Marine sponges are filter-feeding metazoans that can host complex microbial communities which comprise as much as 35% of total sponge biomass. In this thesis I have employed high-throughput, next-generation sequencing technologies to study the sponge microbiota at two different scales. Firstly, I studied complex communities associated with different sponge assemblages, then subsequently conducted an in-depth investigation of an enigmatic sponge symbiont which has largely escaped attention until now. Analysis of the marine sponge microbiota poses unique conceptual and analytical challenges, as microbial species may number in the thousands. One way to overcome this issue is to consider only the persistent and/or abundant species, i.e. the „core‟ community. While this approach has been widely used to analyse diverse biological systems, including sponge microbiota, to date its robustness has not been rigorously evaluated. Thus, in this thesis I systematically evaluated the applicability of the core microbiota approach for the complex microbial communities of three Xestospongia species from southeast Sulawesi (Indonesia), using 16S rRNA gene-based amplicon sequencing (Illumina MiSeq). Different factors for OTU selection were then considered to generate a set of different core communities, including percentage occurrence, minimum abundance threshold and sample set selection. Alpha- and beta- diversity analyses conducted on the core communities were largely insensitive to major changes in core microbiota definition, thus revealing the robustness of this approach when considering closely related sponge species. Furthermore, none of the applied core definitions altered ecological network structure summarising interactions among bacteria within the sponges. Sponge reefs often comprise an array of different and sometimes phylogenetically distant sponge species, with most of them hosting distinct microbial communities. Thus, to further assess the strength and sensitivity of the core microbiota approach in complex sponge assemblages, I analysed the associated bacterial communities of 20 co-occurring sponge species from the south coast of Wellington (New Zealand), using the same 16S rRNA genebased amplicon sequencing approach described above. The application of different core definitions resulted in a marked (and uneven at sponge species level) decrease in bacterial OTU and phylum richness. As a consequence of this decrease in richness, alpha- and betadiversity patterns changed significantly. Therefore, although the application of a core microbiota approach may seem appropriate in closely related systems (e.g. congeneric sponges), I showed that this approach can have a profound influence on the results obtained when studying complex host species assemblages. While sponge microbiota surveys have tended to focus on the study of a few dominant symbionts, other, less prominent members of these diverse communities remain poorly understood. To shed light on one abundant but under-studied community member, I investigated the distribution and phylogenetic status of the sponge symbiont SAUL (spongeassociated unclassified lineage). A meta-analysis of the available literature revealed the ubiquitous distribution of this clade and its association with taxonomically different sponge species. Additionally, the phylogeny of SAUL was revisited using both a 16S rRNA genebased phylogeny and a concatenated set of single-copy marker genes. Phylogenetic analyses revealed the monophyletic nature of this clade and, consequently, I suggest its status as a novel putative candidate phylum. To provide the first information on the putative function of SAUL clade members, I conducted a comprehensive analysis of two draft genomes assembled from sponge metagenome data, revealing novel insights into the physiology of this ubiquitous symbiont. This included the identification of genes encoding several symbiosis factors such as eukaryotic-like repeats (involved in symbiont recognition) and the presence of a CRISPR-Cas defense system, as well as the genomic capability of secondary metabolite production. This thesis represents the first systematic evaluation of the widely applied core microbiota approach, and highlights the importance of testing data sensitivity before its implementation. Moreover, the phylogenetic and genomic analyses of the SAUL lineage conducted here have contributed to expand the knowledge of less prominent and poorly understood sponge-associated microorganisms.

The authors "have intended to make the forefront of sponge research easily accessible to the nonspecialist, illustrating the state of the art of the field,and presenting current controversial issues. For the specialist, we wanted this monograph to be a handy, valuable update on the most recent advances in sponge science."--p. x

Sponges (phylum Porifera) are known to be very rich sources for bioactive compounds, mainly secondary metabolites. Main efforts are devoted to cell- and mariculture of sponges to assure a sustainable exploitation of bioactive compounds from biological starting material. These activities are flanked by improved technologies to cultivate bacteria and fungi which are associated with the sponges. It is the hope that by elucidating the strategies of interaction between microorganisms and their host (sponge), by modern cell and molecular biological methods, a more comprehensive cultivation of the symbiotic organisms will be possible. The next step in the transfer of knowledge to biotechnological applications is the isolation, characterization and structural determination of the bioactive compounds by sophisticated chemical approaches.

he book "Sponge-Associated Microorganisms: Biopotential Studies" explores the various microorganisms associated with marine sponges and their potential applications. The author, M. Sharmal Kumar, focuses on the biopotential of these microorganisms and their role in developing new pharmaceuticals, bioactive compounds, and other natural products. The book provides an in-depth understanding of the diversity of sponge-associated microorganisms and their ecological significance. The author also discusses the importance of marine sponges as a source of bioactive compounds and the potential applications of these compounds in various fields, including medicine, agriculture, and industry. The book covers various topics such as isolation and identification of sponge-associated microorganisms, culture techniques, and methods of screening for bioactive compounds. It also provides insights into the molecular biology of sponge-associated microorganisms and their potential in biotechnology. Overall, "Sponge-Associated Microorganisms: Biopotential Studies" is a valuable resource for researchers, scientists, and students interested in marine microbiology, biotechnology, and natural product discovery. The book is written in an accessible style and is suitable for both beginners and experts in the field.

