Hydrogen sulfide can inhibit and enhance oxygenic photosynthesis in a cyanobacterium from sulfidic springs. (4th March 2015)

• Record Type: Journal Article
• Authors: Klatt, Judith M.; Haas, Sebastian; Yilmaz, Pelin; de Beer, Dirk; Polerecky, Lubos
• Is Part Of: Environmental microbiology. Volume 17:Number 9(2015:Sep.)
• Page Start: 3301
• Page End: 3313
• Publication Date: 2015-03-04
• Subjects: Microbial ecology -- Periodicals; Environmental Microbiology -- Periodicals; 579.17
• DOI: 10.1111/1462-2920.12791
• Languages: English
• ISSNs: 1462-2912

Abstract

<abstract abstract-type="main"> <title>Summary</title> <p>We used microsensors to investigate the combinatory effect of hydrogen sulfide (H<sub>2</sub>S) and light on oxygenic photosynthesis in biofilms formed by a cyanobacterium from sulfidic springs. We found that photosynthesis was both positively and negatively affected by H<sub>2</sub>S: (i) H<sub>2</sub>S accelerated the recovery of photosynthesis after prolonged exposure to darkness and anoxia. We suggest that this is possibly due to regulatory effects of H<sub>2</sub>S on photosystem I components and/or on the Calvin cycle. (ii) H<sub>2</sub>S concentrations of up to 210 μM temporarily enhanced the photosynthetic rates at low irradiance. Modelling showed that this enhancement is plausibly based on changes in the light‐harvesting efficiency. (iii) Above a certain light‐dependent concentration threshold H<sub>2</sub>S also acted as an inhibitor. Intriguingly, this inhibition was not instant but occurred only after a specific time interval that decreased with increasing light intensity. That photosynthesis is most sensitive to inhibition at high light intensities suggests that H<sub>2</sub>S inactivates an intermediate of the oxygen evolving complex that accumulates with increasing light intensity. We discuss the implications of these three effects of H<sub>2</sub>S in the context of cyanobacterial photosynthesis under conditions with diurnally fluctuating light and H<sub>2</sub>S concentrations, such as those occurring in microbial mats and biofilms.</p> </abstract>