Active predation, phylogenetic diversity, and global prevalence of myxobacteria in wastewater treatment plants

Abstract

The operation of modern wastewater treatment plants (WWTPs) is driven by activated sludge microbiota, a complex assemblage of trophically interacting microorganisms. Microbial predation is crucial to fundamental understanding of how biological interactions drive microbiome structuring and functioning of WWTPs. However, predatory bacteria have received little attention regarding their diversity, activity, and ecological function in activated sludge, limiting the exploitation of food web interactions for wastewater microbiome engineering. Here, by using rRNA-stable isotope probing of activated sludge microbiota with 13C-labeled prey bacteria, we uncovered diverse as-yet-uncultivated putative predatory bacteria that actively incorporated 13C-biomass. Myxobacteria, especially Haliangium and the mle1-27 clade, were found as the dominant active predators, refreshing conventional views based on a few predatory isolates of Bdellovibrionota from WWTPs. The identified predatory bacteria showed more selective predation on prey compared with the protists dominated by ciliates, providing in situ evidence for inter-domain predation behavior divergence in activated sludge. Putative predatory bacteria were tracked over a two-year microbiome monitoring effort at a local WWTP, revealing the predominance of Myxococcota (6.5 ± 1.3%) over Bdellovibrionota (1.0 ± 0.2%) lineages. Phylogenetic analysis unveiled highly diverse myxobacteria inhabiting activated sludge and suggested a habitat filtering effect in global WWTPs. Further mining of a global activated sludge microbiome dataset revealed the prevalence of Myxococcota (5.4 ± 0.1%) species and potential impacts of myxobacterial predation on process performance. Collectively, our findings provided unique insights into the predating activity, diversity, and prevalence of Myxococcota species in activated sludge, highlighting their links with wastewater treatment processes via trophic regulation of enteric and functional bacteria.

Antibiotic Removal, Toxicity Reduction, and Antibiotic Resistance Development Inhibition Using Janus Electrochemical Membrane Filtration

“…To further explore the influence of SDZ exposure on the microbiota, the structures of the bacterial communities of different microbiota were obtained by 16S rRNA gene amplicon sequencing of the total DNA. The active bacterial communities were analyzed based on amplicon sequencing of the 16S rRNA . The bacterial community structure (Figure a) indicated that there was no significant difference among three groups of AS microbiota after 7-day exposure.…”

“…The active bacterial communities were analyzed based on amplicon sequencing of the 16S rRNA. 56 The bacterial community structure (Figure 6a) indicated that there was no significant difference among three groups of AS microbiota after 7-day exposure. The metabolically active bacterial communities (Figure 6b) revealed that Nitrospirota of AS-P had higher activities compared to its abundance in the communities of AS-P and the counterpart in AS-N and AS-E.…”

Isolation identification and application of myxobacteria

“…Myxobacteria also show great advantages in environmental governance. The researchers found that two clades of Myxobacteria, Haliangium and mle1-27, were the main active predators, a finding that contradicts conventional wisdom about the small number of predatory isolated Bdellovibrio in wastewater treatment plants (WWTPs) [14]. A study called Reductive activated sludge (SPRAS) illustrates the role of mucobacteria in wastewater treatment.…”

Two reasons to kill: predation and kin discrimination in myxobacteria

“…Such exploitation is likely because soil microbial diversity is high, often consisting of tens of thousands of species per gram [59], as well as dozens of disruptive conspecific isolates [60,61]. During vegetative predation and growth, cheater cells can scavenge nutrients without necessarily contributing to the shared pool of secreted digestive enzymes and secondary metabolites [34], broadly called public goods. During development, exploitation occurs when a subset of genotypes differentiates into mature spores, while the majority of other cells lyse, in perhaps altruistic acts, to provide nutrients for the metabolically costly programme that takes days to unfold [62].…”