Diversity and sulfur oxidation characteristics of cultivable sulfur oxidizing bacteria in hydrothermal fields of Okinawa Trough

Abstract:

The unique geological environment in the hydrothermal fields of Okinawa Trough has formed special biological communities. Sulfur-oxidizing bacteria play an important role in the hydrothermal ecosystem as a key participant in the biogeochemical cycle. [Objective] To study the diversity and sulfur oxidation activity of cultivable sulfur-oxidizing bacteria in the hydrothermal fields of the Okinawa Trough. [Methods] Sulfur-oxidizing bacteria in sediment samples from different sites in the hydrothermal fields of Okinawa Trough were enriched, cultured and isolated using different culture media. The 16S rRNA sequence was used to identify sulfur-oxidizing bacteria and to carry out phylogenetic analysis. Sulfur oxidation activity was measured using the iodometric method. [Results] In total 85 strains of sulfur-oxidizing bacteria were isolated and identified, belonging to Alphaproteobacteria, Gammaproteobacteria, Actinobacteria and Firmicutes. The dominant genera of culturable sulfur-oxidizing bacteria were Hydrogenovibrio, Labrenzia, Thalassospira and Marinobacter. Seven typical sulfur-oxidizing strains showed different degradation activity on sodium thiosulfate that ranged from 31% to 100%. Halomonas titanicae SOB56, Marinobacter antarcticus SOB93, Thioclava indica SOB107 and Hydrogenovibrio thermophiles CJG136 could completely degrade sodium thiosulfate.[Conclusion] The sulfur-oxidizing bacteria in the hydrothermal fields of Okinawa Trough are abundant in diversity, providing experimental materials and theoretical basis for studying the sulfur cycle in hydrothermal regions. A variety of sulfur oxidizing strains have greatly enriched the bacterial species resources and laid the foundation for exploring the energy pathways and molecular mechanisms of sulfur cycle.