Integrating culture dependent and independent methods to cultivate and isolate unculturable acidobacteria from Antarctic permafrost soils Lobna Hudifa Warwick University, UK Antimicrobial resistance is one of the leading threats to human health. Soil bacteria are one of the main reservoirs for antibiotic discovery and in particular, uncultivated bacteria represent a promising source for novel biodiversity and potentially new antibiotics. However, due to the limitations in culturing environmental bacterial species under laboratory conditions, they are poorly studied. To overcome these limitations, we developed a culture-dependent and independent methods to isolate and characterize uncultivated bacteria from Mars Oasis, Antarctica. It involved enriching soil microcosms using selective substrates and conditions, then isolating bacteria on selective media in parallel with indirect analysis of environmental DNA extracted from different microcosm conditions. A collection of 904 isolates was obtained and a high throughput screening of the isolates using 16S long amplicon Nanopore sequencing was done. We found a large and diverse set of bacterial groups. Most of them were classified as Actinobacteria, the second most abundant phylum was Proteobacteria followed by Firmicutes, and a small fraction was identified as Bacteroidota, Deinococcota, Cyanobacteria, Planctomycetota and Acidobacteria. Alignment to the GTDB 16S reference database indicated high levels of novelty on the species level and potentially novel genera for the phyla Acidobacteriota, Cyanobacteria, Planctomycetota and Deinococcota. The analysis of amplicons’ libraries for the 16S rRNA gene targeting the V3 and V4 region for the soil DNA, demonstrated that different microcosm conditions are significantly different in terms of bacterial community composition. The introduction of Inulin, Amylopectin, Cellobiose and Galactomannan shifted the microbial community diversity to increase the prevalence of Acidobacteria, while converting the soil pH to levels 4 and 7.5 decreased the acidobacterial abundance. References 1. Gajdacs M et al., Antibiotics (Basel), 2019. 8(3).2. Belete T M, Human Microbiome Journal, 2019. 113.Weber T et al., J Biotechnol, 2003. 106:2–3. 221–32
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