Search Results (1,371)

Pediococcus pentosaceus is a lactic acid bacterium used inter alia for the fermentation of milk, meat, vegetables, fruits, and even for brewing beer. Several health-promoting effects, such as antibacterial and antifungal activities or microphage and immune system stimulation, have been attributed. Apart from refining foods during the fermentation process, P. pentosaceus strains are added to meat and meat products as protective cultures to improve food safety, while leaving the organoleptic properties untouched. Since knowledge on the latter issue is still limited, we investigated 32 isolates from milk samples and teat canal biofilms regarding their antibacterial efficacy as a prerequisite for possible application as protective cultures. P. pentosaceus strains were unequivocally identified by DNA sequencing of the rrnA gene encoding 16S rRNA. Binary matrices obtained from random amplification of polymorphic DNA experiments showed that all isolates differed by more than 5% and thus represented subspecies. The antibacterial profiles against eight food-borne pathogens and food spoilage bacteria were determined. They efficiently combatted, although to various extents, Gram-negative bacteria such as Pseudomonas aeruginosa or Salmonella enterica, and Gram-positive bacteria such as Staphylococcus aureus and Listeria monocytogenes. Interestingly, acid production was dependent on the presence of the challenged pathogen and did not correlate with the extent of inhibition. Bioinformatic analyses of the genomes of the three top-ranked isolates revealed a pronounced genomic plasticity with a core genome of 1460 genes and additional 91, 130, and 161 unique genes, respectively. Each strain included a set of three, five, or six plasmids and was equipped with different genes encoding bacteriocins. The data suggest that multiple strains of P. pentosaceus should be included in order to optimize the selection of a culture for food preservation. The approach could also be applicable to other bacterial species. Full article

Background: Bacterial resistance to antibiotics continues to rise globally, posing a significant public health challenge and incurring substantial social and economic burdens. In response, the World Health Organization (WHO) has published a list of priority pathogens for which effective treatment options are critically limited. Several antibiotics are categorized as Gram-positive-only (GPO) agents due to their lack of activity against Gram-negative species. Although these compounds often target conserved bacterial processes, their limited spectrum is largely attributed to poor penetration of the Gram-negative outer membrane (OM). Results: In this study, we designed and synthesized a series of adarotene-derived compounds to evaluate the impact of introducing positively charged groups on their interaction with the Gram-negative OM. One of the newly synthesized derivatives, SPL 207, displayed minimum inhibitory concentration (MIC) values ranging from 8 to 64 µM against a panel of Gram-positive and Gram-negative bacteria. The ability of SPL207 to disrupt outer and inner membrane permeability was evaluated using fluorescence assays and confocal microscopy, revealing that the compound compromises membrane integrity across all tested Gram-negative bacteria. Strong synergistic activity was observed in combination with colistin against three P. aeruginosa colistin-resistant strains. Atomistic details of membrane interference were elucidated by molecular dynamics (MD) simulations, with SPL207 clearly acting as a membrane destabilizer by enhancing Ca²⁺ ions diffusion and lipids destabilization. Conclusions: Although the observed MIC values remain above clinically acceptable thresholds, these findings provide a promising proof of concept. The further structural optimization of adarotene derivatives may yield novel broad-spectrum agents with improved antimicrobial potency against MDR pathogens. Full article

