| Summary: | The past decade the awareness for sustainability has come more and more into focus of society in terms of a need for eco-friendlier processes and renewable energies, new and better pharmaceuticals, and agricultural- and aquaculture challenges amongst others. Hence, enzyme technology has emerged as one of the most important technologies to meet future demands. A common consensus is that the marine environments represent a largely untapped potential for industrial applicable enzymes. As deep-sea hydrothermal vent fields have revealed a biodiversity of largely uncultivated microorganisms they have been reviewed as hot spots for finding new biocatalysts. In this study, samples from the Arctic Mid-Ocean- Ridge (AMOR) deep-sea hydrothermal vent fields have been investigated as a source for potential carbohydrate degrading biocatalysts, with a focus on starch degrading enzymes, using a multifaceted approach; isolation of a novel starch degrader (Paper I), integrated sequenced-based meta-omics study of a microbial biofilm (Paper II), genomic analysis of microbial isolates (Paper I and III), and finally, a functional-based screening of a microbial biofilm was conducted (described in detail in section 3.2). In general, the sequence-based screening for glycoside hydrolases (GHs) in all sequencing analyses was low, with Lutibacter profundi LP1T exhibiting the highest amount with 24 GHs (Paper III). However, a purified thermophilic neopullulanase with a melting temperature of 76.4 °C showed a comparable starch degradation capacity as the reference α-amylase from Bacillus licheniformis (Paper I). In comparison, a higher amount of proteases was identified searching against the MEROPS protein database. For both isolates (Paper I and III), protease activity was confirmed on agar plates hydrolysing casein and gelatin. Interestingly, the activity-based screening of a microbial biofilm identified 274 clones with starch degrading activity. Selective sequencing of 106 positive clones did not reveal any homologs of known α-amylases or ...
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