Molecular Microbiological Methods Applied on Ship Ballast Tank Samples
Anne Heyer, Fraddry D'Souza, Arjan Mol and Hans de Wit
from: Applications of Molecular Microbiological Methods (Edited by: Torben L. Skovhus, Sean M. Caffrey and Casey R.J. Hubert). Caister Academic Press, U.K. (2014)
Microbiologically influenced corrosion of steel is a serious problem in the marine environment including offshore and shipping industries. The uses of molecular techniques and electrochemical techniques for evaluating microbial corrosion effects have continued to gain importance. This chapter summarizes a large-scale approach of a simultaneous investigation of corrosion and microbial community within a practical ship ballast tank environment. The corrosion behaviour of ASTM A131 steel, grade EH36 exposed to natural seawater was investigated at two different height levels of the ship ballast tank-sediment and immersion zone. Biofilm samples were scraped from exposed corrosion coupons and subjected to DGGE of PCR-amplified 16S rRNA genes and sequence analysis to characterize the microbial community developed on the sidewall of ship ballast tanks as well as the water phase. In parallel, corrosion was monitored by open circuit potential and linear polarization resistance measurements, indicating a difference in corrosion behaviour at sediment and immersion zone and related to the variation in bacterial community changes. This chapter demonstrates the problem of attached biofilms in the corrosion of ship ballast tanks, which is characterized by a combination of electrochemical and molecular tools read more ...