Inhibition Of Pathogenic Fungi Research Articles

Bacillus Metabolites: Compounds, Identification and Anti-Candida albicans Mechanisms

Candida albicans seriously threatens human health, especially for immunosuppressed groups. The antifungal agents mainly include azoles, polyenes and echinocandins. However, the few types of existing antifungal drugs and their resistance make it necessary to develop new antifungal drugs. Bacillus and its metabolites has antifungal activity against pathogenic fungi. This review introduces the application of Bacillus metabolites in the control of C. albicans in recent years. Firstly, several compounds produced by Bacillus spp. are listed. Then the isolation and identification techniques of Bacillus metabolites in recent years are described, including high-precision separation technology and omics technology for the separation of similar components of Bacillus metabolites. The mechanisms of Bacillus metabolites against C. albicans are distinguished from the inhibition of pathogenic fungi and inhibition of the fungal virulence factors. The purpose of this review is to systematically summarize the recent studies on the inhibition of pathogenic fungi by Bacillus metabolites. The review is expected to become the reference for the control of pathogenic fungi such as C. albicans and the application of Bacillus metabolites in the future.

Cyclo(l-proline-l-serine) Dipeptide Suppresses Seed Borne Fungal Pathogens of Rice: Altered Cellular Membrane Integrity of Fungal Hyphae and Seed Quality Benefits.

Five proline-containing diketopiperazines (Pro-DKPs) produced by antagonistic microorganisms as secondary metabolites were selected and synthesized under laboratory conditions. Out of five synthesized Pro-DKPs, cyclo(l-Pro-l-Ser) (DKP-6) revealed the best inhibition of fungal pathogens (Fusarium verticillioides and Fusarium fujikuroi) of rice under in vitro conditions with effective doses lower than standard fungicide carbendazim. DKP-6 induced stress on the fungal cell membrane integrity, which was revealed by calcofluor white and propidium iodide assays, endorsed by ultra-microscopic details and soluble protein leakage assays. In vivo seed treatment of infested rice seeds with DKP-6 at 2000 μg/mL for 10 h of seed treatment inflicted best reduction in seed rot and seedling blight with respect to control and carbendazim. Significant enhancement in seedling quality parameters were also observed. The work presented the strong influence of cyclo(l-Pro-l-Ser) as a mycocidal seed treatment agent better than synthetic toxic fungicides for rice.

Synergistic effect of natural antifungal agents for postharvest diseases of blackberry fruits.

Blackberry postharvest diseases are caused by fungal pathogens, and treatment of fruits with edible, natural products could reduce the postharvest losses and contribute to food sustainability. Based on the hypothesis that inhibition of fungal pathogens will significantly extend the shelf-life of food products, the effects of natural antifungal agents on fungal pathogens were tested. Two pathogenic fungal isolates, Aspergillus japonicus and Gilbertella persicaria, from infected blackberry fruits were identified morphologically using scanning electron microscopy and confirmed by DNA sequence analysis. The inhibitory effects and synergistic action of natural antifungal agents against the two fungal isolates were investigated. The results obtained demonstrated that the natamycin, chitosan and ferulic acid exhibited significant antifungal activities against the tested strains based on the calculated minimum inhibitory concentration. The best antifungal activity was obtained using a combination of ferulic acid and natamycin, which generated a total synergistic effect on both tested strains with a fractional inhibitory concentration index of 0.281. Application of the selected agents on postharvest blackberry fruits reduced the rot ratio and weight loss and also increased fruit firmness. In addition, the shelf-life of fresh blackberry fruits was extended up to 12-15 days at 4°C and 90 ± 5% relative humidity. The combined utilization of ferulic acid and natamycin showed synergistic antifungal activity against two pathogenic fungal isolates, and extended the shelf life of fresh blackberry fruits up to 12-15 days. © 2018 Society of Chemical Industry.

Inhibition of Fungal Pathogens across Genotypes and Temperatures by Amphibian Skin Bacteria.

