Bacterial biofilms, prevalent in human infections, present a major barrier to effective antibacterial therapy due to limited drug permeability and resistance. Here we introduce a ‘trick-bacteria-with-bacteria’ strategy that employs bacteria modified via calcium chloride treatment and antibiotic loading, followed by ultraviolet inactivation. These modified bacteria integrate selectively into biofilms of the same species, enabling targeted intra-biofilm drug release triggered by local pH and hydrogen peroxide. Species-specific integration is essential, as mismatched strains exhibit spatial segregation due to differences in surface adhesins and protein profiles. The strategy is effective against polymicrobial biofilms and demonstrated efficacy in treating biofilms formed by Staphylococcus aureus, Escherichia coli and Candida albicans. It also reinvigorates biofilm-associated macrophages by inducing the release of biofilm-derived l-arginine, enhancing immune responses. In vivo studies using subcutaneous and bone implant infection models showed stronger biofilm eradication and longer-term immunity in animals treated with modified bacteria compared with those treated with antibiotics, including resistance to re-infection. This approach could be adapted to modify infection-related bacteria from patients for personalized intra-biofilm drug delivery. Chemically modified and permeabilized bacteria allow for antibiotic delivery inside biofilms, inducing long-term immune protection and eradicating implant-related infections in preclinical models.

Could codon composition condition the immediate success and the orientation of horizontal gene transfer? Horizontal gene transfer represents a change in the genome of expression of the transferred gene, and experimental evidence has accumulated indicating that the codon composition of a sequence is an important determinant of its compatibility with the translation machinery of the genome in which it is expressed. This suggests that codon composition influences the phenotype and the fitness conferred by a transferred gene and thus the immediate success of the transfer. To directly test this hypothesis, we characterized the resistance conferred by synonymous variants of a gentamicin resistance gene in three bacterial species: Escherichia coli, Acinetobacter baylyi and Pseudomonas aeruginosa. The strongest determinant of the resistance level conferred was the species in which the resistance gene was transferred, very likely because of important differences in the copy number of the plasmid carrying the gene. Significant differences in resistance were also found between synonymous variants within each of the three species, but more importantly, there was a strong interaction between species and variant: variants conferring high resistance in one species confer low resistance in another. However, the similarity in codon usage between the synonymous variants and the host genome only explained part of the phenotypic differences between variants in one species, P. aeruginosa. Further investigation of alternative explanations did not reveal common universal mechanisms across our three bacterial species. We conclude that codon composition can be a determinant of post-horizontal gene transfer success. However, there are multiple paths leading from synonymous sequence to phenotype, and sensitivity to these different paths is species-specific.

Termination of DNA replication is a surprisingly complex process that contributes critically to genome stability and cell viability. And even though progress was made to establish the consequences that arise if termination is going awry, the precise molecular mechanisms of fork fusion events and the coordination with key factors that ensure that DNA replication is brought to a successful conclusion remain poorly understood. We therefore investigated replication termination in E. coli, focusing specifically on the interplay between replication fork fusions and genomic stability, the Tus–ter replication fork trap, and key DNA-processing enzymes. By utilizing whole genome sequencing, immunoblotting, and recombination reporter assays, we demonstrate that local hyper-recombination is induced wherever forks meet and that the combined loss of factors such as RecG helicase and 3′ exonucleases causes extreme over-replication in the terminus region of the chromosome. Unexpectedly, cells lacking Tus exhibit elevated R-loop levels, revealing an unanticipated connection between the fork trap and R-loop metabolism. These findings underscore the complexity of replication termination and its central role in maintaining bacterial genome stability, while providing mechanistic insights with implications for understanding replication termination in more complex organisms and developing new antimicrobial strategies.

Methanol is a promising one-carbon (C1) feedstock for microbial bioconversion; however, engineered Saccharomyces cerevisiae often faces energetic constrains during its assimilation. Here, we develop SC-AOX25, an energy-efficient methylotrophic S. cerevisiae, through engineering of heterologous methanol-formaldehyde-formate (MFF) oxidation pathways coupled with adaptive laboratory evolution. SC-AOX25 efficiently generates adenosine triphosphate (ATP) and nicotinamide adenine dinucleotide (NADH) during methanol metabolism while co-assimilating methanol-derived intermediates (formaldehyde, formate, and CO₂) via native glyoxylate-serine cycle, pentose phosphate pathway, and reductive glycine pathway. Key energy modules - Fdh1sc, Adh2m, Aoxm, and Rgi2m - are characterized for their roles in ATP/NADH synthesis and methylotrophic growth. Formaldehyde-induced DNA-protein crosslinks (DPCs) and large repeated DNA fragments suggest strategies for methanol detoxification and phenotype enhancement. Utilizing SC-AOX25, we enable CO₂ assimilation through non-native Calvin cycle during methanol fermentation, establishing the engineered strain as a robust and energy-efficient methylotrophic platform for further C1 engineering. Synthetic methylotrophic S. cerevisiae often faces energetic constrains during one-carbon assimilation. Here, the authors address this issue by engineering of heterologous methanol-formate-formaldehyde oxidation pathways to enable CO2 assimilation via non-native Calvin cycle during methanol fermentation.

Nitrogen-fixing microbes are a primary contributor of this important nutrient to the global nitrogen cycle. Biological nitrogen fixation (BNF) through the enzyme nitrogenase requires extensive energy that in whole cells is generally studied during the oxidation of carbohydrates such as sugars. The nitrogen-fixing bacterium Azotobacter vinelandii is a model diazotroph for the study of aerobic BNF. Much is known about metabolism in A. vinelandii when cultured on a simple medium where energy is provided primarily in the form of sucrose or glucose. Outside of the laboratory, this soil bacterium grows on metabolites primarily derived from plant root exudates or from the degradation of dead plant matter. In this work, we expand on previous studies looking at genes that are essential to BNF in A. vinelandii when grown on sucrose medium using transposon sequencing (Tn-seq). We applied Tn-seq to determine the genes essential to growth when the medium was shifted to acetate, succinate or glycerol as the primary carbon and energy source to fuel both growth and BNF. A global overview of the genes of central metabolism and those directing substrates toward central metabolism, along with a selection of unexpected genes that were essential for specific growth substrates, is provided.

Computational analysis of large-scale metagenomics sequencing datasets provides valuable isolate-level taxonomic and functional insights from complex microbial communities. However, the ever-expanding ecosystem of metagenomics-specific methods and file formats makes designing scalable workflows and seamlessly exploring output data increasingly challenging. Although one-click bioinformatics pipelines can help organize these tools into workflows, they face compatibility and maintainability challenges that can prevent replication. To address the gap in easily extensible yet robustly distributable metagenomics workflows, we have developed the Core Analysis Modular Pipeline (CAMP), a module-based metagenomics analysis system written in Snakemake, with a standardized module and directory architecture. Each module can run independently or in sequence to produce target data formats (e.g. short-read preprocessing alone or followed by de novo assembly), and provides output summary statistics reports and Jupyter notebook-based visualizations. We applied CAMP to a set of 10 metagenomics samples, demonstrating how a modular analysis system with built-in data visualization facilitates rich seamless communication between outputs from different analytical purposes. The CAMP ecosystem (module template and analysis modules) can be found at https://github.com/Meta-CAMP.