Connecting chromosome replication with cell growth in bacteria

Seasonal dynamics and functional diversity of soil nematode communities under treated wastewater irrigation in abandoned agricultural soils

The use of treated wastewater (TWW) for agricultural irrigation is becoming more popular as a sustainable alternative to freshwater due to increasing water scarcity. While considerable research exists on the effects of TWW on soil microorganisms, its impact on soil nematodes, key indicators of soil health remains unexplored. This study assessed the effects of two years of TWW irrigation on soil nematode communities in abandoned fields cultivated with Lavender, Anise, Olive and Pomegranate trees. Seasonal soil samples were analyzed for nematode abundance, community composition and ecological indices. TWW irrigation modified soil nematode community structure, favoring the dominance of bacterivores (Acrobeloides) while suppressing plant-parasitic nematodes (Pratylenchus, Bitylenchus). Nematode-based indices showed no significant differences between TWW- and freshwater-irrigated soils, indicating stable and resilient communities. Seasonal precipitation levels strongly influenced nematode abundances, highlighting environmental resilience. Plant species did not create ecological niches, probably due to the strong influence of precipitation and soil properties; nevertheless, plant establishment increased nematode diversity over time, with omnivores and predators emerging alongside bacterivores and fungivores, reflecting recovery dynamics. Even though TWW irrigation is considered a type of disturbance, it facilitated soil nematode diversity and maintained ecological stability. Properly treated wastewater serves as a sustainable irrigation method that enhances soil health and biodiversity, rendering it a viable alternative for agricultural systems in degraded and water-scarce areas under changing climatic conditions.

Streptococcus suis MsmK: Novel Cell Division Protein Interacting with FtsZ and Maintaining Cell Shape

Bacteria of different shapes have adopted distinct mechanisms to faithfully coordinate morphogenesis and segregate their chromosomes prior to cell division. Despite recent focuses and advances, the mechanism of cell division in ovococci remains largely unknown. Streptococcus suis, a major zoonotic pathogen that causes problems in human health and in the global swine industry, is an elongated and ellipsoid bacterium that undergoes successive parallel splitting perpendicular to its long axis. Studies on cell cycle processes in this bacterium are limited. Here, we report that MsmK (multiple sugar metabolism protein K), an ATPase that contributes to the transport of multiple carbohydrates, has a novel role as a cell division protein in S. suis. MsmK can display ATPase and GTPase activities, interact with FtsZ via the N terminus of MsmK, and promote the bundling of FtsZ protofilaments in a GTP-dependent manner in vitro. Deletion of the C-terminal region or the Walker A or B motif affects the affinity between MsmK and FtsZ and decreases the ability of MsmK to promote FtsZ protofilament bundling. MsmK can form a complex with FtsZ in vivo, and its absence is not lethal but results in long chains and short, occasionally anuclear daughter cells. Superresolution microscopy revealed that the lack of MsmK in cells leads to normal septal peptidoglycan walls in mother cells but disturbed cell elongation and peripheral peptidoglycan synthesis. In summary, MsmK is a novel cell division protein that maintains cell shape and is involved in the synthesis of the peripheral cell wall.

IMPORTANCE Bacterial cell division is a highly ordered process regulated in time and space and is a potential target for the development of antimicrobial drugs. Bacteria of distinct shapes depend on different cell division mechanisms, but the mechanisms used by ovococci remain largely unknown. Here, we focused on the zoonotic pathogen Streptococcus suis and identified a novel cell division protein named MsmK, which acts as an ATPase of the ATP-binding cassette-type carbohydrate transport system. MsmK has GTPase and ATPase activities. In vitro protein assays showed that MsmK interacts with FtsZ and promotes FtsZ protofilament bundling that relies on GTP. Superresolution microscopy revealed that MsmK maintains cell shape and is involved in peripheral peptidoglycan synthesis. Knowledge of the multiple functions of MsmK may broaden our understanding of known cell division processes. Further studies in this area will elucidate how bacteria can faithfully and continually multiply in a constantly changing environment.

The Importance of Bacterial Culture to Food Microbiology in the Age of Genomics

Culture-based and genomics methods provide different insights into the nature and behavior of bacteria. Maximizing the usefulness of both approaches requires recognizing their limitations and employing them appropriately. Genomic analysis excels at identifying bacteria and establishing the relatedness of isolates. Culture-based methods remain necessary for detection and enumeration, to determine viability, and to validate phenotype predictions made on the bias of genomic analysis. The purpose of this short paper is to discuss the application of culture-based analysis and genomics to the questions food microbiologists routinely need to ask regarding bacteria to ensure the safety of food and its economic production and distribution. To address these issues appropriate tools are required for the detection and enumeration of specific bacterial populations and the characterization of isolates for, identification, phylogenetics, and phenotype prediction.