scholarly journals Bacteria Belonging to Pseudomonas typographi sp. nov. from the Bark Beetle Ips typographus Have Genomic Potential to Aid in the Host Ecology

Insects ◽  
2020 ◽  
Vol 11 (9) ◽  
pp. 593
Author(s):  
Ezequiel Peral-Aranega ◽  
Zaki Saati-Santamaría ◽  
Miroslav Kolařik ◽  
Raúl Rivas ◽  
Paula García-Fraile
Keyword(s):  
Bark Beetle ◽  
Fungal Pathogens ◽  
Pathogenic Fungi ◽  
Gene Clusters ◽  
Ips Typographus ◽  
In Vitro Tests ◽  
Defense Compounds ◽  
Genes Encoding ◽  
Host Ecology

European Bark Beetle Ips typographus is a secondary pest that affects dead and weakened spruce trees (Picea genus). Under certain environmental conditions, it has massive outbreaks, resulting in the attacks of healthy trees, becoming a forest pest. It has been proposed that the bark beetle’s microbiome plays a key role in the insect’s ecology, providing nutrients, inhibiting pathogens, and degrading tree defense compounds, among other probable traits yet to be discovered. During a study of bacterial associates from I. typographus, we isolated three strains identified as Pseudomonas from different beetle life stages. A polyphasic taxonomical approach showed that they belong to a new species for which the name Pseudomonas typographi sp nov. is proposed. Genome sequences show their potential to hydrolyze wood compounds and synthesize several vitamins; screening for enzymes production was verified using PNP substrates. Assays in Petri dishes confirmed cellulose and xylan hydrolysis. Moreover, the genomes harbor genes encoding chitinases and gene clusters involved in the synthesis of secondary metabolites with antimicrobial potential. In vitro tests confirmed the capability of the three P. typographi strains to inhibit several Ips beetles’ pathogenic fungi. Altogether, these results suggest that P. typographi aids I. typographi nutrition and resistance to fungal pathogens.

Transgenic expression of gallerimycin, a novel antifungal insect defensin from the greater wax moth Galleria mellonella, confers resistance to pathogenic fungi in tobacco

2006 ◽  
Vol 387 (5) ◽  
pp. 549-557 ◽  
Author(s):  
Gregor Langen ◽  
Jafargholi Imani ◽  
Boran Altincicek ◽  
Gernot Kieseritzky ◽  
Karl-Heinz Kogel ◽  
...  
Keyword(s):  
Transgenic Tobacco ◽  
Fungal Pathogens ◽  
Galleria Mellonella ◽  
Ectopic Expression ◽  
Pathogenic Fungi ◽  
Transgenic Expression ◽  
Greater Wax Moth ◽  
Insect Defensin ◽  
Wax Moth

Abstract A cDNA encoding gallerimycin, a novel antifungal peptide from the greater wax moth Galleria mellonella, was isolated from a cDNA library of genes expressed during innate immune response in the caterpillars. Upon ectopic expression of gallerimycin in tobacco, using Agrobacterium tumefaciens as a vector, gallerimycin conferred resistance to the fungal pathogens Erysiphe cichoracearum and Sclerotinia minor. Quantification of gallerimycin mRNA in transgenic tobacco by real-time PCR confirmed transgenic expression under control of the inducible mannopine synthase promoter. Leaf sap and intercellular washing fluid from transgenic tobacco inhibited in vitro germination and growth of the fungal pathogens, demonstrating that gallerimycin is secreted into intercellular spaces. The feasibility of the use of gallerimycin to counteract fungal diseases in crop plants is discussed.

Sordarins: In Vitro Activities of New Antifungal Derivatives against Pathogenic Yeasts, Pneumocystis carinii, and Filamentous Fungi

1998 ◽  
Vol 42 (11) ◽  
pp. 2863-2869 ◽  
Author(s):  
E. Herreros ◽  
C. M. Martinez ◽  
M. J. Almela ◽  
M. S. Marriott ◽  
F. Gomez De Las Heras ◽  
...  
Keyword(s):  
Cryptococcus Neoformans ◽  
Filamentous Fungi ◽  
Fungal Pathogens ◽  
Pneumocystis Carinii ◽  
Pathogenic Fungi ◽  
Pseudallescheria Boydii ◽  
Absidia Corymbifera ◽  
Wide Range ◽  
Blastoschizomyces Capitatus

