Complete genome sequence of an enterotoxigenic strain 2-078382-3 from an infant with diarrhea.

This study presents that strain 2-078382-3, isolated from an infant with diarrhea, has a 5.2 million base pair chromosome with a 43.2% GC content and a 5,600 base pairs plasmid pBFP53 with a 39.

Experimental evolution under different nutritional conditions changes the genomic architecture and virulence of Acinetobacter baumannii.

This study uncovers the molecular processes governing the adaptive evolution of multidrug-resistant (MDR) pathogens without antibiotic pressure. Genomic analysis of MDR Acinetobacter baumannii cells cultured for 8000 generations under starvation conditions (EAB1) or nutrient-rich conditions (EAB2) revealed significant genomic changes, primarily by insertion sequence (IS)-mediated insertions and deletions. Only two Acinetobacter-specific prophage-related deletions and translocations were observed in the EAB1 strain.

The Microbiological Characteristics of Associated With Early Mortality in Patients With Bloodstream Infection.

Background: Despite rapid deaths resulting from bacteremia, the clinical impact of the microbiological characteristics of strains on early mortality (EM) is unclear. We aimed to identify the microbiological characteristics of strains associated with EM.

Methods: Clinical information and isolates from patients with bacteremia from January 2015 to December 2021 were collected.

bacteremia in the Republic of Korea.

In 2015, and were proposed as new species, distinct from and collectively referred to as the complex. However, no clinical reports of these new species exist in Korea. Upon the application of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) for all bloodstream isolates since September 2022, was identified in one patient.

Membrane Proteins as a Regulator for Antibiotic Persistence in Gram-Negative Bacteria.

Antibiotic treatment failure threatens our ability to control bacterial infections that can cause chronic diseases. Persister bacteria are a subpopulation of physiological variants that becomes highly tolerant to antibiotics. Membrane proteins play crucial roles in all living organisms to regulate cellular physiology.

Chemical modulation of SQSTM1/p62-mediated xenophagy that targets a broad range of pathogenic bacteria.

The N-degron pathway is a proteolytic system in which the N-terminal degrons (N-degrons) of proteins, such as arginine (Nt-Arg), induce the degradation of proteins and subcellular organelles via the ubiquitin-proteasome system (UPS) or macroautophagy/autophagy-lysosome system (hereafter autophagy). Here, we developed the chemical mimics of the N-degron Nt-Arg as a pharmaceutical means to induce targeted degradation of intracellular bacteria via autophagy, such as serovar Typhimurium (. Typhimurium), , and as well as (Mtb).

Low Cytoplasmic Magnesium Increases the Specificity of the Lon and ClpAP Proteases.

Proteolysis is a fundamental property of all living cells. In the bacterium Salmonella enterica serovar Typhimurium, the HspQ protein controls the specificities of the Lon and ClpAP proteases. Upon acetylation, HspQ stops being a Lon substrate and no longer enhances proteolysis of the Lon substrate Hha.

Reduced ATP-dependent proteolysis of functional proteins during nutrient limitation speeds the return of microbes to a growth state.

When cells run out of nutrients, the growth rate greatly decreases. Here, we report that microorganisms, such as the bacterium serovar Typhimurium, speed up the return to a rapid growth state by preventing the proteolysis of functional proteins by ATP-dependent proteases while in the slow-growth state or stationary phase. This reduction in functional protein degradation resulted from a decrease in the intracellular concentration of ATP that was nonetheless sufficient to allow the continued degradation of nonfunctional proteins by the same proteases.

Small proteins regulate survival inside macrophages by controlling degradation of a magnesium transporter.

All cells require Mg to replicate and proliferate. The macrophage protein Slc11a1 is proposed to protect mice from invading microbes by causing Mg starvation in host tissues. However, the Mg transporter MgtB enables the facultative intracellular pathogen serovar Typhimurium to cause disease in mice harboring a functional Slc11a1 protein.

