Mycelial Form Research Articles

Oligomycins inhibit Magnaporthe oryzae Triticum and suppress wheat blast disease

Oligomycins are macrolide antibiotics, produced by Streptomyces spp. that show antagonistic effects against several microorganisms such as bacteria, fungi, nematodes and the oomycete Plasmopara viticola. Conidiogenesis, germination of conidia and formation of appressoria are determining factors pertaining to pathogenicity and successful diseases cycles of filamentous fungal phytopathogens. The goal of this research was to evaluate the in vitro suppressive effects of two oligomycins, oligomycin B and F along with a commercial fungicide Nativo® 75WG on hyphal growth, conidiogenesis, conidial germination, and appressorial formation of the wheat blast fungus, Magnaporthe oryzae Triticum (MoT) pathotype. We also determined the efficacy of these two oligomycins and the fungicide product in vivo in suppressing wheat blast with a detached leaf assay. Both oligomycins suppressed the growth of MoT mycelium in a dose dependent manner. Between the two natural products, oligomycin F provided higher inhibition of MoT hyphal growth compared to oligomycin B with a minimum inhibitory concentration of 0.005 and 0.05 μg/disk, respectively. The application of the compounds completely halted conidial formation of the MoT mycelium in agar medium. Further bioassays showed that these compounds significantly inhibited MoT conidia germination and induced lysis. The compounds also caused abnormal germ tube formation and suppressed appressorial formation of germinated spores. Interestingly, the application of these macrolides significantly inhibited wheat blast on detached leaves of wheat. This is the first report on the inhibition of mycelial growth, conidiogenesis, germination of conidia, deleterious morphological changes in germinated conidia, and suppression of blast disease of wheat by oligomycins from Streptomyces spp. Further study is needed to unravel the precise mode of action of these natural compounds and consider them as biopesticides for controlling wheat blast.

Characterization of Extracellular Vesicles Produced by Aspergillus fumigatus Protoplasts.

Extracellular vesicles (EVs) are membranous compartments produced by yeast and mycelial forms of several fungal species. One of the difficulties in perceiving the role of EVs during the fungal life, and particularly in cell wall biogenesis, is caused by the presence of a thick cell wall. One alternative to have better access to these vesicles is to use protoplasts. This approach has been investigated here with Aspergillus fumigatus, one of the most common opportunistic fungal pathogens worldwide. Analysis of regenerating protoplasts by scanning electron microscopy and fluorescence microscopy indicated the occurrence of outer membrane projections in association with surface components and the release of particles with properties resembling those of fungal EVs. EVs in culture supernatants were characterized by transmission electron microscopy and nanoparticle tracking analysis. Proteomic and glycome analysis of EVs revealed the presence of a complex array of enzymes related to lipid/sugar metabolism, pathogenic processes, and cell wall biosynthesis. Our data indicate that (i) EV production is a common feature of different morphological stages of this major fungal pathogen and (ii) protoplastic EVs are promising tools for undertaking studies of vesicle functions in fungal cells.IMPORTANCE Fungal cells use extracellular vesicles (EVs) to export biologically active molecules to the extracellular space. In this study, we used protoplasts of Aspergillus fumigatus, a major fungal pathogen, as a model to evaluate the role of EV production in cell wall biogenesis. Our results demonstrated that wall-less A. fumigatus exports plasma membrane-derived EVs containing a complex combination of proteins and glycans. Our report is the first to characterize fungal EVs in the absence of a cell wall. Our results suggest that protoplasts represent a promising model for functional studies of fungal vesicles.

