Cultivation and metabolic versatility of novel and ubiquitous chemolithoautotrophic Campylobacteria from mangrove sediments

Abstract

Chemolithoautotrophic Campylobacteria spp. are generally associated with sulfide-rich environments, where they play a key role in the cycling of carbon, nitrogen, and sulfur. Yet, only a limited number of cultured isolates are currently available. In this study, we isolated seven potentially new species belonging to three new genera from mangrove sediments, which significantly expanded our understanding of the species diversity within the class Campylobacteria . These isolates demonstrated diverse and unique metabolic potentials for CO 2 fixation, sulfur oxidation, hydrogen oxidation, nitrogen metabolism, and oxygen respiration, making them well adapted to the sulfur-rich, nitrogen-limited, and low-oxygen habitats they inhabit. The frequent detection of these novel species in marine and mangrove sediments, as revealed by 16S rRNA gene sequences in public databases, indicates a potential preference for oxygen-limited environments. Overall, this study promotes our understanding of the in situ function and ecological role of Campylobacteria , especially in previously overlooked carbon-rich sediment ecosystems.