The expanded specificity and physiological role of a widespread N-degron recognin.

All cells use proteases to maintain protein homeostasis. The proteolytic systems known as the N-degron pathways recognize signals at the N terminus of proteins and bring about the degradation of these proteins. The ClpS protein enforces the N-degron pathway in bacteria and bacteria-derived organelles by targeting proteins harboring leucine, phenylalanine, tryptophan, or tyrosine at the N terminus for degradation by the protease ClpAP.

Activator of one protease transforms into inhibitor of another in response to nutritional signals.

All cells use proteases to adjust protein amounts. Proteases maintain protein homeostasis by degrading nonfunctional toxic proteins and play regulatory roles by targeting particular substrates in response to specific signals. Here we address how cells tune protease specificity to nutritional signals.

A protein that controls the onset of a virulence program.

The mechanism of action and contribution to pathogenesis of many virulence genes are understood. By contrast, little is known about anti-virulence genes, which contribute to the start, progression, and outcome of an infection. We now report how an anti-virulence factor in serovar Typhimurium dictates the onset of a genetic program that governs metabolic adaptations and pathogen survival in host tissues.

Reduction in adaptor amounts establishes degradation hierarchy among protease substrates.

ATP-dependent proteases control critical cellular processes, including development, physiology, and virulence. A given protease may recognize a substrate directly via an unfoldase domain or subunit or indirectly via an adaptor that delivers the substrate to the unfoldase. We now report that cells achieve differential stability among substrates of a given protease by modulating adaptor amounts.

Sequestration from Protease Adaptor Confers Differential Stability to Protease Substrate.

According to the N-end rule, the N-terminal residue of a protein determines its stability. In bacteria, the adaptor ClpS mediates proteolysis by delivering substrates bearing specific N-terminal residues to the protease ClpAP. We now report that the Salmonella adaptor ClpS binds to the N terminus of the regulatory protein PhoP, resulting in PhoP degradation by ClpAP.

Reducing Ribosome Biosynthesis Promotes Translation during Low Mg Stress.

The synthesis of ribosomes is regulated by both amino acid abundance and the availability of ATP, which regenerates guanosine triphosphate (GTP), powers ribosomes, and promotes transcription of rRNA genes. We now report that bacteria supersede both of these controls when experiencing low cytosolic magnesium (Mg), a divalent cation essential for ribosome stabilization and for neutralization of ATP's negative charge. We uncover a regulatory circuit that responds to low cytosolic Mg by promoting expression of proteins that import Mg and lower ATP amounts.

(1)H NMR-based metabolite profiling of planktonic and biofilm cells in Acinetobacter baumannii 1656-2.

Acinetobacter baumannii is an aerobic and gram-negative pathogenic bacterium that is resistant to most antibiotics. Recently, A. baumannii 1656-2 exhibited the ability to form biofilms under clinical conditions.

AFM probing the mechanism of synergistic effects of the green tea polyphenol (-)-epigallocatechin-3-gallate (EGCG) with cefotaxime against extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli.

Background: Extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae poses serious challenges to clinicians because of its resistance to many classes of antibiotics.

Methods And Findings: The mechanism of synergistic activity of a combination of (-)-epigallocatechin-3-gallate (EGCG) and β-lactam antibiotics cefotaxime was studied on Extended-spectrum β-lactamase producing Escherichia coli (ESBL-EC), by visualizing the morphological alteration on the cell wall induced by the combination using atomic force microscopy (AFM). Cells at sub-MICs (sub-minimum inhibitory concentrations) of cefotaxime were initially filamentated but recovered to the normal shape later, whereas cells at sub-MICs of EGCG experienced temporal disturbance on the cell wall such as leakage and release of cellular debris and groove formation, but later recovered to the normal shape.

Biochemical characterization of ferredoxin-NADP(+) reductase interaction with flavodoxin in Pseudomonas putida.

