Meta-analysis cum machine learning approaches address the structure and biogeochemical potential of marine copepods associated bacteriobiome

Copepods are the dominant members of the zooplankton community and the most abundant form of life. It is imperative to obtain insights into the Copepod Associated Bacteriobiomes (CAB) to identify specific bacterial taxa associated within a copepod and to understand how they vary between different copepods. Analysing the potential genes within the CAB may reveal their intrinsic role in the biogeochemical cycles. For this, machine-learning models and PICRUSt2 analysis were deployed to analyse 16S rDNA gene sequences (~16.5 million reads) of CAB belonging to five different copepod genera viz., Acartia spp., Calanus spp., Centropages sp., Temora spp., and Pleuromamma spp. Overall, we predict 50 sub-OTUs (Gradient Boosting Classifier) as important s-OTUs in five copepod genera. Among these, 15 s-OTUs were predicted as important s-OTUs in Calanus spp. and 20 s-OTUs as important s-OTUs in Pleuromamma spp. Four bacterial genera Acinetobacter johnsonii, Phaeobacter, Vibrio shilonii and Piscirickettsiaceae were identified as important s-OTUs in Calanus spp., and bacterial genera Marinobacter, Alteromonas, Desulfovibrio, Limnobacter, Sphingomonas, Methyloversatilis, Enhydrobacter and Coribacteriaceae were predicted as important s-OTUs in Pleuromamma spp. for the first time. Our meta-analysis revealed that the CAB of Pleuromamma spp. had a high proportion of potential genes responsible for methanogenesis and nitrogen fixation, whereas CAB of Temora spp. had a high proportion of potential genes involved in assimilatory sulphate reduction, denitrification and cyanocobalamin synthesis. The CAB of Pleuromamma spp. and Temora spp. have potential genes accountable for iron transport.