Growth Of Pathogens Research Articles

Inhibition of Food-Borne Pathogen Growth and Biogenic Amine Synthesis by Spice Extracts

Food-borne pathogens and their toxins cause significant health problems in humans. Formation of biogenic amines (BAs) produced by microbial decarboxylation of amino acids in food is undesirable because it can induce toxic effects in consumers. Therefore, it is crucial to investigate the effects of natural additives with high bioactivity like spice extracts to inhibit the growth of these bacteria and the formation of BAs in food. In the present study, the antibacterial effects of diethyl ether spice (sumac, cumin, black pepper, and red pepper) extracts at doses of 1% (w/v) on Gram-positive (Staphylococcus aureus and Enterococcus faecalis) and Gram-negative (Klebsiella pneumoniae, Pseudomonas aeruginosa, Campylobacter jejuni, Aeromonas hydrophila, Salmonella Paratyphi A, and Yersinia enterocolitica) food-borne pathogen bacterial strains (FBP) were established. In addition, the accumulation of ammonia (AMN), trimethylamine (TMA), and biogenic amines (BAs) in tyrosine decarboxylase broth (TDB) was investigated by using high performance liquid chromatography (HPLC). Sumac extract exhibited the highest antibacterial potential against all FBPs, followed by cumin and peppers. AMN (570.71 mg/L) and TMA (53.66 mg/L) production were strongly inhibited by sumac extract in the levels of 55.10 mg/L for Y. enterocolitica and 2.76 mg/L for A. hydrophila, respectively. With the exception of S. aureus, black pepper dramatically reduced the synthesis of putrescine, serotonin, dopamine, and agmatine by FBP especially for Gram-negative ones. Furthermore, sumac extracts inhibited histamine and tyramine production by the majority of FBP. This research suggests the application of sumac extracts as natural preservatives for inhibiting the growth of FBPs and limiting the production of AMN, TMA, and BAs.

Morpho-Molecular Characterization and In vitro Management of the Pestalotiopsis palmarum (Cooke) Steyaert Causing the Grey Blight of Coconut

The solitary species of the genus Cocos is the coconut palm (Cocos nucifera L.). The coconut palm is affectionately known as "Kalpa Vriksha," which translates to "the tree of heaven. The causal organism of grey blight was identified based on the morphological characteristics i.e., five-celled conidia had three middle cells that ranged in colour from light brown to dark brown further confirmed through PCR analysis as Pestalotiopsis palmarum. In cultural characteristics, maximum radial growth occurred in PDA, with V-8 juice agar showing the least growth (65.00 mm). The optimal pH for pathogen growth was 6 (338.11 mg). Fungicide evaluation revealed ziram as highly efficient among non-systemic fungicides, while carbendazim and thiophonate methyl were most effective among systemic ones. Trifloxystrobin 25% + tebuconazole 50% EC emerged as the most effective combi product, inhibiting pathogen growth by 88.02%. Among bio-agents, T. viride-2 displayed the highest mycelial inhibition (71.30%). Turmeric exhibited the highest botanical efficacy (48.03%), whereas lantana had the least impact (3.37%).

Identification of polyphenol extracts from flaxseed and study on its bacteriostatic mechanism

In this paper, the polyphenol components of flaxseed were identified, and their antibacterial effect and mechanism of action against pathogenic bacteria were studied. Results showed that 14 phenolic acids and 15 flavonoids were identified in flaxseed. Among them, 5 phenolic acids, including ferulic acid, vanillic acid, sinapic acid, gallic acid, 4-hydroxybenzoic acid, as well as 6 flavonoids, including vitexin, quercitrin, quercetin, apigenin, kaempfero1, (+)-dihydroquercetin, were the main phenolic compounds in flaxseed and have been quantitatively analyzed and determined. The content of sinapic acid and quercetin accounted for over 42.67% of flaxseed polyphenol extract. The Oxford Cup method confirmed the antibacterial effect of flaxseed polyphenol extract on Staphylococcus aureus, Escherichia coli, Listeria monocytogenes, Salmonella and Pseudomonas fluorescens. The experimental data showed that flaxseed polyphenol extract had a strong inhibitory effect on the growth of both common food-borne pathogens and non-food-borne pathogens. Flaxseed polyphenols increased the permeability of microbial cell membrane, resulting in microbial protein leakage, cell membrane depolarization, and decreased intracellular ATP content, and increased cell membrane potential and cell contents leakage. The results of this study clarified the composition of flaxseed polyphenol and provided a new way for the comprehensive utilization of flaxseed.