Peptidorhamnomannan from Lomentospora prolificans modulates the inflammatory response in macrophages infected with Candida albicans

BackgroundPeptidorhamnomannan is a glycoconjugate that consists of a peptide chain substituted by O- and N-linked glycans, present on the cell surface of Lomentospora prolificans, a saprophytic fungus which is widely distributed in regions with temperate climates. O-linked oligosaccharides from peptidorhamnomannan isolated from Lomentospora prolificans conidia are recognized by macrophages mediating macrophage - conidia interaction. In this work, peptidorhamnomannan was isolated from L. prolificans mycelium cell wall and its role in macrophage - Candida albicans interaction was evaluated.ResultsPurified peptidorhamnomannan inhibits the reactivity of rabbit immune sera to mycelial and conidia forms of L. prolificans, indicating that this glycoconjugate is exposed on the fungal surface and can mediate interaction with host immune cells. We demonstrated that peptidorhamnomannan leads to TNF-α production in J774 macrophages for 1, 2 and 3 h of incubation, suggesting that this glycoconjugate may have a beneficial role in the response to fungal infections. In order to confirm this possibility, the effect of peptidorhamnomannan on the macrophage - C. albicans interaction was evaluated. Macrophages treated with peptidorhamnomannan led to a lower fungal survival, suggesting that peptidorhamnomannan induces an increased fungicidal activity in macrophages. Furthermore, TNF-α levels were measured in supernatants after macrophage - C. albicans interaction for 1, 2 and 3 h. Peptidorhamnomannan treatment led to a higher TNF-α production at the beginning of the interaction. However, the release of TNF-α was not maintained after 1 h of incubation. Besides, peptidorhamnomannan did not show any inhibitory or fungicidal effect in C. albicans when used at 100 μg/ml but it was able to kill C. albicans at a concentration of 400 μg/ml.ConclusionWe suggest that peptidorhamnomannan acts as a molecular pattern on the invading pathogen, promotes TNF-α production and, thus, increases macrophage fungicidal activity against Candida albicans.

The Human Pathogen Paracoccidioides brasiliensis Has a Unique 1-Cys Peroxiredoxin That Localizes Both Intracellularly and at the Cell Surface

Paracoccidioides brasiliensis is a temperature-dependent dimorphic fungus that causes systemic paracoccidioidomycosis, a granulomatous disease. The massive production of reactive oxygen species (ROS) by the host's cellular immune response is an essential strategy to restrain the fungal growth. Among the ROS, the hydroperoxides are very toxic antimicrobial compounds and fungal peroxidases are part of the pathogen neutralizing antioxidant arsenal against the host's defense. Among them, the peroxiredoxins are highlighted, since some estimates suggest that they are capable of decomposing most of the hydroperoxides generated in the host's mitochondria and cytosol. We presently characterized a unique P. brasiliensis 1-Cys peroxiredoxin (PbPrx1). Our results reveal that it can decompose hydrogen peroxide and organic hydroperoxides very efficiently. We showed that dithiolic, but not monothiolic compounds or heterologous thioredoxin reductant systems, were able to retain the enzyme activity. Structural analysis revealed that PbPrx1 has an α/β structure that is similar to the 1-Cys secondary structures described to date and that the quaternary conformation is represented by a dimer, independently of the redox state. We investigated the PbPrx1 localization using confocal microscopy, fluorescence-activated cell sorter, and immunoblot, and the results suggested that it localizes both in the cytoplasm and at the cell wall of the yeast and mycelial forms of P. brasiliensis, as well as in the yeast mitochondria. Our present results point to a possible role of this unique P. brasiliensis 1-Cys Prx1 in the fungal antioxidant defense mechanisms.

Genetic analysis of Streptomyces albus J1074 mia mutants suggests complex relationships between post-transcriptional tRNAXXA modifications and physiological traits.