Lipopolysaccharide (LPS), an essential structural molecule in the outer membrane of Gram-negative bacteria, is recognized as a principal trigger of inflammatory responses and oxidative stress. Thus, the control and clearance of LPS is essential to inhibit LPS-induced excessive inflammation, oxidative stress, and liver injury. In recent years, some native bioactive peptides, such as human β-defensin 126 (DEFB126) and thymopentin (TP5), have been reported to have inhibitory effects against LPS-induced inflammation and oxidative stress. However, the cytotoxicity, weak stability, and poor biological activity have hindered their practical application and clinical development. The development of novel hybrid peptides is a promising approach for overcoming these problems. In this study, we designed a novel hybrid peptide [DTP, DEFB126 (1-39)-TP5] that combines the active center of DEFB126 and full-length thymopentin (TP5). Compared to the parental peptides, DTP has a longer half-life, lower cytotoxicity, and greater anti-inflammatory and antioxidant activity. The anti-inflammatory and antioxidant effects of DTP were demonstrated in a murine LPS-induced sepsis model, which showed that DTP successfully inhibited the indicators associated with LPS-induced liver injury; decreased the contents of TNF-α, IL-6, and IL-1β; increased the level of glutathione (GSH); and improved the activities of catalase (CAT) and superoxide dismutase (SOD). Furthermore, our study revealed that the anti-inflammatory and antioxidant activities of DTP were associated with LPS neutralization, blockade of LPS binding to the Toll-like receptor 4/myeloid differentiation factor 2 (TLR4/MD-2) complex, reduction in reactive oxygen species content, and inhibition of the activation of the nuclear factor kappa-B (NF-кB) signaling pathway. These results elucidate the structural and functional properties of the peptide DTP, reveal its underlying molecular mechanisms, and shed light on its potential as a multifunctional agent for applications in agriculture, food technology, and clinical therapeutics. Full article

Multidrug-resistant Gram-negative bacteremia (MDR-GNB) is a significant health threat associated with increased morbidity and mortality rates. Patients with cancer are particularly vulnerable to MDR-GNB due to immunosuppression and frequent healthcare exposure. The aim of this study was to evaluate risk factors, 30-day mortality, and outcomes in cancer and non-cancer patients. We conducted a retrospective study of adult patients aged 18 years or older with MDR-GNB who were hospitalized at Ochsner LSU Health—Academic Medical Center between January 2018 and July 2022. We collected data about demographics, comorbidities, cancer diagnosis, causative organisms, infection source, antibiotic therapy, and clinical outcomes. A total of 112 patients with MDR-GNB were included, where 31 patients (27.7%) had cancer and 81 patients (72.3%) did not. Cancer patients were more frequently male and white (74.2% vs. 58.0%, p = 0.114 and 45.2% vs. 25.9%, p = 0.031). Diabetes mellitus was more common in non-cancer patients, but it was associated with increased mortality risk in the cancer group (OR = 2.39, 95% CI: 1.125–5.074). Enterobacteriaceae species were the most frequently isolated organisms (83.0%), with no significant difference between groups. The most common source of infection was genitourinary (49.1%). ICU admission was more frequent in non-cancer patients (49.4% vs. 25.8%, p = 0.024). However, cancer patients had a higher ICU admission mortality risk (OR 2.156, 95% CI: 1.058–4.395) and recent hospitalization rates (67.7% vs. 40.7%, p = 0.011), both associated with increased mortality risk. Cancer patients had a significantly higher 30-day mortality rate (39.0% vs. 16.4%, p = 0.017; OR = 3.012, 95% CI: 1.190–7.622) and hospice admissions (22.6% vs. 3.7%, p = 0.002; OR = 7.583, 95% CI: 1.819–31.618). These findings emphasize the urgent need for early microbiological identification, targeted antimicrobial therapy, and improved infection control strategies. Given the rising prevalence of MDR-GNB pathogens, future research is needed for prompt appropriate antibacterial therapy based on risk stratification and enhanced antimicrobial stewardship programs as these are critical for high-risk cancer patients. Full article

This study investigated the synergistic effects of microorganism inactivation using underwater plasma, focusing on applications relevant to food safety. The underwater plasma was generated by capillary electrodes in 10% saltwater circulated at 5 t/h. Two representative bacteria, Escherichia coli (Gram-negative) and Microbacterium testaceum (Gram-positive), were selected due to their relevance to food and water contamination. Inactivation kinetics were assessed through first-order rate constants (k) under direct, indirect, and total (combined) treatments. The rate constant (k-value) difference between total and indirect treatment for E. coli reached 0.1015 at 5 min of discharge, while M. testaceum showed a smaller difference of 0.0083 at 20 min. These results suggest that microorganisms pre-damaged by direct plasma exposure become more susceptible to long-lived reactive species like hydrogen peroxide. The findings indicate that underwater plasma holds significant potential as an effective non-thermal disinfection method for brine solutions, fresh produce, and food-contact surfaces. Full article