Microbial threats and sustainable solutions for molluscan aquaculture

Abstract Aquaculture is responsible for producing almost half of the world’s seafood. As the global climate changes and population continues to increase, we must prepare for increased disease in aquatic animals, a risk compounded by high-density aquafarms that are necessary to keep up with demand. This review will highlight major microbial threats to aquaculture and current and alternative solutions to these threats with consideration for the accessibility of the proposed solutions. Molluscs are ideal for sustainable aquaculture because they require less inputs than most other protein sources, and through filter feeding, they improve local ecosystem health. However, they are also plagued by microbial diseases, and rising water temperatures will only exacerbate this problem by enhancing pathogen survival, range, and growth. At the same time, microbial treatments hold great promise for reducing disease burden and increasing yield and food safety. In order to combat threats to sustainable aquaculture, it is critical to monitor and predict microbial behavior in coastal water and animal populations, explore sustainable microbial treatment options such as probiotics and phage therapy, reduce reliance on antimicrobials, and develop mitigation strategies through partnership with mollusc farmers, government regulators, industry, academic researchers, and indigenous peoples.

CD73 contributes to the pathogenesis of fusion-negative rhabdomyosarcoma through the purinergic signaling pathway

Rhabdomyosarcoma (RMS) is the most common type of soft tissue sarcoma in children and adolescents. Fusion-negative RMS (FN-RMS) accounts for more than 80% of all RMS cases. The long-term event-free survival rate for patients with high-grade FN-RMS is below 30%, highlighting the need for improved therapeutic strategies. CD73 is a 5' ectonucleotidase that hydrolyzes AMP to adenosine and regulates the purinergic signaling pathway. We found that CD73 is elevated in FN-RMS tumors that express high levels of TWIST2. While high expression of CD73 contributes to the pathogenesis of multiple cancers, its role in FN-RMS has not been investigated. We found that CD73 knockdown decreased FN-RMS cell growth while up-regulating the myogenic differentiation program. Moreover, mutation of the catalytic residues of CD73 rendered the protein enzymatically inactive and abolished its ability to stimulate FN-RMS growth. Overexpression of wildtype CD73, but not the catalytically inactive mutant, in CD73 knockdown FN-RMS cells restored their growth capacity. Likewise, treatment with an adenosine receptor A2A-B agonist partially rescued FN-RMS cell proliferation and bypassed the CD73 knockdown defective growth phenotype. These results demonstrate that the catalytic activity of CD73 contributes to the pathogenic growth of FN-RMS through the activation of the purinergic signaling pathway. Therefore, targeting CD73 and the purinergic signaling pathway represents a potential therapeutic approach for FN-RMS patients.