Proteins MiaA and MiaB catalyze sequential isopentenylation and methylthiolation, respectively, of adenosine residue in 37th position of tRNAXXA. The mia mutations were recently shown by us to affect secondary metabolism and morphology of Streptomyces. However, it remained unknown as to whether both or one of the aforementioned modifications is critical for colony development and antibiotic production. Here, we addressed this issue through analysis of Streptomyces albus J1074 strains carrying double miaAmiaB knockout or extra copy of miaB gene. The double mutant differed from wild-type and miaA-minus strains in severity of morphological defects, growth dynamics, and secondary metabolism. Introduction of extra copy of miaB gene into miaA mutant restored aerial mycelium formation to the latter on certain solid media. Hence, miaB gene might be involved in tRNA thiomethylation in the absence of miaA; either MiaA- or MiaB-mediated modification appears to be enough to support normal metabolic and morphological processes in Streptomyces.

Antifungal activity of hypocrellin compounds and their synergistic effects with antimicrobial agents against Candida albicans.

Summary Candida albicans is a common human fungal pathogen. The previous study revealed that quinone compounds showed antimicrobial activity against C. albicans by inhibiting cell growth. However, it was unclear whether quinones have other antifungal effects against C. albicans in addition to fungicidal effects. In this study, we assessed the inhibitory activity of a total of 25 quinone compounds against C. albicans morphological transition, which is essential for the pathogenicity of C. albicans. Several quinones exhibited strong inhibition of mycelium formation by C. albicans SC5314. Three leading compounds, namely hypocrellins A, B and C, also exhibited marked attenuation of C. albicans SC5314 virulence in both human cell lines and mouse infection models. These three compounds significantly suppressed the proliferation of C. albicans SC5314 cells in a mouse mucosal infection model. Intriguingly, hypocrellins not only attenuated the cytotoxicity of a nystatin‐resistant C. albicans strain but also showed excellent synergistic effects with antifungal agents against both wild‐type C. albicans SC5314 and the drug‐resistant mutant strains. In addition, hypocrellins A, B and C interfered with the biological functions and virulence of various clinical Candida species, suggesting the promising potential of these compounds for development as new therapeutic agents against infections caused by Candida pathogens.

A Comprehensive Investigation of Potential Novel Marine Psychrotolerant Actinomycetes sp. Isolated from the Bay-of-Bengal.

Background: This study was carried out to classify the diversity of the deep marine psychrotolerant actinomycetes sp. nov., in the Bay of Bengal and exploit the production of cold-active industrial and pharmaceutical biomolecules.Objective: 1) Characterization, optimum the growth conditions and classify the diversity of the novel isolated deep marine psychrotolerant actinomycetes sp from the Bay-of-Bengal. 2) Screening for industrially important biocatalysts and determine the antimicrobial activities against the five dreadful pathogens. 3) The differential expression profiling of the candidate genes to regulate the biosynthesis of selected enzymes.Methods: The cold-adapted actinomycetes were isolated from the deep marine water collections at 1200 mts below the surface in Bay-of-Bengal. The phenotypic and genotypic characterizations have been carried out to understand the persistent diversity of this novel marine psychrotolerant actinomycetes species. The production of cold-active enzymes, such as amylase, cellulase, lipase, pectinase, and L-asparaginase, were screened and the expression profiling genes were determined by using qRT PCR. The antibacterial and antifungal activities have also been investigated.Results: A total number of 37 novel actinomycetes were isolated and the phenotypic and genotypic characterizations identified the genus, dominated by Streptomyces (17 distinct sub-groups) as the major group, followed by Micromonospora, Actinopolyspora, Actinosynnema, Streptoverticillium, Saccharopolyspora, Nocardiopsis, and Nocardia. The optimum growth and abundant mycelium formation are observed at 15°C to 20°C and also capability for thriving at 4°C. All the isolates exhibited a significant role in the production of biocatalysts, and the antagonistic activities were also noted against five major selected pathogens.Conclusion: The Streptomyces from the Bay-of-Bengal have high biosynthetic potential and can serve as a good resource for the exploration of bioactive natural products.

FgHtf1 Regulates Global Gene Expression towards Aerial Mycelium and Conidiophore Formation in the Cereal Fungal Pathogen Fusarium graminearum.