ABSTRACT GM 193663, GM 211676, GM 222712, and GM 237354 are new semisynthetic derivatives of the sordarin class. The in vitro antifungal activities of GM 193663, GM 211676, GM 222712, and GM 237354 against 111 clinical yeast isolates of Candida albicans,Candida kefyr, Candida glabrata, Candida parapsilosis, Candida krusei, and Cryptococcus neoformans were compared. The in vitro activities of some of these compounds against Pneumocystis carinii, 20 isolates each of Aspergillus fumigatus and Aspergillus flavus, and 30 isolates of emerging less-common mold pathogens and dermatophytes were also compared. The MICs of GM 193663, GM 211676, GM 222712, and GM 237354 at which 90% of the isolates were inhibited (MIC90s) were 0.03, 0.03, 0.004, and 0.015 μg/ml, respectively, for C. albicans, including strains with decreased susceptibility to fluconazole; 0.5, 0.5, 0.06, and 0.12 μg/ml, respectively, for C. tropicalis; and 0.004, 0.015, 0.008, and 0.03 μg/ml, respectively, forC. kefyr. GM 222712 and GM 237354 were the most active compounds against C. glabrata, C. parapsilosis, and Cryptococcus neoformans. AgainstC. glabrata and C. parapsilosis, the MIC90s of GM 222712 and GM 237354 were 0.5 and 4 μg/ml and 1 and 16 μg/ml, respectively. The MIC90s of GM 222712 and GM 237354 againstCryptococcus neoformans were 0.5 and 0.25 μg/ml, respectively. GM 193663, GM 211676, GM 222712, and GM 237354 were extremely active against P. carinii. The efficacies of sordarin derivatives against this organism were determined by measuring the inhibition of the uptake and incorporation of radiolabelled methionine into newly synthesized proteins. All compounds tested showed 50% inhibitory concentrations of <0.008 μg/ml. Against A. flavus and A. fumigatus, the MIC90s of GM 222712 and GM 237354 were 1 and 32 μg/ml and 32 and >64 μg/ml, respectively. In addition, GM 237354 was tested against the most important emerging fungal pathogens which affect immunocompromised patients. Cladosporium carrioni, Pseudallescheria boydii, and the yeast-like fungi Blastoschizomyces capitatus and Geotrichum clavatum were the most susceptible of the fungi to GM 237354, with MICs ranging from ≤0.25 to 2 μg/ml. The MICs of GM 237354 against Trichosporon beigelii and the zygomycetesAbsidia corymbifera, Cunninghamella bertholletiae, and Rhizopus arrhizus ranged from ≤0.25 to 8 μg/ml. Against dermatophytes, GM 237354 MICs were ≥2 μg/ml. In summary, we concluded that some sordarin derivatives, such as GM 222712 and GM 237354, showed excellent in vitro activities against a wide range of pathogenic fungi, includingCandida spp., Cryptococcus neoformans, P. carinii, and some filamentous fungi and emerging invasive fungal pathogens.

ISOLATION, IDENTIFICATION AND CHARACTERIZATION OF BACTERIAL ANTAGONISTS OF THE DRAGON FRUIT FUNGAL PATHOGEN Neoscytalidium dimidiatum

2021 ◽  
Vol 44 (02) ◽  
Author(s):  
NGUYEN NGOC AN ◽  
HUA HUYNH MINH THAO ◽  
HO NGUYEN HOANG YEN ◽  
NGUYEN THI DIEU HANH ◽  
NGUYEN LE HIEN HOA ◽  
...  
Keyword(s):  
Fungal Pathogens ◽  
Pathogenic Fungi ◽  
Fungal Spore ◽  
Stem Canker ◽  
Antagonistic Effect ◽  
Fruit Rot ◽  
Economic Losses ◽  
Neoscytalidium Dimidiatum ◽  
Dragon Fruit

