Pedobacter vanadiisoli sp. nov., isolated from soil of a vanadium mine

Exploration of social spreading reveals behavior is prevalent among Pedobacter and P. fluorescens isolates, and shows variations in induction of phenotype

Within soil, bacteria are found in multi-species communities, where interactions can lead to emergent community properties. Studying bacteria in a social context is critical for investigation of community-level functions. We previously showed that co-cultured Pseudomonas fluorescens Pf0-1 and Pedobacter sp. V48 engage in interspecies social spreading (ISS) on a hard agar surface, a behavior which required close contact and depended on the nutritional environment. Here, we investigate whether social spreading is widespread among P. fluorescens and Pedobacter isolates, and whether the requirements for interaction vary. We find that this phenotype is not restricted to the interaction between P. fluorescens Pf0-1 and Pedobacter sp. V48, but is a prevalent behavior found in one clade in the P. fluorescens group and two clades in the Pedobacter genus. We show that the interaction with certain Pedobacter isolates occurred without close contact, indicating induction of spreading by a putative diffusible signal. As with ISS by Pf0-1+V48, motility of interacting pairs is influenced by the environment, with no spreading behaviors (or induction of motility) observed under high nutrient conditions. While Pf0-1+V48 require low nutrient but high NaCl conditions, in the broader range of interacting pairs the high salt influence was variable. The prevalence of motility phenotypes observed here and found within the literature indicates that community-induced locomotion in general, and social spreading in particular, is likely important within the environment. It is crucial that we continue to study microbial interactions and their emergent properties to gain a fuller understanding of the functions of microbial communities. Importance Interspecies social spreading (ISS) is an emergent behavior observed when P. fluorescens Pf0-1 and Pedobacter sp. V48 interact, during which both species move together across a surface. Importantly, this environment does not permit movement of either individual species. This group behavior suggests that communities of microbes can function in ways not predictable by knowledge of the individual members. Here we have asked whether ISS is widespread and thus potentially of importance in soil microbial communities. The significance of this research is the demonstration that surface spreading behaviors are not unique to the Pf0-1-V48 interaction, but rather is a more widespread phenomenon observed among members of distinct clades of both P. fluorescens and Pedobacter isolates. Further, we identify differences in mechanism of signaling and nutritional requirements for ISS. Emergent traits resulting from bacterial interactions are widespread and their characterization is necessary for a complete understanding of microbial community function.

Pedobacter ghigonii sp. nov., Isolated from the Microbiota of the Planarian Schmidtea mediterranea

The planarian S. mediterranea is a platyhelminth with worldwide distribution that can regenerate any part of its body after amputation and has the capacity to eliminate a large spectrum of human bacterial pathogens. Surprisingly, the microbiota of S. mediterranea remains poorly investigated. Using the culturomics strategy to study the bacterial component of planarians, we isolated a new bacterial strain, Marseille-Q2390, which we characterized with the taxono-genomic approach that associates phenotypic assays and genome sequencing and analysis. Strain Marseille-Q2390 exhibited a 16S rRNA sequence similarity of 99.36% with Pedobacter kyungheensis strain THG-T17T, the closest phylogenetic neighbor. It is a white-pigmented, Gram-negative, and rod-shaped bacterium. It grows in aerobic conditions and belongs to the family Sphingobacteriaceae. The genome of strain Marseille-Q2390 is 5,919,359 bp-long, with a G + C content of 40.3%. By comparing its genome with other closely related strains, the highest Orthologous Average Nucleotide Identity (Ortho-ANI) and digital DNA-DNA hybridization (dDDH) values were 85.71% and 30.50%, respectively, which were found with Pedobacter soli strain 15-51T. We conclude that strain Marseille-Q2390T is sufficiently different from other nearby species to be classified within a new species for which we propose the name Pedobacter ghigonii sp. nov.

Pedobacter quisquiliarum sp. nov., isolated from activated sludge

A Gram-stain-negative, aerobic, rod-shaped, bacterium, C62-2^T, was isolated from activated sludge in Fujian Province, China. Phylogenetic analysis of the 16S rRNA gene sequences showed that it was closely related to Pedobacter duraquae WB 2.1-25^T (97.92 %), Pedobacter bambusae THG-G118^T (97.40 %), Pedobacter cryoconitis A37^T (97.37 %) and Pedobacter caeni LMG 22862^T (97.3 %). Cells grew aerobically at 20-37 °C (optimum, 30 °C), pH 5.0-8.0 (optimum, pH 7.0) and in the presence of 0-3.0 % (w/v) NaCl. Strain C62-2^T contained MK-7 as the major menaquinone and the major polar lipid was phosphatidylethanolamine. The major cellular fatty acids were iso-C15 : 0, summed feature 3 (C16 : 1ω6c, C16 : 1ω7c) and iso-C17 : 0 3-OH. The DNA G+C content was 43.2 mol% (Tm) and DNA-DNA reassociation values were 35.4 % between strain C62-2^T and P. duraquae WB 2.1-25^T. On the basis of phenotypic, chemotaxonomic and phylogenetic comparisons with the closely related species and DNA-DNA relatedness values, it was concluded that strain C62-2^T represents a novel species within the genus Pedobacter, for which the name Pedobacterquisquiliarum sp. nov. is proposed. The type strain is C62-2^T (=CGMCC 1.15343^T=NBRC 111767^T).