Stress Response of <i>Mesosutterella multiformis</i> Mediated by Nitrate Reduction

• Main Authors: Nao Ikeyama, Moriya Ohkuma, Mitsuo Sakamoto
• Format: Article
• Language: English
• Published: MDPI AG 2020-12-01
• Series: Microorganisms
• Subjects: <i>Mesosutterella multiformis</i>; the family <i>Sutterellaceae</i>; nitrate reduction; nitrate; nitrite; filament formation
• Online Access: https://www.mdpi.com/2076-2607/8/12/2003

Bacterial stress responses are closely associated with the survival and colonization of anaerobes in the human gut. <i>Mesosutterella multiformis</i> JCM 32464^T is a novel member of the family <i>Sutterellaceae</i>, an asaccharolytic bacterium. We previously demonstrated energy generation via heme biosynthesis, which is coupled with nitrate reductase. Here, physiological and morphological changes in <i>M. multiformis</i> induced by exposure to nitrate were investigated. The ability of <i>M. multiformis</i> to reduce nitrate was determined using a colorimetric assay. A unique morphology was observed during nitrate reduction under anaerobic conditions. The association between nitrate concentration and cell size or cellular fatty acid composition was evaluated. Nitrate-induced responses of <i>M. multiformis</i> were compared to those of related species. An increase in cellular filamentation and the ratio of saturated: unsaturated fatty acids was mediated specifically by nitrate. This indicates a decrease in cell fluidity and low leakage. Furthermore, a similar response was not observed in other related species cultured in the presence of nitrate. Hence, the nitrate-induced stress response in new anaerobes such as <i>M. multiformis</i> was demonstrated. The response could also be involved in the conservation of menaquinones and the maximization of nitrate reduction.