Search Results (8,701)

Background/Objectives: Antimicrobial resistance (AMR) contributes to millions of deaths globally each year, creating an urgent need for new therapeutic agents. Antimicrobial peptides (AMPs) have emerged as promising candidates due to their potential to combat AMR pathogens. This study aimed to evaluate the antimicrobial activity of an AMP from a soil-derived bacterial isolate against Gram-negative bacteria. Method: Soil bacteria were isolated and screened for antimicrobial activity. The bioactive peptide was purified and determined its structure and antimicrobial efficacy. Genomic analysis was conducted to predict the biosynthetic gene clusters (BGCs) responsible for AMP production. Results: Genomic analysis identified the isolate as Paenibacillus sp. Na14, which exhibited low genomic similarity (61.0%) to other known Paenibacillus species, suggesting it may represent a novel species. The AMP from the Na14 strain exhibited heat stability up to 90 °C for 3 h and retained its activity across a broad pH range from 3 to 11. Structural analysis revealed that the Na14 peptide consisted of 14 amino acid residues, adopting an α-helical structure. This peptide exhibited bactericidal activity at concentrations of 2–4 µg/mL within 6–12 h, and its killing rate was concentration-dependent. The peptide was found to disrupt the bacterial membranes. The Na14 peptide shared 64.29% sequence similarity with brevibacillin 2V, an AMP from Brevibacillus sp., which also belongs to the Paenibacillaceae family. Genomic annotation identified BGCs associated with secondary metabolism, with a particular focus on non-ribosomal peptide synthetase (NRPS) gene clusters. Structural modeling of the predicted NRPS enzymes showed high similarity to known NRPS modules in Brevibacillus species. These genomic findings provide evidence supporting the similarity between the Na14 peptide and brevibacillin 2V. Conclusions: This study highlights the discovery of a novel AMP with potent activity against Gram-negative pathogens and provides new insight into conserved AMP biosynthetic enzymes within the Paenibacillaceae family. Full article

Ensuring bacterial safety of blood transfusions remains a critical focus in medicine. We investigated a novel pathogen reduction technology utilizing nylon functionalized with synthetic dyes (nylon affinity networks) to capture and remove bacteria from plasma. In the initial screening process, we spiked phosphate buffer solution (PBS) and human plasma (1 mL each) with 10 or 100 colony forming units (cfu) of either Escherichia coli or Staphylococcus epidermidis, exposed the suspensions to affinity networks and assessed the extent of bacterial reduction using agar plate cultures as the assay output. Nineteen synthetic dyes were tested. Among these, Alcian Blue exhibited the best performance with both bacterial strains in both PBS and plasma. Next, bacterial suspensions of approximately 1 and 2 cfu/mL in 10 and 50 mL, respectively, were treated with Alcian Blue affinity networks in three sequential capture steps. This procedure resulted in complete bacterial depletion, as demonstrated by the lack of bacterial growth in the remaining fraction. The viability of the captured bacteria was confirmed by plating the post-treatment affinity networks on agar. Alcian Blue affinity networks captured and sequestered a few plasma proteins identified by liquid chromatography tandem mass spectrometry. These findings support the potential applicability of nylon affinity networks to enhance transfusion safety, although additional investigations are needed. Full article

Multidrug-resistant (MDR) strains of Klebsiella pneumoniae present an acute threat as they continue to disseminate globally. Phage therapy has shown promise as a powerful approach to combat MDR infections, but narrow phage host ranges make development of broad acting therapeutics more challenging. The goal of this effort was to use in vitro directed evolution (the “Appelmans protocol”) to isolate K. pneumoniae phages with broader host ranges for improved therapeutic cocktails. Five myophages in the genus Jiaodavirus (family Straboviridae) with complementary activity were mixed and passaged against a panel of 11 bacterial strains including a permissive host and phage-resistant clinical isolates. Following multiple rounds of training, we collected phage variants displaying altered specificity or expanded host ranges compared with parental phages when tested against a 100 strain diversity panel of K. pneumoniae. Some phage variants gained the ability to lyse previously phage-resistant strains but lost activity towards previously phage-susceptible strains, while several variants had expanded activity. Whole-genome sequencing identified mutations and recombination events impacting genes associated with host tropism including tail fiber genes that most likely underlie the observed changes in host ranges. Evolved phages with broader activity are promising candidates for improved K. pneumoniae therapeutic phage cocktails. Full article