Symbiotic bacteria may dampen the impacts of infectious diseases on hosts by inhibiting pathogen growth. However, our understanding of the generality of pathogen inhibition by different bacterial taxa across pathogen genotypes and environmental conditions is limited. Bacterial inhibitory properties are of particular interest for the amphibian-killing fungal pathogens (Batrachochytrium dendrobatidis and Batrachochytrium salamandrivorans), for which probiotic applications as conservation strategies have been proposed. We quantified the inhibition strength of five putatively B. dendrobatidis-inhibitory bacteria isolated from woodland salamander skin against six Batrachochytrium genotypes at two temperatures (12 and 18°C). We selected six genotypes from across the Batrachochytrium phylogeny: B. salamandrivorans, B. dendrobatidis-Brazil and four genotypes of the B. dendrobatidis Global Panzootic Lineage (GPL1: JEL647, JEL404; GPL2: SRS810, JEL423). We performed 96-well plate challenge assays in a full factorial design. We detected a Batrachochytrium genotype by temperature interaction on bacterial inhibition score for all bacteria, indicating that bacteria vary in ability to inhibit Batrachochytrium depending on pathogen genotype and temperature. Acinetobacter rhizosphaerae moderately inhibited B. salamandrivorans at both temperatures (μ = 46–53%), but not any B. dendrobatidis genotypes. Chryseobacterium sp. inhibited three Batrachochytrium genotypes at both temperatures (μ = 5–71%). Pseudomonas sp. strain 1 inhibited all Batrachochytrium genotypes at 12°C and four Batrachochytrium genotypes at 18°C (μ = 5–100%). Pseudomonas sp. strain 2 and Stenotrophomonas sp. moderately to strongly inhibited all six Batrachochytrium genotypes at both temperatures (μ = 57–100%). All bacteria consistently inhibited B. salamandrivorans. Using cluster analysis of inhibition scores, we found that more closely related Batrachochytrium genotypes grouped together, suggesting that bacterial inhibition strength may be predictable based on Batrachochytrium relatedness. We conclude that bacterial inhibition capabilities change among bacterial strains, Batrachochytrium genotypes and temperatures. A comprehensive understanding of bacterial inhibitory function, across pathogen genotypes and temperatures, is needed to better predict the role of bacterial symbionts in amphibian disease ecology. For targeted conservation applications, we recommend using bacterial strains identified as strongly inhibitory as they are most likely to produce broad-spectrum antimicrobial agents at a range of temperatures.

Inhibition of bacterial and fungal pathogens by the orphaned drug auranofin.

We identified auranofin as an antimicrobial compound utilizing a high-throughput screen using a Caenorhabditis elegans-Staphylococcus aureus infection model. Results/methodology: Treatment of infected nematodes with auranofin resulted in a prolonged survival rate of 95%, reached with 0.78 μg/ml. Further investigation of the antimicrobial activity of auranofin found inhibition against S. aureus, Enterococcus faecium and Enterococcus faecalis. Importantly, the fungal pathogens Cryptococcus neoformans was also effectively inhibited with an MIC at 0.5 μg/ml. Auranofin appears to target the thioredoxin system. This work provides extensive additional data on the antibacterial effects of auranofin that includes both reference and clinical isolates and reports a novel inhibition of fungal pathogens by this compound.

Test Antifungal Phatogen Extract Secondary Metabolites Of Endophytic Fungi Raru Plant (Cotylelobium melanoxylon)

This study aims to determine the ability of extracts secondary metabolites of endophytic fungi raru plant Siarang (Cotylelobium melanoxylon) in inhibiting the growth of pathogenic fungi. Pathogenic fungi tested were Collectotrichum, Fusarium oxysporum, Candida albicans and Sclerotium rolfsii. Test antifungal pathogens carried out by using the method of Kirby-Bour, ie by measuring the clear zone located around the paper disc which is the zone of growth inhibition of pathogenic fungi. Measurement of inhibition zone is done by using a caliper or ruler. The results showed that the secondary metabolites of endophytic fungi extracts could inhibit the growth of pathogenic fungus Candida albicans is the clear zone of 10.23 mm. Keywords : endophytic fungus, Cotylelobium melanoxylon, extract of secondary metabolites, fungal pathogens, inhibition zone

Antifungal Proteins: Potent Candidate for Inhibition of Pathogenic Fungi

Antifungal Proteins: Potent Candidate for Inhibition of Pathogenic Fungi

Biocontrol ofPhytophthora infestans, Fungal Pathogen of Seedling Damping Off Disease in Economic Plant Nursery

This research aims to control Seedling damping off disease in plants by using antagonistic actinomycetes against the causative fungi.Phytophthora infestanswas isolated from the infected tomato plant seedling obtained from an economic plant nursery in Amphoe Pak Chong, Nakhon Ratchasima Province, Thailand. The chitinolyticStreptomyces rubrolavendulaeS4, isolated from termite mounds at the grove of Amphoe Si-Sawat, Kanchanaburi Province, Thailand, was proven to be the most effective growth inhibition of fungal pathogens tested on potato dextrose agar. Tomato and chili seedlings that colonized with antagonisticS. rubrolavendulaeS4 were grown inP. infestansartificial inoculated peat moss. Percents of noninfested seedling in fungal contaminated peat moss were compared to the controls with uninoculated peat moss. InP. infestanscontaminated peat moss, the percents of survival of tomato and chili seedling were significantly increased () from 51.42 to 88.57 and 34.10 to 76.71 for theS. rubrolavendulaeS4 treatment, respectively. TheS. rubrolavendulaeS4 also showed high efficiency equivalent to fungicide, metalaxyl with no significant difference (). It was clearly demonstrated thatS. rubrolavendulaeS4 can prevent the tomato and chili seedling damping off disease in economic plant nurseries.