Mechanism of Tol/Pal System in Antibacterial Therapies

The Tol/Pal system is a group of complex proteins found in Gram-negative bacteria that has a crucial function in bacterial outer membrane development and safety. It is a promising target for potential antibacterial therapy. Initially, this Tol/Pal system was thought to be associated with the uptake of toxins such as colicins by Escherichia coli. However, the latest research has revealed that this system has much broader features beyond that. The system has been extensively studied, and this article discusses some of the conclusions drawn from those studies. Most significantly, the Tol/Pal system is a prerequisite for the pathogenicity of many Gram-negative bacteria, indicating that it has a remarkable role in how these bacteria cause diseases. Moreover, this system plays a vital role in the growth and overall fitness of specific pathogens. This indicates that it may be a promising target for growing antimicrobial therapies. Significantly, one of the proteins in this system, called Pal, is highly recognizable through the immune system and may trigger each of the adaptive and innate immune responses. A lot of these features make the Tol/Pal system an exciting area of research for the development of antibacterial therapies, in particular for dealing with stubborn infections caused by gram-negative pathogens, which are resistant to a couple of drugs. This paper offers an outline of the mechanisms of the Tol/ Pal system within the context of bacterial disease development and its potential utilization as a vaccine to counter respective bacterial infections.

Pengendalian Jamur Ganoderma dengan Metode Perbanyakan Jamur Trichoderma pada Pembibitan Kelapa Sawit di PT PP London Sumatra Bah Lias Research Station

Ganoderma sp. generally attacks the roots or base of the tree, whether it's alive or dead. There are also other species of Ganoderma whose caps attach directly to the tree. If Ganoderma grows on wood or a tree, then it falls into the category of "lignicolous" fungi. Ganoderma sp. can cause basal stem rot (BSR) disease in oil palm or other productive plants such as rubber, coconut, and tea. The equipment used in this activity includes digital scales, beakers, measuring cups, ovens, LAF, petri dishes, needle probes, hotplates, bunsen burners, aluminum foil, autoclaves, knives, heat-resistant plastic or polypropylene, wool thread, cotton plugs, hoses, newspapers, and rubber. The materials used include potato extract, sugar, agar powder, distilled water, RWB, corn, and fine bran. 200 grams of potato extract, 10 grams of sugar, and 12 grams of agar powder are dissolved in 1000 ml of distilled water, and the rubber wood inoculum is cut into pieces measuring 6 cm x 6 cm x 6 cm and boiled for 7 hours. The experimental technique is carried out by combining the Ganoderma starter culture developed in RWB (Rubber Wood Block), then mixed with Trichoderma in its soil medium. After that, it is planted in oil palm seedlings in polybags and the percentage of oil palm seedling deaths is observed up to 12 months of age. Trichoderma, which acts as an antagonistic microbe, can suppress the growth of pathogens. By propagating Trichoderma fungi, which is one way to utilize biological agents to control 18 plant pests and diseases, it can also inhibit the percentage of deaths in oil palm seedlings. Propagating Trichoderma fungi on a nursery scale is used as a control for pests and diseases, especially Ganoderma fungi, which are currently still a pathogen in oil palm growth. By propagating Trichoderma fungi, it also cannot rule out the possibility of Ganoderma fungi growing.

Volatile organic compounds of the soil bacterium Bacillus halotolerans suppress pathogens and elicit defense-responsive genes in plants

Volatile organic compounds (VOCs) produced by bacteria play an important, yet relatively unexplored role in interactions between plants and phytopathogens. In this study, the soil bacterium Bacillus halotolerans NYG5 was identified as a potent biocontrol agent against several phytopathogenic fungi (Macrophomina phaseolina, Rhizoctonia solani, Pythium aphanidermatum, and Sclerotinia sclerotiorum) through the production of VOCs. NYG5-emitted VOCs also inhibited the growth of bacterial pathogens (Agrobacterium tumefaciens, Xanthomonas campestris, Clavibacter michiganensis, and Pseudomonas syringae). When cultured in various growth media, NYG5 produced a variety of VOCs. Five distinct VOCs (2-methylbutanoic acid, 5-methyl-2-hexanone, 2,3-hexanedione, 2-ethyl-1-hexanol, and 6-methyl-2-heptanone) were identified using headspace GC-MS. 2,3-Hexanedione exhibited potent lethal effects on the tested phytopathogens and nematicidal activity against Meloidogyne javanica at a concentration of 50 ppm. In addition, 0.05 ppm 2,3-hexanedione stimulated the expression of pathogenesis-related genes 1 and 2 in Arabidopsis thaliana. Interestingly, 2,3-hexanedione is used as a food additive at higher concentrations than those tested in this study. Hence, 2,3-hexanedione is a promising biologically active compound that might serve as a sustainable alternative to common chemical pesticides and an elicitor of plant defense.