Background/Objectives: Mycobacterium abscessus is an opportunistic pathogen causing infections mainly in patients with immunosuppression and chronic pulmonary pathologies. Extended treatment periods are needed to tackle this pathogen, bacterial eradication is rare, and recurrence can take place with time. New alternative treatments are being investigated, such as bacteriophage therapy. This work describes the characterization of the mycobacteriophage P3MA, showing its ability to infect clinical and standard M. abscessus strains. Methods: Phylogenetic analysis, electron microscopy, growth curves, biofilm assays, checkerboard, and granuloma-like medium studies were performed. Results: P3MA inhibited the growth of clinical samples in both planktonic and biofilm states as well as in a granuloma-like model. The study of the interaction with antibiotics revealed that P3MA exhibited an antagonistic effect combined with clarithromycin, indifference with amikacin, and synergy with imipenem. Conclusions: All these results suggest that, after genetic engineering, P3MA could be a promising candidate for phage therapy in combination with imipenem, including lung infections. Full article

Astragalus sinicus, a key leguminous green manure widely cultivated in Southern China’s rice-based cropping systems, plays a pivotal role in sustainable agriculture by enhancing soil organic matter sequestration, improving rice yield, and elevating grain quality. The symbiotic nitrogen-fixing association between A. sinicus and its matching rhizobia is fundamental to its agronomic value; however, suboptimal inoculant efficiency and field application methodologies constrain its full potential. To address these limitations, we conducted a multi-phase study involving (1) rhizobial strain screening under controlled greenhouse conditions, (2) an optimized lyophilization protocol evaluating cryoprotectant (trehalose, skimmed milk powder and others), and (3) seed pelleting trails with rhizobial viability and nodulation assessments over different storage periods. Our results demonstrate that Mesorhizobium huakuii CCBAU 33470 exhibits a superior nitrogen-fixing efficacy, significantly enhancing key traits in A. sinicus, including leaf chlorophyll content, tiller number, and aboveground biomass. Lyophilized inoculants prepared with cryoprotectants (20% trehalose or 20% skimmed milk powder) maintained >90% bacterial viability for 60 days and markedly improved nodulation capacity relative to unprotected formulations. The optimized seed pellets sustained high rhizobial loads (5.5 × 10³ cells/seed) with an undiminished viability after 15 days of storage and nodulation ability after 40 days of storage. This integrated approach of rhizobial selection, inoculant formulation, and seed coating overcomes cultivation bottlenecks, boosting symbiotic nitrogen fixation for A. sinicus cultivation. Full article

Biotechnological research increasingly focuses on developing new drugs to counter the rise of antibiotic-resistant strains in hospitals. This study aimed to create bacterial lysates from antibiotic-resistant pathogens isolated from patients and medical instruments across hospital departments. Identification was performed based on morphological, cultural, and biochemical characteristics, as well as 16S rRNA gene sequencing using the BLAST algorithm. Strain viability was assessed using the Miles and Misra method, while sensitivity to eight antibacterial drug groups and biosafety between cultures were evaluated using agar diffusion. From 15 clinical sources, 25 pure isolates were obtained, and their phenotypic and genotypic properties were studied. Carbohydrate fermentation testing confirmed that the isolates belonged to the genera Escherichia, Citrobacter, Klebsiella, Acinetobacter, Pseudomonas, Staphylococcus, Haemophilus, and Streptococcus. The cultures exhibited good viability (10⁹–10¹⁰ CFU/mL) and compatibility with each other. Based on prevalence and clinical significance, three predominant hospital pathogens (Klebsiella pneumoniae 12 BL, Pseudomonas aeruginosa 3 BL, and Acinetobacter baumannii 24 BL) were selected to develop a bacterial lysate consortium. Lysates were prepared with physical disruption using a French press homogenizer. The resulting product holds industrial value and may stimulate the immune system to combat respiratory pathogens prevalent in Kazakhstan’s healthcare settings. Full article