The 1,3,4-thiadiazole core has attracted significant attention due to its unique electronic structure, physicochemical properties, and wide-ranging pharmacological potential. This heterocyclic scaffold exhibits a broad spectrum of biological activities, often attributed to its capacity to modulate enzyme function, interact with receptors, and disrupt key biochemical pathways in both pathogens and host cells. Additionally, 1,3,4-thiadiazoles typically display favorable pharmacokinetic properties, including high metabolic stability and appropriate lipophilicity, which enhance their drug-likeness and bioavailability. This review presents an overview of antibacterial and antifungal compounds bearing the 1,3,4-thiadiazole scaffold that have been reported over the past five years. This publication details the chemical structures of novel 1,3,4-thiadiazole derivatives and reports the results of antibacterial and antifungal activity assays conducted against a range of microbial strains. Furthermore, it provides conclusions regarding the structural features that influence the observed biological activity of the synthesized compounds. Antimicrobial activity assessments conducted against ten Gram-negative and nine Gram-positive bacterial strains revealed that 79 newly synthesized 1,3,4-thiadiazole derivatives exhibited either superior inhibitory efficacy relative to standard reference antibiotics or achieved a high level of bacterial growth suppression, defined as 90–100% inhibition. In antifungal assays, the compounds were evaluated against 25 fungal species representing 15 genera. Among the tested derivatives, 75 compounds demonstrated antifungal potency exceeding that of reference antifungal agents or produced growth inhibition within the 90–100% range. The information provided herein may serve as a valuable resource for medicinal and agricultural chemists engaged in the development of novel drug candidates and plant protection agents. Full article

Background: The Enterobacteriaceae family is the most heterogeneous group of Gram-negative bacilli, with both environmental and clinical relevance. Although many of these species are part of the normal intestinal microbiota, species such as Escherichia coli, Klebsiella pneumoniae, and Proteus mirabilis are among the most common opportunistic pathogens, frequently responsible for nosocomial infections, including urinary tract infections, bacteraemia, and pneumonia. Based on these concerns, these species are increasingly being studied for their ability to develop antimicrobial resistance, often mediated by extended spectrum β-lactamase or carbapenemase production. The present study aims to analyse the antimicrobial resistance profiles of Enterobacteriaceae isolated from a southern Italian hospital focusing on the species of major clinical importance. Methods: A retrospective analysis was carried out on biological samples collected between 2019 and 2023 at the Microbiology Laboratory of the San Pio Hospital, Vasto (Italy). Eight hundred ninety patients were included, with an average age of 73 years. Bacterial identification was carried out using bacterial culture and biochemical methods, while antimicrobial sensitivity was assessed by using the automated Walk Away System. Results: The most frequently isolated species were Escherichia coli (63.2%), Klebsiella spp. (21.9%), and Proteus spp. (8.8%). All isolates showed resistance to at least one antimicrobial and most to more than four. The highest resistance rates were observed for Cefotaxime (16.0%), followed by Ampicillin (15.6%) and Ciprofloxacin (13.2%). Conclusions: The high prevalence of antimicrobial resistance among clinically relevant Enterobacteriaceae species is a growing clinical challenge. The results of this study, which describe the trend of resistance among Enterobacteriaceae in a local hospital, could help to raise awareness highlighting the urgent need for more advanced diagnostic tools and new therapeutic strategies to treat infections caused by multi-resistant microorganisms. Full article