Role of Chitinolytic Enzymes and Volatile Compounds Produced by Endophytic Bacteria in the Inhibition of Mango ( Mangifera indica L.) Root Rot Pathogens

Endophytic and rhizobacteria isolated from different crops of Goa were studied for the chitinolytic activity and inhibition of fungal pathogens. Fifty-eight isolates were screened in vitro against three fungal pathogens, ., Macrophomina phaseolina , Rhizoctonia solani and Sclerotium rolfsii which cause seedling and graft mortality in mango nurseries. Results indicated that 40% of the isolates effectively inhibited the growth of all the three pathogens and 34% inhibited the growth of M. phaseolina and S. rolfsii under in vitro conditions. Chitinolytic ability of the isolates was tested by growing them in minimal synthetic medium with 0.2% colloidal chitin. Twelve isolates effectively utilized colloidal chitin as a sole carbon source for their growth. Quantitative chitinase assay revealed that the isolates produced significant amounts of chitinase in the minimal medium and the crude chitinase extract of nine endophytic (EB65, EB69, EBh11, EC2, EC2a, EC14, EC18, ESC4, ET14) and three rhizobacteria (IISR6, PDBC-AB2, RBh42) inhibited the mycelial growth as well as sclerotial germination of R. solani and S. rolfsii. Quantitative assay of chitinase showed that three endophytic bacteria (EBh11, EC18 and EC14) showed maximum chitinase activity. Chitinolytic bacteria reduced the population of all the three fungi when introduced into the soil. Further, most of the isolates produced IAA and solubilized inorganic phosphate in the medium. This study reveals that chitinolytic bacteria, especially endophytes with growth promoting mechanisms, could be better biocontrol agents in the suppression of soil borne phytopathogens.

Screening and characterization of antifungal clusterbean (Cyamopsis tetragonoloba) rhizobacteria

About 377 guar (Cyamopsis tetragonoloba) rhizobacteria were isolated from cultivated soils of north-west India (Thar Desert) and their antifungal activity against Macrophomina phaseolina (strains of groundnut, mungbean and guar) and Fusarium oxysporum (strains of chickpea and cumin) was examined. Isolates were characterised for generic types and physiological/functional diversity. About 19% isolates representing 24% locations were inhibitory to fungal growth. Isolates 009071, 009073, 009078 and 102354 recorded maximum inhibition of pathogenic fungi on plates. Isolate 034206 gave highest %RI, 009073 showed maximum protease activity and 102354 gave highest salt tolerance. Net house and field screening results revealed that isolates 004052, 009071, 009073, 001001, 094340 and 102354 had potential for biocontrol of disease. Partial sequencing of 16S rRNA gene of 61 isolates showed that 85% of isolates belonged to genus Bacillus. Phylogenetically, however, there were four clusters in the Bacillus group comprising of Bacillus subtilis, B. cereus, B. pumilus and B. sphaericus. One isolate was identified as B. flexus, while six isolates were Bacillus spp. Four isolates were identified as Achromobacter xylosoxidans, two as Bacterium (unclassified bacteria), and one each as Ochrobactrum intermedium, Pseudomonas aeruginosa and Ralstonia sp.

Bacterial inhibition of fungal growth and pathogenicity

Antifungal activity has been detected in many bacterial genera, both saprophytes and human pathogens, including Actinomadura, Actinoplanes, Arthrobacter, Micromonospora, Streptomyces, Nocardia, Mycobacterium, Aureobacterium, Bacillus, Bre6ibacterium, Lactobacillus, Rhodococcus, Micrococcus, Streptococcus, Enterococcus, Escherichia, Proteus, Klebsiella, Enterobacter, Serratia, Pseudomonas, Burkholderia, Stenotrophomonas, Agrobacterium, Alcaligenes, Azotobacter, Clostridium and Fusobacterium . A variety of methods have been used to detect this activity in vitro . Presumably, this activity confers an ecological advantage on a bacterial population which competes with other species in a particular habitat. The significance of this activity includes the following. First, development of therapeutic antifungal drugs. Second, development of plant protection agents. Third, fungal growth inhibition within the human body in sites with a normal flora with effects on the pathogenesis and course of human infection. Fourth, inhibition of pathogenic fungi in human clinical specimens, reducing the likelihood of in vitro culture of fungi.

Inhibition of pathogenic fungi in vitro by p-hydroxy methyl benzoate.

p-hydroxy methyl benzoate is fungistatic, in rather low concentrations, to pathogenic fungi. 0.1 %p-hydroxy methyl benzoate was required to inhibit growth ofCandida albicans andMonosporium apiospermum on a Sabouraud's agar medium.Trichophyton mentagrophytes, T. tonsurans, Geotrichum sp.,Sporotrichum schenckii, Blastomyces dermatitidis andCryptococcus neoformans failed to grow in the presence of 0.05 %p-hydroxy methyl benzoate. Growth ofEpidermophyton floccosum, Microsporum audouini, M. canis, M. gypseum, Trichophyton ferrugineum, T. rubrum, Hormodendrum compactum, H. Pedrosoi, Phialophora verrucosa, Nocardia asteroides, Coccidioides immitis, Haplosporangium parvum andHistoplasma capsulatum was suppressed by 0.025 % but not by 0.0125 % of this compound.