Oligo(ethylene glycol) methyl ether methacrylate based hydrogel with intrinsic antibacterial activity against Pseudomonas aeruginosa as a model of a major wound infecting human pathogen

Wound dressings represent the first important defense line against potentially life-threatening infections. Successful materials should unify efficiency, simplicity of production with the ease of application. Cationic polymers based on quaternary ammonium salt moieties along the polymer chain promise high efficacy against growth of relevant pathogens including drug-resistant strains. We present a novel and easy-to-handle wound dressing material based on the well-defined copolymers of oligo(ethylene glycol) methyl ether methacrylate (OEGMA) and 2-(dimethylamino)ethyl methacrylate (DMAEMA), using quaternization with 1,6-dibromohexane for hydrogel formation. The material obtained from this robust approach was perfectly biocompatible with human dermal fibroblasts and revealed an auspicious degree of intrinsic antibacterial activity against P. aeruginosa as a model pathogen for hospital-acquired infections. Formation of bacterial biofilms was prevented in early- and late-stages and even planktonic cells were killed upon gel contact. The rheological properties of the hydrogel materials were comprehensively characterized in both dry and swollen states. Excellent biological performance and appropriate viscoelastic properties qualify the hydrogels from our production approach as truly promising novel wound dressing materials with long-lasting and contact-active bactericidal activities. We believe that this charmingly simple procedure and the mechanical properties of the hydrogel may open new avenues towards cost-effective next-generation first-line wound-care materials.

Review on functionalized pectin films for active food packaging

AbstractOwing to environmental distresses and growing demands for food safety, biopolymers have found noble applications in food packaging films as they are biodegradable, biocompatible and non‐toxic. Pectin, polysaccharide based biomass was considered a promising substrate in fabricating polymeric films because of its advantages concerning film‐forming ability, low cost, bioactivity, compatibility with other polymers with a distinctive oxygen barrier capacity, which helps in improving shelf life of commodities. Introducing active agents into the packaging films focus to prolong the shelf life and preserve the sensorial quality and safety of packaged foods devoid of contamination. Antimicrobial agents or secondary metabolites derived from plants and fungi are perceived as promising natural bio‐active agents integrated into films to prevent microbial deterioration. Pectin has been greatly utilized in active packaging films incorporated with natural additives such as essential oils, nanoparticles, free fatty acids and phenolic compounds that inhibit/retard the growth of major foodborne pathogens. The above‐mentioned functionalization of pectin films with bio‐active compounds enhanced microbial resistance and contemporarily influenced the mechanical strength and barrier properties of the film. This review is intended to focus on the background of pectin, its source and the utilization of pectin in active packaging films, and the types and method of incorporation of natural compounds. Specific emphasis has been given to the types of bioactive compounds incorporated into pectin films and their impact on the functional properties of the films. This review will benefit researchers in exploring innovative methods of incorporating bioactive compounds into pectin‐based films.

Screening of core microorganisms in healthy and diseased peaches and effect evaluation of biocontrol bacteria (Burkholderia sp.)

