Functional Profiling Reveals Altered Metabolic Activity in Divers’ Oral Microbiota During Commercial Heliox Saturation Diving

Abstract

Background: The extreme environment in saturation diving affects all life forms, including the bacteria that reside on human skin and mucosa. The oral cavity alone is home to hundreds of different bacteria. In this study, we examined the metabolic activity of oral bacteria from healthy males during commercial heliox saturation diving. We focused on environmentally induced changes that might affect the divers’ health and fitness.Methods: We performed pathway abundance analysis using PICRUSt2, a bioinformatics software package that uses marker gene data to compute the metabolic activity of microbial communities. The analysis is based on 16S rRNA metagenomic data generated from the oral microbiota of 23 male divers before, during, and after 4weeks of commercial heliox saturation diving. Environmentally induced changes in bacterial metabolism were computed from differences in predicted pathway abundances at baseline before, versus during, and immediately after saturation diving.Results and Conclusion: The analysis predicted transient changes that were primarily associated with the survival and growth of bacteria in oxygenated environments. There was a relative increase in the abundance of aerobic metabolic pathways and a concomitant decrease in anaerobic metabolic pathways, primarily comprising of energy metabolism, oxidative stress responses, and adenosylcobalamin biosynthesis. Adenosylcobalamin is a bioactive form of vitamin B12 (vitB12), and a reduction in vitB12 biosynthesis may hypothetically affect the divers’ physiology. While host effects of oral bacterial vitamin metabolism are uncertain, this is a finding that concurs with the existing recommendations for vitB12 supplements as part of the divers’ diet, whether to boost antioxidant defenses in bacteria or their host or to improve oxygen transport during saturation diving.

Microbiota dysbiosis in odontogenic rhinosinusitis and its association with anaerobic bacteria

“…Interestingly, when comparing the functional categories of the bacterial OTUs by using PICRUSt2 17 , we observed a decrease in the abundance of microbes involved in several TCA cycle related metabolic pathways in ORS group (mean proportion difference > 0.5 as compared to nORS group), which is known much important for aerobic growth. An increase of pathways involved in ORS group were found mainly in the vitB12 biosynthesis pathways that was reported significantly decreased in the oral microbiota filled with elevated partial pressures of oxygen during diving 27 .…”

Predicting Personalized Diets Based on Microbial Characteristics between Patients with Superficial Gastritis and Atrophic Gastritis

“…Furthermore, AG_N-associated beneficial bacteria, Weissella and Bacteroides, produce bacteriocins to inhibit pathogens and ameliorate inflammation, which can be considered as a protective role for AG_N [36,37]. Peptostreptococcus possessing lactic acid and Atopobium producing H2S are acid-forming bacteria that are not conducive to the balance of stomach acid and can be used as indicators of AG_N progression [38,39]. However, the number of harmful bacteria was significantly increased in patients with AG_P.…”

Oxy-Inflammation in Humans during Underwater Activities

“…Mrakic-Sposta et al [ 178 ] found an increase in oxidative stress-related biomarkers, including 8-deoxyguanosine, 3-nitrotyrosine, and neopterin, due to prolonged exposure to higher pO 2 value. Furthermore, saturation divers showed elevated concentrations of IL-6, the first cytokine released into the circulation during inflammation response [ 10 , 178 , 179 , 180 , 181 , 182 ], and creatinine in the post-dive stage, reflecting the systemic effects induced by hyperoxia, hyperbaric pressure, and exercise at depth [ 150 ].…”