characteristics, which makes local studies crucial to understand the development of the biofilm and its electrochemical influence on the surface. In this study, microbial community associated with MIC over stainless steel 316L was analysed after exposure to natural seawater from East South Pacific coast. Stainless steel coupons were incubated in a running-seawater laboratory set-up during 15 weeks of ageing. Biofilm characterization was performed by Illumina high-throughput sequencing analysis of microbial community composition and structure (bacteria and eukaryotes). Additionally, isolation of diatoms from the final community was performed and in vitro experiments using those isolates were finally developed to determine its influence on MIC of coupons surface. Microbial community analysis results showed that the biofilm colonizing the coupons had higher diversity in comparison with the community from the surrounding seawater after 15 weeks of ageing. These results suggest that the composition of a mature biofilm is determined by micro-environmental conditions (metal-biofilm), rather than by the seawater inoculum. Microscopic analysis showed localized corrosion development along with presence of diatoms in the mature biofilm. Determination of diatoms influence showed a differentiated effect in comparison with bacterial culture on in vitro experiments. Small eukaryotes influence on corrosion is still poorly explored but studies of its abundance in biofouling phenomenon and its relation with primary biofilm can bring new insights and key discoveries for marine MIC understanding.
展开▼