A novel Gram-negative bacterium, designated strain SN16^T, was isolated from a harmful algal bloom (HAB). Strain SN16^T exhibited potent, broad-spectrum algicidal activity against the colony-forming alga Phaeocystis globosa and eight other HAB-causing species, highlighting its potential as a promising candidate for the biological control of HABs. A phylogenetic analysis of 16S rRNA gene sequences placed strain SN16^T within the genus Flagellimonas. The average nucleotide identity (ANI) and digital DNA–DNA hybridization (dDDH) values between strain SN16^T and its relatives were 75.4–91.4% and 19.3–44.0%, respectively. These values fall below the established thresholds for species delineation, confirming that SN16^T represents a novel species. A chemotaxonomic analysis revealed its dominant cellular fatty acids to be iso-C_15:0 and iso-C_15:1 G. The major polar lipid was phosphatidylethanolamine, and the primary respiratory quinone was menaquinone-6. Genome mining identified 11 biosynthetic gene clusters (BGCs), including those encoding for terpenes, ribosomal peptide synthetases, and non-ribosomal peptide synthetases. By integrating BGC analysis with the observed algicidal activities, we predicted that pentalenolactone and xiamycin analogues are the likely causative compounds. Based on this polyphasic evidence, strain SN16^T is proposed as a novel species of the genus Flagellimonas, named Flagellimonas algicida sp. nov. This is the first report of Flagellimonas species exhibiting broad-spectrum algicidal activity, including activity against the colonial form of P. globosa—a key ecological challenge in HAB mitigation. Full article

As aquaculture expands globally, understanding immune responses in non-traditional farmed species like Octopus vulgaris under varying environmental conditions is increasingly important. This study investigated lysozyme activity, a key innate immune marker, in cell-free hemolymph of O. vulgaris following experimental challenge with four Gram-negative fish pathogens (Photobacterium damselae subsp. piscicida, P. damselae subsp. damselae, Vibrio alginolyticus, and V. anguillarum O1) at two temperatures (21 ± 0.5 °C and 24 ± 0.5 °C). These pathogens were selected because octopus farming frequently occurs near fish aquaculture facilities, raising the potential for pathogen crossover. A total of 216 wild octopuses were injected intramuscularly or intravenously and sampled on days 0, 3, and 7 post-challenge. Lysozyme activity varied by pathogen, injection route, sampling time, and temperature. A significant time- and temperature-dependent increase was observed, especially in IM-challenged groups exposed to Photobacterium species. Elevated temperatures supported a more prolonged immune response. These results highlight lysozyme as a responsive biomarker of innate immunity in O. vulgaris and emphasize the role of environmental factors in immune modulation. This work provides a foundation for disease monitoring and health management in cephalopod aquaculture. Future research should examine long-term lysozyme dynamics, broader pathogen exposure, molecular mechanisms, and additional environmental stressors such as salinity and pollution. Full article

This study aimed to identify bacterial isolates associated with mortality events in Salmo trutta rearing farms in Spain and to assess their antibiotic resistance profiles. The analysis covered five fish farms: two with a recent history of antibiotic use and three without any antibiotic application in the six months prior to sampling. Tissue samples were collected from moribund fish displaying clinical signs such as erratic swimming, ocular hemorrhages, fin hemorrhages, and skin lesions during disease outbreaks in 2022 and 2023. The samples were analyzed using real-time PCR, amplification and sequencing of the 16S rRNA gene and the ITS-1 intergenic spacer, and MALDI-TOF mass spectrometry. A total of 19 bacterial isolates were identified, with Gram-negative bacteria, particularly Aeromonas spp., being the most prevalent. Other identified taxa included Plesiomonas sp., Hafnia alvei, Pseudomonas fulva, and Kluyvera intermedia, as well as Gram-positive species such as Carnobacterium maltaromaticum, Lactococcus sp., and Enterococcus faecium. Notably, resistant strains were found in four of the five farms, even in those that had not administered antibiotics, suggesting that environmental contamination and anthropogenic factors may significantly contribute to the spread of resistance. Environmental stressors—such as sudden increases in water temperature and high turbidity caused by suspended organic matter—appeared to precede mortality peaks. The findings highlight the role of Aeromonas spp. as a key bacteria associated with mortality events in S. trutta and underscore the multifactorial nature of antibiotic resistance in aquaculture. No florfenicol-resistant isolates were detected in the farms where it is routinely used, indicating that florfenicol remains an effective antibiotic in aquaculture. However, the continuous and systematic monitoring of its use remains essential. The detection of bacteria not traditionally associated with fish pathology in samples from diseased animals suggests the need for further studies into their pathogenic potential. Overall, this descriptive study emphasizes the importance of preventive health strategies, prudent antibiotic use, and environmental monitoring to mitigate bacterial diseases and limit the spread of antimicrobial resistance in brown trout farming. These findings align with a One Health perspective, linking aquaculture practices, ecosystem integrity, and public health. Full article

