Genetic techniques were employed to investigate the archaeal, bacterial and eukaryotic communities associated with the Antarctic sponges Kirkpatrickia varialosa, Latrunculia apicalis, Homaxinella balfourensis, Mycale acerata and Sphaerotylus antarcticus. The sponges and seawater for the analyses were obtained from sites in McMurdo Sound: adjacent to McMurdo Station (MM), Scott Base (SB) and Cape Armitage (CA).Rarefaction analysis was performed to determine the number of unique bacterial clones as a proportion of the estimated total diversity.Archaeal PCR product was not detected from seawater, H. balfourensis or S. antarcticus samples. 150 archaeal clones (50 each from L. apicalis, K. varialosa, and M. acerata ) were screened by RFLP analysis, 4 unique operational taxonomic units (OTUs) wre observed. RFLP analysis screened 250 sponge-derived bacterial clones, 61 were unique OTUs not detected during examination of 160 seawater-derived clones and were subsequently sequenced for phylogenetic determination. Of the 160 seawater bacterial clones, 103 exhibited unique banding patterns, creating distinct seawater operational taxonomic units (OTUs).The phylogenetic affiliation of sponge-derived bacteria was assessed by 16S rRNA sequencing of cloned DNA fragments. Denaturing gradient gel electrophoresis (DGGE) was used to determine the profiles of 18S rRNA-defined eukaryotic populations from replicate sponge specimens at the 3 Antarctic sites. Samples analysed by DGGE were K. varialosa (K), L. apicalis (L), M. acerata (M) and seawater (SW). 2-4 replicates were used per sample type.Neighbour-joining phylogenetic trees were formed from analysis of: 889 bp of 16S rRNA gene sequence from Antarctic archaeal clones 1-4; 857 bp of 16S rRNA gene sequence from Antarctic bacterial clones; and 304 bp of bacterial 16S rRNA gene sequence retrieved from DGGE. Branches were also found using the Fitch-Margoliash or maximum parsimony methods.The bacterial communities associated with Antarctic sponges primarily clustered within the Gamma and Alpha proteobacteria and the Cytophaga/Flavobacterium of Bacteroidetes group.GenBank Accession Numbers were assigned to: 4 unique Antarctic archaeal sequences detected in M. acerata (AY320198, AY320199, AY320200, AY320201).
The study aimed to describe the microbial species composition, the stability of the host-bacterium associations and the spatial variability in sponge-derived microbial communities.
54 sponge-derived unique bacterial clones which produced suitable sequence data for phylogenetic analysis, GenBank Accession Numbers in brackets (AY321378, AY321379, AY321380, AY321381, AY321382, AY321383, AY321384, AY321385, AY321386, AY321387, AY321388, AY321389, AY321390, AY321391, AY321392, AY321393, AY321394, AY321395, AY321396, AY321397, AY321398, AY321399, AY321400, AY321401, AY321402, AY321403, AY321404, AY321405, AY321406, AY321407, AY321408, AY321409, AY321410, AY321411, AY321412, AY321413, AY321414, AY321415, AY321416, AY321417, AY321418, AY321419, AY321420, AY321421, AY321422, AY321423, AY321424, AY321425, AY321426, AY321427, AY321428, AY321429, AY321430, AY321431, AY321432); 10 bands for which high quality eukaryotic sequence data was obtained (AY320202, AY320203, AY320204, AY320205, AY320206, AY320207, AY320208, AY320209, AY320210, AY320211); and high-quality sequences for 19 bacterial bands (AY320212, AY320213, AY320214, AY320215, AY320216, AY320217, AY320218, AY320219, AY320220, AY320221, AY320222, AY320223, AY320224, AY320225, AY320226, AY320227, AY320228, AY320229, AY320230).
