Defining Genomic and Predicted Metabolic Features of the Acetobacterium Genus

Abstract

Acetogens are anaerobic bacteria capable of fixing CO2 or CO to produce acetyl coenzyme A (acetyl-CoA) and ultimately acetate using the Wood-Ljungdahl pathway (WLP). Acetobacterium woodii is the type strain of the Acetobacterium genus and has been critical for understanding the biochemistry and energy conservation in acetogens. Members of the Acetobacterium genus have been isolated from a variety of environments or have had genomes recovered from metagenome data, but no systematic investigation has been done on the unique and various metabolisms of the genus. To gain a better appreciation for the metabolic breadth of the genus, we sequenced the genomes of 4 isolates (A. fimetarium, A. malicum, A. paludosum, and A. tundrae) and conducted a comparative genome analysis (pan-genome) of 11 different Acetobacterium genomes. A unifying feature of the Acetobacterium genus is the carbon-fixing WLP. The methyl (cluster II) and carbonyl (cluster III) branches of the Wood-Ljungdahl pathway are highly conserved across all sequenced Acetobacterium genomes, but cluster I encoding the formate dehydrogenase is not. In contrast to A. woodii, all but four strains encode two distinct Rnf clusters, Rnf being the primary respiratory enzyme complex. Metabolism of fructose, lactate, and H2:CO2 was conserved across the genus, but metabolism of ethanol, methanol, caffeate, and 2,3-butanediol varied. Additionally, clade-specific metabolic potential was observed, such as amino acid transport and metabolism in the psychrophilic species, and biofilm formation in the A. wieringae clade, which may afford these groups an advantage in low-temperature growth or attachment to solid surfaces, respectively. IMPORTANCE Acetogens are anaerobic bacteria capable of fixing CO2 or CO to produce acetyl-CoA and ultimately acetate using the Wood-Ljungdahl pathway (WLP). This autotrophic metabolism plays a major role in the global carbon cycle and, if harnessed, can help reduce greenhouse gas emissions. Overall, the data presented here provide a framework for examining the ecology and evolution of the Acetobacterium genus and highlight the potential of these species as a source for production of fuels and chemicals from CO2 feedstocks.

Microbial Ecological Mechanism for Long-Term Production of High Concentrations of n -Caproate via Lactate-Driven Chain Elongation

“…At the same time, several genera showed opposing trends in changes in relative abundances. Cutibacterium (formerly Propionibacterium), which is known as a propionate-producing genus (42), was the most typical genus among them. Its relative abundance increased by more than 17 times (0.351% 6 0.418% versus 6.08% 6 6.08%, P , 0.02) from phase 1 to phase 2, but it finally declined back to 0.480% 6 1.36% (phase 4) as the HRT shortened over time.…”

“…The lactate fermentation-associated bacteria Enterococcaceae and Lactobacillaceae have the key genes encoding enzymes that catalyze the oxidation of lactate to acetyl-CoA. Eight families, Bacillaceae, Actinomycetaceae, Eubacteriaceae, Enterococcaceae, Rubeoparvulaceae, Lactobacillaceae, Runimococcaceae, and Lachnospiraceae, have the pta and ackA genes, encoding phosphate acetyltransferase and acetate kinase for acetate formation from acetyl-CoA (42). Three families, Bacillaceae, Planococcaceae, and Propionibacteriaceae, possess all of the genes of the Wood-Werkman cycle needed for propionate production.…”

Glacial Ice Age Shapes Microbiome Composition in a Receding Southern European Glacier

“…Microorganisms that synthesize organic compounds by fixing carbon dioxide (phototrophs and chemolithotrophs) and those that degrade organic matter participate in the carbon cycle. This autotrophic metabolism plays a major role in the global carbon cycle and can help reduce greenhouse gas emissions ( Ross et al, 2020 ). These microorganisms are greatly influenced by the melting of glacial ice layers.…”

The Neuroprotective Effects of Spray-Dried Porcine Plasma Supplementation Involve the Microbiota−Gut−Brain Axis

“…SDP supplementation also augmented the abundance of other bacterial genera of the Firmicutes phylum, such as Acetobacterium , which is an acetyl-CoA producer [ 58 ]. Increased acetyl-CoA levels improve cognitive function during aging [ 59 ] and acetyl-CoA is the main precursor of butyrate [ 60 ].…”