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This thesis offers findings of compounds with potential pharmaceutical application from North-Atlantic Scotia Expedition derived deep sea microbes. The list of accomplishments in developing new pharmaceuticals and other useful products originating from Nature is long, and this list is on the rise. In the last decade, marine bioprospecting alone has generated three novel drugs that are in clinical use today. Given this success, we draw motivation to continue along this path of further bioprospecting efforts in the hope to find exploitable products as drugs or drug leads from natural sources. Isolated organisms were selected for further analysis based on their antiSMASH genomic or bioinformatic data encoded with desired gene clusters. Crude extracts from selected organisms were also prioritised based on the mass spectrometry data (LCMS). High-resolution mass spectrometry (HR-MS) was used to identify components in the samples to guide us with prioritisation. The other technique used to prioritise samples were influenced by the biological activity observed. Fractions of crude extracts from the selected organisms were subjected to biological activity test using Escherichiacoli and Staphylococcus aureus. The aim of this PhD work and scope has been divided into two major topics: (1)isolation, purification, discovery and characterization of SMs from Bacteria andfilamentous fungi. The results of this investigation were isolation and characterisation of compounds from Aspergillus versicolor: meleagrine, rugulosuvine, and pseudoboydin-B. From Kocuria marina organism I isolated bacillomycin D1, D3 and D5 and from Shewanella Vesiculosa I isolated indole-3-acetic acid (IAA) and brevianamide F.I was able to predict and link all the isolated compounds to their biosynthetic origin based on the bioinformatic data obtained and also fractions from which these compounds were isolated were subjected to biological activity assessment. The compounds showed reasonable activity against selected microorganism.

This project used a variety of genetic markers to investigate the evolution and population genetics of hydrothermal vent fauna that were recovered from the Scotia Sea, in the Atlantic sector of the Southern Ocean. The origins of one of these species, an undescribed species of Kiwa sp. found on the East Scotia Ridge (ESR) and its constituent family Kiwaidae, a group of vent and seep-associated decapod squat lobsters (infraorder Anomura) was investigated using a concatenated nine-gene dataset and key divergences were dated using fossil calibrations. These results confirm earlier research showing Kiwaidae reside in the superfamily Chirostyloidea, but form a monophyletic clade with the non-chemosynthetic family Chirostylidae and not Eumunididae. Chirostyloid families diverged in the Cretaceous, although extant Kiwaidae radiated in the Eocene, consistent with many other chemosynthetic taxa that appear recently derived. The basal tree position of Pacific species (and the Alaska location of a likely stem-lineage kiwaid fossil) suggests kiwaids originated in the East Pacific. Within a Southern Hemisphere clade, the divergence between the southeastern Pacific K. hirsuta and a non-Pacific lineage (Kiwa sp. ESR and Southwest Indian Ridge kiwaids) is no earlier than 25.9 Ma, consistent with a spread from the Pacific into the Scotia Sea and beyond via now-extinct active ridge connections or mediated by a Miocene onset of the Antarctic Circumpolar Current (ACC) through a newly-opened Drake Passage. This project also investigated the population genetics of three undescribed species found at two vent fields ~ 440 km apart at either end of the ESR: Kiwa sp., a peltospirid gastropod and Lepetodrilus sp. limpets. Lepetodrilus sp. was also found at the Kemp Caldera, a submerged part of the South Sandwich Islands (SSI). Analyses of cytochrome c oxidase subunit 1 (COI) as well as microsatellite loci developed from Roche 454 sequence libraries revealed no differentiation along the ESR for all three species consistent with panmixia, or the dominance of non-equilibrium processes between vent field colonies within a metapopulation, possibly enhanced further by cold-induced arrested larval development. Despite apparent connectivity along the ESR, both COI and microsatellites revealed differentiation between ESR limpets and Kemp Caldera limpets ~ 95 km to the east, possibly owing to the hydrographic isolation of the caldera. Both COI and microsatellite diversity patterns were consistent with recent (< 1 Ma) demographic expansions for all three species (although the influence of selection sweeps on COI cannot be discounted); a pattern observed worldwide at vent communities and may reflect demographic instability over time as a consequence of the stochastic birth and death of vent colonies within a metapopulation. Different COI bottleneck ages between the three species (excluding the influence of possible selection) as well as the absence of kiwaids and peltospirids at Kemp, have been attributed to differences in life history, in particular larval morphology and presumed dispersal strategy. These results highlight the role of larval dispersal of vent fauna along active spreading ridges, both in maintaining vent metapopulations across vent colonies prone to stochastic birth and extinction in the short term, but also in the spread of taxa globally and the formation of biogeographic provinces. The likelihood that the three species presented here exist at vents east of the ESR and SSI, prompts further exploration along ridges in the South Atlantic, in order to investigate the effect of the ACC in enhancing gene flow and delineating biogeographic provinces.

Microphytobenthos are the dominant primary producers on estuarine mudflats playing a key role in the functioning of the ecosystem. Studies into microphytobenthic ecology have previously been limited by scale but the advent of fine scale analysis techniques (gm) as well as non-destructive sampling has enabled the system to be examined at a level not previously possible. This study examined the formation, structure and function of microphytobenthic biofilms using non-destructive (remote sensing by PAM fluorescence; fibreoptic light microprofiling) and destructive (cryo-freezing and Low temperature scanning electron microscopy) sampling. Many microphytobenthic organisms are motile and have evolved complex migratory strategies. Microphytobenthic migratory patterns are widely described but much remains to be elucidated about the controlling factors. The fluorescence parameter F015 (minimum fluorescence yield after 15 minutes dark adaptation) was used to monitor short-term changes in biomass at the sediment surface. Light, tidal state, endogeny and combinations thereof were all shown to control migration, demonstrating that predictable migratory rhythms cannot be assumed. Microscale sectioning showed that chlorophyll a was always concentrated in the top 400 gm (the photosynthetically active biomass). Clear migratory patterns were not detected using microscale sectioning therefore indicating that migration occurs over a scale < 400gm. Despite no changes in the chlorophyll a content in the surface layers, LTSEM analysis demonstrated diurnal taxonomic shifts providing circumstantial evidence that microphytobenthic cells sub-cycle at the sediment surface to optimise fitness. The light extinction co-efficient (k) of microphytobenthic biofilms significantly vaned with site, assemblage and also over time. 90% of the surface PPFD had always been attenuated by 400, and in many cases before 200. Traditional microphytobenthic primary productivity models do not account for changes in the spatial and temporal distribution of biomass or light attenuation and therefore their applicability to the real situation may be limited.