The homeobox gene family of transcription factors (HTF) controls many developmental pathways and physiological processes in eukaryotes. We previously showed that a conserved HTF in the plant-pathogenic fungus Fusarium graminearum, Htf1 (FgHtf1), regulates conidium morphology in that organism. This study investigated the mechanism of FgHtf1-mediated regulation and identified putative FgHtf1 target genes by a chromatin immunoprecipitation assay combined with parallel DNA sequencing (ChIP-seq) and RNA sequencing. A total of 186 potential binding peaks, including 142 genes directly regulated by FgHtf1, were identified. Subsequent motif prediction analysis identified two DNA-binding motifs, TAAT and CTTGT. Among the FgHtf1 target genes were FgHTF1 itself and several important conidiation-related genes (e.g., FgCON7), the chitin synthase pathway genes, and the aurofusarin biosynthetic pathway genes. In addition, FgHtf1 may regulate the cAMP-protein kinase A (PKA)-Msn2/4 and Ca2+-calcineurin-Crz1 pathways. Taken together, these results suggest that, in addition to autoregulation, FgHtf1 also controls global gene expression and promotes a shift to aerial growth and conidiation in F. graminearum by activation of FgCON7 or other conidiation-related genes.IMPORTANCE The homeobox gene family of transcription factors is known to be involved in the development and conidiation of filamentous fungi. However, the regulatory mechanisms and downstream targets of homeobox genes remain unclear. FgHtf1 is a homeobox transcription factor that is required for phialide development and conidiogenesis in the plant pathogen F. graminearum In this study, we identified FgHtf1-controlled target genes and binding motifs. We found that, besides autoregulation, FgHtf1 also controls global gene expression and promotes conidiation in F. graminearum by activation of genes necessary for aerial growth, FgCON7, and other conidiation-related genes.

Aerial mycelium formation in rare thermophilic Actinobacteria on media solidified with agar and gellan gum

This study investigated aerial mycelium formation in 12 isolates of rare thermophilic Actinobacteria from Indonesia on four different media (International Streptomyces Project ISP 1, ISP 2, ISP 3, and Bennett’s solidified with agar and gellan gum). The results from media solidified with agar showed that aerial mycelium formation was observed on 9 isolates as follows: 3 isolates on ISP 1 agar (Amycolatopsis and Microbispora); 3 isolates on ISP 2 agar (Amycolatopsis and Microbispora); 9 isolates on ISP 3 agar (Actinoallomurus, Amycolatopsis, Microbispora, Thermobispora, and Streptoalloteichus); and 2 isolates of Amycolatopsis on Bennett’s agar. Aerial mycelium formation was not observed in 3 isolates (Microbispora and Nocardia) on all media solidified with agar. The results from media solidified with gellan gum showed that aerial mycelium formation was observed in all 12 isolates as follows: 8 isolates on ISP 1 gellan gum (Amycolatopsis, Microbispora, Nocardia and Thermobispora); 5 isolates on ISP 2 gellan gum (Amycolatopsis, Microbispora, and Nocardia); 11 isolates on ISP 3 gellan gum (Actinoallomurus, Amycolatopsis, Microbispora, Nocardia, Thermobispora, and Streptoalloteichus); and 5 isolates on Bennett’s agar (Amycolatopsis, Microbispora, Nocardia, and Streptoalloeichus). These results indicate that the media solidified with gellan gum induced aerial mycelium formation in larger number of rare thermophilic Actinobacteria isolates compared to media solidified with agar.