Biological antagonists serve as the most important green alternatives to chemical fungicides, a class of microorganism that inhibits the growth of pathogenic fungi to reduce fruit incidence. In this paper, healthy and diseased peach fruit was selected for amplicon sequencing of the epiphytic microbiota on their surface to obtain a comprehensive understanding. Community structure, diversity and LefSe analysis were performed to screen Acetobacter, Muribaculaceae and Burkholderia as the core bacteria, Mycosphaerella, Penicillium and Alternaria as the core fungi, they showed significant differences and were highly enriched. Two strains fungi (Penicillium K3 and N1) and one strain antagonistic bacteria (Burkholderia J2) were isolated. The in intro test results indicated the bacterial suspension, fermentation broth and volatile organic compounds of antagonistic bacteria J2 were able to significantly inhibit pathogen growth. In vivo experiments, peach was stored at 28 °C for 6 days after different treatments, and samples were taken every day. It was found that Burkholderia J2 enhanced peach resistance by increasing the activities of antioxidant-related enzymes such as SOD, POD, PAL, PPO, GR, MDHAR, and DHAR. The results improved that Burkholderia J2 has great biocontrol potential and could be used as a candidate strain for green control of blue mold.

Study of the effect of bacteria of the genus <i>Pseudomonas</i> on the growth and toxin production of the fungus <i>Fusarium graminearum</i> <i>in vitro</i>

Aim. To study the potential of bacteria strains P. chlororaphis BZR 245‐F and Pseudomonas sp. BZR 523‐2 to inhibit the growth of Fusarium ear blight pathogens through the example of the fungus F. graminearum and to reduce the accumulation of deoxynivalenol (DON) and zearalenone (ZEN) in vitro. Materials and Methods. Antifungal metabolites of Pseudomonas bacteria were analysed by thin layer chromatography and bioautography. An experiment on the effect of liquid culture and supernatant of bacteria on the growth and toxin production of the fungus F. graminearum in vitro was carried out on wheat grain. Analysis of grain for mycotoxins was carried out by HPLC‐HRMS. Results. The ability of strains P. chlororaphis BZR 245‐F and Pseudomonas sp. BZR 523‐2 to produce antifungal metabolites was found, while inhibiting the growth of the fungus F. graminearum 60318 in vitro. The content of DON decreases both under the action of the liquid culture and supernatant of P. chlororaphis BZR 245‐F bacteria by 60 % and 70 %, respectively, and the liquid culture and supernatant of Pseudomonas sp. BZR 523‐2 bacteria by 75 % and 90 %, respectively. The accumulation of ZEN is also significantly suppressed under the influence of liquid cultures and supernatants of bacterial strains. The amount of ZEN decreases under the influence of liquid culture and supernatant of P. chlororaphis BZR 245‐F bacteria by 80 % and 95 %, respectively. Liquid culture and supernatant of Pseudomonas sp. BZR 523‐2 bacteria inhibited the accumulation of ZEN by 60 % and 84 %, respectively. Conclusion. The results obtained through the study of the effect of liquid cultures and supernatants of P. chlororaphis BZR 245‐F and Pseudomonas sp. BZR 523‐2 strains on the growth and toxin production of the fungus F. graminearum 60318 in vitro allow us to consider these strains as potential producers of effective biofungicides against toxin‐producing fungi. Further studies of these bacterial strains in vitro and in vivo on plants are needed.

Evaluation of air impingement for dry-cleaning nonfat dry milk residues on a stainless-steel surface.

The use of air jet impingement to remove residues from surfaces in food manufacturing operations offers an alternative to the use of water and liquid cleaning agents. During this investigation, air impingement was used to remove nonfat dry milk (NFDM) residues from a stainless-steel surface. The influence of the water activity (aw ) of the residue, the time after the residue reached an equilibrium water activity, and the thickness of residue at the time of removal from the surface have been investigated. All three factors had a significant effect on the time for removal. An increase in the water activity, the time at equilibrium, the sample thickness, or a combination of all three resulted in an increase in the time required to remove the deposits. Visible changes in the structure of deposits were observed as NFDM samples equilibrated to water activities above 0.43. NFDM residues with water activities less than 0.33 were removed within 1s of using air impingement regardless of wall shear stress. When the water activities were greater than 0.50, the thickness of deposit was greater than 1mm, and the time after reaching an equilibrium water activity was over 7days, more than 5min of air impingement with wall shear stress over 9.48Pa was required to remove the residue. The results from these experiments indicated that air impingement has the potential to provide effective cleaning in manufacturing facilities for low-moisture foods. PRACTICAL APPLICATION: The introduction of water in low-moisture food environments is often undesirable due to the possibility of pathogenic microorganism growth. The normal cleaning operations in the food industry use water as a cleaning agent. This study evaluates the application of air impingement technology as a dry-cleaning method.