A strictly aerobic, straight-rod, motile Gram-negative bacterium, SDUM041083^T, was isolated from marine sediment in Xiaoshidao, Weihai, China, in the formation of yellowish-brown colonies. Its growing conditions are as follows: 20–40 °C, pH 5.5–9.5, and 0.5–11% (w/v) NaCl. Phylogenetic analysis of the 16S rRNA gene sequence showed that SDUM041083^T was related to members of the genus Microbulbifer. Strain SDUM041083^T showed the highest 16S rRNA gene sequence similarity (98.23%) with Microbulbifer okinawensis JCM 16147^T. The primary cellular fatty acids of SDUM041083^T were iso-C11:0 3-OH, iso-C11:0, and iso-C15:0. The respiratory quinone of SDUM041083^T was Q-8, and the polar lipids were phosphatidylglycerol, phosphatidylethanolamine, and one aminolipid. The genomic DNA G+C content of SDUM041083^T was 57.5 mol%. The phenotypic and genotypic characteristics of SDUM041083^T indicate that the strain should be classified as a new species representing the genus Microbulbifer, with the name Microbulbifer weihaiensis sp. nov. being proposed. The type strain was SDUM041083^T (=KCTC 8896^T = MCCC 1H01537^T). Comparative genomic analysis showed that the 32 Microbulbifer species shared 1446 core genes and differed mainly in terms of lipid metabolism, signal transduction and xenobiotic biodegradation and metabolism. Preliminary research showed that SDUM041083^T has the potential to degrade chitin. Biogeographic distribution analysis showed that the marine environments constitute the main habitat of the genus Microbulbifer. Full article

The emergence and dissemination of extended-spectrum beta-lactamase (ESBL)-producing bacteria pose a major public health threat, necessitating a One Health approach to addressing this threat. Thus, the diversity, ESBL production, and potential public health implications of Gram-negative bacteria recovered from man-made lakes and surrounding lettuce in Yamoussoukro, Côte d’Ivoire were assessed in this study. Also, the lakes’ physicochemical parameters were assessed and correlated with bacteria community using Pearson correlation. A total of 68 Gram-negative bacterial isolates were recovered from the samples and identified via 16S rDNA gene sequencing. Phylogenetic analysis suggested multiple genus-/species-level variations within the isolates. Escherichia coli was the most prevalent in lake water (39.5%), while Acinetobacter was the dominant genus in lettuce (30%). E. coli isolates showed high resistance to ampicillin (90.9%), cefepime (72.7%), cefotaxime (68.2%), and aztreonam (63.6%). Moreover, ESBL production was confirmed in E. coli isolates (22.05%), predominantly mediated by the bla_CTX-M gene. Multidrug-resistant phenotypes were widespread, yielding similar multiple antibiotic resistance index (MARI) values in water (0.27–0.63) and lettuce (0.27–0.81). These data indicate high environmental contamination, which unfortunately is not being taken into account by lettuce producers according to an interview. Statistical analyses showed a significant relationship between bacterial diversity and lakes’ physicochemical parameters, including dissolved oxygen, pH, and turbidity. The basic education level of farmers, the prevalence of ESBL-producing E. coli, and the high prevalence of MDR Gram-negative bacteria in both environmental and crop sources in Yamoussoukro underscore the need for both integrated surveillance and management strategies to mitigate potential microbial public health risks within a One Health framework. Full article