Genome rearrangements and megaplasmid loss in the filamentous bacterium Kitasatospora viridifaciens are associated with protoplast formation and regeneration

Filamentous Actinobacteria are multicellular bacteria with linear replicons. Kitasatospora viridifaciens DSM 40239 contains a linear 7.8 Mb chromosome and an autonomously replicating plasmid KVP1 of 1.7 Mb. Here we show that lysozyme-induced protoplast formation of the multinucleated mycelium of K. viridifaciens drives morphological diversity. Characterisation and sequencing of an individual revertant colony that had lost the ability to differentiate revealed that the strain had not only lost most of KVP1 but also carried deletions in the right arm of the chromosome. Strikingly, the deletion sites were preceded by insertion sequence elements, suggesting that the rearrangements may have been caused by replicative transposition and homologous recombination between both replicons. These data indicate that protoplast formation is a stressful process that can lead to profound genetic changes.

Comparison of gamma-decalactone biosynthesis by yeast Yarrowia lipolytica MTLY40-2p and W29 in batch-cultures

Gamma-decalactone is an interesting flavuring compound with an intense oily-peachy aroma. It is commonly used in food and cosmetic industry. Biotechnological methods of its synthesis are based on the processes of fatty acid degradation, mainly ricinoleic acid, which is the main component of castor oil. The aim of this study was to compare the productivity of gamma-decalactone in batch cultures of two strains of Yarrowia lipolytica, wild strain W29 and its derived mutant MTLY40-2p, grown in flasks and a bioreactor. We analyzed the concentration of gamma-decalactone in the aqueous and oil phase, the optical density of the medium, the yield of yeast dry matter and the particle size distribution in the particular media. The modified strain had a higher aroma synthesis capacity. This strain grown in flasks produced thrice as much gamma-decalactone (5.5 ± 0.16 g/L) as compared to the wild-type strain (1.8 ± 0.03 g/L). During the 7-day biotransformation, the mutant strain did not have the ability to degrade gamma-decalactone, whereas in the biotransformation using the wild-type strain, reutilization was observed after the third day. Regardless of the type of culture, larger amounts of gamma-decalactone were accumulated in the lipid phase. Cultivation in a bioreactor resulted in a lower biomass yield and a lower concentration of lactone compared to flask culture, regardless of the strain used. The MTLY40-2p strain grew in mycelium form and tended to aggregate cells.

Study on the mycelium growth and primordial formation of king oyster mushroom (Pleurotus eryngii) on cardboard and spent coffee ground

Cultivation of edible mushrooms on urban wastes represents one of the most economically and cost-effective organic recycling processes. An effective tool to identify necessary nutrients for the production of fruiting bodies on the specialty substrates is mycelium growth. Hence, mycelium of king oyster mushroom (Pleurotus eryngii) were experimentally evaluated on cardboard and spent coffee ground (SCG) substrates for the mycelial growth rate, density and primordial formation. Studies were carried out using five different substrate formulations viz., 100% cardboard (TS1), 100% SCG (TS2), 50% cardboard+50% SCG (TS3), 70% cardboard+30% SCG (TS4) and 30% cardboard+70% SCG (TS5). The efficiency of different yeast extract concentrations (i.e. 1, 5, 10, 20, 30 and 50 g/l) as a supplement in potato dextrose agar media (PDA) on P. eryngii growth was also determined. The concentration of 1 g/l of yeast extract showed the best effects on mycelial growth and primordia formation of P. eryngii, while high concentration of yeast extract (550 g/l) did not show any beneficial influence. Combination between cardboard and SCG, especially substrate formulations of 30% cardboard+70% SCG increased mycelial density and number of primordial formations of P. eryngii compared to the substrates of cardboard or SCG alone. The results revealed a potential opportunity for commercial cultivation of edible mushrooms, especially P. eryngii for utilization of different recyclable residues as well as urban generated wastes reduction.

