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BMC Microbiology May 2024Globally, drought stress poses a significant threat to crop productivity. Improving the drought tolerance of crops with microbial biostimulants is a sustainable strategy...
Globally, drought stress poses a significant threat to crop productivity. Improving the drought tolerance of crops with microbial biostimulants is a sustainable strategy to meet a growing population's demands. This research aimed to elucidate microbial biostimulants' (Plant Growth Promoting Rhizobacteria) role in alleviating drought stress in oil-seed crops. In total, 15 bacterial isolates were selected for drought tolerance and screened for plant growth-promoting (PGP) attributes like phosphate solubilization and production of indole-3-acetic acid, siderophore, hydrogen cyanide, ammonia, and exopolysaccharide. This research describes two PGPR strains: Acinetobacter calcoaceticus AC06 and Bacillus amyloliquefaciens BA01. The present study demonstrated that these strains (AC06 and BA01) produced abundant osmolytes under osmotic stress, including proline (2.21 and 1.75 µg ml), salicylic acid (18.59 and 14.21 µg ml), trehalose (28.35 and 22.74 µg mg FW) and glycine betaine (11.35 and 7.74 mg g) respectively. AC06 and BA01 strains were further evaluated for their multifunctional performance by inoculating in Arachis hypogaea L. (Groundnut) under mild and severe drought regimes (60 and 40% Field Capacity). Inoculation with microbial biostimulants displayed distinct osmotic-adjustment abilities of the groundnut, such as growth parameters, plant biomass, photosynthetic pigments, relative water content, proline, and soluble sugar in respective to control during drought. On the other hand, plant sensitivity indexes such as electrolyte leakage and malondialdehyde (MDA) contents were decreased as well as cooperatively conferred plant drought tolerance by induced alterations in stress indicators such as catalase (CAT), ascorbate peroxidase (APX), and superoxide dismutase (SOD). Thus, Acinetobacter sp. AC06 and Bacillus sp. BA01 can be considered as osmolyte producing microbial biostimulants to simultaneously induce osmotic tolerance and metabolic changes in groundnuts under drought stress.
Topics: Arachis; Droughts; Stress, Physiological; Proline; Bacillus amyloliquefaciens; Soil Microbiology; Osmotic Pressure; Betaine; Indoleacetic Acids; Salicylic Acid; Acinetobacter; Hydrogen Cyanide; Trehalose
PubMed: 38745279
DOI: 10.1186/s12866-024-03320-6 -
Diagnostic Microbiology and Infectious... Jul 2024Combinations of the β-lactam/β-lactamase inhibitor sulbactam-durlobactam and seventeen antimicrobial agents were tested against strains of Acinetobacter baumannii in...
Combinations of the β-lactam/β-lactamase inhibitor sulbactam-durlobactam and seventeen antimicrobial agents were tested against strains of Acinetobacter baumannii in checkerboard assays. Most combinations resulted in indifference with no instances of antagonism. These results suggest sulbactam-durlobactam antibacterial activity against A. baumannii is unlikely to be affected if co-dosed with other antimicrobial agents.
Topics: Sulbactam; Acinetobacter baumannii; Azabicyclo Compounds; Microbial Sensitivity Tests; Anti-Bacterial Agents; Humans; Acinetobacter calcoaceticus; beta-Lactamase Inhibitors; Acinetobacter Infections; Drug Combinations
PubMed: 38735147
DOI: 10.1016/j.diagmicrobio.2024.116344 -
Bioscience Reports May 2024The soluble glucose dehydrogenase (sGDH) from Acinetobacter calcoaceticus has been widely studied and is used, in biosensors, to detect the presence of glucose, taking...
The soluble glucose dehydrogenase (sGDH) from Acinetobacter calcoaceticus has been widely studied and is used, in biosensors, to detect the presence of glucose, taking advantage of its high turnover and insensitivity to molecular oxygen. This approach, however, presents two drawbacks: the enzyme has broad substrate specificity (leading to imprecise blood glucose measurements) and shows instability over time (inferior to other oxidizing glucose enzymes). We report the characterization of two sGDH mutants: the single mutant Y343F and the double mutant D143E/Y343F. The mutants present enzyme selectivity and specificity of 1.2 (Y343F) and 5.7 (D143E/Y343F) times higher for glucose compared with that of the wild-type. Crystallographic experiments, designed to characterize these mutants, surprisingly revealed that the prosthetic group PQQ (pyrroloquinoline quinone), essential for the enzymatic activity, is in a cleaved form for both wild-type and mutant structures. We provide evidence suggesting that the sGDH produces H2O2, the level of production depending on the mutation. In addition, spectroscopic experiments allowed us to follow the self-degradation of the prosthetic group and the disappearance of sGDH's glucose oxidation activity. These studies suggest that the enzyme is sensitive to its self-production of H2O2. We show that the premature aging of sGDH can be slowed down by adding catalase to consume the H2O2 produced, allowing the design of a more stable biosensor over time. Our research opens questions about the mechanism of H2O2 production and the physiological role of this activity by sGDH.