This review explores the biofilm architecture and drug resistance of Enterococcus faecalis in clinical and environmental settings. The biofilm in E. faecalis is a heterogeneous, three-dimensional, mushroom-like or multilayered structure, characteristically forming diplococci or short chains interspersed with water channels for nutrient exchange and waste removal. Exopolysaccharides, proteins, lipids, and extracellular DNA create a protective matrix. Persister cells within the biofilm contribute to antibiotic resistance and survival. The heterogeneous architecture of the E. faecalis biofilm contains both dense clusters and loosely packed regions that vary in thickness, ranging from 10 to 100 µm, depending on the environmental conditions. The pathogenicity of the E. faecalis biofilm is mediated through complex interactions between genes and virulence factors such as DNA release, cytolysin, pili, secreted antigen A, and microbial surface components that recognize adhesive matrix molecules, often involving a key protein called enterococcal surface protein (Esp). Clinically, it is implicated in a range of nosocomial infections, including urinary tract infections, endocarditis, and surgical wound infections. The biofilm serves as a nidus for bacterial dissemination and as a reservoir for antimicrobial resistance. The effectiveness of first-line antibiotics (ampicillin, vancomycin, and aminoglycosides) is diminished due to reduced penetration, altered metabolism, increased tolerance, and intrinsic and acquired resistance. Alternative strategies for biofilm disruption, such as combination therapy (ampicillin with aminoglycosides), as well as newer approaches, including antimicrobial peptides, quorum-sensing inhibitors, and biofilm-disrupting agents (DNase or dispersin B), are also being explored to improve treatment outcomes. Environmentally, E. faecalis biofilms contribute to contamination in water systems, food production facilities, and healthcare environments. They persist in harsh conditions, facilitating the spread of multidrug-resistant strains and increasing the risk of transmission to humans and animals. Therefore, understanding the biofilm architecture and drug resistance is essential for developing effective strategies to mitigate their clinical and environmental impact. Full article

The perianal skin is a unique “skin–gut” boundary that serves as a critical hotspot for the exchange and evolution of antibiotic resistance genes (ARGs). However, its role in the dissemination of antimicrobial resistance (AMR) has often been underestimated. To characterize the resistance patterns in the perianal skin environment of patients with perianal diseases and to investigate the drivers of AMR in this niche, a total of 51 bacterial isolates were selected from a historical strain bank containing isolates originally collected from patients with perianal diseases. All the isolates originated from the skin site and were subjected to antimicrobial susceptibility testing, whole-genome sequencing, and co-occurrence network analysis. The analysis revealed a highly structured resistance pattern, dominated by two distinct modules: one representing a classic Staphylococcal resistance platform centered around mecA and the bla operon, and a broad-spectrum multidrug resistance module in Gram-negative bacteria centered around tet(A) and predominantly carried by IncFIB and other IncF family plasmids. Further analysis pinpointed IncFIB-type plasmids as potent vehicles driving the efficient dissemination of the latter resistance module. Moreover, numerous unexplained resistance phenotypes were observed in a subset of isolates, indicating the potential presence of emerging and uncharacterized AMR threats. These findings establish the perianal skin as a complex reservoir of multidrug resistance genes and a hub for mobile genetic element exchange, highlighting the necessity of enhanced surveillance and targeted interventions in this clinically important ecological niche. Full article

The emergence and spread of antimicrobial resistance among pathogens are significantly reducing available therapeutic options, highlighting the urgent need for novel and complementary treatment strategies. Antimicrobial photodynamic therapy (aPDT) is a promising alternative approach that can overcome antimicrobial resistance through a multitarget mechanism of action, exerting direct bactericidal and fungicidal effects with minimal risk of resistance development. Although aPDT has shown efficacy against a variety of pathogens, data on its activity against large collections of clinical multidrug-resistant strains are still limited. In this study, we assessed the antimicrobial activity of the photosensitizer RLP068/Cl combined with a red light-emitting LED source at 630 nm (Molteni Farmaceutici, Italy) against a large panel of Gram-negative and Gram-positive bacterial strains harboring relevant resistance traits and Candida species. Our results demonstrated the significant microbicidal activity of RLP068/Cl against all of the tested strains regardless of their resistance phenotype, with particularly prominent activity against Gram-positive bacteria (range of bactericidal concentrations 0.05–0.1 µM), which required significantly lower exposure to photosensitizer compared to Candida and Gram-negative species (range 5–20 µM). Overall, these findings support the potential use of RLP068/Cl-mediated aPDT as an effective therapeutic strategy for the management of localized infections caused by MDR organisms, particularly when conventional therapeutic options are limited. Full article

Background/Objectives: Actinobacteria are one of the largest bacterial phyla. These microbes produce bioactive compounds, such as antifungals, antibiotics, immunological modulators, and anti-tumor agents. Studies on actinobacteria isolated from the Brazilian Savannah biome (Cerrado) are scarce and mostly address metagenomics or the search for hydrolytic enzyme-producing microbes. Solanum lycocarpum (lobeira) is a tree widely employed in regional gastronomy and pharmacopeia in Central Brazil. Methods: In this work, 60 actinobacteria isolates were purified from the rhizosphere of S. lycocarpum. Eight Streptomyces spp. isolates were selected for in vitro antifungal activity against Cryptococcus neoformans H99, the C. neoformans 89-610 fluconazole-tolerant strain, C. gattii NIH198, Candida albicans, C. glabrata, and C. parapsilosis. The ability of the aqueous extracts of the isolates to induce the in vitro secretion of tumor necrosis factor (TNF-α), nitric oxide (NO), interleukin-6 (IL-6), and IL-10 by murine macrophages was also evaluated. Results: All extracts showed antifungal activity against at least two yeast species. Streptomyces spp. LAP11, LDB2, and LDB17 inhibited C. neoformans growth by 40–93%. Most extracts (except LAP2) also inhibited C. gattii. None inhibited C. albicans, but all inhibited C. glabrata (40–90%). Streptomyces sp. LAP8 extract increased nitric oxide production by approximately 347-fold in murine macrophages, while LDB11 extract suppressed LPS-induced TNF-α production by 70% and simultaneously increased IL-10 secretion, suggesting immunosuppressive potential. Conclusions: The results revealed that Cerrado actinobacteria-derived aqueous extracts are potential sources of antifungal and immunomodulatory biocompounds. Full article