Lactic Acid Bacteria-Fermented Diet Containing Bacterial Extracellular Vesicles Inhibited Pathogenic Bacteria in Striped Beakfish (Oplegnathus fasciatus)

In recent years, probiotics have received considerable attention for improving the health of aquaculture organisms, such as fish and shrimp, by stimulating immune activity and increasing growth rates. Oplegnathus fasciatus is a common and economically important cultured fish species in Asia. In this study, we aimed to investigate the potential of lactic acid bacteria (LAB; Limosilactobacillus reuteri)-fermented feed to promote growth and enhance immune function in O. fasciatus. The feed contained the highest proportion of LAB after L. reuteri fermentation for 3 days in anaerobic conditions. Oplegnathus fasciatus was fed LAB-fermented feed for 30 days. The administration of LAB-fermented feed (live bacteria > 109 CFU/g) significantly increased the growth rate (weight gain = 174.8%; FCR = 4.23) and intestinal probiotic levels of O. fasciatus. After LAB-fermented feeding, the immunity index was evaluated by superoxide anion production, the phagocytic activity of leukocytes, and bactericidal and lysozyme activities in the serum of O. fasciatus. We found that LAB-fermented feed treatment potentially elevated the proportions of intestinal Bifidobacterium, Blautia, and Dorea species and reduced pathogenic bacterial growth (Acinetobacter, Escherichia_Shigella, and Megasphaera) in O. fasciatus. This study demonstrated that LAB-fermented feed containing extracellular vesicles improves growth performance and the inhibition of pathogenic Acinetobacter baumannii.

Electrolyzed Saline Targets Biofilm Periodontal Pathogens In Vitro

Preventing the development and recurrence of periodontal diseases often includes antimicrobial mouthrinses to control the growth of the periodontal pathogens. Most antimicrobials are nonselective, targeting the symbiotic oral species as well as the dysbiosis-inducing ones. This affects the overall microbial composition and metabolic activity and consequently the host–microbe interactions, which can be detrimental (associated with inflammation) or beneficial (health-associated). Consequently, guiding the antimicrobial effect for modulating the microbial composition to a health-associated one should be considered. For such an approach, this study investigated electrolyzed saline as a novel rinse. Electrolyzed saline was prepared from sterile saline using a portable electrolysis device. Multispecies oral homeostatic and dysbiotic biofilms were grown on hydroxyapatite discs and rinsed daily with electrolyzed saline (EOS). Corresponding positive (NaOCl) and negative (phosphate-buffered saline) controls were included. After 3 rinses, biofilms were analyzed with viability quantitative polymerase chain reaction and scanning electron microscopy. Supernatants of rinsed biofilms were used for metabolic activity analysis (high-performance liquid chromatography) through measuring organic acid content. In addition, human oral keratinocytes (HOKs) were exposed to EOS to test biocompatibility (cytotoxicity and inflammation induction) and also to rinsed biofilms to assess their immunogenicity after rinsing. Rinsing the dysbiotic biofilms with EOS could reduce the counts of the pathobionts (>3 log10 Geq/mm2 reduction) and avert biofilm dysbiosis (≤1% pathobiont abundance), leading to the dominance of commensal species (≥99%), which altered both biofilm metabolism and interleukin 8 (IL-8) induction in HOKs. EOS had no harmful effects on homeostatic biofilms. The scanning electron micrographs confirmed the same. In addition, tested concentrations of EOS did not have any cytotoxic effects and did not induce IL-8 production in HOKs. EOS showed promising results for diverting dysbiosis in in vitro rinsed biofilms and controlling key periopathogens, with no toxic effects on commensal species or human cells. This novel rinsing should be considered for clinical applications.