Inhibitory effect of Fungastop and Bion against carrot soft rot caused by Sclerotinia sclerotiorum

This study was conducted to assess likely inhibitory effects of Fungastop™ and Acibenzolar-S-Methyl (Bion®) against carrot rot caused by Sclerotinia sclerotiorum during postharvest phase. The results showed that Fungastop was able to markedly decrease mycelial growth and sclerotia formation of three isolates of the pathogen. In addition, Fungastop significantly reduced myceliogenic and carpogenic germination of sclerotia in the three tested isolates of S. sclerotiorum. Fungastop showed high antifungal efficacy against carrot rot in vivo as carrots were inoculated with the pathogen 2.5 h after treatment with Bion and Fungastop. However inhibitory effect of Bion against the disease was higher than Fungastop over time. The enzymatic tests revealed that Bion was able to significantly enhance levels of enzyme activities related to disease resistance including β-N-acetyl hexosaminidase, endochitinase, chitin 1,4-β-chitobiosidase and β −1,3-glucanase six days after treatment. In addition, activities of phenylalanine ammonia lyase and peroxidase were markedly increased four days after treatment. Bion showed higher effect in increasing enzyme activities related to disease resistance than Fungastop. The treatment with Fungastop and Bion enhanced relative conductivity of S. sclerotiorum mycelia over 160 min compared with control. The treatment with Fungastop increased the cell membrane permeability of mycelia more than Bion.

Talaromyces (Penicillium) marneffei and Mycobacterium tuberculosis coinfection in a HIV negative patient in Amritsar Punjab, India

A 54-year-old, male patient with a history of Pulmonary Tuberculosis and Diabetes mellitus for the past 20 years was admitted to a tertiary care hospital with chief complaints of high-grade fever with chills, productive cough and a one month history of loss of appetite and generalized malaise. On FNAC of cervical lymph nodes; impression of tubercular pathology (AFB positive) was reported. Talaromyces (Penicillium) marneffei and Mycobacterium tuberculosis co-infection was confirmed. Talaromyces marneffei (Penicillium marneffei) is a thermally dimorphic fungus that can cause severe infections particularly in immunocompromised patients was first discovered in 1956 in the regions of Southeast Asia. It exists as mycelia form at 25 °C and yeast like form at 37 °C. A large number of T. marneffei infected patients who are HIV negative have been reported in recent years.

Characterisation of the interaction of Pseudomonas putida and Pseudomonas tolaasii with Trichoderma aggressivum

Green mould disease is caused by Trichoderma aggressivum which colonizes mushroom compost and reduces yield. Two Pseudomonas species are associated with mushroom compost: Pseudomonas putida, which stimulates mushroom pinning, and Pseudomonas tolaasii which has a negative effect on crop production. The aim of this work was to characterize T. aggressivum – Pseudomonas interactions as these may be important factors in the development of green mould disease. P. tolaasii supernatant inhibited growth by 57% but P. putida stimulated growth of T.aggressivum by 44%. Tolaasin production was identified in P. tolaasii cultures with a peak at 96 h. Fluorescent microscopy examination of T. aggressivum hyphae revealed that exposure to P. tolaasii supernatant decreased mycelial formation while increasing the abundance of conidia. Label free proteomic analysis of changes in the abundance of T. aggressivum proteins indicated that exposure to P. tolaasii supernatant lead to an oxidative stress response and catabolic enzyme activation (mitochondrial import inner membrane translocase complex (5.7-fold), oxidoreductase (5.2-fold), glucoamylase (5.1-fold)). Exposure of T. aggressivum to P. putida supernatant lead to an increase in the abundance of proteins associated with growth and development (structural constituents of ribosome (20-fold), H/ACA ribonucleoprotein complex subunit (18-fold), DNA binding and nucleosome assembly protein (5.3-fold), and prefoldin (5-fold)). These results indicate that exposure to P. putida can stimulate the growth of T. aggressivum and this interaction may be an important factor in increasing green mould disease in mushroom crops and so reducing yield.

