Soda pans of the Pannonian steppe are unique environments regarding their physical and chemical characteristics: shallowness, high turbidity, intermittent character, alkaline pH, polyhumic organic carbon concentration, hypertrophic condition, moderately high salinity, sodium and carbonate ion dominance. The pans are highly productive environments with picophytoplankton predominance. Little is known about the planktonic bacterial communities inhabiting these aquatic habitats, therefore amplicon sequencing and shotgun metagenomics were applied to reveal their composition and functional properties. Results showed a taxonomically complex bacterial community which was distinct from other soda lakes regarding its composition, e.g. the dominance of class Alphaproteobacteria was observed within phylum Proteobacteria. The shotgun metagenomic analysis revealed several functional gene components related to the harsh and at the same time hypertrophic environmental conditions, e.g. proteins involved in stress response, transport and hydrolase systems targeting phytoplankton-derived organic matter. This is the first detailed report on the indigenous planktonic bacterial communities coping with the multiple extreme conditions present in the unique soda pans of the Pannonian steppe.

Near-complete genome sequences of seven picornavirus (PV) strains isolated from different terrestrial tortoise species were determined and characterized. The genome organization of the strains proved to be similar and displayed a typical PV layout, and the polyprotein-encoding regions showed low similarity to those of other PVs. The predicted regions of the tortoise PV genomes were related to the corresponding genome parts of viruses belonging to distinct genera, implying modular evolution of these novel viruses. Our results suggest that these tortoise PVs belong to a prototype species in a separate proposed genus in the family Picornaviridae, tentatively called Topivirus (Tortoise picornavirus).