Culture-dependent and 16S metagenomics analyses of blue-bell tunicate Clavelina coerulea microbiome

The season diversity of the microbial associated with the blue bell tunicate, Clavelina coerulea was investigated in this study. Marine tunicate samples were collected from Pulau Bidong, Terengganu during the pre-monsoon (October) and post-monsoon seasons (May). Using the culture dependent approach, bacteria were isolated, morphologically characterized, and genetically identified by sequencing the 16S rDNA. Forty-six (46) bacteria isolates were obtained with significant variation observed in both seasons. However, majority of the bacterial isolated belonged to the class Y-Proteobacteria. Microbiota enumeration was also done using the culture-independent approaches and Next Generation Sequencing (NGS) technology. Result obtained revealed 764,742 valid reads belonging to 343 total operational taxonomic units (OTUs). Of all the 11 phyla associated with the tunicate, Proteobacteria, Bacteroidetes, Firmicutes, Actinobacteria and Acidobacteria were the most prevalent in both seasons. Also, 49 families were found in both season out of the 91 microbiota identified. The families left were exclusive to the post and pre-monsoon season (20 and 22 families respectively). Since salinity was the most varied water quality observed in the current study, it was thought to be one of the major drivers of the seasonal variation in bacterial diversity associated with the blue bell tunicate, C. coerulea.