Topics: Acinetobacter calcoaceticus; Hydrogen Peroxide; Glucose 1-Dehydrogenase; Bacterial Proteins; Mutation; Glucose; Substrate Specificity; PQQ Cofactor; Crystallography, X-Ray
PubMed: 38687614
DOI: 10.1042/BSR20240102 -
International Journal of Molecular... Apr 2024The potato dry rot disease caused by spp. seriously reduces potato yield and threatens human health. However, potential biocontrol agents cannot guarantee the stability...
The potato dry rot disease caused by spp. seriously reduces potato yield and threatens human health. However, potential biocontrol agents cannot guarantee the stability and activity of biocontrol. Here, 18 synthetic microbial communities of different scales were constructed, and the synthetic microbial communities with the best biocontrol effect on potato dry rot disease were screened through in vitro and in vivo experiments. The results show that the synthetic community composed of , , , , and has the best biocontrol activity. Metabolomics results show that interacts with other member strains to produce caproic acid and reduce the disease index to 38.01%. Furthermore, the mycelial growth inhibition after treatment with caproic acid was 77.54%, and flow cytometry analysis showed that the living conidia rate after treatment with caproic acid was 11.2%. This study provides potential value for the application of synthetic microbial communities in potatoes, as well as the interaction mechanisms between member strains of synthetic microbial communities.
Topics: Solanum tuberosum; Plant Diseases; Caproates; Fusarium; Microbiota
PubMed: 38674022
DOI: 10.3390/ijms25084437 -
Comparative Immunology, Microbiology... Jun 2024To evaluate the frequency of Acinetobacter spp., belonging to both Acinetobacter calcoaceticus-baumannii (ACB) and non-ACB complex, and their antibiotic resistance...
Evidence and antibiotic resistance profiles of clinical Acinetobacter calcoaceticus-Acinetobacter baumannii (ACB) and non-ACB complex members in companion animals: A 2020-2022 retrospective study.
To evaluate the frequency of Acinetobacter spp., belonging to both Acinetobacter calcoaceticus-baumannii (ACB) and non-ACB complex, and their antibiotic resistance profiles in veterinary medicine, a three-year (2020-2022) retrospective study was carried out on sick companion animals. Epidemiological data from different clinical canine, feline, and equine samples, were acquired. For each strain, MALDI-TOF MS identification and susceptibility to a panel of 11 antibiotics, by Kirby-Bauer and E-test methods, were performed. Out of 628 bacteriological examinations, 2.5% resulted positive for strains belonging to Acinetobacter genus. Frequencies of 2.3%, 1.9%, and 3% were obtained from both in-visiting and hospitalized dogs, cats, and horses, respectively. Members of ACB-complex accounted for 50% of isolates. Since all strains resulted susceptible to aminoglycosides and polymyxins, no pandrug-resistant (PDR) species were recorded. While 12.5% A. baumannii resulted extensively-drug resistant (XDR), a higher percentage of multidrug-resistant strains was recorded among non-ACB strains (35.5%) than ACB strains (25%). Susceptibility was observed in the same percentage in both groups (62.5%). All ACB strains confirmed their intrinsic resistances. Non-ACB species showed lower resistances against antipseudomonal penicillins plus beta-lactamase inhibitors (P=0.1306), III generation cephalosporins (P=0.0547), and tetracyclines (P=0.0209) than ACB species. Carbapenem-resistance was observed for XDR A. baumannii (12.5%) and, in particular for MDR non-ACB complex members (25%). To our knowledge, A. lactucae represents the first description in two sick dogs in Italy. Furthermore, our results emphasize the role of non-ACB-complex species as important zoonotic pathogens, which could be reservoirs of clinically relevant resistance profiles.