Dragon fruit or pitahaya (Hylocereus spp.) are famous for their nutrient-rich favourable taste, which brings high economic value to subtropical and tropical countries. However, dragon fruit cultivation all over the world is threatened by fungal pathogens and among them, Neoscytalidium dimidiatum has recently been shown to be responsible for stem canker and fruit rot which cause big economic losses. In order to find an environmentally friendly way to control this pathogen, five out of sixty-nine bacterial isolates used in a screening test for antifungal activity were selected. All five strains appeared to be aerobic Gram positive spore forming bacteria suggesting that they all belong to the Bacillus genus. Cell-free culture supernatants of these strains were found to strongly inhibit both fungal spore germination and mycelia growth in vitro for at least 5 days. The strain D19 which possessed the highest antagonistic effect was further identified to be Bacillus amyloliquefaciens, a well-known species shown to have antifungal effect against several other pathogenic fungi. Thus, the results of this study opened a new promising perspective to prevent Neoscytalidium dimidiatum infection during cultivation of dragon fruit.

scholarly journals A Novel Automethylation Reaction in the Aspergillus nidulans LaeA Protein Generates S-Methylmethionine

2013 ◽  
Vol 288 (20) ◽  
pp. 14032-14045 ◽  
Author(s):  
Alexander N. Patananan ◽  
Jonathan M. Palmer ◽  
Graeme S. Garvey ◽  
Nancy P. Keller ◽  
Steven G. Clarke
Keyword(s):  
Amino Acid ◽  
Aspergillus Nidulans ◽  
Point Mutations ◽  
Pathogenic Fungi ◽  
Gene Clusters ◽  
Methionine Residue ◽  
Cell Extracts ◽  
Animal Pathogens

The filamentous fungi in the genus Aspergillus are opportunistic plant and animal pathogens that can adapt to their environment by producing various secondary metabolites, including lovastatin, penicillin, and aflatoxin. The synthesis of these small molecules is dependent on gene clusters that are globally regulated by the LaeA protein. Null mutants of LaeA in all pathogenic fungi examined to date show decreased virulence coupled with reduced secondary metabolism. Although the amino acid sequence of LaeA contains the motifs characteristic of seven-β-strand methyltransferases, a methyl-accepting substrate of LaeA has not been identified. In this work we did not find a methyl-accepting substrate in Aspergillus nidulans with various assays, including in vivo S-adenosyl-[methyl-3H]methionine labeling, targeted in vitro methylation experiments using putative protein substrates, or in vitro methylation assays using whole cell extracts grown under different conditions. However, in each experiment LaeA was shown to self-methylate. Amino acid hydrolysis of radioactively labeled LaeA followed by cation exchange and reverse phase chromatography identified methionine as the modified residue. Point mutations show that the major site of modification of LaeA is on methionine 207. However, in vivo complementation showed that methionine 207 is not required for the biological function of LaeA. LaeA is the first protein to exhibit automethylation at a methionine residue. These findings not only indicate LaeA may perform novel chemistry with S-adenosylmethionine but also provide new insights into the physiological function of LaeA.

scholarly journals In vitro interactions between primycin and different statins in their effects against some clinically important fungi

2010 ◽  
Vol 59 (2) ◽  
pp. 200-205 ◽  
Author(s):  
Ildikó Nyilasi ◽  
Sándor Kocsubé ◽  
Miklós Pesti ◽  
Gyöngyi Lukács ◽  
Tamás Papp ◽  
...  
Keyword(s):  
Fungal Pathogens ◽  
Rhizopus Oryzae ◽  
Fungal Growth ◽  
Pathogenic Fungi ◽  
Titration Method ◽  
Antifungal Activities ◽  
Opportunistic Pathogenic ◽  
The Given ◽  
In Vitro Interactions

The in vitro antifungal activities of primycin (PN) and various statins against some opportunistic pathogenic fungi were investigated. PN completely inhibited the growth of Candida albicans (MIC 64 μg ml−1) and Candida glabrata (MIC 32 μg ml−1), and was very effective against Paecilomyces variotii (MIC 2 μg ml−1), but had little effect on Aspergillus fumigatus, Aspergillus flavus or Rhizopus oryzae (MICs >64 μg ml−1). The fungi exhibited different degrees of sensitivity to the statins; fluvastatin (FLV) and simvastatin (SIM) exerted potent antifungal activities against a wide variety of clinically important fungal pathogens. Atorvastatin, rosuvastatin and lovastatin (LOV) had a slight effect against all fungal isolates tested, whereas pravastatin was completely ineffective. The in vitro interactions between PN and the different statins were investigated using a standard chequerboard titration method. When PN was combined with FLV, LOV or SIM, both synergistic and additive effects were observed. The extent of inhibition was higher when these compounds were applied together, and the concentrations of PN and the given statin needed to block fungal growth completely could be decreased by several dilution steps. Similar interactions were observed when the variability of the within-species sensitivities was investigated.

