Preliminary analysis ofChloroflexipopulations in full-scale UASB methanogenic reactors

Abstract

Aims:The phylum Chloroflexi is frequently found in high abundance in methanogenic reactors, but their role is still unclear as most of them remain uncultured and understudied. Hence, a detailed analysis was performed in samples from five up-flow anaerobic sludge blanket (UASB) full-scale reactors fed different industrial wastewaters. Methods and Results: Quantitative PCR show that the phylum Chloroflexi was abundant in all UASB methanogenic reactors, with higher abundance in the reactors operated for a long period of time, which presented granular biomass. Both terminal restriction fragment length polymorphism and 16S rRNA gene amplicon sequencing revealed diverse Chloroflexi populations apparently determined by the different inocula. According to the phylogenetic analysis, the sequences from the dominant Chloroflexi were positioned in branches where no sequences of the cultured representative strains were placed. Fluorescent in situ hybridization analysis performed in two of the reactors showed filamentous morphology of the hybridizing cells. Conclusions: While members of the Anaerolineae class within phylum Chloroflexi were predominant, their diversity is still poorly described in anaerobic reactors. Due to their filamentous morphology, Chloroflexi may have a key role in the granulation in methanogenic UASB reactors. Significance and Impact of the Study: Our results bring new insights about the diversity, stability, dynamics and abundance of this phylum in full-scale UASB reactors which aid in understanding their function within the reactor biomass. However, new methodological approaches and analysis of bulking biomass are needed to completely unravel their role in these reactors. Combining all this knowledge with reactor operational parameters will allow to understand their participation in granulation and bulking episodes and design strategies to prevent Chloroflexi overgrowth. 2005). The anaerobic treatment of wastewater can produce energy in the form of methane, with a low biomass production, high efficiency and a low energy demand (Van Lier 2008;Angelidaki et al. 2011). In Uruguay, these systems have been applied for the treatment of several agroindustrial wastewaters from dairy, brewery and Journal of Applied Microbiology 126, 667--683

Evaluation of an anaerobic baffled reactor for pretreating black water: Potential application in rural China

“…At phylum level, the proportion of Chloroflexi was the highest no matter in which compartment, and it was in good accordance with some pervious reports. It has been widely reported that Chloroflexi is abundant in anaerobic digestion reactors, and the potential capacity of Chloroflexi for carbohydrate degradation was reported in previous studies (Bovio et al, 2019;Rivière et al, 2009). Firmicutes was also pointed out as being related to the degradation of carbon compounds.…”

The Phylogeny, Biodiversity, and Ecology of the Chloroflexi in Activated Sludge

“…The phylum ‘ Chloroflexi , embraces an ecologically and physiologically diverse group of bacteria, which have been detected in an increasingly wide range of anaerobic habitats including sediments, hot springs, methanogenic anaerobic sludge digesters where they are highly abundant and play an important fermentative role as well as contributing to sludge granulation (Hug et al, 2013; McIlroy et al, 2016; Sun et al, 2016; Xia et al, 2016; Petriglieri et al, 2018; Bovio et al, 2019), the human oral cavity (Campbell et al, 2014), Anammox reactors (Kindaichi et al, 2012; Cao et al, 2016; Wang et al, 2016) and activated sludge communities (Björnsson et al, 2002; Kragelund et al, 2007a, 2011; Speirs et al, 2009, 2011, 2017; Yamada and Sekiguchi, 2009; Hanada, 2014; McIlroy et al, 2018; Andersen et al, 2019; Nierychlo et al, 2019). This is not the place to explore in detail their still evolving systematics, which have been dealt with elsewhere (Hanada, 2014).…”

Cultivation and characterization of a novel clade of deep-sea Chloroflexi: providing a glimpse of the phylum Chloroflexi involved in sulfur cycling

“…Despite the Chloroflexi bacteria being among the first widespread microbial lineages discovered in deep-sea environments we still lack cultured representatives (especially those with relative fast growing rate) for this group and their detailed physiological, genetic and ecological properties are currently almost completely obscure [13,23,24]. For example, until now, only basic physiological characteristics of two cultured strains of Chloroflexi with extremely slow growth rate (doubling time from 1.5 days to 19 days) from the deep-sea sediments are available [10,23], and their central metabolisms and contributions to biogeochemical processes including sulfur cycling are largely unknown.…”

“…These microorganisms are the primary drivers of elemental cycles within deep marine subsurface sediments and play key roles in the recycling of biogeochemical nutrients to the water column [4]. Members of the phylum Chloroflexi widely distributed in various environments with high abundance, for example, in some marine subsurface sediments the number of Chloroflexi bacteria is shown to be closely equivalent to other total bacterial counts [3,[5][6][7][8], strongly suggesting that the phylum Chloroflexi is an essential group to maintain the population equilibrium of marine subsurface ecosystems [9][10][11][12].…”