Topics: Animals; Retrospective Studies; Dogs; Cats; Acinetobacter Infections; Horses; Anti-Bacterial Agents; Acinetobacter baumannii; Microbial Sensitivity Tests; Drug Resistance, Multiple, Bacterial; Dog Diseases; Cat Diseases; Pets; Acinetobacter calcoaceticus; Horse Diseases
PubMed: 38663213
DOI: 10.1016/j.cimid.2024.102185 -
Frontiers in Microbiology 2024The complex, or Acb complex, consists of six species: , and . is the most clinically significant of these species and is frequently related to healthcare-associated...
INTRODUCTION
The complex, or Acb complex, consists of six species: , and . is the most clinically significant of these species and is frequently related to healthcare-associated infections (HCAIs). Clustered regularly interspaced short palindromic repeat (CRISPR) arrays and associated genes () constitute bacterial adaptive immune systems and function as variable genetic elements. This study aimed to conduct a genomic analysis of Acb complex genomes available in databases to describe and characterize CRISPR systems and genes.
METHODS
Acb complex genomes available in the NCBI and BV-BRC databases, the identification and characterization of CRISPR-Cas systems were performed using CRISPRCasFinder, CRISPRminer, and CRISPRDetect. Sequence types (STs) were determined using the Oxford scheme and ribosomal multilocus sequence typing (rMLST). Prophages were identified using PHASTER and Prophage Hunter.
RESULTS
A total of 293 genomes representing six Acb species exhibited CRISPR-related sequences. These genomes originate from various sources, including clinical specimens, animals, medical devices, and environmental samples. Sequence typing identified 145 ribosomal multilocus sequence types (rSTs). CRISPR-Cas systems were confirmed in 26.3% of the genomes, classified as subtypes I-Fa, I-Fb and I-Fv. Probable CRISPR arrays and genes associated with CRISPR-Cas subtypes III-A, I-B, and III-B were also detected. Some of the CRISPR-Cas systems are associated with genomic regions related to Cap4 proteins, and toxin-antitoxin systems. Moreover, prophage sequences were prevalent in 68.9% of the genomes. Analysis revealed a connection between these prophages and CRISPR-Cas systems, indicating an ongoing arms race between the bacteria and their bacteriophages. Furthermore, proteins associated with anti-CRISPR systems, such as AcrF11 and AcrF7, were identified in the and genomes.
DISCUSSION
This study elucidates CRISPR-Cas systems and defense mechanisms within the Acb complex, highlighting their diverse distribution and interactions with prophages and other genetic elements. This study also provides valuable insights into the evolution and adaptation of these microorganisms in various environments and clinical settings.
PubMed: 38655087
DOI: 10.3389/fmicb.2024.1335997 -
Microbiology Resource Announcements Apr 2024We report the whole-genome sequence and antibiotic-resistance gene profile of an isolate, designated AC001_UM, taken from soil along the Red River in Winnipeg,...
We report the whole-genome sequence and antibiotic-resistance gene profile of an isolate, designated AC001_UM, taken from soil along the Red River in Winnipeg, Manitoba, Canada. The genome comprised 3,916,544 nucleotides (GC content: 38.7%). Antibiotic-resistance gene analysis revealed a class D β-lactamase and three efflux pump families.
PubMed: 38634680
DOI: 10.1128/mra.01122-23 -
Journal of Global Antimicrobial... Apr 2024To report trends in carbapenem resistance and difficult-to-treat resistance (DTR) among clinical isolates of Gram-negative priority pathogens collected by the ATLAS...
OBJECTIVES
To report trends in carbapenem resistance and difficult-to-treat resistance (DTR) among clinical isolates of Gram-negative priority pathogens collected by the ATLAS global surveillance program from 2018 to 2022.
METHODS
Reference broth microdilution testing was performed in a central laboratory for 79,214 Enterobacterales, 30,504 Pseudomonas aeruginosa, and 13,500 Acinetobacter baumannii-calcoaceticus complex isolates collected by a constant set of 157 medical centres in 49 countries in Asia Pacific (APAC), Europe (EUR), Latin America (LATAM), Middle East-Africa (MEA), and North America (NA) regions. MICs were interpreted by 2023 CLSI M100 breakpoints. β-lactamase genes were identified for meropenem-nonsusceptible (MIC ≥2 mg/L) Enterobacterales isolates.
RESULTS
Carbapenem-resistant Enterobacterales (CRE) detection increased (P < 0.05) in APAC, EUR, LATAM, and MEA regions and decreased in NA, while annual DTR percentages increased in all five regions. Carbapenem-resistant P. aeruginosa (CRPA; decreased in MEA region) and carbapenem-resistant A. baumannii-calcoaceticus complex (CRAB; decreased in MEA region and increased in EUR) remained relatively stable over time in all regions, although notably, annual percentages of CRAB and DTR A. baumannii-calcoaceticus complex isolates were consistently >25 percentage points lower in NA than in other regions. For all regions except NA, the majority of changes in CRE percentages could be attributed to hospital-acquired infections. Among meropenem-nonsusceptible Enterobacterales, KPC was the most frequent carbapenemase in NA and EUR each year. NDM was the most prevalent carbapenemase detected in 2022 in other global regions.