Control of Postharvest Fungal Pathogens by Antifungal Compounds from Penicillium expansum

2013 ◽  
Vol 76 (11) ◽  
pp. 1879-1886 ◽  
Author(s):  
WAFA ROUISSI ◽  
LUISA UGOLINI ◽  
CAMILLA MARTINI ◽  
LUCA LAZZERI ◽  
MARTA MARI
Keyword(s):  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Fungal Pathogens ◽  
Solid Phase ◽  
Petri Dish ◽  
Pathogenic Fungi ◽  
Penicillium Expansum ◽  
Colletotrichum Acutatum ◽  
Volatile Organic

The fungicidal effects of secondary metabolites produced by a strain of Penicillium expansum (R82) in culture filtrate and in a double petri dish assay were tested against one isolate each of Botrytis cinerea, Colletotrichum acutatum, and Monilinia laxa and six isolates of P. expansum, revealing inhibitory activity against every pathogen tested. The characterization of volatile organic compounds released by the R82 strain was performed by solid-phase microextraction–gas chromatographic techniques, and several compounds were detected, one of them identified as phenethyl alcohol (PEA). Synthetic PEA, tested in vitro on fungal pathogens, showed strong inhibition at a concentration of 1,230 μg/ml of airspace, and mycelium appeared more sensitive than conidia; nevertheless, at the concentration naturally emitted by the fungus (0.726 ± 0.16 μg/ml), commercial PEA did not show any antifungal activity. Therefore, a combined effect between different volatile organic compounds produced collectively by R82 can be hypothesized. This aspect suggests further investigation into the possibility of exploiting R82 as a nonchemical alternative in the control of some plant pathogenic fungi.

scholarly journals The Sodium-Driven Flagellar Motor Controls Exopolysaccharide Expression in Vibrio cholerae

2004 ◽  
Vol 186 (15) ◽  
pp. 4864-4874 ◽  
Author(s):  
Crystal M. Lauriano ◽  
Chandradipa Ghosh ◽  
Nidia E. Correa ◽  
Karl E. Klose
Keyword(s):  
Vibrio Cholerae ◽  
Gene Transcription ◽  
Biofilm Formation ◽  
Diarrheal Disease ◽  
Response Regulator ◽  
Gene Clusters ◽  
Signaling Cascade ◽  
Genes Encoding ◽  
Life Threatening

ABSTRACT Vibrio cholerae causes the life-threatening diarrheal disease cholera. This organism persists in aquatic environments in areas of endemicity, and it is believed that the ability of the bacteria to form biofilms in the environment contributes to their persistence. Expression of an exopolysaccharide (EPS), encoded by two vps gene clusters, is essential for biofilm formation and causes a rugose colonial phenotype. We previously reported that the lack of a flagellum induces V. cholerae EPS expression. To uncover the signaling pathway that links the lack of a flagellum to EPS expression, we introduced into a rugose flaA strain second-site mutations that would cause reversion back to the smooth phenotype. Interestingly, mutation of the genes encoding the sodium-driven motor (mot) in a nonflagellated strain reduces EPS expression, biofilm formation, and vps gene transcription, as does the addition of phenamil, which specifically inhibits the sodium-driven motor. Mutation of vpsR, which encodes a response regulator, also reduces EPS expression, biofilm formation, and vps gene transcription in nonflagellated cells. Complementation of a vpsR strain with a constitutive vpsR allele likely to mimic the phosphorylated state (D59E) restores EPS expression and biofilm formation, while complementation with an allele predicted to remain unphosphorylated (D59A) does not. Our results demonstrate the involvement of the sodium-driven motor and suggest the involvement of phospho-VpsR in the signaling cascade that induces EPS expression. A nonflagellated strain expressing EPS is defective for intestinal colonization in the suckling mouse model of cholera and expresses reduced amounts of cholera toxin and toxin-coregulated pili in vitro. Wild-type levels of virulence factor expression and colonization could be restored by a second mutation within the vps gene cluster that eliminated EPS biosynthesis. These results demonstrate a complex relationship between the flagellum-dependent EPS signaling cascade and virulence.

