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Responses of Clostridia to oxygen: from detoxification to adaptive strategies

2021; Wiley; Volume: 23; Issue: 8 Linguagem: Inglês

10.1111/1462-2920.15665

1462-2920

Claire Morvan, Filipe Folgosa, Nicolas Kint, Miguel Teixeira, Isabelle Martin‐Verstraete,

Gut microbiota and health

Summary Clostridia comprise bacteria of environmental, biotechnological and medical interest and many commensals of the gut microbiota. Because of their strictly anaerobic lifestyle, oxygen is a major stress for Clostridia. However, recent data showed that these bacteria can cope with O 2 better than expected for obligate anaerobes through their ability to scavenge, detoxify and consume O 2 . Upon O 2 exposure, Clostridia redirect their central metabolism onto pathways less O 2 ‐sensitive and induce the expression of genes encoding enzymes involved in O 2 ‐reduction and in the repair of oxidized damaged molecules. While Faecalibacterium prausnitzii efficiently consumes O 2 through a specific extracellular electron shuttling system requiring riboflavin, enzymes such as rubrerythrins and flavodiiron proteins with NAD(P)H‐dependent O 2 ‐ and/or H 2 O 2 ‐reductase activities are usually encoded in other Clostridia. These two classes of enzymes play indeed a pivotal role in O 2 tolerance in Clostridioides difficile and Clostridium acetobutylicum . Two main signalling pathways triggering O 2 ‐induced responses have been described so far in Clostridia. PerR acts as a key regulator of the O 2 ‐ and/or reactive oxygen species–defence machinery while in C . difficile , σ B , the sigma factor of the general stress response also plays a crucial role in O 2 tolerance by controlling the expression of genes involved in O 2 scavenging and repair systems.