Characterization of archaeal symbionts of sponges from the coral reef ecosystems of the Gulf of Mannar, Southeast coast of India.

Sponges accommodate a diverse group of microorganisms with varied metabolic capabilities. The bacterial associates of sponges are widely studied while our understanding of archaeal counterparts is scanty. In the present study, we report the archaeal associates of two sponges, (NCBI barcode: KX454492) and sp. (NCBI barcode: KX454495), found in the coral reef ecosystems of Gulf of Mannar, India. Archaea in the water column was predominated by members of class Halobacteria of Phylum (97%) followed by a minor fraction (3%) of sp. of phylum . Interestingly, was identified as the sole archaeal population associated with the two sponges studied, among which sp. occuppied 80 and 100% of the sequences in the clone library of and sp. respectively. Other archaea found in the were (10%) and unclassified ones (10%). The study identified sp. as a unique symbiotic archaeon of sponges, and sp. The existence of host driven factors in selecting specific associates from a diverse group of archaea in the environment may need further investigations.