Isolation and Inoculation Effect of Trichoderma reesei on Growth and Yield of Barley

In today’s world, usage of chemical fertilizers has become necessity for betterment of crop yield; however they have negative impact on the environment, quality of soil and human health. Therefore, involvement of substitute for chemical fertilizers is an essential requirement of present time. Plant growth promoting fungi (PGPF) serves as a best alternative in place of chemicals to enhance plant growth, crop productivity and improve nutrients availability for plants. They also show an involvement in ceasing growth of plant pathogens, hence acting as a bio control agent. The aim of our study is to screen and examine plant growth promoting fungi effect on barley crop. A total seven fungal strains were isolated from wheat rhizosphere. The isolated fungal strains were screened for their In vitro plant growth promotional traits. Among total, one isolate 14F found positive for five different plant growth promoting traits. This isolate was further identified at molecular level by amplification and sequencing of ITS gene region and was identified as Trichoderma reesei. Trichoderma reesei was inoculated with barley seeds and its effects were analyzed. Significant increase was observed in terms of plant height (root length and shoot length), plant weight (Dry and wet weight) as compared to un-inoculated plants. This Trichoderma strain could become a fantastic bio-fertilizer for sustainable agriculture.

Plant pathogenic bacterium Ralstonia solanacearum can rapidly evolve tolerance to antimicrobials produced by Pseudomonas biocontrol bacteria.

Soil-borne plant pathogens significantly threaten crop production due to lack of effective control methods. One alternative to traditional agrochemicals is microbial biocontrol, where pathogen growth is suppressed by naturally occurring bacteria that produce antimicrobial chemicals. However, it is still unclear if pathogenic bacteria can evolve tolerance to biocontrol antimicrobials and if this could constrain the long-term efficacy of biocontrol strategies. Here we used an in vitro experimental evolution approach to investigate if the phytopathogenic Ralstonia solanacearum bacterium, which causes bacterial wilt disease, can evolve tolerance to antimicrobials produced by Pseudomonas bacteria. We further asked if tolerance was specific to pairs of R. solanacearum and Pseudomonas strains and certain antimicrobial compounds produced by Pseudomonas. We found that while all R. solanacearum strains could initially be inhibited by Pseudomonas strains, this inhibition decreased following successive subculturing with or without Pseudomonas supernatants. Using separate tolerance assays, we show that the majority of R. solanacearum strains evolved increased tolerance to multiple Pseudomonas strains. Mechanistically, evolved tolerance was most likely linked to reduced susceptibility to orfamide lipopeptide antimicrobials secreted by Pseudomonas strains in our experimental conditions. Some levels of tolerance also evolved in the control treatments, which was likely correlated response due to adaptations to the culture media. Together, these results suggest that plant-pathogenic bacteria can rapidly evolve increased tolerance to bacterial antimicrobial compounds, which could reduce the long-term efficacy of microbial biocontrol.

Macrophage plasticity enhanced by camel milk peptide attributes in wound healing in diabetic rats

Diabetes Mellitus during wound healing alters macrophage recruitment, leading to delayed healing. The present study focuses on impact of camel milk peptide (CMP) on macrophage plasticity during their recruitment during wound healing stages. The Swiss albino rats were distributed into three groups: a normal wounded group (control), a wounded diabetic group, and a wounded diabetic group treated with CMP daily. The diabetic rats showed a significantly compromised level of monocyte chemoattractant protein-1 (MCP-1) and macrophage inflammatory protein (MIP-1α) relative gene expression, anti-CD31, anti-Mac-3, and anti-CD68 staining than the control group. Macrophages were considerably depleted in diabetic group animals upon initiating the inflammatory phase, while the protein significantly reversed the same. Also, there was marked increase in pathogenic bacterial growth at the wound sites of diabetic rats. On the contrary, in CMP-diabetic rats, levels of pathogenic bacteria were comparable to normal control animals. Diabetic rats demonstrated a reduction in matrix metalloproteinase (MMP-9 and MMP-13) expression while increased TNF-α levels compared to control rats. In addition, they also showed significantly reduced expression of VEGF and fibroblast growth factors (FGF) genes and IL-10 during the proliferation phase. However, all these parameters exhibited a considerably reversed trend in the CMP treated diabetic rats. Hence, CMP-treated diabetic rats demonstrated a transition to the M2 phenotype, highlighting macrophage recruitment's critical role in healing of wounds in hyperglycemic rats.

