AMB Express最新文献

Aeromonas hydrophila, a Gram-negative bacterium, poses significant threats to aquaculture, leading to substantial economic losses. Its pathogenicity is primarily driven by a sophisticated quorum sensing (QS) system that regulates virulence factors. This study investigates saponins extracted from the sea cucumber Holothuria leucospilota as potential natural inhibitors of QS in A. hydrophila, offering a novel disease management strategy for aquaculture. Specimens of H. leucospilota were collected, and saponins were extracted from their Cuvierian tubules through a process of homogenization, solvent extraction, and purification. The saponin extract's minimum bactericidal concentration (MBC) and minimum inhibitory concentration (MIC) against A. hydrophila were found to be 80 μg/mL and 30 μg/mL, respectively. Hemolysin, lipase, and protease are examples of QS-regulated virulence factors whose activities were found to be significantly reduced by sub-MIC levels of saponins. Additionally, swarming motility and biofilm formation were notably inhibited. A significant downregulation of the QS genes ahyI and ahyR was observed, indicating an effective disruption of the QS system.These findings suggest that saponins from H. leucospilota can inhibit the QS system in A. hydrophila, thereby reducing its pathogenicity. This disruption offers a promising method for controlling bacterial infections without directly killing the bacteria, potentially mitigating antibiotic resistance. The study highlights the potential of marine-derived compounds as natural QS inhibitors, contributing to environmentally friendly aquaculture practices. Overall, it provides evidence that sea cucumber saponins could serve as a novel class of anti-QS agents, presenting a new perspective on disease management in aquaculture and other bacterial infection contexts.

The ever-increasing use of phosphonates and their derivatives has resulted in the discharge of large quantities of these materials into the ecosystem, causing pollution and harmful shifts in microbiome composition. We conducted an extensive phylogenetic analysis to address this mounting problem and to help determine suitable microbes for bioremediation in specific environments. The 84 microorganisms included in our study span the gamut of species and occupied habitats. They degrade phosphonates by expressing an enzyme complex; CP-Lyase transcribed from 14 cistrons. Of the organisms studied, 12, 39, and 25 are singularly suitable for mostly freshwater, marine, or terrestrial habitats, respectively. Others adapted to multihabitats include Calothrix sp. PCC 7507 (both freshwater and marine habitats), Escherichia coli, Kaistia soli, Limoniibacter endophyticus, Marivita sp. and Virgibacillus dokdonensis (both marine and terrestrial habitats), Acidithiobacillus ferrooxidans (both freshwater and terrestrial habitats), with Paenibacillus contaminans suitable for freshwater, marine, and terrestrial habitats. All organisms were statistically rooted to glutathione peroxidase for phylogenetic perspective with tree topology dependent upon 50% or greater support. Clustered genes have been shown to have co-evolved based on striking nucleotide similarity and clade groupings within the tree topologies generated.

Colorectal cancer (CRC) is a prevalent disease with a high mortality rate and is significantly affected by microbial dysbiosis. Recent research suggests that modulation of the gut microbiome can have therapeutic benefits and that Angiotensin-II Type 1 Receptor (AT1R) can stimulate cell growth, angiogenesis, and resistance to apoptosis in various cancers. In this study, the adjunctive administration of Lactobacillus spp. and telmisartan, an AT1R blocker, was explored in the treatment of CRC. The effect of telmisartan and a mixture of probiotic species, Lactobacillus delbrueckii and Lactobacillus fermentum, was assessed on key biomarkers and selected gut microbiota taxa in 1,2-dimethylhydrazine-induced CRC in rats. Angiogenesis, inflammation, and apoptosis were assessed by measuring vascular endothelial growth factor (VEGF), carcinoembryonic antigen (CEA), Interleukin 6 (IL-6), and Annexin V levels, respectively. The relative abundance of selected gut microbial taxa, including Bacteroides spp., Clostridium spp., Clostridium coccoides, Ruminococcus spp., and Lactobacillus spp. was analyzed to determine the change in the microbial composition in the different experimental groups of the animal model. This study demonstrated that the unique combination therapy using a Lactobacillus mixture and telmisartan effectively reduced VEGF and IL-6 levels, indicating decreased angiogenesis and inflammation. Lactobacillus spp. co-administration with telmisartan boosted programmed cell death, reversed dysbiosis, improved histopathological outcomes, and reduced CEA levels. These findings offer a new perspective on the role of Lactobacillus spp. and telmisartan in CRC treatment. Further research on their adjunctive use and therapeutic potential are needed to enhance clinical efficacy.

