Polyphasic analysis of an Azoarcus-Leptothrix-dominated bacterial biofilm developed on stainless steel surface in a gasoline-contaminated hypoxic groundwater

Abstract

Pump and treat systems are widely used for hydrocarbon-contaminated groundwater remediation. Although biofouling (formation of clogging biofilms on pump surfaces) is a common problem in these systems, scarce information is available regarding the phylogenetic and functional complexity of such biofilms. Extensive information about the taxa and species as well as metabolic potential of a bacterial biofilm developed on the stainless steel surface of a pump submerged in a gasoline-contaminated hypoxic groundwater is presented. Results shed light on a complex network of interconnected hydrocarbon-degrading chemoorganotrophic and chemolitotrophic bacteria. It was found that besides the well-known hydrocarbon-degrading aerobic/facultative anaerobic biofilm-forming organisms (e.g., Azoarcus, Leptothrix, Acidovorax, Thauera, Pseudomonas, etc.), representatives of Fe(2+)-and Mn(2+)-oxidizing (Thiobacillus, Sideroxydans, Gallionella, Rhodopseudomonas, etc.) as well as of Fe(3+)- and Mn(4+)-respiring (Rhodoferax, Geobacter, Magnetospirillum, Sulfurimonas, etc.) bacteria were present in the biofilm. The predominance of β-Proteobacteria within the biofilm bacterial community in phylogenetic and functional point of view was revealed. Investigation of meta-cleavage dioxygenase and benzylsuccinate synthase (bssA) genes indicated that within the biofilm, Azoarcus, Leptothrix, Zoogloea, and Thauera species are most probably involved in intrinsic biodegradation of aromatic hydrocarbons. Polyphasic analysis of the biofilm shed light on the fact that subsurface microbial accretions might be reservoirs of novel putatively hydrocarbon-degrading bacterial species. Moreover, clogging biofilms besides their detrimental effects might supplement the efficiency of pump and treat systems.

Defining the Optimal Region of Interest for Hyperemia Grading in the Bulbar Conjunctiva

“…Then, we computed the specificity, sensitivity, accuracy, and precision of each method. All the segmentation methods were implemented in C++ with the OpenCV library [13]. Table 3 depicts the results for the state-of-the-art conjunctiva segmentation techniques.…”

Biofilm Forming Bacteria during Thermal Water Reinjection

“…), and Fe 3+ -and Mn 4+ -respiring bacteria (Rhodoferax, Geobacter, Magnetospirillum, Sulfurimonas, etc.) were detected by Benedek et al in a bacterial biofilm, developed on the stainless steel surface of a pump submerged in a gasoline-contaminated hypoxic groundwater [27]. According to [28] iron acquisition may be coupled with Fe 3+ reduction, which is needed during intracellular magnetite synthetization.…”

Microbiota in a cooling-lubrication circuit and an option for controlling triethanolamine biodegradation

“…were found to be significantly overrepresented and may therefore be regarded as characteristic members of the biofilm microbiota. All of them are known for biofilm formation and can be found in contaminated watery environments (Teixeira and Oliveira 2002;Benedek et al 2016;Auguet et al 2017;Jia et al 2018). While Pseudomonas was the most abundant genus in all sites, specific Pseudomonas OTUs appeared to be distinctive for influent (linear discriminant analysis score, LDA 5.3) and biofilm samples (LDA 4.3 and 2.5).…”