Phylogenetic Diversity Of Sponge Associated Fungi And The Urease From Sponge-associated Microbs

Compared to the diversity of sponge-associated bacteria, the diversity ofsponge-associated fungi remain largely unknown, particularly the community-levelactivity of fungi associated with sponge remains unknown. In this study, weinvestigated and compared the fungi community profiles of two marine spongesTheonella swinhoei and Xestospongia testudinaria from the South China Sea by18SrRNA vs18S rRNA gene analysis. Three fungal phyla Ascomycota, Basidiomycotaand Blastocladiomycota were detected and the transcriptional activity of18S rRNAgenes indicated that the majority of sponge-associated fungi were of protein synthesispotential. OTUs affiliated with Pezizomycotina (mainly Eurotiales, Pleosporales andCapnodiales) dominated the fungal communities in two sponges, whereasBasidiomycota was poorly represented by OTUs of18S rRNA gene. Particularly,Blastocladiomycota was found in sponge for the first time. This study providedinsights into the protein synthesis potential of sponge-associated fungi communities,which played a basis for understanding the ecological role of fungi and theirassociation with sponge host.Urea represents one of the dominant organic nitrogenous compounds in the oligotrophicoceans. Compared to the knowledge of nitrogen transformation of nitrogen fixationammonia oxidization, nitrate and nitrite reduction, the urea utilization in sponges remainsnearly unknown. Phylogenetically diverse bacterial ureC genes were detected in the totalRNA of sponge microbiota, i.e.,8operative taxonomic units (OTUs) in ureC-R library.Blast and phylogenetic analyses showed that most of the ureC sequences were similarwith the microbial components in sponge X. testudinaria. In addition, we tried statisticalmedium optimization of urease produced bacteria Bacillus licheniformis B81seperated from sponge. The optimized medium were glucose25g，peptone12.5g，beef-extracts5g，Yeast extract6.5g，KH2PO42g，NaCl1g，urea0.625%，Ni(NO3)2 0.00625%,1L ASW.Urease activity were increased170%. This study highlighted therole of sponge bacterial symbionts in the urea utilization, extending our understanding ofnitrogen cycling mediated by sponge microbes.