Malt Agar Research Articles

Efecto de diferentes medios de cultivo sobre la patogenicidad de Aspergillus flavus en frutos de higo

<p><em>Aspergillus flavus</em> es un hongo que infecta diversos alimentos, entre ellos el higo. Se han utilizado diferentes medios de cultivo para su aislamiento y crecimiento. El objetivo de esta investigación fue evaluar la patogenicidad de <em>A. flavus</em> crecido en diferentes medios de cultivo sobre higos. Se incubó<em> A. flavus</em> en 5 medios de cultivo (CZAPEK, agar V8, PDA, Dextrosa Sabouraud y agar de Malta) y de éstos, se realizaron dos suspensiones de esporas (1 x 104 y 1 x 105 Esp mL-1). Los frutos se inocularon y se evaluó porcentaje de infección y severidad. La cepa desarrollada en medio CZAPEK (1 x 104 Esp mL-1) fue la que generó mayor porcentaje de infección (64%), sin embargo, fue estadísticamente similar al PDA y Agar de Malta (53 y 51%, respectivamente). La cepa del medio PDA (1 x 104 Esp mL-1) mostró mayor severidad (2.4) y fue estadísticamente similar a los medios evaluados, con excepción del agar V8. Lo frutos inoculados con la cepa del agar V8 (1 x 104 Esp mL-1) tuvieron el menor porcentaje de infección (24%) y severidad (1.64), siendo estadísticamente diferente al resto de los tratamientos. Las cepas de <em>A. flavus</em> incubada en CZAPEK y PDA tuvieron mayor patogenicidad en los frutos de higo.</p>

Characterization of indoor air mycobiota of two locals in a food industry, Cuba

The aim of this work was to characterize the air mycobiota of two production plants, one of artisanal chocolate and another of products for special regimes in a food factory in Cuba at different times of the year. The air was sampled during 1 year every 25 days distributed in rainy season and non-rainy. The method proposed by Omeliansky was applied and four bacteriostats were used: chloramphenicol, lactic acid, sodium chloride, and iodized common salt with malt agar extract in Petri dishes exposed for 1 h. The temperature and relative humidity were monitored to determine their influence on the fungal concentration, which was higher in the rainy season. Among the main fungi isolated from the air mycobiota of these production plants, Neurospora crassa was the predominant species along with the genera Aspergillus and Trichoderma. In addition, other less frequent genera as Cladosporium and Fusarium were detected. However, Penicillium and Mucor were predominant and non-frequent in the artisanal chocolate area. The adequate constructive design of the production plants and the correct location of dehumidifiers were identified as important elements to decrease the fungal contamination. Likewise, this study suggests the use of iodized salt as an economic alternative in air microbiological sampling of indoor environments.

Phenotypic methods versus PCR-RFLP for the identification of dermatophyte species isolated from patients with dermatophytosis in Egypt

Background: Dermatophytes are major causative agents of cutaneous fungal infections worldwide. Identification of dermatophyte species is based on macroscopic and microscopic morphology on different culture media. Molecular methods such as PCR-RFLP are rapid, reliable and precise identification methods. This local study aimed to identify the spectrum of dermatophyte species among the studied patients population using different phenotypic and genotypic methods. Materials and methods: Hair, skin and nail specimens were collected from 135 patients with clinically suspected cases of dermatophytosis. All specimens were subjected to microscopic examination using KOH and culture on SDA and dermasel agar. Phenotypic identification was done by colony and microscopic morphology, and subculture on malt, PDA, lactrimel and urea agar plates. Molecular identification was done by PCR-RFLP using Mva I. Results: Out of 135 patients included in the study, 78 (57.8%) were positive by culture for dermatophytes. Five different species were identified, the most commonly isolated species was M. canis (51.3%) followed by T. violaceum (42.3%). PCR-RFLP correctly identified the isolated dermatophyte species, producing unique restriction patterns. Conclusion: Dermatophytosis is common in Egypt where humid hot climate and animal contact play important role in the spread of these fungi. The use of PCR-RFLP directly on clinical specimens rather than its use in the identification of dermatophytes from culture media is recommended. Keywords: Dermatophytosis, Dermasel agar, SDA, Sporulation media, PCR-RFLP

Sodium butyrate inhibits planktonic cells and biofilms of Trichosporon spp.