Isolation of Serratia Marcescens from the Soil and In vitro Prodigiosin Production as Source of Antibiotic, Active against Oxacillin-Resistant Staphylococcus aureus

Background: Wide range of microorganisms produced secondary metabolites as microbial activities in extended habitats.
 Aims: The aim of this research is the extraction of the red colored pigment, prodigiosin from Serratia marcesens isolated from the soil and evaluate its antibacterial activity against different strains of oxacillin/methicillin-resistant Staphylococcus S. aureus.
 Study Design: Two isolates, namely, RMN1 and RMN2, belonging to the Genus, Serratia from two soil samples collected from two strategic locations in University of Abuja, Nigeria were isolated. The isolates were morphologically distinct on the basis of spore colour, aerial and substrate mycelium formation and production of diffusible pigment. Isolates were Gram stained, observed under a microscope and were seen to be Gram negative. Biochemical tests revealed that the two isolates were catalase and citrate positive, and were oxidase negative. One of the two isolates was observed to have significant antibiotic producing potential, and the antibacterial activity of the produced antibiotics (red pigment extracted from cultural supernatants of the isolates grown on Peptone glycerol agar) was assessed using the agar-well diffusion method and streaking agar method.
 Results: The results indicated that the pigment extracted in vitro had varying antibacterial activity at different concentrations of 500 mg/ml, 250 mg/ml, 125 mg/ml and 62.5 mg/ml against four strains of the test organism (Staphylococcus aureus) titled S1 to S4, the extracted pigment was more effective at concentration 500 mg/ml against the antibiotic resistant S. aureus with the MIC at 125 mg/ml. 
 Conclusion: The results indicated that the soil of this region could be a good source of prodigiosin having antibacterial activity and thus enable the use of micro-organisms as biological control agents.

Diagnosis of human sporotrichosis in Campos dos Goytacazes, Rio de Janeiro, Brazil.

Sporotrichosis is an infectious fungal zoonosis associated with traumatic implantation in the skin of dimorphic fungi of the Sporothrix schenckii complex. The objective of this study was to diagnose sporotrichosis in patients in the city of Campos dos Goytacazes, and to establish correlations between positive laboratory results and dermatological and topographical aspects of the lesions and personal traits of the patients, such as sex, age and profession. We collected samples from 22 patients with suspect lesions, which were sent to the laboratory for direct microscopic analysis after Gram staining, followed by mycological culture by seeding the material in 4% Sabouraud dextrose agar (Himedia®) supplemented with chloramphenicol (50 mg/Lt) and cycloheximide (400 mg/Lt - Sigma-Aldrich, USA). The dishes were incubated at 25-30oC. For confirmation of the diagnosis, the strains isolated in mycelial form were converted to yeast form by culture in yeast-peptone-dextrose (YPD) agar at 37oC for up to 15 days. The positive results demonstrated that the disease was most frequently diagnosed in women between the ages of 19 and 60 years, and that 18 (81.8%) of the patients reported having contact with pet cats. The occupations of those positive for sporotrichosis were not related to the disease. The upper limbs were the body region most often afflicted, with observation in the majority of cases of ulcerated lesions, although five patients also had nodular lesions. Additionally, the observation of lymphatic cords was frequent. In recent years, sporotrichosis has been diagnosed with relative frequency in Campos dos Goytacazes, causing great concern among public health officials and practitioners.

Action Mechanism of Streptomyces diastatochromogenes KX852460 Against Rhizoctonia solani AG-3 Involving Basidiospores Suppression and Oxidative Damage