The rhizosphere microbiome plays an important role in carbon- and nitrogen-cycling in soil and in the stress response of plants. It also affects the function of the ammonium transporter (AmtB) that senses nitrogen levels inside and outside the cells of the associative nitrogen-fixing bacterium GXGL-4A. However, the potential mechanism of the interaction between the AmtB deletion mutant of GXGL-4A (∆amtB) and microorganisms in the rhizosphere of plants under low-nitrogen stress is still unclear. As revealed by transcriptome analyses, mutation of the amtB gene in GXGL-4A resulted in a significant up-regulation of many functional genes associated with nitrogen fixation and transportation at transcription level. The application of ∆amtB changed the nitrogen level in the rhizosphere of cucumber seedlings and reshaped the microbial community structure in the rhizosphere, enriching the relative abundance of Actinobacteriota and Gemmatimonadota. Based on bacterial functional prediction analyses, the metabolic capacities of rhizobacteria were improved after inoculation of cucumber seedlings with the original strain GXGL-4A or the ∆amtB mutant, resulting in the enhancement of amino acids, lipids, and carbohydrates in the cucumber rhizosphere, which promoted the growth of cucumber plants under a low-nitrogen stress condition. The results contribute to understanding the biological function of gene amtB, revealing the regulatory role of the strain GXGL-4A on cucumber rhizosphere nitrogen metabolism and laying a theoretical foundation for the development of efficient nitrogen-fixing bacterial agents for sustainable agricultural production. Full article

Cancer and infectious diseases are major causes of global morbidity and mortality stressing the need to find novel drugs with promising dual anticancer and antimicrobial efficacy. Gold complexes have been studied for the past years due to their anticancer properties, with a few of them displaying antimicrobial properties, which support their pharmacological interest. Within this scope, we investigated six gold bisdithiolate complexes [Au (bdt)₂]⁻ (1), [Au (dcbdt)₂]⁻ (2), [Au (3-cbdt)₂]⁻ (3), [Au (4-cbdt)₂]⁻ (4), [Au (pdt)₂]⁻ (5) and [Au (dcdmp)₂]⁻ (6), and) against the ovarian cancer cell lines A2780 and A2780cisR, the Gram-positive bacteria Staphylococcus aureus Newman, the Gram-negative bacteria Escherichia coli ATCC25922 and Burkholderia contaminans IST408, and the pathogenic yeasts Candida glabrata CBS138 and Candida albicans SC5134. Complexes 2 and 6, with ligands containing aromatic pyrazine or phenyl rings, substituted with two cyanonitrile groups, showed after 24 h of incubation high anticancer activities against A2780 ovarian cancer cells (IC₅₀~5 µM), being also able to overcome cisplatin resistance in A2780cisR cells. Both complexes induced the formation of ROS, activated caspase-3/7, and induced necrosis (LDH release) in a dose-dependent way, in a greater extent in the case of 6. Among the bacterial and fungal strains tested, only complex 6 presented antimicrobial activity against S. aureus Newman, indicating that this complex is a potential novel anticancer and antibacterial agent. These results delve into the structure-activity relationship of the complexes, considering molecular alterations such as replacing a phenyl group for a pyrazine group, and the inclusion of one or two cyanonitrile appendage groups, and their effects on biological activity. Overall, both complexes were found to be promising leads for the development of future anticancer drugs against low sensitive or cisplatin resistant tumors. Full article