scholarly journals A novel glyco-conjugate vaccine against fungal pathogens

2005 ◽  
Vol 202 (5) ◽  
pp. 597-606 ◽  
Author(s):  
Antonella Torosantucci ◽  
Carla Bromuro ◽  
Paola Chiani ◽  
Flavia De Bernardis ◽  
Francesco Berti ◽  
...  
Keyword(s):  
Conjugate Vaccine ◽  
Fungal Pathogens ◽  
Pathogenic Fungi ◽  
Immune Serum ◽  
Vaginal Fluid ◽  
Vaginal Infections ◽  
Lethal Challenge ◽  
Immune Effector ◽  
Effector Cells

To generate a vaccine to protect against a variety of human pathogenic fungi, we conjugated laminarin (Lam), a well-characterized but poorly immunogenic β-glucan preparation from the brown alga Laminaria digitata, with the diphtheria toxoid CRM197, a carrier protein used in some glyco-conjugate bacterial vaccines. This Lam-CRM conjugate proved to be immunogenic and protective as immunoprophylactic vaccine against both systemic and mucosal (vaginal) infections by Candida albicans. Protection probably was mediated by anti-β-glucan antibodies as demonstrated by passive transfer of protection to naive mice by the whole immune serum, the immune vaginal fluid, and the affinity-purified anti-β-glucan IgG fractions, as well as by administration of a β-glucan–directed IgG2b mAb. Passive protection was prevented by adsorption of antibodies on Candida cells or β-glucan particles before transfer. Anti-β-glucan antibodies bound to C. albicans hyphae and inhibited their growth in vitro in the absence of immune-effector cells. Remarkably, Lam-CRM–vaccinated mice also were protected from a lethal challenge with conidia of Aspergillus fumigatus, and their serum also bound to and markedly inhibited the growth of A. fumigatus hyphae. Thus, this novel conjugate vaccine can efficiently immunize and protect against two major fungal pathogens by mechanisms that may include direct antifungal properties of anti-β-glucan antibodies.

scholarly journals Deacetylation of Fungal Exopolysaccharide Mediates Adhesion and Biofilm Formation

mBio ◽  
2016 ◽  
Vol 7 (2) ◽  
Author(s):  
Mark J. Lee ◽  
Alexander M. Geller ◽  
Natalie C. Bamford ◽  
Hong Liu ◽  
Fabrice N. Gravelat ◽  
...  
Keyword(s):  
Biofilm Formation ◽  
Fungal Pathogens ◽  
Molecular Mechanisms ◽  
Pathogenic Fungi ◽  
Gene Clusters ◽  
Biosynthetic Gene Cluster ◽  
Bacterial Biofilm ◽  
Invasive Infection ◽  
Biosynthetic Gene ◽  
Adhesive Properties

