Cultivation of elusive microbes unearthed exciting biology

Many newly-discovered microbial phyla have been studied solely by cultivation-independent techniques such as metagenomics. Much of their biology thus remains elusive, because the organisms have not yet been isolated and grown in the lab. Katayama et al. lift the curtain on some intriguing biology by cultivating and studying bacteria from the elusive OP9 phylum (Atribacterota)

BacStalk: A comprehensive and interactive image analysis software tool for bacterial cell biology

Prokaryotic cells display a striking subcellular organization. Studies of the underlying mechanisms in different species have greatly enhanced our understanding of the morphological and physiological adaptation of bacteria to different environmental niches. The image analysis software tool BacStalk is designed to extract comprehensive quantitative information from the images of morphologically complex bacteria with stalks, flagella, or other appendages. The resulting data can be visualized in interactive demographs, kymographs, cell lineage plots, and scatter plots to enable fast and thorough data analysis and representation. Notably, BacStalk can generate demographs and kymographs that display fluorescence signals within the two-dimensional cellular outlines, to accurately represent their subcellular location. Beyond organisms with visible appendages, BacStalk is also suitable for established, non-stalked model organisms with common or uncommon cell shapes. BacStalk, therefore, contributes to the advancement of prokaryotic cell biology and physiology, as it widens the spectrum of easily accessible model organisms and enables highly intuitive and interactive data analysis and visualization

BacStalk: A comprehensive and interactive image analysis software tool for bacterial cell biology

Prokaryotic cells display a striking subcellular organization. Studies of the underlying mechanisms in different species have greatly enhanced our understanding of the morphological and physiological adaptation of bacteria to different environmental niches. The image analysis software tool BacStalk is designed to extract comprehensive quantitative information from the images of morphologically complex bacteria with stalks, flagella, or other appendages. The resulting data can be visualized in interactive demographs, kymographs, cell lineage plots, and scatter plots to enable fast and thorough data analysis and representation. Notably, BacStalk can generate demographs and kymographs that display fluorescence signals within the two-dimensional cellular outlines, to accurately represent their subcellular location. Beyond organisms with visible appendages, BacStalk is also suitable for established, non-stalked model organisms with common or uncommon cell shapes. BacStalk, therefore, contributes to the advancement of prokaryotic cell biology and physiology, as it widens the spectrum of easily accessible model organisms and enables highly intuitive and interactive data analysis and visualization

Determinants of Bacterial Morphology : From Fundamentals to Possibilities for Antimicrobial Targeting

Bacterial morphology is extremely diverse. Specific shapes are the consequence of adaptive pressures optimizing bacterial fitness. Shape affects critical biological functions, including nutrient acquisition, motility, dispersion, stress resistance and interactions with other organisms. Although the characteristic shape of a bacterial species remains unchanged for vast numbers of generations, periodical variations occur throughout the cell (division) and life cycles, and these variations can be influenced by environmental conditions. Bacterial morphology is ultimately dictated by the net-like peptidoglycan (PG) sacculus. The species-specific shape of the PG sacculus at any time in the cell cycle is the product of multiple determinants. Some morphological determinants act as a cytoskeleton to guide biosynthetic complexes spatiotemporally, whereas others modify the PG sacculus after biosynthesis. Accumulating evidence supports critical roles of morphogenetic processes in bacteria-host interactions, including pathogenesis. Here, we review the molecular determinants underlying morphology, discuss the evidence linking bacterial morphology to niche adaptation and pathogenesis, and examine the potential of morphological determinants as antimicrobial targets

Planctoellipticum variicoloris gen. nov., sp. nov., a novel member of the family Planctomycetaceae isolated from wastewater of the aeration lagoon of a sugar processing plant in Northern Germany

