Sulfide production and oxidation by heterotrophic bacteria under aerobic conditions

Abstract

Sulfide (H2S, HS− and S2−) oxidation to sulfite and thiosulfate by heterotrophic bacteria, using sulfide:quinone oxidoreductase (SQR) and persulfide dioxygenase (PDO), has recently been reported as a possible detoxification mechanism for sulfide at high levels. Bioinformatic analysis revealed that the sqr and pdo genes were common in sequenced bacterial genomes, implying the sulfide oxidation may have other physiological functions. SQRs have previously been classified into six types. Here we grouped PDOs into three types and showed that some heterotrophic bacteria produced and released H2S from organic sulfur into the headspace during aerobic growth, and others, for example, Pseudomonas aeruginosa PAO1, with sqr and pdo did not release H2S. When the sqr and pdo genes were deleted, the mutants also released H2S. Both sulfide-oxidizing and non-oxidizing heterotrophic bacteria were readily isolated from various environmental samples. The sqr and pdo genes were also common in the published marine metagenomic and metatranscriptomic data, indicating that the genes are present and expressed. Thus, heterotrophic bacteria actively produce and consume sulfide when growing on organic compounds under aerobic conditions. Given their abundance on Earth, their contribution to the sulfur cycle should not be overlooked.

Comparison of sulfide‐oxidizingSulfurimonasstrains reveals a new mode of thiosulfate formation in subsurface environments

“…Aerobic and phototrophic S 0 oxidizing bacteria and archaea have shown sulfur oxidation phenotypes similar to that of CVO, yielding sulfite, thiosulfate and sulfate as intermediates or end products (Brune, ; Kletzin, ; Rohwerder and Sand, ; Frigaard and Dahl, ; Xia et al ., ). However, in these microorganisms, oxygen‐dependent enzyme systems (e.g.…”

Homoacetogenesis and microbial community composition are shaped by pH and total sulfide concentration

“…The genus of Sphingobium has been reported to contain mostly aerobic and facultative anaerobic soil bacteria (Ushiba et al , 2003; Singh and Lal, 2009; Berney et al , 2014; Chaudhary et al , 2017; Esposti and Romero, 2017). It has also been reported to perform sulfur respiration (Xia et al , 2017), i.e. capable of producing H 2 S through reduction in organosulfur compounds and oxidizing this self‐produced H 2 S, under aerobic conditions.…”

OxyR senses reactive sulfane sulfur and activates genes for its removal in Escherichia coli

“…Our systematic study of H 2 S n stress unveiled that TrxA, TrxB, GrxB, GrxC and GrxD may function as a house-keeping machinery to prevent the buildup of intracellular RRS to toxic levels; OxyR-regulated GrxA, TrxC and KatG may function as emergency backups to deal environmentally confronted or abnormally over-accumulated sulfane sulfur. Glutathione redoxins and thioredoxins reduce sulfane sulfur to H 2 S that is released out of the cell for microorganisms growing under anaerobic conditions (Abe et al, 2007; Sato et al, 2011; Xia et al, 2017) . For bacteria or animal host with SQR, the released H 2 S is captured and oxidized back to sulfane sulfur under aerobic conditions (Lagoutte et al, 2010) .…”

“…For bacteria or animal host with SQR, the released H 2 S is captured and oxidized back to sulfane sulfur under aerobic conditions (Lagoutte et al, 2010) . For E. coli and bacteria without SQR, H 2 S will be released even under aerobic conditions (Li et al, 2019; Xia et al, 2017) .…”

“…On the flipside, elimination pathways are less investigated. Aerobic microorganisms may apply persulfide dioxygenase to remove excessive sulfane sulfur (Xia et al, 2017) , and the persulfide dioxygenase expression can be induced by sulfane sulfur via sulfane sulfur-sensing transcription factors (H et al, 2017; Lira et al, 2018; Luebke et al, 2014) .…”