Transcriptional Response of Staphylococcus aureus to Sunlight in Oxic and Anoxic Conditions

Abstract

The transcriptional response of Staphylococcus aureus strain Newman to sunlight exposure was investigated under both oxic and anoxic conditions using RNA sequencing to gain insight into potential mechanisms of inactivation. S. aureus is a pathogenic bacterium detected at recreational beaches which can cause gastrointestinal illness and skin infections, and is of increasing public health concern. To investigate the S. aureus photostress response in oligotrophic seawater, S. aureus cultures were suspended in seawater and exposed to full spectrum simulated sunlight. Experiments were performed under oxic or anoxic conditions to gain insight into the effects of oxygen-mediated and non-oxygen-mediated inactivation mechanisms. Transcript abundance was measured after 6 h of sunlight exposure using RNA sequencing and was compared to transcript abundance in paired dark control experiments. Culturable S. aureus decayed following biphasic inactivation kinetics with initial decay rate constants of 0.1 and 0.03 m2 kJ−1 in oxic and anoxic conditions, respectively. RNA sequencing revealed that 71 genes had different transcript abundance in the oxic sunlit experiments compared to dark controls, and 18 genes had different transcript abundance in the anoxic sunlit experiments compared to dark controls. The majority of genes showed reduced transcript abundance in the sunlit experiments under both conditions. Three genes (ebpS, NWMN_0867, and NWMN_1608) were found to have the same transcriptional response to sunlight between both oxic and anoxic conditions. In the oxic condition, transcripts associated with porphyrin metabolism, nitrate metabolism, and membrane transport functions were increased in abundance during sunlight exposure. Results suggest that S. aureus responds differently to oxygen-dependent and oxygen-independent photostress, and that endogenous photosensitizers play an important role during oxygen-dependent indirect photoinactivation.

Microbiomes of Inflammatory Thoracic Aortic Aneurysms Due to Giant Cell Arteritis and Clinically Isolated Aortitis Differ From Those of Non-Inflammatory Aneurysms

“…Porphyrins are a group of metabolites that have previously been linked to inflammation in acne via production of reactive oxygen species [36]. Several microbial species have been found to increase the secretion of porphyrins and upregulate enzymes responsible for porphyrin metabolism when exposed to hemin, an iron containing porphyrin found in hemoglobin [37, 38]. Consistent with these reports, we found that porphyrin metabolism was predicted to be upregulated in our aortitis group.…”

Effect of sunlight and salinity on the survival of pathogenic and non‐pathogenic strains of Vibrio parahaemolyticus in water microcosms

“…This phototoxicity, which is considered as a major contributor of bacterial die-off in the marine ecosystem (Lozano et al, 2020;Zaafrane & Maatouk, 2012), is the result of reactive oxygen species (ROS) such as superoxide, hydrogen peroxide, and hydroxyl radical generated by a natural or an artificial photosynthesizers when they are exposed to sunlight radiations (Imlay, 2019;Zinser, 2018). The ROS action has been recognized as an important factor causing DNA, protein, and lipid alteration and ultimately causes bacteria death (Ezraty et al, 2017;Hong et al, 2019;Matallana-Surget & Wattiez, 2013;McClary & Boehm, 2018).…”

Effects of Yellow Light on Airborne Microbial Composition and on the Transcriptome of Typical Marker Strain in Ward

“…For these three representative vital pathogenic bacteria of nosocomial infection, many studies have revealed the inactivation effect of visible light. For example, McClary and Boehm irradiated S. aureus with full spectrum light 6 hours and measured transcript abundance by RNA sequencing to find out that S. aureus was inhibited by full spectrum sunlight [ 20 ]. Exposing S. aureus , P. aeruginosa , and E. coli strains to a single blue laser irradiation (450 nm) and counting the number of living bacteria, De Sousa et al concluded that blue light significantly inhibited the growth of bacteria under low-intensity conditions [ 21 ].…”