Strengthening the genomic surveillance of Francisella tularensis by using culture-free whole-genome sequencing from biological samples.

Francisella tularensis is a highly infectious bacterium that causes the zoonotic disease tularemia. The development of genotyping methods, especially those based on whole-genome sequencing (WGS), has recently increased the knowledge on the epidemiology of this disease. However, due to the difficulties associated with the growth and isolation of this fastidious pathogen in culture, the availability of strains and subsequently WGS data is still limited. To surpass these constraints, we aimed to implement a culture-free approach to capture and sequence F. tularensis genomes directly from complex samples. Biological samples obtained from 50 common voles and 13 Iberian hares collected in Spain were confirmed as positive for F. tularensis subsp. holarctica and subjected to a WGS target capture and enrichment protocol, using RNA oligonucleotide baits designed to cover F. tularensis genomic diversity. We obtained full genome sequences of F. tularensis from 13 animals (20.6%), two of which had mixed infections with distinct genotypes, and achieved a higher success rate when compared with culture-dependent WGS (only successful for two animals). The new genomes belonged to different clades commonly identified in Europe (B.49, B.51 and B.262) and subclades. Despite being phylogenetically closely related to other genomes from Spain, the detected clusters were often found in other countries. A comprehensive phylogenetic analysis, integrating 599 F. tularensis subsp. holarctica genomes, showed that most (sub)clades are found in both humans and animals and that closely related strains are found in different, and often geographically distant, countries. Overall, we show that the implemented culture-free WGS methodology yields timely, complete and high-quality genomic data of F. tularensis, being a highly valuable approach to promote and potentiate the genomic surveillance of F. tularensis and ultimately increase the knowledge on the genomics, ecology and epidemiology of this highly infectious pathogen.

Evaluation of SYP-34773's resistance risk and its impact on the activity of mitochondrial respiratory electron transport chain complex I in Phytophthora litchii.

SYP-34773 is a low-toxicity pyrimidine amine compound, which was synthesized by modifying the lead compound diflumetorim. Previous literature has shown that it can strongly inhibit the mycelial growth of several important plant pathogens, including Phytophthora litchii. However, the resistance risk of SYP-34773 has not been reported for P. litchii. The mean effective concentration (EC50 ) value of SYP-34773 against the mycelial growth of 111 P. litchii isolates was 0.108 ± 0.008 μg mL-1 , which can be used as the baseline sensitivity for SYP-34773 resistance detection in the future. Six mutants were obtained from two parental strain through fungicide induction, whose resistance factors fell between 194- and 687-fold, with stability. Results regarding mycelial growth, sporangial production, sporangial germination, zoospore release, cystspore germination, and pathogenicity showed that the mutants' compound fitness index values were significantly lower than those of their parental isolate. Furthermore, there was no cross-resistance between SYP-34773 and diflumetorim in P. litchii. Significant inhibition of the mitochondrial complex I enzyme activity in two wild-type P. litchii isolates, but not in mutants, was observed upon treatment with SYP-34773. The resistance risk of SYP-34773 in P. litchii is moderate, and resistance management strategies should be adopted in field use. SYP-34773 is a mitochondrial complex I inhibitor, and SYP-34773-resistant P. litchii isolates did not show cross-resistance against diflumetorim. © 2023 Society of Chemical Industry.