Aquirufa esocilacus sp. nov., Aquirufa originis sp. nov., Aquirufa avitistagni, and Aquirufa echingensis sp. nov. discovered in small freshwater habitats in Austria during a citizen science project.

Within a citizen science project, 112 freshwater habitats in Austria were sampled to get bacterial cultures belonging to the genus Aquirufa using a strategy for targeted isolation. We focused on these bacteria because they are widespread and represent typical freshwater bacteria and, furthermore, the typic red pigmentation facilitates preselection. Among the 113 obtained Aquirufa strains were HETE-83D, KTFRIE-69F, OSTEICH-129V and PLAD-142S6K, originating from small ponds and a creek. Phylogenetic reconstructions with 16S rRNA gene sequences and genome-based analyses with amino acid sequences of 501 core genes showed that all four strains belonged to the A. antheringensis branch of the genus Aquirufa. Calculation of whole-genome average nucleotide identity values and digital DNA-DNA hybridization values revealed that they represent in each case a new species. The genome sizes of the four strains were between 2.5 and 2.8 Mbp and the G + C values were between 41.4 and 41.8%. Like all type strains of the genus Aquirufa, cells were rod-shaped, and liquid cultures and colonies on agar plates were red-pigmented, likely due to carotenoids. All strains except OSTEICH-129V showed gliding motility on soft agar plates. All strains grew aerobically but only PLAD-142S6K could grow weakly under anaerobic conditions. We propose here to establish the names Aquirufa esocilacus sp. nov. for strain HETE-83D (= DSM 118087 = JCM 37094), Aquirufa originis sp. nov. for KTFRIE-69F (= DSM 117798 = JCM 37095), Aquirufa avitistagni for OSTEICH-129V (= DSM 118088 = JCM 37100) and Aquirufa echingensis sp. nov. for PLAD-142S6K (= DSM 117799 = JCM 37096).