Due to their evolutionary divergence from mammals, zebrafish (Zf, Danio rerio), which are frequently employed in biomedical research, provide a distinctive viewpoint on innate immune systems. The Toll-like receptor 4/myeloid differentiation factor 2/cluster of differentiation 14 (TLR4/MD-2/CD14) complex in mammals detects lipopolysaccharide (LPS), a crucial component of Gram-negative bacteria, and it causes potent inflammatory reactions through a Toll/interleukin-1 receptor domain-containing adapter-inducing interferon-β (TRIF)-dependent and myeloid differentiation primary response 88 (MyD88)-dependent pathways. However, key components of this system, such as a responsive TLR4 axis and a functional CD14 ortholog, are absent in Zf. The Zf species nevertheless reacts to LPS, which leads to research into other recognition systems. This review looks at a number of TLR4-independent processes in Zf, such as scavenger receptors (SRs) including scavenger receptor class B type 1 (SR-BI) and cluster of differentiation 36 (CD36), nucleotide-binding oligomerization domain-containing protein 1 (NOD1)-dependent cytosolic sensing, peptidoglycan recognition proteins (PGRPs), Complement Component 3 (C3), and caspase-1-like protein 2 (Caspy2)-mediated inflammasome activation. An alternative and flexible immune system that makes up for the lack of canonical TLR4 signaling is revealed by these mechanisms. Additionally, the discovery of lymphocyte antigen 96 (ly96), an ortholog of MD-2 found in Zf, suggests evolutionary similarity; however, as it is only functional in artificial systems, it demonstrates minimal overlap with mammalian MD-2 activity. Knowing these pathways provides important information for studying inflammation, infection, and immunological modulation in vertebrates using Zf as a model. It also clarifies the evolutionary flexibility of innate immune recognition. Full article

Bacterial diseases are widespread in pet birds, posing a severe threat in nestlings and birds with weakened immune systems, often resulting in high mortality during the first days after hatching. This study aimed to describe the pathological findings of a natural bacterial co-infection with Klebsiella pneumoniae and Pseudomonas aeruginosa in nestling European goldfinches (Carduelis carduelis), as a cause of mortality after hatching. Eight nestlings kept in a breeding facility showed an inability to move, anorexia, and respiratory distress, and were found dead between 1 and 4 days of life. Gross pathological findings included diffuse pneumonia with edema and multifocal hemorrhages and occasionally hepatic necrosis. On histopathology, the main findings in all examined birds included severe, subacute bronchopneumonia and severe necrotizing hepatitis. Gram-negative bacilli were observed in parabronchial walls, within pulmonary arteries and surrounding hepatocellular necrotic foci. Lungs, livers and kidneys were sampled for bacteriological examination, resulting in two Gram-negative bacterial isolates. Four housekeeping genes (i.e., 16S rRNA; rpoB; khe; ecfX) were amplified and sequenced for bacterial identification at species level. Although K. pneumoniae and P. aeruginosa are common Gram-negative pathogens and are often co-isolated in human bacterial pneumonia, co-infection with these bacteria has not been documented in nestling goldfinches to date. Pathogen identification is essential for formulating a correct etiological diagnosis and further selecting the most appropriate therapeutic strategy. Full article

Cellulose, the most abundant polymer on this planet, is widely produced by plants and many bacterial species. Certain cyanobacterial species also synthetize cellulose, though typically at much lower yields compared to other bacteria. Cyanobacteria are particularly intriguing in this context, as they uniquely combine the features of Gram-negative bacteria with plant-like features, such as oxygenic photosynthesis and CO₂ fixation. This review highlights the structure and biosynthesis of cellulose in cyanobacteria, and explores the distinctive features compared with those of bacterial and vascular plants. We also discuss current strategies to enhance cellulose production in cyanobacteria through genetic engineering, synthetic redesign and environmental modulation, and propose key knowledge gaps. This review thus provides a foundation for advancing both fundamental understanding and the development of sustainable cellulose-based biotechnologies. Full article