Comparative 16S rRNA gene surveys of granular sludge from three upflow anaerobic bioreactors treating purified terephthalic acid (PTA) wastewater

Abstract

The microbial communities from three upflow anaerobic bioreactors treating purified terephthalic acid (PTA) wastewater were characterized with 16S ribosomal RNA gene sequencing surveys. Universal bacterial and archaeal primers were used to compare the bioreactor communities to each other. A total of 1,733 bacterial sequences and 383 archaeal sequences were characterized. The high number of Syntrophus spp. and Pelotomaculum spp. found within these reactors indicates efficient removal of benzoate and terephthalate. Under anaerobic conditions benzoate can be degraded through syntrophic associations between these bacteria and hydrogen-scavenging microbes, such as Desulfovibrio spp. and hydrogenotrophic methanogens, which remove H(2) to force the thermodynamically unfavourable reactions to take place. The authors did not observe a relatively high percentage of hydrogenotrophic methanogens with the archaeal gene survey because of a high acetate flux (acetate is a main component in PTA wastewater and is the main degradation product of terephthalate/benzoate fermentation), and because of the presence of Desulfovibrio spp. (a sulfate reducer that scavenges hydrogen). The high acetate flux also explains the high percentage of acetoclastic methanogens from the genus Methanosaeta among the archaeal sequences. A group of uncultured bacteria (OD1) may be involved in the degradation of p-toluate (4-methyl benzoate), which is a component of PTA wastewater.

Use of a Hierarchical Oligonucleotide Primer Extension Approach for Multiplexed Relative Abundance Analysis of Methanogens in Anaerobic Digestion Systems

“…5). These findings were in high accordance with those from several previous studies (25,28,(35)(36)(37). The dominance of the Methanosaeta population indicated its success within the niche for the production of methane from acetate, a common constituent in industrial wastewater (23) as well as a central metabolite resulting from the anaerobic fermentation of substances.…”

Microbial Community Involved in Anaerobic Purified Terephthalic Acid Treatment Process

“…Figure 3.3 summarizes the relative abundances of known methanogens Chen et al 2004;3, Chen et al 2004;4, Perkins et al 2011;5, Wu et al 2001a;6, Narihiro et al 2015. and syntrophs in previously reported microbial community analyses of anaerobic processes degrading PTA-related compounds, including full-scale reactors (Perkins et al 2011), lab-scale reactors (Chen 2008;Chen et al 2004;Perkins et al 2011;Wu et al 2001a, b), and batch enrichment cultures (Narihiro et al 2015). For methanogenic archaea, Methanosaeta populations were detected as the major constituent with relatively high abundances in all reactors (>60% of total archaeal populations).…”

“…The hydrogenotrophic methanogens predominant in the communities were observed to be substrate-dependent. Methanolinea were abundant (2.6-19.5%) in the PTA/TA-treating communities (Chen 2008;Chen et al 2004;Perkins et al 2011;Wu et al 2001b), whereas Methanoculleus (27.3-38.0%) were found in the benzoatefed batch enrichment cultures (Narihiro et al 2015), respectively. In addition, Methanospirillum, Methanobacterium, and Methanomassiliicoccus were detected as minor hydrogenotrophic populations in several processes.…”

“…In TA-treating processes, Syntrophorhabdus-related populations predominated in reactors operated under mesophilic conditions (74.5% of total bacterial population) (Wu et al 2001b), while those related to Pelotomalucum were abundant (9.2-47.9%) in higher temperature processes (hypermesophilic and thermophilic) (Chen 2008;Chen et al 2004). In addition to these syntrophs, members of the benzoate-degrading genus Syntrophus were also identified in mesophilic communities treating PTA and other petrochemical process wastewaters and also specifically degrading p-Tol and benzoate (25.0-75.6%) (Perkins et al 2011;Narihiro et al 2015;Wu et al 2001a).…”

“…From engineering and microbiological perspectives, it is important to identify the key members contributing to each microbial guild and further understand how they interact and metabolize aromatic compounds in PTA wastewater. So far, a fairly limited number of the microbial community analysis for anaerobic reactors treating PTA-related compounds, such as TA (Chen 2008;Chen et al 2004;Li et al 2014;Lykidis et al 2011;Perkins et al 2011;Wu et al 2001b), p-Tol (Wu et al 2001a), and benzoate (Narihiro et al 2015;Wu et al 2001b) has been investigated using both 16S rRNA gene-based molecular tools (e.g., Sanger-based clone libraries, pyrosequencing, and Illumina sequencing) and microscopic analyses (e.g., transmission electron microscope; TEM, scanning electron microscope; SEM, and CSLM-FISH). Although information regarding the microbial consortia responsible for PTA wastewater remediation is still limited, these pioneering studies provide essential insights into anaerobic microbial biodegradation of PTA-related compounds.…”