Cultivation and functional characterization of 79 planctomycetes uncovers their unique biology

When it comes to the discovery and analysis of yet uncharted bacterial traits, pure cultures are essential as only these allow detailed morphological and physiological characterization as well as genetic manipulation. However, microbiologists are struggling to isolate and maintain the majority of bacterial strains, as mimicking their native environmental niches adequately can be a challenging task. Here, we report the diversity-driven cultivation, characterization and genome sequencing of 79 bacterial strains from all major taxonomic clades of the conspicuous bacterial phylum Planctomycetes. The samples were derived from different aquatic environments but close relatives could be isolated from geographically distinct regions and structurally diverse habitats, implying that ‘everything is everywhere’. With the discovery of lateral budding in ‘Kolteria novifilia’ and the capability of the members of the Saltatorellus clade to divide by binary fission as well as budding, we identified previously unknown modes of bacterial cell division. Alongside unobserved aspects of cell signalling and small-molecule production, our findings demonstrate that exploration beyond the well-established model organisms has the potential to increase our knowledge of bacterial diversity. We illustrate how ‘microbial dark matter’ can be accessed by cultivation techniques, expanding the organismic background for small-molecule research and drug-target detection. © 2019, The Author(s), under exclusive licence to Springer Nature Limited.

We appreciate the help of C. Wiegand, A. Scharmach and B. Schink in naming the isolates appropriately according to community standards. We are also grateful to I. Lagkouvardos and A. Kioukis for enabling our analyses on the IMNGS platform. We thank L. van Niftrik for providing bacterial biomass from anaerobic lab-scale bioreactors. The GHOSTDABS project provided the left-most image in the upper panel of Fig. 1. We further thank J. Piel for scientific discussion and C. Spröer for help with the sequencing of the planctomycetal strains. This work was funded by the Deutsche Forschungsgemeinschaft (grant no. JO 893/4-1) and the Volkswagen foundation (experiment no. 89256). M.Y.G. was funded by the NIH IRP at the US National Library of Medicine. Work in the Mascher lab was supported by the Deutsche Forschungsgemeinschaft (grant no. MA2837/2-2) and the Bundeministerium für Bildung und Forschung in the framework of the ERAnet Synthetic Biology (project: ERASynBio2-ECFexpress). R.A. and A.M. were funded by the Max Planck Society.