CONCLUSION
CRE, CRPA, CRAB, and DTR rates vary among global regions over time highlighting the need for continuing surveillance to inform treatment strategies and antimicrobial stewardship.
PubMed: 38608936
DOI: 10.1016/j.jgar.2024.03.020 -
Open Forum Infectious Diseases Apr 2024In a previous study, the efficacy and safety of sulbactam-durlobactam vs colistin for the treatment of patients with carbapenem-resistant complex (CRABC) infections...
Clinical Outcomes for Patients With Monomicrobial vs Polymicrobial Complex Infections Treated With Sulbactam-Durlobactam or Colistin: A Subset Analysis From a Phase 3 Clinical Trial.
BACKGROUND
In a previous study, the efficacy and safety of sulbactam-durlobactam vs colistin for the treatment of patients with carbapenem-resistant complex (CRABC) infections were evaluated in a randomized controlled phase 3 trial. Both arms were dosed on a background of imipenem-cilastatin to treat coinfecting gram-negative pathogens. Thirty-six percent of infections in the primary efficacy population were polymicrobial.
METHODS
A subset analysis was performed to compare clinical and microbiological outcomes at test of cure (7 ± 2 days after the last dose) for patients with monomicrobial and polymicrobial CRABC infections. Minimal inhibitory concentrations of antibiotics against baseline isolates were determined by broth microdilution according to Clinical and Laboratory Standards Institute methodology.
RESULTS
Clinical cure, 28-day all-cause mortality, and microbiological outcomes were similar for patients in the sulbactam-durlobactam treatment arm with monomicrobial or polymicrobial infections. Patients in the colistin arm with monomicrobial CRABC infections had higher mortality rates with worse clinical and microbiological outcomes as compared with those with polymicrobial infections. For patients who received sulbactam-durlobactam, imipenem susceptibility of coinfecting gram-negative pathogens trended with clinical benefit for patients with polymicrobial infections. When tested in vitro, durlobactam restored imipenem susceptibility to the majority of coinfecting gram-negative pathogens from the sulbactam-durlobactam arm. This phenotype appeared to be related to the clinical outcome in 13 of 15 evaluable cases.
CONCLUSIONS
These results suggest that the use of sulbactam-durlobactam plus a carbapenem could be an effective approach to treat polymicrobial infections that include CRABC, but additional clinical data are needed to demonstrate efficacy.
PubMed: 38595956
DOI: 10.1093/ofid/ofae140 -
Antimicrobial Agents and Chemotherapy May 2024s complex (ABC) causes severe, difficult-to-treat infections that are frequently antibiotic resistant. Sulbactam-durlobactam (SUL-DUR) is a targeted... (Randomized Controlled Trial)
Randomized Controlled Trial
s complex (ABC) causes severe, difficult-to-treat infections that are frequently antibiotic resistant. Sulbactam-durlobactam (SUL-DUR) is a targeted β-lactam/β-lactamase inhibitor combination antibiotic designed to treat ABC infections, including those caused by multidrug-resistant strains. In a global, pathogen-specific, randomized, controlled phase 3 trial (ATTACK), the efficacy and safety of SUL-DUR were compared to colistin, both dosed with imipenem-cilastatin as background therapy, in patients with serious infections caused by carbapenem-resistant ABC. Results from ATTACK showed that SUL-DUR met the criteria for non-inferiority to colistin for the primary efficacy endpoint of 28-day all-cause mortality with improved clinical and microbiological outcomes compared to colistin. This report describes the characterization of the baseline ABC isolates from patients enrolled in ATTACK, including an analysis of the correlation of microbiological outcomes with SUL-DUR MIC values and the molecular drivers of SUL-DUR resistance.
Topics: Humans; Acinetobacter baumannii; Sulbactam; Anti-Bacterial Agents; Microbial Sensitivity Tests; Acinetobacter Infections; Colistin; Azabicyclo Compounds; Drug Resistance, Multiple, Bacterial; Acinetobacter calcoaceticus; Cilastatin, Imipenem Drug Combination; Male
PubMed: 38567976
DOI: 10.1128/aac.01698-23