Journal of Bacteriology

Streptococcus pneumoniae (the pneumococcus) is one of the most common bacterial causes of middle ear infections (otitis media) in children. These infections are highly prevalent but can be persistent and challenging to treat. The pneumococcus is a highly genetically diverse organism, but the precise molecular factors that drive infection of the ear are not fully understood. Bacterial metabolic capacity is known to play an important role in infection. Here, we explored the metabolic capacity of...

Clustered regularly interspaced short palindromic repeat (CRISPR)-associated (Cas) systems form the adaptive immunity of prokaryotes, conferring sequence-specific protection against genetic parasites. Here, we functionally characterized the type I-F CRISPR-Cas system of Pseudomonas aeruginosa ATCC 10145 (PA10145), which led us to discover the existence of an isolated CRISPR array unique to this system. Its core CRISPR-Cas system is composed of a cas operon flanked by two divergently organized...

Mycobacterium tuberculosis (Mtb) survives host defenses by adapting to host conditions, including acid stress, during infection. A critical survival strategy involves pH homeostasis, mediated by complex signaling systems that regulate metabolic reprogramming and stress responses. While the lysine acetyltransferase Rv0998 is known to support Mtb hypoxia adaptation and metabolic flexibility, its role in acid stress remains unexplored. Here, we investigated the consequences of rv0998 deletion in...

Structural maintenance of chromosomes (SMC) complexes play conserved roles in chromosome organization, segregation, and repair in all domains of life. In Bacillus subtilis, SMC is required for the segregation of newly replicated origins. To investigate whether other proteins function with SMC in this process, we performed a synthetic lethal screen with an smc hypomorphic allele (smc*) that is mildly defective in chromosome segregation. In addition to recovering previously reported genetic...

Spores of Bacillus species are metabolically dormant and resistant to many agents but can come back to life in germination triggered by a variety of small molecules; these spore properties vary depending on the conditions and media for spore formation. In the current work, we have compared the properties of Bacillus subtilis spores made in a rich medium and an extremely poor medium. Notably, spores made in the poor liquid medium had lowered resistance to wet heat and somewhat lowered resistance...

Francisella tularensis is a highly virulent, gram-negative bacterial pathogen that causes the zoonotic disease tularemia. F. tularensis infects a variety of host cells and replicates intracellularly while evading and interfering with host immune responses. The molecular mechanisms that facilitate the intracellular replication and virulence of F. tularensis are poorly understood. The Francisella genome contains a set of pil genes that code for the assembly of surface fibers termed type IV pili...

The MprBA two-component system (TCS) plays a critical role in Mycobacterium tuberculosis persistence and forms a signaling pathway with the alternative sigma factors SigE and SigB. Here, we demonstrate that the MprBA-SigE-SigB signaling pathway is activated in Mycobacterium smegmatis under multiple stress conditions associated with respiratory inhibition, including genetic inactivation of the aa(3) cytochrome c oxidase, treatment with the bcc(1) complex inhibitor Q203, hypoxia, high ionic...

Clostridioides difficile is an urgent threat to human health. Current treatments for C. difficile infections (CDIs) are antibiotics and microbiome restoration therapy (MRT) for recurrent cases. However, antibiotics contribute to antibiotic resistance and recurrent CDIs, and the long-term sustainability and accessibility of MRTs remain to be determined. Since a dysbiotic gut microbiome is the primary risk factor for CDI, a better understanding of the interactions between C. difficile, the...

Acinetobacter baumannii has evolved from a relatively overlooked nosocomial pathogen into one of the most concerning multidrug-resistant threats worldwide. Its global dissemination, accelerated by healthcare-associated transmission and the emergence of carbapenem-resistant strains, has established A. baumannii as a critical priority pathogen. While initially studied primarily through the lens of antimicrobial resistance, growing evidence indicates that the remarkable success of A. baumannii...

Salmonella enterica encounters acid stress during gastrointestinal transit and within the phagosomal environment of macrophages. Acid stress resistance has been well characterized in Salmonella enterica serovar Typhimurium, but comparative studies in the human-adapted Salmonella enterica serovar Typhi are limited. We compared the growth of S. Typhimurium 14028s and S. Typhi Ty2 at pH values ranging from 3 to 8 and observed that Salmonella enterica serovar Typhimurium exhibits enhanced growth at...

Bdellovibrio bacteriovorus is a gram-negative Proteobacterium that has evolved to use a novel, predatory, intrabacterial lifestyle. Once encountered under a microscope, in a lecture, or a textbook, it is seldom forgotten. B. bacteriovorus speedily collides with, enters, modifies, and kills other gram-negative bacteria. Residing inside the periplasm of the dead prey for several hours, it uses prey molecules for growth and replication, only bursting out from that temporary home when its progeny...

The oxidation of manganese from Mn(II) to Mn(III) or Mn(IV) is a common trait in the Pseudomonas genus. Many pseudomonads oxidize Mn enzymatically using one or more multicopper oxidases (MnxG and McoA) and in some cases a heme peroxidase (MopA). The oxidation of Mn leads to the extracellular precipitation of reactive Mn oxides in association with extracellular polymeric substances (EPS). Here, we review the current state of knowledge on Mn oxidation and biomineralization in pseudomonads. While...

Antibiotic resistance presents an urgent global crisis, exacerbated by antibiotic overuse. Understanding the regulation of resistance genes within bacterial populations can inform strategies to prevent the spread of antibiotic resistance, and reveal how antibiotics shape microbial communities. We identified upregulation of five antibiotic resistance loci in Bacillus subtilis colonies on solid growth media, following exposure to subinhibitory chloramphenicol concentrations. Notably, four...

Bacterial metabolism is composed of a complex system of anabolic and catabolic processes, and productive growth results from the regulated interplay of these processes. Genetic and biochemical studies on the LT2 type strain of Salmonella enterica serovar Typhimurium determined the need for RidA to prevent metabolic stress caused by 2-aminoacrylate (2AA). RidA is an enamine deaminase, and in its absence, 2AA accumulates and can irreversibly damage critical pyridoxal 5'-phosphate-dependent...

The clustered regularly interspaced short palindromic repeats (CRISPR)-Cas system has facilitated gene editing of different organisms. Specifically, programmable base editing enables stable conversion of a single nucleotide to another nucleotide without causing DNA double-strand breaks. Cas9-derived base editors, including adenine and cytidine base editors, catalyze the formation of transition mutations with high efficiency. The third-generation cytidine base editors comprise a nickase-Cas9...