This book summarizes the latest advances in sponge science through a concise selection of studies presented at the VIII World Sponge Conference. The collection of articles reflects hot, ongoing debates in molecular research, such as the monophyletic versus paraphyletic nature of the sponge group, or the new awareness on pros and cons of standard barcodes and other markers in sponge taxonomy and phylogeny. It also features articles showing how the new sequencing technologies reveal the functional and phylogenetic complexity of the "microbial universe" associated to sponge tissues. The ecological interactions of sponges, the effects of nutrients and pollutants, the variability in reproductive patterns, and the processes generating genotypic and phenotypic variability in sponge populations are covered in several contributions. Zoogeography, population structure and dynamics are also approached with both traditional and molecular tools. The effect of anthropogenic disturbance on the natural environment finds its place in this volume with papers dealing with metal accumulation and the potential role of sponges as biomonitors. Biodiversity data from unexplored tropical and deep sea areas are presented. We hope readers will enjoy the selection of papers, which we believe represent collectively a significant contribution to our current understanding of sponges. Previously published in Hydrobiologia, vol. 687, 2012

The main focus of this book entitled is to provide an up-to-date coverage of marine sponges and their significance in the current era. This book is an attempt to compile an outline of marine sponge research to date, with specific detail on these bioactive compounds, and their pharmacological and biomedical applications. The book encompasses twenty chapters covering various topics related to Marine Sponges. Initial couple of chapters deal about the worldwide status of marine sponge research, the recent findings regarding dynamics of sponges, and several interesting research areas, that are believed to be deserving of increased attention. Variety of sponges, their toxicology, metagenomics, pharmaceutical significance and their possible applications in biomedicine has been discussed in detail. The second half of this part includes chapters on chemical ecology of marine sponges followed by the discussion on importance of bioeroding sponges in aquaculture systems. The following four chapters of the book deal majorly with the chemical molecules of marine sponges. In the fifth chapter, marine sponge-associated actinobacteria and their pysicochemical properties have been discussed followed by their bioactive potential. The biological application of marine sponges has been presented in later chapters with the classification of biologically active compounds being explored in detail. The second half of the book presents the vast repertoire of secondary metabolites from marine sponges, which include terpenoids, heterocycles, acetylenic compounds, steroids and nucleosides. Further, the bioactive potential of these compounds has also been discussed. One of the constituent chapter elaborates the bioactive alkaloids from marine sponges namely, pyridoacridine, indole, isoquinolene, piperidene, quinolizidine, steroidal and bromotyrosine alkaloids isolated from them. In the next couple of chapters, important sponge polymers and the anticancer effects of marine sponge compounds have been presented. The most interesting aspect of sponge biology is their use in biomedical arena. An effort has been made in this book, to cover the major constituents of sponges and their biomedical potentials. The major portion of sponge body is composed of collagen and silica and used in tissue engineering as scaffold material. This part of the book compiles chapters delineating the isolation of sponge biomaterials including collagen and their use in medical diagnostics. Overall, this book would be an important read for novice and experts in the field of sponge biology.

Deliberately breaking with the classical biology-centered description of marine organisms and their products, this reference emphasizes microbial technology over basic biology, setting it apart from its predecessors. As such, it systematically covers the technology behind high-value compounds for use as pharmaceuticals, nutraceuticals or cosmetics, from prospecting to production issues. Following a definition of the field, the book goes on to address all industrially important aspects of marine microbial biotechnology. The first main part contains a description of the major production organisms, from archaebacteria to cyanobacteria to algae and symbionts, including their genetic engineering. The remaining four parts look at commercially important compounds produced by these microorganisms together with their applications. Throughout, the emphasis is on technological considerations, and the future potential of these organisms or compound classes is discussed. A valuable and forward-looking resource for innovative biotechnologists in industry as well as in academia.

"Sponges (Porifera) are among the earliest Metazoa. Their association with diverse microbes is raising many new questions in ecology, evolution, and biotechnology. However, despite much interest in these associations, large gaps still remain in our understanding of the individual phylogenies of these sponge-associated bacteria, as well as their community-level ecology. The establishment of a sponge-microbe experimental system is imperative to facilitate future analyses of these associations. Many sponges can be explanted with relative ease, but it remains unknown how the microbial community changes from parent to clone. Here I used denaturing gradient gel electrophoresis (DGGE) to investigate how the microbial community of the New Zealand demosponge Ancorina alata changes using two methods of aquaculture (open ocean and flow-through aquarium) under various time treatments. As no experimental system has been set up to study the microbial ecology of NZ sponges, this should greatly facilitate investigation of NZ sponge-associated microbial communities. Secondly, although the field of sponge microbial ecology is expanding, there remains a paucity of studies addressing broad ecological questions of these bacteria on the community level. I test whether the diversity-stability relationships documented in other ecosystems (e.g. grasslands, gut microbiota, and synthetic microcosms) can be observed in sponge-associated bacterial communities. Finally, previous tag pyrosequencing data had indicated that the bacterial community of the NZ sponge Stelletta maori is dominated by up to 12 operational taxonomic units (OTUs) within the phylum Fusobacteria. This phylum is poorly understood in the marine environment and has never been reported in such high abundance in a marine sponge, making it a potential exception to the general pattern of sponge-associated bacterial communities worldwide. I investigate the occurrence of this phylum in S. maori using a suite of molecular techniques I developed including PCR for phylogenetic analysis, DGGE for community structure analysis, and fluorescence in situ hybridization for localization and quantification of bacterial cells"--Abstract.

The emphasis is on new and exciting facets of the subject, notably biotechnology, fish and shellfish pathology and deep-sea microbiology. The volume also provides a sound introduction to the main elements of marine microbiology: indluding the habitats and ecology of marine micro-organisms, their taxonomy, and a practical guide to microbiological techniques and methods.