Abstract
Four non-pigmented, off-white to ivory strains, SH527(T), SH661(T), SH664(T) and SH668(T), have been isolated from sewage sludge or leakage water of a compost heap in Northern Germany as part of an isolation campaign conducted by Heinz Schlesner, Kiel University in the 1980s-early 2000s. Analyses based on five phylogenetic markers place the novel strains in the genus Planctomicrobium in the family Planctomycetaceae within the phylum Planctomycetota. All four strains are aerobic heterotrophs with a neutrophilic and mesophilic growth profile. Genome sequencing revealed relatively small genomes compared to the relatives in the same family, with strain SH668(T) having the currently smallest genome (4.81 Mbp) of any described member of the family Planctomycetaceae. The analysis of genome-encoded features suggests a metabolism better adapted to the degradation of polysaccharides rather than of lignocellulose-derived aromatic compounds. The collected data justifies the delineation of the novel isolates from the sole species in the genus, Planctomicrobium piriforme. The four isolates belong to four separate novel species, for which we introduce the names Planctomicrobium limosum sp. nov., Planctomicrobium stercoris sp. nov., Planctomicrobium aquicomposti sp. nov. and Planctomicrobium mucosum sp. nov. The novel taxa are represented by the following isolates as respective type strains: SH527(T) (= CECT 30937(T) = KCTC 102136(T)), SH661(T) (= DSM 116760(T) = KCTC 102128(T)), SH664(T) (= DSM 116388(T) = KCTC 102081(T)) and SH668(T) (= DSM 116585(T) = KCTC 102080(T)).