The occurrence of mosquito-borne diseases is increasing, and their geographical range is expanding due to climate change. New control measures are urgently needed to combat these debilitating and, in some cases, fatal diseases. Bacteria of the genus Bacillus are of interest due to the production of bioactive compounds, including those useful for insect control. The discovery and characterization of new species of Bacillus with mosquito larvicidal activity may offer opportunities to develop new products for vector control. In this study, we evaluated larvicidal activity, described morphological characteristics, and sequenced and analyzed the genome of a bacterial strain (GD02.13) isolated from the Amazon region. The metabolites produced by GD02.13 are as effective in killing Aedes aegypti larvae as the commercial product Natular™ DT (Spinosad). Furthermore, the morphological characteristics of the GD02.13 spores and crystal inclusions resemble those previously described for B. thuringiensis. A phylogenetic analysis based on 443 single-copy orthologs indicated that the bacterial strain GD02.13 belongs to the Bacillus thuringiensis species. Its genome, which was assembled and has a size of 6.6 Mb, contains 16 secondary metabolite biosynthetic gene clusters and genes encoding insecticidal proteins, predicted based on sequence similarity. The data obtained in this study support the development of new insecticide products based on the strain GD02.13 of B. thuringiensis.

The rise of deaths by resistant bacteria is a global threat to public health systems. Klebsiella pneumoniae is a virulent pathogen that causes serious nosocomial infections. The major obstacle to bacterial treatment is antibiotic resistance, which necessitates the introducing of alternative therapies. Phage therapy has been regarded as a promising avenue to fight multidrug-resistant (MDR) pathogens. In the current study, a novel phage vB_KpnP_KP17 was isolated from sewage, and its lytic potential was investigated against K. pneumoniae. The isolated phage vB_KpnP_kP17 was lytic to 17.5% of tested K. pneumoniae isolates. One step growth curve indicated a virulent phage with a short latent period (20 min) and large burst size (331 PFU/cell). Additionally, vB_KpnP_kP17 maintained its activity against planktonic cells over a wide range of pH, temperature and UV irradiation intervals. The potential of vB_KpnP_KP17 as antibiofilm agent was revealed by the biofilm inhibition assay. The isolated phage vB_KpnP_KP17 at multiplicity of infection (MOI) of 10 inhibited more than 50% of attached biofilms of tested K. pneumoniae isolates. The genome of vB_KpnP_kP17 was characterized and found to be a linear dsDNA of 39,936 bp in length and GC content of 52.85%. Additionally, the absence of toxicity, virulence and antibiotic resistance genes further confirms the safety of vB_KpnP_KP17 for clinical applications. These characteristics make vB_KpnP_KP17 of a potential therapeutic value to manage MDR K. pneumoniae infections. Additionally, the formulation of vB_KpnP_KP17 in a cocktail with other lytic phages or with antibiotics could be applied to further limit biofilm-producing K. pneumoniae infections.

Obesity is a complex disorder influenced by various factors, including gut microbiota, which play a crucial role in metabolic regulation. This study is aimed to investigate the effects of Bacteroides thetaiotaomicron and Bacteroides fragilis, along with their derivatives-outer membrane vesicles (OMVs) and cell-free supernatant (CFS)-on the expression and secretion of satiety hormones in the murine intestinal secretin tumor cell line (STC-1). We examined the expression of peptide YY (PYY), glucagon-like peptide-1 and -2 (GLP-1 and GLP-2, encoded by the GCG gene), the enzyme prohormone convertase-1 (PC1/PCSK1 gene), and the receptors G protein-coupled receptor 119 and 120 (GPR119 and GPR120), and G-protein-coupled bile acid receptor (TGR5). Our results demonstrate that live B. fragilis significantly increased PYY expression and secretion. B. thetaiotaomicron CFS notably upregulated GCG, PCSK1, GPR119, GPR120, and TGR5 expression, leading to elevated GLP-1 secretion. B. fragilis CFS decreased GPR119, GPR120, and GCG expression. OMVs from B. thetaiotaomicron at 50 µg/ml significantly enhanced GCG and PCSK1 expression, while B. fragilis OMVs generally decreased gene expression, except for PYY protein abundance. Inactive B. thetaiotaomicron and B. fragilis increased GCG mRNA levels and GLP-1 concentration, with inactive B. fragilis also elevating GLP-2 protein levels.This study suggests that B. thetaiotaomicron and its derivatives, particularly CFS and OMVs, have potential as next-generation probiotics, postbiotics, and paraprobiotics for modulating satiety hormones and managing obesity. Further research is warranted to explore their mechanisms and therapeutic applications in vivo.

