Biology subjects

Peeters, S. H.

Publications and source records attributed to Peeters, S. H..

3 recordsLinked to original sources

bioRxiv2025

Adaptation and response of verrucomicrobial methanotrophs to heat and acidity

Acidophilic microorganisms thrive in environments where the external pH is orders of magnitude lower than their intracellular pH. Verrucomicrobial methanotrophs of the family Methylacidiphilaceae, including Methylacidiphilum and Methylacidimicrobium, inhabit extremely acidic geothermal environments and can grow at a pH < 1.0 and temperatures up to 65 {degrees}C. We analyzed and compared their membrane fatty acid compositions at pH 3.0 across strains with different temperature optima. Thermophilic Methylacidiphilum strains almost exclusively contain saturated fatty acids, while mesophilic Methylacidimicrobium strains incorporate 16-47% unsaturated fatty acids. Notably, the thermophile Methylacidiphilum fumariolicum SolV increases unsaturated fatty acid content in response to a 10 {degrees}C temperature decrease. Genomic analysis revealed a conserved fatty acid biosynthesis pathway. Despite constitutive expression of predicted pH homeostasis genes, SolV did not upregulate them upon changing the pH from 3.0 to 1.7. However, genes involved in methane oxidation were strongly upregulated, suggesting a potential metabolic adaptation to extreme acidity.

microbiology↗

bioRxiv2022

Methanotrophs are vigorous H2S oxidizers using a sulfide:quinone oxidoreductase and a ba3-type terminal oxidase

Hydrogen sulfide (H2S) is produced in a wide range of anoxic environments where sulfate (SO42-) reduction is coupled to decomposition of organic matter. In the same environments, methane (CH4) is the end product of an anaerobic food chain and both H2S and CH4 diffuse upwards into oxic zones where aerobic microorganisms can utilize these gases. Methane-oxidizing bacteria are known to oxidize a major part of the produced CH4 in these ecosystems, mitigating the emissions of this potent greenhouse gas to the atmosphere. However, how methanotrophy is affected by toxic H2S is largely unexplored. Here, we show that a single microorganism can oxidize CH4 and H2S simultaneously. By oxidizing H2S, the thermoacidophilic methanotroph Methylacidiphilum fumariolicum SolV can alleviate the inhibitory effects on CH4 oxidation. In response to H2S, strain SolV upregulated a type III sulfide:quinone oxidoreductase (SQR) and a sulfide-insensitive ba3-type terminal oxidase to dissipate the reducing equivalents derived from H2S oxidation. Through extensive chemostat cultivation of M. fumariolicum SolV we demonstrate that it converts high loads of H2S to elemental sulfur (S0). Moreover, we show chemolithoautotrophy by tracing 13CO2 fixation into new biomass by using H2S as sole energy source. Molecular surveys revealed several putative SQR sequences in a range of proteobacterial methanotrophs from various environments, suggesting that H2S detoxification is much more widespread in methanotrophs than previously assumed, enabling them to connect carbon and sulfur cycles in new ways.

microbiology↗

bioRxiv2019

The novel shapeshifting bacterial phylum Saltatorellota

Our current understanding of a free-living bacterium - capable of withstanding a variety of environmental stresses-is represented by the image of a peptidoglycan-armored rigid casket. The making and breaking of peptidoglycan greatly determines cell shape. The cytoplasmic membrane follows this shape, pressed towards the cell wall by turgor pressure. Consequently, bacteria are morphologically static organisms, in contrast to eukaryotic cells that can facilitate shape changes. Here we report the discovery of the novel bacterial phylum Saltatorellota, that challenges this concept of a bacterial cell. Members of this phylum can change their shape, are capable of amoeba-like locomotion and trunk-formation through the creation of extensive pseudopodia-like structures. Two independent Saltatorellota cells can fuse, and they employ various forms of cell division from budding to canonical binary fission. Despite their polymorphisms, members of the Saltatorellota do possess a peptidoglycan cell wall. Their genomes encode flagella and type IV pili as well as a bacterial actin homolog, the saltatorellin. This protein is most similar to MamK, a dynamic filament-forming protein, that aligns and segregates magnetosome organelles via treadmilling. We found saltatorellin to form filaments in both, E. coli and Magnetospirillum gryphiswaldense, leading to the hypothesis that shapeshifting and pseudopodia formation might be driven by treadmilling of saltatorellin.

microbiology↗