Abstract In the present study, we characterise a strain isolated from the wastewater aeration lagoon of a sugar processing plant in Schleswig (Northern Germany) by Heinz Schlesner. As a pioneer in planctomycetal research, he isolated numerous strains belonging to the phylum Planctomycetota from aquatic habitats around the world. Phylogenetic analyses show that strain SH412T belongs to the family Planctomycetaceae and shares with 91.6% the highest 16S rRNA gene sequence similarity with Planctopirus limnophila DSM 3776T. Its genome has a length of 7.3 Mb and a G + C content of 63.6%. Optimal growth of strain SH412T occurs at pH 7.0–7.5 and 28 °C with its pigmentation depending on sunlight exposure. Strain SH412T reproduces by polar asymmetric division (“budding”) and forms ovoid cells. The cell size determination was performed using a semi-automatic pipeline, which we first evaluated with the model species P. limnophila and then applied to strain SH412T. Furthermore, the data acquired during time-lapse analyses suggests a lifestyle switch from flagellated daughter cells to non-flagellated mother cells in the subsequent cycle. Based on our data, we suggest that strain SH412T represents a novel species within a novel genus, for which we propose the name Planctoellipticum variicoloris gen. nov., sp. nov., with strain SH412T (= CECT 30430T = STH00996T, the STH number refers to the Jena Microbial Resource Collection JMRC) as the type strain of the new species

Characterization of the first planctomycetal outer membrane protein identifies a channel in the outer membrane of the anammox bacterium Kuenenia stuttgartiensis

Planctomycetes are a bacterial phylum known for their complex intracellular compartmentalization. While most Planctomycetes have two compartments, the anaerobic ammonium oxidizing (anammox) bacteria contain three membrane-enclosed compartments. In contrast to a long-standing consensus, recent insights suggested the outermost Planctomycete membrane to be similar to a Gram-negative outer membrane (OM). One characteristic component that differentiates OMs from cytoplasmic membranes (CMs) is the presence of outer membrane proteins (OMPs) featuring a β-barrel structure that facilitates passage of molecules through the OM. Although proteomic and genomic evidence suggested the presence of OMPs in several Planctomycetes, no experimental verification existed of the pore-forming function and localization of these proteins in the outermost membrane of these exceptional microorganisms. Here, we show via lipid bilayer assays that at least two typical OMP-like channel-forming proteins are present in membrane preparations of the anammox bacterium Kuenenia stuttgartiensis. One of these channel-forming proteins, the highly abundant putative OMP Kustd1878, was purified to homogeneity. Analysis of the channel characteristics via lipid bilayer assays showed that Kustd1878 forms a moderately cation-selective channel with a high current noise and an average single-channel conductance of about 170-190pS in 1M KCl. Antibodies were raised against the purified protein and immunogold localization indicated Kustd1878 to be present in the outermost membrane. Therefore, this work clearly demonstrates the presence of OMPs in anammox Planctomycetes and thus firmly adds to the emerging view that Planctomycetes have a Gram-negative cell envelope

Anammox planctomycetes have a peptidoglycan cell wall

Planctomycetes are intriguing microorganisms that apparently lack peptidoglycan, a structure that controls the shape and integrity of almost all bacterial cells. Therefore, the planctomycetal cell envelope is considered exceptional and their cell plan uniquely compartmentalized. Anaerobic ammonium-oxidizing (anammox) Planctomycetes play a key role in the global nitrogen cycle by releasing fixed nitrogen back to the atmosphere as N2. Here using a complementary array of state-of-the-art techniques including continuous culturing, cryo-transmission electron microscopy, peptidoglycan-specific probes and muropeptide analysis, we show that the anammox bacterium Kuenenia stuttgartiensis contains peptidoglycan. On the basis of the thickness, composition and location of peptidoglycan in K. stuttgartiensis, we propose to redefine Planctomycetes as Gram-negative bacteria. Our results demonstrate that Planctomycetes are not an exception to the universal presence of peptidoglycan in bacteria

Anammox Planctomycetes have a peptidoglycan cell wall

Planctomycetes are intriguing microorganisms that apparently lack peptidoglycan, a structure that controls the shape and integrity of almost all bacterial cells. Therefore, the planctomycetal cell envelope is considered exceptional and their cell plan uniquely compartmentalized. Anaerobic ammonium-oxidizing (anammox) Planctomycetes play a key role in the global nitrogen cycle by releasing fixed nitrogen back to the atmosphere as N-2. Here using a complementary array of state-of-the-art techniques including continuous culturing, cryo-transmission electron microscopy, peptidoglycan-specific probes and muropeptide analysis, we show that the anammox bacterium Kuenenia stuttgartiensis contains peptidoglycan. On the basis of the thickness, composition and location of peptidoglycan in K. stuttgartiensis, we propose to redefine Planctomycetes as Gram-negative bacteria. Our results demonstrate that Planctomycetes are not an exception to the universal presence of peptidoglycan in bacteria