Trichosporon spp. have been increasingly recognized as an important pathogen of invasive and disseminated infections in immunocompromised patients. These species are prone to form biofilms in medical devices such as catheters and prosthesis, which are associated with antifungal resistance and therapeutic failure. Therefore, new antifungals with a broader anti-biofilm activity need to be discovered. In the present study we evaluate the inhibitory potential of sodium butyrate (NaBut) – a histone deacetylase inhibitor that can alter chromatin conformation – against planktonic and sessile cells of T. asahii and T. inkin. Minimum inhibitory concentration (MIC) of NaBut against planktonic cells was evaluated by microdilution and morphological changes were analyzed by optical microscopy on malt agar supplemented with NaBut. Biofilms were evaluated during adhesion, development and after maturation for metabolic activity and biomass, as well as regarding ultrastructure by scanning electron microscopy and confocal laser scanning microscopy. NaBut inhibited the growth of planktonic cells by 50% at 60 mM or 120 mM (p < 0.05) and also reduced filamentation of Trichosporon spp. NaBut reduced adhesion of Trichosporon cells by 45% (10xMIC) on average (p < 0.05). During biofilm development, NatBut (10xMIC) reduced metabolic activity and biomass up to 63% and 81%, respectively (p < 0.05). Mature biofilms were affected by NaBut (10xMIC), showing reduction of metabolic activity and biomass of approximately 48% and 77%, respectively (p < 0.05). Ultrastructure analysis showed that NaBut (MIC and 10xMIC) was able to disassemble mature biofilms. The present study describes the antifungal and anti-biofilm potential of NaBut against these opportunist emerging fungi.

Convergent evolution of semiochemicals across Kingdoms: bark beetles and their fungal symbionts

Convergent evolution of semiochemical use in organisms from different Kingdoms is a rarely described phenomenon. Tree-killing bark beetles vector numerous symbiotic blue-stain fungi that help the beetles colonize healthy trees. Here we show for the first time that some of these fungi are able to biosynthesize bicyclic ketals that are pheromones and other semiochemicals of bark beetles. Volatile emissions of five common bark beetle symbionts were investigated by gas chromatography-mass spectrometry. When grown on fresh Norway spruce bark the fungi emitted three well-known bark beetle aggregation pheromones and semiochemicals (exo-brevicomin, endo-brevicomin and trans-conophthorin) and two structurally related semiochemical candidates (exo-1,3-dimethyl-2,9-dioxabicyclo[3.3.1]nonane and endo-1,3-dimethyl-2,9-dioxabicyclo[3.3.1]nonane) that elicited electroantennogram responses in the spruce bark beetle Ips typographus. When grown on malt agar with 13C d-Glucose, the fungus Grosmannia europhioides incorporated 13C into exo-brevicomin and trans-conophthorin. The enantiomeric compositions of the fungus-produced ketals closely matched those previously reported from bark beetles. The production of structurally complex bark beetle pheromones by symbiotic fungi indicates cross-kingdom convergent evolution of signal use in this system. This signaling is susceptible to disruption, providing potential new targets for pest control in conifer forests and plantations.

Stimulating Production of Pigment-Type Secondary Metabolites from Soft Rotting Wood Decay Fungi ("Spalting" Fungi).

