Journal of Bacteriology

Type III Chromatic Acclimation (CA3) in Fremyella diplosiphon has traditionally served as a model for cyanobacterial acclimation to red and green light. CA3 is controlled by the red-green responsive Rca phosphorelay system, including the cyanobacteriochrome RcaE. However, regulation of pigmentation persists in the absence of RcaE, which is attributed to the Cgi system. Nothing is known about how the Cgi regulatory system senses light color to differentially regulate pigment expression. DpxA is a...

Sporulation is a widespread but incompletely characterized trait among gut commensals, where it underpins microbial persistence, transmission, and ecological resilience. Most insights into spore biology derive from Bacilli and Clostridia; however, little is known about sporulation in phylogenetically distant gut-associated lineages. Turicibacter sanguinis, a strict anaerobe linked to host serotonin metabolism, lipid homeostasis, and neurodegenerative disease, represents one such understudied...

Staphylococcus aureus is a globally prevalent gram-positive pathogen that can cause numerous types of infection. Due to host nutritional immunity and iron (Fe) sequestration, S. aureus experiences Fe limitation during infection. To overcome this, S. aureus expresses an arsenal of Fe acquisition systems whose expression is coordinated through the Fe-binding transcriptional regulator, Fur. Here, from a screen to identify S. aureus mutants defective for Fe-restricted growth, we identified several...

Phosphonates are alternative phosphorus sources widely present in environmental settings and in commercially relevant compounds such as pesticides and antibiotics. In Escherichia coli, uptake and assimilation of phosphonates are mediated by the 14-gene phnCDEFGHIJKLMNOP operon. In the laboratory, strain K-12 and its derivatives, phnE, encoding the phosphonate permease, carry an 8 bp insertion that causes a frameshift and premature termination. Early studies reported unusually high frequencies of...

Carbon starvation links nutrient sensing to bacterial morphogenesis, but the molecular pathway connecting glucose limitation to division failure remains unclear. In Streptococcus suis SC19, glucose limitation elevated RelA abundance and intracellular (p)ppGpp levels, slowed bacterial growth, and induced a reproducible spherical morphotype associated with selective impairment of peptidoglycan insertion. Inducible and constitutive RelA expression recapitulated the starvation phenotypes and...

The CenIR regulatory system of Clostridioides difficile comprises a predicted transcriptional repressor, CenI, and a predicted membrane metalloprotease, CenR. The physiological role of CenIR and activating signal(s) are not known. CenIR belongs to the BlaIR family of regulators that mediate resistance to β-lactam antibiotics. In canonical BlaIR systems, binding of a β-lactam to the extracellular transpeptidase domain of BlaR triggers proteolysis of BlaI and, thus, induction of a closely linked...

The 10th American Society for Microbiology Conference on Biofilms was held in person on 9-13 November 2025 in Portland, OR. The diverse mixture of over 300 oral and poster presentations resoundingly embodied the vitality of biofilm research across a wide range of topics and multiple scientific disciplines. Special activities, including a pre-conference symposium for early-career researchers, Lunch and Learn sessions, the Paul Stoodley imaging workshop, and various networking events, further...

Listeria monocytogenes (Lm) is a major foodborne pathogen capable of persisting on fresh produce and in food-processing environments. Although exopolysaccharides (EPSs) are recognized as central components of resilient bacterial biofilms, Lm biofilms have long been considered to be EPS-less or EPS-poor. We previously identified a listerial EPS, Pss, whose biosynthesis is encoded by the highly conserved pss operon and is stimulated by elevated c-di-GMP levels. However, the prevalence of Pss in...

Prophages, as the integrated or plasmid-like forms of temperate bacteriophage genomes, are critical genetic elements that establish stable interactions with their hosts, profoundly impacting host physiology and ecology. Prophages confer multiple advantages to their hosts. They promote changes in the bacterial genome structure and function-such as rearrangements, introduction of novel genes, and gene expression reprogramming-that often enhance bacterial fitness and persistence. Active prophages...

The mycomembrane of mycobacteria, which is composed primarily of long-chain mycolic acids, is critical for cell survival, structural integrity, and resistance to environmental stress; however, its underlying synthesis mechanisms remain incompletely understood. This study investigated the role of the mycolyltransferase Ag85A, a key enzyme in mycomembrane synthesis, in regulating plasma membrane domains and cell envelope organization in Mycobacterium smegmatis. Using ∆ag85A deletion mutants, we...

The mycobacterial cell envelope consists of multiple covalently linked layers that must be synthesized in a coordinated manner to maintain cell wall integrity. Despite the importance of this coordination, its molecular mechanisms remain poorly understood. PgfA (polar growth factor A) interacts with trehalose monomycolate lipids (TMMs) and the TMM transporter MmpL3. PgfA promotes TMM transport in the periplasm and functions as an upstream regulator of polar growth. How TMM transport is linked to...

Quorum sensing (QS) plays a central role in the adaptive biology of Streptococcus mutans, yet the extent to which competence-stimulating peptide (CSP) signaling intersects with membrane vesicle production and function remained unclear. In this study, CSP activation markedly increased membrane vesicle output during the stationary phase and drove extensive changes in vesicle protein composition. Proteomic analysis revealed broad remodeling of vesicle cargo, including shifts in subcellular origin,...

Antimicrobial resistance (AMR) is a global health crisis shaped by complex ecological and evolutionary processes that often occur in polymicrobial communities. Metagenomics enables culture-independent profiling of microbial DNA directly from clinical or environmental samples, providing an unparalleled view of community composition, resistome content, and the mobile genetic elements that drive horizontal gene transfer (HGT). Yet, a recurring challenge is that metagenomic detection of...

Listeria monocytogenes can grow as a saprophyte on decaying plant material and switch to a pathogenic lifestyle. This switch is mediated by the virulence regulator PrfA, which activates the expression of most virulence genes. PrfA activity is tightly regulated by several mechanisms to ensure that virulence genes are only expressed within the host. One of these regulatory mechanisms is the sugar-dependent inhibition. In the presence of readily metabolizable sugars, which are imported via...

Prevotella melaninogenica is a core member of the human oral and respiratory microbiomes, often representing more than 10% of microbial populations in both healthy and diseased lungs. Despite its prevalence in these oxygenated environments, P. melaninogenica has been historically classified as a strict obligate anaerobe, ostensibly unable to survive oxygen concentrations exceeding 0.05%. This creates a fundamental biological paradox as the organism consistently persists in the lower respiratory...