ABSTRACT
Within the last decade researchers have gained a significant understanding of the role of biofilms in the onset of microbial-influenced corrosion in anthropogenic water systems. Biofilms are the preferred habitat for microorganisms and in this environment they are protected from harsh chemical treatments, shear stress, and predators. Within the biofilm matrix, microorganisms thrive in conditions responsible for promoting a corrosive environment. The types of bacteria responsible for corrosion vary from system to system. In this study we used a novel biomonitoring system installed in 26 unique industrial water systems across the United States. These systems provided not only a diverse geographical biofilm sample set but also allowed the evaluation in the seasonal variation within the biofilm samples collected from the same system. Metagenomic sequence analysis was utilized to provide a new understanding of the variations in bacterial populations existing in biofilms. Data revealed from the analysis will provide insight on the phylogenetically and metabolically distinct species present in the biofilms. This will aid in the formation of new anti-biofilm strategies to help minimize microbial-influenced corrosion.
INTRODUCTION
The word “corrosion” is derived from the Latin corrodere meaning “gnaw through” [1] and it is a global problem impacting almost every aspect of our lives. From medical implanted devices to our Nation’s infrastructure, concrete, plastic, or metal we are in a constant battle to combat the effects of corrosion. It has been estimated that close to $2 trillion is spent globally on replacing corroded equipment and structures with an additional $8 billion being spent on corrosion inhibition strategies [2,3]. Microbial Influenced Corrosion, or MIC, accounts for approximately 20% of all corrosion issues globally [4]. MIC is a form of corrosion where a consortium of bacteria, fungi, or algae existing predominately within a biofilm on a surface influence or accelerate the rate at which that surface is degraded [2,5]. A biofilm is a complex community of surface attached microorganisms held together by a protective gelatinous secretion called extracellular polymeric substance (EPS) that is commonly referred to as slime. The EPS is a complex mixture of water, carbohydrates, proteins, DNA, and other molecules that gel together to give the biofilm the slimy feel and appearance. It is this structure that protects the bacterial community from the harsh external environment while at the same time drawing in essential nutrients from the surrounding habitat [5,6,7]. Research into the formation and structures of multispecies biofilms strongly suggests that each biofilm is totally unique and is a product of the surrounding environment at that precise time and place. It is the symbiotic nature of the biofilm that the microorganisms and the substrate on which the biofilm is formed that makes MIC one of the most nefarious forms of corrosion. The dynamic nature of the biofilm can result in multiple corrosion mechanisms, (localized generation of corrosive substances, formation of differential concentration cells, inactivation of corrosion inhibitors etc.), [2] occurring on the surface simultaneously making it difficult to remediate or prevent with a single approach or treatment [2-7].