Burdock (Arctium lappa L.) is a medicinal and edible homologous plant whose roots contain many bioactive substances such as polysaccharides and phenolics. This study explored the integration of burdock powder and lactic acid bacteria fermentation to enhance the nutritional quality, sensory attributes, and flavor profiles of duck sausages. Three bacterial strains, Lacticaseibacillus casei, L. helveticus, and L. plantarum, were selected based on sensory analysis, and their effects on sausage properties were evaluated through combined fermentation trials. The results demonstrated that duck sausages fermented with L. plantarum and L. helveticus and supplemented with 3% burdock powder (PHB group) exhibited > 1.5-fold higher antioxidant activity (ABTS at 85.2 μmol trolox/g and DPPH at 92.7 μmol trolox/g, respectively; p < 0.05) and 15% increase in total phenolic content (8.24 mg gallic acid/g) compared to non-fermented counterparts. The PHB formulation also enhanced color stability (lightness, redness, yellowness), textural characteristics (hardness, springiness, cohesiveness), and sensory acceptability. Volatile compound analysis revealed a reduction in off-odor aldehydes (hexanal, (E)-2-octenal, (E)-2-decenal, and (E,E)-2,4-decadienal) and increased production of desirable aromatic compounds like tetramethyl-pyrazine. These findings highlight the potential of combining lactic acid bacteria fermentation with burdock powder to develop functional duck sausages with improved nutritional and sensory properties. Full article

Palindromic antimicrobial peptides (PAMs) constitute versatile scaffolds for the design and optimization of anticancer agents with applications in therapy, diagnosis, and/or monitoring. In the present study, fluorolabeled peptides derived from the palindromic sequence RWQWRWQWR containing fluorescent probes, such as 2-Aminobenzoyl, 5(6)-Carboxyfluorescein, and Rhodamine B, were obtained. RP-HPLC analysis revealed that the palindromic peptide conjugated to Rhodamine B (RhB-RWQWRWQWR) exhibited the presence of isomers, likely corresponding to the open-ring and spiro-lactam forms of the fluorescent probe. This equilibrium is dependent on the peptide sequence, as the RP-HPLC analysis of dimeric peptide (RhB-RRWQWR-hF-KKLG)₂K-Ahx did not reveal the presence of isomers. The antibacterial activity of the fluorescent peptides depends on the probe attached to the sequence and the bacterial strain tested. Notably, some fluorescent peptides showed activity against reference strains as well as sensitive, resistant, and multidrug-resistant clinical isolates of E. coli, S. aureus, and E. faecalis. Fluorolabeled peptides 1-Abz (MIC = 62 µM), RhB-1 (MIC = 62 µM), and Abz-1 (MIC = 31 µM) exhibited significant activity against clinical isolates of E. coli, S. aureus, and E. faecalis, respectively. The RhB-1 (IC₅₀ = 61 µM), Abz-1 (IC₅₀ = 87 µM), and RhB-2 (IC₅₀ = 35 µM) peptides exhibited a rapid, significant, and concentration-dependent cytotoxic effect on HeLa cells, accompanied by morphological changes characteristic of apoptosis. RhB-1 (IC₅₀ = 18 µM) peptide also exhibited significant cytotoxic activity against breast cancer cells MCF-7. These conjugates remain valuable for elucidating the possible mechanisms of action of these novel anticancer peptides. Rhodamine-labeled peptides displayed cytotoxicity comparable to that of their unlabeled analogues, suggesting that cellular internalization constitutes a critical early step in their mechanism of action. These findings suggest that cell death induced by both unlabeled and fluorolabeled peptides proceeds predominantly via apoptosis and is likely contingent upon peptide internalization. Functionalization at the N-terminal end of the palindromic sequence can be evaluated to develop systems for transporting non-protein molecules into cancer cells. Full article

Streptococcus pyogenes (GAS) is a leading cause of acute otitis media (AOM) and its complications. This study aimed to evaluate the antimicrobial resistance of all isolated bacterial agents recovered from children with AOM and to perform the emm typing of GAS isolates. Antibiotic susceptibility testing was evaluated according to EUCAST criteria. Phenotyping and genotyping were performed for the macrolide-resistant GAS isolates. All GAS isolates were subjected to emm typing. Among the 103 AOM cases considered, we identified GAS isolates (39.4%), Staphylococcus aureus (26.6%), Haemophilus influenzae (13.8%), Streptococcus pneumoniae (11.7%), Moraxella catarrhalis (7.4%), and Serratia marcescens (1.1%). GAS exhibited 32.4% macrolide resistance and 10.8% clindamycin resistance. The M phenotype and mefE gene (18.9%) were the most common, followed by cMLSB (10.8% with ermB), a combination of mefA and ermB (8.1%), and iMLSB (2.7% with ermA). The most prevalent emm types were emm12 (27.0%), emm1 (21.6%), and emm3 (16.2%). The most common GAS emm types identified among AOM patients in this study are found worldwide and are associated with invasive infections in various countries. This may influence the virulence and invasive potential of these strains. Full article