The family Gemmataceae accommodates aerobic, chemoorganotrophic planctomycetes, which inhabit various freshwater ecosystems, wetlands and soils. Here, we describe a novel member of this family, strain PX52^T, which was isolated from a boreal eutrophic lake in Northern Russia. This isolate formed pink-pigmented colonies and was represented by spherical cells that occurred singly, in pairs or aggregates and multiplied by budding. Daughter cells were highly motile. PX52^T was an obligate aerobic chemoorganotroph, which utilized various sugars and some heteropolysaccharides. Growth occurred at pH 5.0–7.5 (optimum pH 6.5) and at temperatures between 10 and 30 °C (optimum 20–25 °C). The major fatty acids were C_18 : 1ɷ7c, C_18 : 0 and βOH-C_16:0; the major intact polar lipid was trimethylornithine, and the quinone was MK-6. The complete genome of PX52^T was 9.38 Mb in size and contained nearly 8000 potential protein-coding genes. Among those were genes encoding a wide repertoire of carbohydrate-active enzymes (CAZymes) including 33 glycoside hydrolases (GH) and 87 glycosyltransferases (GT) affiliated with 17 and 12 CAZy families, respectively. DNA G+C content was 65.6 mol%. PX52^T displayed only 86.0–89.8 % 16S rRNA gene sequence similarity to taxonomically described Gemmataceae planctomycetes and differed from them by a number of phenotypic characteristics and by fatty acid composition. We, therefore, propose to classify it as representing a novel genus and species, Limnoglobus roseus gen. nov., sp. nov. The type strain is strain PX52^T (=KCTC 72397^T=VKM B-3275^T).

During the last five decades, the Aral Sea has gradually changed from a saline water body to a hypersaline lake. Microbial community inhabiting the Aral Sea has been through a succession and continuous adaptation during the last 50 years of increasing salinization, but so far, the microbial diversity has not been explored. Prokaryotic diversity of the Large Aral Sea using cultivation‐independent methods based on determination of environmental 16S rRNA gene sequences revealed a microbial community related to typical marine or (hyper) saline‐adapted Bacteria and Archaea. The archaeal sequences were phylogenetically affiliated with the order Halobacteriales, with a large number of operational taxonomic units constituting a novel cluster in the Haloferacaceae family. Bacterial community analysis indicated a higher diversity with representatives belonging to Proteobacteria, Actinobacteria and Bacteroidetes. Many members of Alphaproteobacteria and Gammaproteobacteria were affiliated with genera like Roseovarius, Idiomarina and Spiribacter which have previously been found in marine or hypersaline waters. The majority of the phylotypes was most closely related to uncultivated organisms and shared less than 97% identity with their closest match in GenBank, indicating a unique community structure in the Large Aral Sea with mostly novel species or genera.

A novel species of the genus Methylocystis is proposed based on polyphasic evidence from strain SC2^T, isolated from the heavily polluted Saale River near Wichmar, Germany. Digital DNA–DNA hybridization and phylogenomic analyses demonstrate that strain SC2^T represents a distinct species within the genus, clearly separated from its closest relatives, namely Methylocystis suflitae NLS-7^T, Methylocystis rosea SV97^T, Methylocystis silviterrae FS^T, and Methylocystis hirsuta CSC1^T. As is typical of the family Methylocystaceae, cells possess intracytoplasmic membranes arranged parallel to the cytoplasmic membrane, and the dominant fatty acids are C18:1ω8c and C18:1ω7c. The strain grows aerobically on methane as the primary carbon and energy source and expresses both low- and high-affinity particulate methane monooxygenase (pMMO), but lacks the soluble form. The species epithet reflects the strain’s ability to utilize hydrogen as an alternative energy source. A further feature is its use of asparagine as an osmoprotectant, enhancing salt tolerance. Genomic analysis reveals complete pathways for nitrogen fixation, denitrification, and hydrogen oxidation. These genetic and physiological characteristics support the designation of a novel species, for which the name Methylocystis hydrogenophila sp. nov. is proposed. The type strain is SC2^T (=DSM 114506 = NCIMB 15437).

We investigated how prior maize cultivation shapes rhizosphere microbiome assembly, testing the extend to which the microbiome established by an initial maize crop maintains stability or undergoes compositional shifts toward decomposer communities during root decayy, and how legacies of previous maize generations influence these dynamics. Soil microcosms were established using either naïve “fresh soil” or “legacy soil” from consecutive maize monoculture. Microbial succession in the maize rhizosphere was tracked across initial growth, root decay, and subsequent regrowth.Magnetic resonance imaging (MRI) was used for non-invasive spatio-temporal tracking of roots, root decay, and root channels. Precise MRI imaging-guided sampling of recolonized biopores and newly formed root zones, combined with 16S, ITS, and 18S amplicon sequencing, enabled profiling of bacteria, fungi, and protists, including consumers (Cercozoa) and potential root pathogens (Oomycota, Phytomyxea), offering a multi-trophic perspective on microbiome assembly.Microbial succession followed a reproducible but incomplete growth–decay–regrowth cycle. Root-associated consortia shifted toward decomposer dominance after root death and only partially reassembled during subsequent plant growth. This resulted in (i) a persistent core microbiome, (ii) taxa confined to decayed biopores or associated with living roots, and (iii) a bacterial community exhibiting strong turnover between rhizosphere and decay phases. Thus, root decomposition irreversibly altered microbiome reassembly trajectories.Approximately 10% of new roots recolonized existing biopores, using them as low-resistance pathways that promoted deeper rooting. In legacy soil, this mosaic of root and microbial legacies increased beta-diversity dispersion during regrowth, leading to greater heterogeneity in bacterial and cercozoan communities. Plants grown in legacy soil developed smaller root systems, and microbial communities remained distinct from those in fresh soil across all phases, demonstrating persistent effects of cropping history. Together, our results show how past crop history shapes the spatial inoculum landscape and feeds back on rhizosphere assembly and plant performance.