Microbial epibiotic community of the deep-sea galatheid squat lobster Munidopsis alvisca

Life at hydrothermal vent sites is based on chemosynthetic primary producers that supply heterotrophic microorganisms with substrates and generate biomass for higher trophic levels. Often, chemoautotrophs associate with the hydrothermal vent megafauna. To investigate attached bacterial and archaeal communities on deep-sea squat lobsters, we collected ten specimens from a hydrothermal vent in the Guaymas Basin (Gulf of California). All animals were identified as Munidopsis alvisca via morphological and molecular classification, and intraspecific divergence was determined. Amplicon sequencing of microbial DNA and cDNA revealed significant differences between microbial communities on the carapaces of M. alvisca and those in ambient sea water. Major epibiotic bacterial taxa were chemoautotrophic Gammaproteobacteria, such as Thiotrichaceae and Methylococcaceae, while archaea were almost exclusively represented by sequences affiliated with Ca. Nitrosopumilus. In sea water samples, Marine Group II and III archaea and organoheterotrophic Alphaproteobacteria, Flavobacteriia and Planctomycetacia were more dominant. Based on the identified taxa, we assume that main metabolic processes, carried out by M. alvisca epibiota, include ammonia, methane and sulphide oxidation. Considering that M. alvisca could benefit from sulphide detoxification by its epibiota, and that attached microbes are supplied with a stable habitat in proximity to substrate-rich hydrothermal fluids, a mutualistic host-microbe relationship appears likely.

Automated summary

Life at hydrothermal vent sites relies on chemosynthetic primary producers supplying substrates for heterotrophic microorganisms and biomass for higher trophic levels. Bacterial and archaeal communities attached to deep-sea squat lobsters differ significantly from those in ambient sea water. The epibiotic bacteria on the lobsters are mainly chemoautotrophic Gammaproteobacteria, while archaea are predominantly affiliated with Ca. Nitrosopumilus. Sea water samples have a higher abundance of Marine Group II and III archaea, as well as organoheterotrophic Alphaproteobacteria, Flavobacteriia, and Planctomycetacia. The identified taxa suggest that the main metabolic processes carried out by the lobster epibionts include ammonia, methane, and sulphide oxidation. A mutualistic host-microbe relationship is likely due to the lobster benefiting from sulphide detoxification by its epibionts.