A small group of soft rotting wood decay fungi produce extracellular pigments as secondary metabolites in response to stress and as a means of resource capture. These fungi are collectively known as "spalting fungi" and have been used in wood art for centuries. The pigments produced by these fungi are finding increasing usage in industrial dye applications and green energy but remain problematic to grow in batch culture. Additionally problematic is that the pigments, especially the blue-green pigment known as xylindein, produced by Chlorociboria species, have yet to be fully synthesized. In order to further research development of these pigments and find success in areas such as textile and paint dyeing, wood UV protection, and organic photovoltaic cells, methods must be developed to mass produce the pigments. To date, three distinct methods have been developed, with varying degrees of success depending upon the fungal species (amended malt agar plates, shake liquid culture, and stationary liquid culture). This chapter details these three methods, their history, advantages and disadvantages, as well as their potential for industrial scale-up in the future. Graphical Abstract.

Mycelial Growth Characteristics of Pleurotus citrinopileatus and Pleurotus platypus in Culture Media Variants

Pleurotus species, because of their flexible temperature and environmental requirements, have more cultivated species than any other mushrooms. As one of the preliminary experiments for standardizing the cultivation technique of Pleurotus citrinopileatus and Pleurotus platypus, this work was done to find out the basic nutrient requirements and hence the effect of seven different growth media namely Potato dextrose agar (PDA), Malt extract agar (MEA), Yeast malt agar (YMA), Sabouraud's dextrose agar (SDA), Czapek dox agar (CDA), Glucose peptone agar (GPA) and Oat meal agar (OMA) on the mycelial growth of these mushrooms at room temperature(28°C) for a period of 8 days. Since the mycelium of Pleurotus platypus showed a non-symmetrical spreading pattern, the average growth was measured drawing cross sections on the petriplate. The experiments were done in six replications and colony diameter (CD), mycelial density (MD), growth rate (GR) of the mycelium were recorded. The CD of both Pleurotus citrinopileatus and Pleurotus platypus showed outstanding results in PDA medium with a GR of 1.13cm/day and 0.75cm/day respectively. The highest MD for Pleurotus citrinopileatus was indicated in PDA and MEA and for Pleurotus platypus it was in PDA, MEA and YMA. Though mycelial density did not follow the same pattern of inference as colony diameter, there was a positive correlation between CD and MD in all the experimental plates. The overall study proved PDA followed by MEA to be the most suitable media for culturing both Pleurotus citrinopileatus and Pleurotus platypus under in vitro conditions.

Detection of antibiotic-producing Actinobacteria in the sediment and water of Ma'in thermal springs (Jordan).

Detection of new Actinobacteria is significant to discover new antibiotics because development of new antibiotics is connected to the characterization of novel bacterial taxa. This study has focused on the identification and isolation of antibiotic-producing Actinobacteria from the sediment and the water of Ma'in thermal springs (48-59°C) situated in the center area of Jordan. Samples of sediment and water were transferred to glucose yeast malt agar medium and Actinobacteria were cultivated, isolated and identified according to scanning electron microscopy and 16S rRNA gene analysis. Antibacterial activities of the isolates were then tested against different test bacteria by agar well diffusion method. Three different species of Actinobacteria were isolated (M1-1, M2-2, M3-2) from sediment samples. Based on 16S rRNA gene analysis, isolate M1-1 was found to have only 90% identity percentage with Nocardiopsis sp., however, isolates M2-2 and M3-2 were found to be closely related Streptomyces sp. (97%) and Nocardioides luteus (99%), respectively. The antibacterial activity showed that strain M1-1 is active against P. aeruginosa ATCC 2785 (inhibition zone, 9 mm). Strain M2-2 was found to be active against S. aureus ATCC 29213 (12 mm), B. cereus ATCC 11778 (11 mm), and E. coli ATCC 25922 (9 mm). In respect to strain M3-2, it was found to be active against S. aureus ATCC 29213 (14 mm) and B. cereus ATCC 11778 (9 mm). There were no actinobacterial isolates obtained from water samples despite their significant diversity revealed by our previous metagenomic analysis, which showed the presence of 13 different species dominated by Arthrobacter (an Actinobacterium belonging to family Actinomycetales). There were 17 different Actinobacteria that could be detected in Ma'in thermal springs (13 unculturable species and 3 culturable species). The culturable Actinobacteria were found to have some antimicrobial activity. Further chemical analysis of the bioactive compounds is recommended.

