Growth and characterization of Escherichia coli DH5α biofilm on concrete surfaces as a protective layer against microbiologically influenced concrete deterioration (MICD)

Abstract

Biofilms of selected bacteria strains were previously used on metal coupons as a protective layer against microbiologically influenced corrosion of metals. Unlike metal surfaces, concrete surfaces present a hostile environment for growing a protective biofilm. The main objective of this research was to investigate whether a beneficial biofilm can be successfully grown on mortar surfaces. Escherichia coli DH5α biofilm was grown on mortar surfaces for 8 days, and the structure and characteristics of the biofilm were studied using advanced microscopy techniques such as scanning electron microscopy and confocal laser scanning microscopy in combination with fluorescence in situ hybridization, live/dead, extracellular polymer staining, ATP analysis, and membrane filtration. A biofilm layer with a varying thickness of 20-40 μm was observed on the mortar surface. The distribution of live and dead bacteria and extracellular polymers varied with depth. The density of the live population near the mortar surface was the lowest. The bacteria reached their highest density at three fourths of the biofilm depth and then decreased again near the biofilm-liquid interface. Overall, the results indicated a healthy biofilm growth in the chosen growth period of 8 days, and it is expected that longer growth periods would lead to formation of a more resistant biofilm with more coverage of mortar surfaces.

The importance of sewer biofilms

“…Moreover, the investigation of biofilm‐based solutions for sewer management has yielded further innovative avenues. Soleimani et al have investigated the feasibility of coating sewer surfaces with a biofilm of fast‐growing bacteria that are capable of surviving in the oxygen‐deficient environment in the sewers . They hypothesize that the presence of such a biofilm layer will preclude the establishment of SRBs as they will be out‐competed for nutrients by the fast‐growing bacteria.…”

Distribution and population structure characteristics of microorganisms in urban sewage system

“…Problems (e.g., odor, corrosion, or pathogens) are induced by the complex reactions of carbon, nitrogen, and sulfur in the microbial community, which occur in the sediment and biofilm and threaten the effective operation of the sewage system (Liu et al 2015b). Therefore, previous studies mainly focused on microbial communities and their sulfuric reactions in the sediment or biofilm, which were conducted based on cultured substrate in a lab-scale; however, these studies do not reflect the complexity of environmental conditions inside the sewage system (Mohanakrishnan et al 2008;Hisashi et al 2009;Jiang et al 2010;Soleimani et al 2013). The influence of operational conditions on the shift of microbial communities inside the sediment has hardly been explored.…”

“…Previous studies of complex microbial communities within the sewage system mainly focused on microbial population structures of influents that enter treatment plants (McLellan et al 2010;VandeWalle et al 2012) and the distribution of functional microbial populations for sulfur cycles within the biofilms of the drainage pipe, which most are simulated using a lab-scale reactor (Okabe et al 2007;Soleimani et al 2013). However, the complex dynamic process of sewage systems causes alternate changes in the aerobic and anaerobic conditions inside drainage pipes regardless of spatial or temporal dimensions (Yongsiri et al 2003).…”

Understanding interactions between cementitious materials and microorganisms: a key to sustainable and safe concrete structures in various contexts

“…In other cases, the formation of microbial biofilm on the surface of cement-based materials can provide a protective layer against biological deterioration, e.g. either by the excretion of protective organic polymers (EPS = ExoPolymeric Substances), where beneficial precipitation of calcium carbonate can occur for example [69], or by the proliferation of non-aggressive microbes capable of competing with undesirable microorganisms [70,71]. Also, the metabolites produced by some fungi or lichens, such as oxalic acid, can protect Ca-bearing materials by the precipitation of calcium oxalate at their surface [72,73].…”