Transcriptional analysis of freshwater bacterium Polynucleobacter asymbioticus strain QLW-P1DMWA-1T

Polynucleobacter asymbioticus strain QLW-P1DMWA-1T represents a group of highly successful heterotrophic planktonic bacteria, dwelling in freshwater systems (lakes, ponds, and streams) across all climatic zones and across all continents. This includes habitats characterised by strongly fluctuating environmental conditions. So the experiments were designed to mimick winter and summer scenarios with additional impact of UV irradiation. Comparative transcriptomic studies were conducted to analyse gene-expression levels in contrasting experimental conditions. Overall, molecular candidates were revealed that may contribute in rapid acclimatisation of this strain in their immediate environment. Bacterial cells were incubated in 500ml R2A liquid media, and samples were kept in sterile but UV permeable polyethylene bags. Samples were incubated at 26ºC (at constant rotation of 200 rpm). When the culture reached the O.D. of 0.1, the samples were transferred to their treatment incubators i.e. (a). 26ºC samples continued at the sample temperature; (b). second batch was transferred to 4ºC incubator; (c). third batch also continued incubation at 26ºC but with supplemented with 2x30 minutes of UV irradiation daily. Samples were harvested with RNAlaterTM solution. Agilent 60-mer Microarray was designed that contained strain QLW-P1DMWA-1T genome represented with 2123 genes.