Flavodoxin (Fld) has been demonstrated to bind to ferredoxin- NADP(+) reductase A (FprA) in Pseudomonas putida. Two residues (Phe(256), Lys(259)) of FprA are likely to be important for interacting with Fld based on homology modeling. Sitedirected mutagenesis and pH-dependent enzyme kinetics were performed to further examine the role of these residues.

Pleiotropic effects of the mioC mutation on the physiology of Pseudomonas aeruginosa PAO1.

Flavodoxin (Fld) is a bacterial electron-transfer protein that possesses flavin mononucleotide as a prosthetic group. In the genomes of the Pseudomonas species, the mioC gene is the sole gene, annotated Fld, but its function remains unclear. In this study, phenotype microarray analysis was performed using the wild-type and mioC mutant of pathogenic Pseudomonas aeruginosa PAO1.

Seasonal changes in nitrogen-cycle gene abundances and in bacterial communities in acidic forest soils.

The abundance of genes related to the nitrogen biogeochemical cycle and the microbial community in forest soils (bacteria, archaea, fungi) were quantitatively analyzed via real-time PCR using 11 sets of specific primers amplifying nifH, bacterial amoA, archaeal amoA, narG, nirS, nirK, norB, nosZ, bacterial 16S rRNA gene, archaeal 16S rRNA gene, and the ITS sequence of fungi. Soils were sampled from Bukhan Mountain from September of 2010 to July of 2011 (7 times). Bacteria were the predominant microbial community in all samples.

ATP-dependent RecG helicase is required for the transcriptional regulator OxyR function in Pseudomonas species.

The oxyR gene appears to reside in an operon with the recG helicase gene in many bacteria, including pathogenic Pseudomonas aeruginosa and Pseudomonas putida. Analysis of P. putida transcriptomes shows that many OxyR-controlled genes are regulated by the ATP-dependent RecG helicase and that RecG alone modulates the expression of many genes.

Effects of non-ionic solute stresses on biofilm formation and lipopolysaccharide production in Escherichia coli O157:H7.

The addition of non-ionic solutes such as sucrose and polyethylene glycol (PEG) to a culture of Escherichia coli O157:H7 stimulated formation of a biofilm on an abiotic surface. Possible factors involved in this increased biofilm formation were evaluated, i.e.

Change in gene abundance in the nitrogen biogeochemical cycle with temperature and nitrogen addition in Antarctic soils.

The microbial community (bacterial, archaeal, and fungi) and eight genes involved in the nitrogen biogeochemical cycle (nifH, nitrogen fixation; bacterial and archaeal amoA, ammonia oxidation; narG, nitrate reduction; nirS, nirK, nitrite reduction; norB, nitric oxide reduction; and nosZ, nitrous oxide reduction) were quantitatively assessed in this study, via real-time PCR with DNA extracted from three Antarctic soils. Interestingly, AOB amoA was found to be more abundant than AOA amoA in Antarctic soils. The results of microcosm studies revealed that the fungal and archaeal communities were diminished in response to warming temperatures (10 °C) and that the archaeal community was less sensitive to nitrogen addition, which suggests that those two communities are well-adapted to colder temperatures.

Detection of genetically modified microorganisms in soil using the most-probable-number method with multiplex PCR and DNA dot blot.

The principal objective of this study was to detect genetically modified microorganisms (GMMs) that might be accidentally released into the environment from laboratories. Two methods [plate counting and most-probable-number (MPN)] coupled with either multiplex PCR or DNA dot blots were compared using genetically modified Escherichia coli, Pseudomonas putida, and Acinetobacter oleivorans harboring an antibiotic-resistance gene with additional gfp and lacZ genes as markers. Alignments of sequences collected from databases using the Perl scripting language (Perl API) and from denaturing gradient gel electrophoresis analysis revealed that the gfp, lacZ and antibiotic-resistance genes (kanamycin, tetracycline, and ampicillin) in GMMs differed from the counterpart genes in many sequenced genomes and in soil DNA.