GROWTH RESPONSE OF Ganoderma sp. MYCELIUM TREATED WITH ROOT EXUDATES OF HERBACEOUS PLANTS

The purpose of the study was to study response of Ganoderma sp. that were given exudate treatment of plant roots. Ganoderma sp. is a pathogen that causes stem rot at base of oil palm. In addition to oil palm this fungus can attack hard and woody crops such as coconut, rubber, tea, cocoa etc. Isolate used is Ganoderma sp. Bio-10197 code obtained from Phytopathology laboratory SEAMEO BIOTROP Bogor. Mycelium Ganoderma sp. reproduced in malt agar media until mycelium grows over agar surface. Ganoderma mycelium was inoculated on 1x1x5 cm rubber wood pieces for 14 days until the mycelium grew over rubber sticks. The exudate used from ganyong (Canna edulis Kerr), garut (Maranta arundinacea Linn.), Ginger (Zingiber officinale Rosc.), Turmeric (Curcuma domestica Val.), Galangal (Alpinia galanga (L.) Sw.) and lidah mertua (Sansevieria trifasciata). The design used in this study was a complete randomized design (RAL) with 7 treatments consisting of 5 repeatations. The results of this study indicate that the mycelium experienced inhibition of growth, especially in the treatment of root exudate galangal shown by 60,81% percentage and tongue-in-law with a percentage of 59,58% colonization. On observation of growth characteristics of mycelium Ganoderma sp. visible zone delimited in the form of a brown mycelium pile suspected as an indication of mycelium rejection of bioactive compounds contained exudate.

Effect of different culture media, temperature and pH on growth and sporulation of Alternaria carthami

Among the eight culture media tested for the growth of Alternaria carthami, the potato dextrose agar showed highest growth (90.00 mm) followed by potato malt agar (84.16 mm) and yeast mannitol agar (73.33 mm). The colony growth recorded in different temperature ranged from 5.66 mm at 5°C to 85.66 mm at 30°C. The highest mycelial growth (85.66 mm) was recorded at 30°C with excellent sporulation followed by 25°C (83.83 mm) and 20°C (66.33 mm). The colony growth recorded with all the pH levels was ranged from 30.50 mm at pH 4.0 to 85.83 mm at pH 6.5, the maximum mycelial growth (85.83 mm) was recorded at pH 6.5 with excellent sporulation, followed by pH 6 (82.00 mm) and pH 7 (70.33 mm) with excellent and good sporulation, respectively.

Морфолого-культуральні властивості рідкісного лікарського гриба Sparassis crispa (Sparassidaceae, Polyporales)

