Novel Fungal Diversity In The Mangrove Sediment Revealed By Long- And Short-Metabarcoding Sequencing Data
Ming Sheng Ng1,2, Edward Cheung1, Nathaniel Soon2, Benjamin J. Wainwright2 and Ying Chang1,2*
Department of Biological Sciences, National University of Singapore, Singapore
Science Division, Yale-NUS college, Singapore
Mangroves are among the most carbon-rich ecosystems, owing to the high productivity of mangrove trees and the low decomposition rate of organic carbon in the largely anoxic sediment. Microorganisms are the key players in the carbon cycle and their community structure is tightly linked to the carbon emissions from mangrove sediments. Thus far most of the research efforts on mangrove sediment microbes have focused on the prokaryotes, while fungi are left nearly untouched.
In this study, we took an approach combining the traditional ITS2-based Illumina metabarcoding and the rDNA-based PacBio long metabarcoding sequencing to characterize the fungal diversity along a 1-m vertical axis in Singapore mangroves. To investigate the interactions between fungi and other microorganisms, we also examined the bacterial and archaeal communities in the same sediment samples using 16S V4 region as the barcode. While the diversity and richness of fungal community decreased with depth, the overall community composition was poorly structured by depth. Co-occurrence network analysis based on ITS2 and 16S-v4 data showed that on fungi were the more influential group in comparison to prokaryotes at the surface and subsurface layer, but less so in the deeper sediments. Phylogenetic inference based on rDNA data clustered significant portions of ASVs within the early-diverging lineages of Chytridiomycota, Aphelida and Cryptomycota. In addition, all three groups showed high phylogenetic diversity and many ASVs were found distantly related to the known reference sequences, suggesting that novel fungal diversity awaits discovery in the mangrove sediments.