| A large number of novel compounds with significant medical potential have been isolated from sponges, motivating efforts to develop cultivation techniques for the sustainable production of sponge biomass. The examination and isolation of microbial populations associated with marine sponges has similarly drawn great interest due to the discovery of previously undescribed bacteria within sponge tissues, some of which have been found be the source of these compounds. As the association of sponges with bacteria is such a widespread phenomenon, microorganisms may also play an essential part in the metabolism and physiology of these animals. This thesis represents an effort to better understand the relationships between sponges, their associated microbial communities and the applicability of three dimensional cell culture techniques for the cultivation of sponges in an effort to understand some of the factors which may influence the growth of these simple animals in vitro.;With over 6000 species of marine sponges, surprisingly little attention has been paid to the taxonomic affiliation of the sponge species being investigated. The phylogeny of the Demospongiae is poorly defined but overgeneralized statements have been made regarding sponge metabolism and physiology, the success of reported cell cultures and the diversity of microbial association, in this large phyla of animals. Examination of the phylogeny of sponges with respect to their success in cell culture revealed that a degree of taxonomic specificity exists, and as such gave an explanation for the failure of attempted cultures of Axinella polycapella and the relative success of Clathria (Microciona) prolifera.;The bacterial population of the marine sponge Axinella corrugata , a tropical sponge species which had been put forward as a model organism for cell culture was explored, motivated by the possibility that bacteria in the sponges native habitat are integral to their physiology and metabolism. Further more, through the characterization of bacterial phylotypes, may be possible to rationally design conditions for the isolation of bacteria derived from sponges. To begin to understand the interaction between sponges and their bacterial associates, 16S rDNA shotgun libraries were constructed for 6 samples of this sponge, exploring the temporal and individual differences in their bacterial population. Nine persistent phylotypes were found. Phylogenetic assessment of the identity of these phylotypes may give insight into their cultivablility.;In the examination of the microbial populations of Axinella corrugata an archaeal phylotype closely related to Cenarchaeum symbiosum , first described in the sponge Axinella aff. emphmexicana, was discovered. Other subsequent reports on similar archaea were also made in other axinellid sponges, Axinella damicornis, Axinella verrucosa and a third axinellid sponge, prompting the investigation of the breadth of this sponge-specific interaction. Twenty three poriferean species for the presence of archaea, focusing on the family Axinellidae. Nineteen showed evidence of archaeal communities from Group C1a (Marine Group I; Crenarchaeota), with three of these also showing evidence of Archaea from Group E2 (Marine Group II; Euryarchaeota). Within the Crenarchaeota, two strongly-supported sponge-specific Glades were identified corresponding to the sponge family Axinellidae, and a novel sponge Glade denoted Clade C. These findings suggest that these archaea have evolved closely with their sponge hosts and are likely to play an important role in their metabolism. |