This research was aimed to study the effect of ethyl acetate extracts from Streptomyces diastatochromogenes KX852460 on action mechanism at various stages of life cycle of Rhizoctonia solani AG-3, such as sclerotia, mycelium, basidiospores and hyphae. Suppression of sclerotia and mycelium was determined by measuring the inhibition zones. While morphology of mycelium and hyphae formation were observed by scanning electron microscopy and transmission electron microscopy, respectively, the basidiospores formation and ROS generation were detected by confocal laser scanning microscopy. Extract from S. diastatochromogenes KX852460 had 96% inhibition effect against the mycelium, formation of the sclerotia decreased from 71.73 to 0% as the concentration of the treatment increased from 1 × 10−4 to 7 × 10−4 mM and 88.22–97% inhibition effect on disease lesion. Suppression of basidiospores was one of the significant approaches evidenced by visualization using confocal laser scanning microscopy. Scanning electron microscopy analysis showed changes in morphological attributes of R. solani AG-3 caused by ethyl acetate extract of bacteria. Transmission electron microscopic observation revealed suppression of hyphae. Generation of endogenous ROS and oxidative damage were evidenced by the confocal laser scanning microscopy. Ethyl acetate extracts from Streptomyces diastatochromogenes KX852460 exhibited potential antagonistic action against the R. solani AG-3 at various stages of its life cycle including sclerotia, mycelium, basidiospores and hyphae which could be utilized as biocontrol agent.

Primer informe de Nodulosporium (Xylariaceae) en Theobroma cacao L. en Chiapas, México y pruebas de patogenicidad


 Nodulosporium es un hongo ampliamente distribuido y que se encuentra en zonas tropicales y se ha reportado como fitopatógeno ocasionando muerte descendente, pudriciones y resinosis, también se le considera como un potencial agente de control biológico de otros hongos y oomicetos. El estado teleomorfo se encuentra en estado solitario y en racimos, y se ha reportado como endófito, saprofito o fitopatógeno débil. La variedad criolla de cacao Theobroma cacao, es de gran relevancia ecológica, económica y cultural en el estado de Chiapas; sin embargo, presenta alta susceptibilidad a enfermedades a diferencia de otras variedades importantes, afectando la calidad y producción. En Villa de Comaltitlán Chiapas se observaron frutos de cacao con características típicas de síntomas de pudrición. El objetivo fue identificar los hongos asociados a frutos de cacao enfermos con síntomas de pudrición. Se identificaron morfológicamente los hongos Aspergillus sp., Penicillium sp., Rhizopus sp., Trichoderma sp., y Nodulosporium sp. Se informa por primera ocasión la presencia de Nodulosporium sp., en frutos de cacao con síntomas de pudrición de Villa de Comaltitlán, Chiapas, México. Se describe las características morfológicas y morfométricas de Nodulosporium sp. e Hypoxylon sp., y su identificación molecular. Se confirmó la patogenicidad de Nodulosporium sp., en follaje del cultivo causando clorosis y deshidratación de la hoja, y se recuperó en forma de picnidios y micelio con conidios, correspondiendo a su teleomorfo, identificado como Hypoxylon morfológica y molecularmente con los oligonucleótidos ITS4-ITS5.

Overexpression of the diguanylate cyclase CdgD blocks developmental transitions and antibiotic biosynthesis in Streptomyces coelicolor.

Cyclic dimeric GMP (c-di-GMP) has emerged as the nucleotide second messenger regulating both development and antibiotic production in high-GC, Gram-positive streptomycetes. Here, a diguanylate cyclase (DGC), CdgD, encoded by SCO5345 from the model strain Streptomyces coelicolor, was functionally identified and characterized to be involved in c-di-GMP synthesis through genetic and biochemical analysis. cdgD overexpression resulted in significantly reduced production of actinorhodin and undecylprodigiosin, as well as completely blocked sporulation or aerial mycelium formation on two different solid media. In the cdgD-overexpression strain, intracellular c-di-GMP levels were 13-27-fold higher than those in the wild-type strain. In vitro enzymatic assay demonstrated that CdgD acts as a DGC, which could efficiently catalyze the synthesis of c-di-GMP from two GTP molecules. Heterologous overproduction of cdgD in two industrial Streptomyces strains could similarly impair developmental transitions as well as antibiotic biosynthesis. Collectively, our results combined with previously reported data clearly demonstrated that c-di-GMP-mediated signalling pathway plays a central and universal role in the life cycle as well as secondary metabolism in streptomycetes.