ABSTRACTThe moldAspergillus fumigatuscauses invasive infection in immunocompromised patients. Recently, galactosaminogalactan (GAG), an exopolysaccharide composed of galactose andN-acetylgalactosamine (GalNAc), was identified as a virulence factor required for biofilm formation. The molecular mechanisms underlying GAG biosynthesis and GAG-mediated biofilm formation were unknown. We identified a cluster of five coregulated genes that were dysregulated in GAG-deficient mutants and whose gene products share functional similarity with proteins that mediate the synthesis of the bacterial biofilm exopolysaccharide poly-(β1-6)-N-acetyl-d-glucosamine (PNAG). Bioinformatic analyses suggested that the GAG cluster geneagd3encodes a protein containing a deacetylase domain. Because deacetylation ofN-acetylglucosamine residues is critical for the function of PNAG, we investigated the role of GAG deacetylation in fungal biofilm formation. Agd3 was found to mediate deacetylation of GalNAc residues within GAG and render the polysaccharide polycationic. As with PNAG, deacetylation is required for the adherence of GAG to hyphae and for biofilm formation. Growth of the Δagd3mutant in the presence of culture supernatants of the GAG-deficient Δuge3mutant rescued the biofilm defect of the Δagd3mutant and restored the adhesive properties of GAG, suggesting that deacetylation is an extracellular process. The GAG biosynthetic gene cluster is present in the genomes of members of thePezizomycotinasubphylum of theAscomycotaincluding a number of plant-pathogenic fungi and a single basidiomycete species,Trichosporon asahii, likely a result of recent horizontal gene transfer. The current study demonstrates that the production of cationic, deacetylated exopolysaccharides is a strategy used by both fungi and bacteria for biofilm formation.IMPORTANCEThis study sheds light on the biosynthetic pathways governing the synthesis of galactosaminogalactan (GAG), which plays a key role inA. fumigatusvirulence and biofilm formation. We find that bacteria and fungi use similar strategies to synthesize adhesive biofilm exopolysaccharides. The presence of orthologs of the GAG biosynthetic gene clusters in multiple fungi suggests that this exopolysaccharide may also be important in the virulence of other fungal pathogens. Further, these studies establish a molecular mechanism of adhesion in which GAG interacts via charge-charge interactions to bind to both fungal hyphae and other substrates. Finally, the importance of deacetylation in the synthesis of functional GAG and the extracellular localization of this process suggest that inhibition of deacetylation may be an attractive target for the development of novel antifungal therapies.

scholarly journals Conservation of a gene cluster reveals novel cercosporin biosynthetic mechanisms and extends production to the genus Colletotrichum

2017 ◽  
Author(s):  
Ronnie de Jonge ◽  
Malaika K. Ebert ◽  
Callie R. Huitt-Roehl ◽  
Paramita Pal ◽  
Jeffrey C. Suttle ◽  
...  
Keyword(s):  
Sugar Beet ◽  
Gene Cluster ◽  
Fungal Pathogens ◽  
Plant Pathogens ◽  
Pathogenic Fungi ◽  
Gene Clusters ◽  
Phylogenomic Analysis ◽  
First Case ◽  
Horizontal Transfers ◽  
Fungal Genus

AbstractSpecies in the genus Cercospora cause economically devastating diseases in sugar beet, maize, rice, soy bean and other major food crops. Here we sequenced the genome of the sugar beet pathogen C. beticola and found it encodes 63 putative secondary metabolite gene clusters, including the cercosporin toxin biosynthesis (CTB) cluster. We show that the CTB gene cluster has experienced multiple duplications and horizontal transfers across a spectrum of plant pathogenic fungi, including the wide host range Colletotrichum genus as well as the rice pathogen Magnaporthe oryzae. Although cercosporin biosynthesis has been thought to-date to rely on an eight gene CTB cluster, our phylogenomic analysis revealed gene collinearity adjacent to the established cluster in all CTB cluster-harboring species. We demonstrate that the CTB cluster is larger than previously recognized and includes cercosporin facilitator protein (CFP) previously shown to be involved with cercosporin auto-resistance, and four additional genes required for cercosporin biosynthesis including the final pathway enzymes that install the unusual cercosporin methylenedioxy bridge. Finally, we demonstrate production of cercosporin by Colletotrichum fioriniae, the first known cercosporin producer within this agriculturally important genus. Thus, our results provide new insight into the intricate evolution and biology of a toxin critical to agriculture and broaden the production of cercosporin to another fungal genus containing many plant pathogens of important crops worldwide.Significance StatementSpecies in the fungal genus Cercospora cause diseases in many important crops worldwide. Their success as pathogens is largely due to the secretion of cercosporin during infection. We report that the cercosporin toxin biosynthesis (CTB) cluster is ancient and was horizontally transferred to diverse fungal pathogens on an unprecedented scale. Since these analyses revealed genes adjacent to the established CTB cluster, we evaluated their role in C. beticola to show that four are necessary for cercosporin biosynthesis. Finally, we confirmed that the apple pathogen Colletotrichum fioriniae produces cercosporin, the first case outside the family Mycosphaerellaceae. Other Colletotrichum plant pathogens also harbor the CTB cluster, which points to a wider concern that this toxin may play in virulence and human health.

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