The bacterial diversity associated with eroding sponges belonging to the Cliona viridis species complex is scarcely known. Cliona thomasi described from the West Coast of India is a new introduction to the viridis species complex. In this study, we determined the bacterial diversity associated with C. thomasi using next-generation sequencing. The results revealed the dominance of Proteobacteria followed by Cyanobacteria, Actinobacteria and Firmicutes. Among Proteobacteria, the Alphaproteobacteria were found to be the most dominant class. Furthermore, at the genus level, Rhodothalassium were highly abundant followed by Endozoicomonas in sponge samples. The beta-diversity and species richness measures showed remarkably lower diversity in Cliona thomasi than the ambient environment. The determined lower bacterial diversity in C. thomasi than the environmental samples, thus, categorized it as a low microbial abundance (LMA). Functional annotation of the C. thomasi–associated bacterial community indicates their possible role in photo-autotrophy, aerobic nitrification, coupling of sulphate reduction and sulphide oxidization. The present study unveils the bacterial diversity in bioeroding C. thomasi, which is a crucial step to determine the functions of the sponge holobiont in coral reef ecosystem.

与属于Cliona viridis物种复合体的侵蚀海绵相关的细菌多样性鲜为人知。从印度西海岸描述的Cliona thomasi是对viridis物种复合体的新介绍。在这项研究中，我们使用下一代测序确定了与梭状芽孢杆菌相关的细菌多样性。结果显示，变形菌门占主导地位，其次是蓝藻门、放线菌门和厚壁菌门。在 Proteobacteria 中，Alphaproteobacteria 被发现是最主要的类别。此外，在属水平上，Rhodothalassium含量很高，其次是Endozoicomonas在海绵样品中。Beta 多样性和物种丰富度测量表明Cliona thomasi 的多样性显着低于周围环境。C. thomasi 中确定的细菌多样性低于环境样品，因此，将其归类为低微生物丰度 (LMA)。C. thomasi相关细菌群落的功能注释表明它们在光自养、好氧硝化、硫酸盐还原和硫化物氧化的耦合中可能发挥作用。本研究揭示了生物侵蚀C. thomasi 中的细菌多样性，这是确定海绵全息生物在珊瑚礁生态系统中的功能的关键步骤。