Non-tuberculous mycobacterial (NTM) infections have emerged as a significant public health concern, posing a threat to human health. This study aims to identify various NTM strains from bronchoalveolar lavage fluid, assess their drug resistance profiles, and investigate the risk factors associated with NTM disease. Gene chip technology was used to identify NTM strains. The broth microdilution method assessed the drug sensitivity of isolated NTM pathogenic bacteria, determining their minimum inhibitory concentrations (MICs). Logistic regression analysis identified potential risk factors for NTM disease. Results showed the slow-growing NTM strains isolated from bronchoalveolar lavage fluid to be predominantly Mycobacterium avium and Mycobacterium intracellulare, accounting for 32.05% and 29.49% of the isolates, respectively. The rapidly growing NTM strains were mainly Mycobacterium chelonae and Mycobacterium abscessus, each constituting 25.64% of the isolates. Mycobacterium avium was found to be sensitive to clarithromycin, while linezolid demonstrated high antibacterial efficacy against Mycobacterium intracellulare. In drug susceptibility testing of Mycobacterium chelonae and Mycobacterium abscessus, amikacin exhibited the highest sensitivity, followed by clarithromycin. For patients with NTM-positive cultures, the risk factors for NTM lung disease included age (45-60 years, > 60 years), a smoking history exceeding 10 years, chronic obstructive pulmonary disease (COPD), bronchiectasis, immunocompromised status, and the presence of thin-walled pulmonary cavities. Collectively, this study elucidates the distribution of NTM strains, their drug susceptibility profiles, and key risk factors for NTM lung disease, highlighting the need for proactive screening, early intervention, and targeted preventive strategies to improve diagnosis and optimize treatment outcomes.

Resistant and virulent strains of Klebsiella pneumoniae (K. pneumoniae) are rapidly disseminated among both hospitalized patients and communities, therefore, the identification of the genes responsible for virulence and resistance, along with the clonal relatedness of these strains, could be beneficial in the management of the dissemination of these strains among patients. The aim of the present study was to assess antibiotic susceptibility, virulence and resistance genes, as well as the genetic relatedness of K. pneumoniae strains isolated from patients admitted to four hospitals in Mazandaran, Iran. A total of 95 K. pneumoniae were gathered from hospitalized patients. All isolates were confirmed using biochemical and conventional microbiological methods, followed by the assessment of susceptibility patterns through disk diffusion and the detection of resistance and virulence genes using conventional PCR. The genetic diversity of clinical isolates was determined using the Enterobacterial Repetitive Intergenic Consensus PCR (ERIC-PCR) technique. The resistance frequencies varied, with the highest being for ampicillin/sulbactam (95.8%) and the lowest for fosfomycin (3.2%). Only one strain displayed a non-MDR profile against all antibiotics tested. Virulence-associated genes were detected, such as mrkD (90.5%), fimH (80%), entB (92.6%), iutA (25.3%), and ybtS (68.4%). Genes associated with efflux pumps and outer membrane porins included acrAB (98.9%), tolC (95.8%), mdtK (83.2%), ompK35 (95.8%), and ompK36 (92.6%). Based on ERIC-PCR patterns with a 90% similarity, the isolates were categorized into 17 distinct clusters. While the majority of isolates had a same profile and were grouped in the predominant pattern, 11 isolates were identified as singletons. Our study indicates that the prevalence of MDR K. pneumoniae carrying virulence genes and exhibiting close relatedness underscores the urgent need for effective strategies to control and prevent infections caused by K. pneumoniae.

To assess bacterial vaginosis (BV)-related primary molecular diagnostic markers of Lactobacillus crispatus, Gardnerella vaginalis, Fannyhessea vaginae, bacterial vaginosis-associated bacteria 2 (BVAB-2), Megasphaera-1 and Megasphaera-2 and to discover molecular diagnostic indicators of BV with the most economic value for the efficient diagnosis of BV.All vaginal secretion specimens, including 122 BV-positive cases and 130 BV-negative controls were collected. First, quantitative polymerase chain reaction (PCR) was used to determine the levels of above the six bacteria. Then, the detection rates, sensitivity, specificity, diagnostic threshold, and receiver operating characteristic (ROC) curve were compared. Megasphaera-1 and Megasphaera-2 were detected in the BV-positive group, with a low detection rate of 35.25% and 19.67% respectively. The sensitivity and specificity of the above four bacteria were 95.90%/72.31%, 82.79%/92.48%, 72.13%/95.38%, and 56.56%/94.62% respectively, using the cut-off value for the diagnosis of BV. When combinations of L. crispatus with G. vaginalis, F. vaginae, and BVAB-2 were performed respectively, their sensitivity and specificity were 99.29%/97.79%, 98.86%/98.72%, and 98.22%/98.51% in sequence.It is difficult to diagnose BV using only one species, however, combinations of L. crispatus with G. vaginalis or F. vaginae showed a better diagnostic effect, particularly with the combination of L. crispatus and G. vaginalis.

The use of fluorescent proteins to study protein expression and localisation has become common practice in the life sciences. While methods to create gene fusions and replacements with fluorescent proteins in model organisms have rapidly developed, there exist far fewer well-established protocols applicable to non-model bacteria. Here, we present a comprehensive account of an allelic-exchange-based mutagenesis strategy using the I-SceI endonuclease in a clinical strain of S. maltophilia. We demonstrate the use of this strategy for the creation of in-frame insertions of fluorescent proteins and entire gene replacements for the purposes of studying protein localisation and expression. This protocol requires minimal setup, and once optimised, can produce mutants in a matter of weeks. We expect this strategy to be of use for laboratories working with poorly-characterised strains and/or bacteria for which information is scarce.