&lt;p&gt;A verification of &lt;em&gt;S&lt;/em&gt;&lt;em&gt;parassis&lt;/em&gt;&lt;em&gt; crispa&lt;/em&gt;&lt;em&gt; &lt;/em&gt;(Wulfen) Fr. strains of the IBK Mushroom Culture Collection using molecular-genetic and cultural-morphological methods were done. For all &lt;em&gt;S. crispa&lt;/em&gt; strains a complete determination of the nucleotide sequences of the internal transcribed spacer: ITS1, 5.8S and ITS2 regions of rRNA, as well as the partial determination of 18S and 28S sequences surrounding the ITS, was performed. As a result of the search in the gene bank, the &lt;em&gt;S&lt;/em&gt;&lt;em&gt;. &lt;/em&gt;&lt;em&gt;crispa&lt;/em&gt; samples deposited there showed 99-98% identity with the sequences we received, thus confirming the species of the examined strains. On the basis of the sequences we received, investigated strains were registered in NCBI GenBank. To confirm the taxonomic affiliation of the strains we studied their cultural and morphological characteristics. Microstructures of vegetative mycelium by optical and scanning electron microscopy were investigated. In all &lt;em&gt;S. crispa&lt;/em&gt; cultures we observed the hyphae with regular one-sided gapless clamp connections, numerous secretory cells on the surface of the hyphae, anastomoses, filamentous strands and films. We studied the growth rate and morphology of the strains on seven agar nutrient media. According to the radial growth rate of &lt;em&gt;S. crispa&lt;/em&gt; cultures can be placed to the very slowly growing mushrooms, growth rate of 0,5−2,8 mm/day. We found the selective media such as malt agar with the addition of pine sawdust (SS) and larch sawdust (SM) as most favorable for the vegetative growth and generative stage for all strains, temperature of incubation was 26 ± 0.1 °C. For mycelial growth the critical temperature was 39 ± 0.1 °C for &lt;em&gt;S. crispa&lt;/em&gt; strains 312, 314 and 40 ± 0.1 °C for the strains 304, 2004. We confirmed belonging of studied strains to &lt;em&gt;S. &lt;/em&gt;&lt;em&gt;с&lt;/em&gt;&lt;em&gt;rispa&lt;/em&gt; species according to established morphological and cultural characteristics. This result coincided with the results of DNA typing. Thus, the obtained mycelium growth parameters on nutrient media, micro- and macromorphological characteristics can be used as additional taxonomic characteristics of &lt;em&gt;S. &lt;/em&gt;&lt;em&gt;с&lt;/em&gt;&lt;em&gt;rispa&lt;/em&gt; culture in the vegetative stage of growth.&lt;strong&gt; &lt;/strong&gt;The strain &lt;em&gt;S. &lt;/em&gt;&lt;em&gt;с&lt;/em&gt;&lt;em&gt;rispa&lt;/em&gt; 314 may become a potential producer for new fungal biotechnologies in Ukraine in the near future and reintroduction of this species in the nature.&lt;/p&gt;

Screening of antibiotic-producing Streptomyces from marine sediments of Bangladesh

Antimicrobial resistance is a rising concern in the treatment of infectious diseases and the discovery of potential antimicrobial compounds is needed to combat against it. The focus of this study was the in vitro antimicrobial activities of Streptomyces obtained from the soil samples collected from different places of Cox’s Bazar, Bangladesh. A total of 156 isolates was obtained from thirty soil samples using two selective media namely yeast malt agar and starch casein agar. The isolates were morphologically distinct on the basis of spore mass color, reverse slide color, aerial and substrate mycelia formation and production of diffusible pigment. Among the isolates, 12 exhibited good antimicrobial activity against the tested micro-organisms. Isolates were subjected to biochemical characterization and identified as Streptomyces spp. The results suggest that the Streptomyces species could be a promising source for potential antibacterial agents.

First Report of Alder Phytophthora Closely Related to P. uniformis on Alnus glutinosa Seedling in Finland

The allotriploid Phytophthora x alni (Brasier & S.A. Kirk) Husson, Ioos & Marcais and its progenitors, the diploid P. uniformis (Brasier & S.A. Kirk) Husson, Ioos & Aguayo and the allotetraploid P. x multiformis (Brasier & S.A. Kirk) Husson, Ioos & Frey are the causal agents of alder decline in Europe. In June 2015, a dark, ca. 40 mm stem lesion was found on one out of 100 inspected Alnus glutinosa (L.) Gaertn seedlings in Mantyharju, Finland. Surface wood pieces from the lesion edges were plated onto malt agar (MEA). Cultures on carrot piece agar (CPA) showed appressed colony with woolly aerial mycelium. Oogonia (O mean 44.8 µm, n = 50) and oospores (O mean 40.0 µm, n = 50) developed after 7 days at 20 °C in the dark. They were commonly smooth walled and 49 out of 50 of the amphigynous antheridia were single celled. Sporangia (21.7 µm x 18.1 µm, n = 50) were produced on pea broth, with 2-day flooding with soil extract, and they were commonly unpapillate and obpyriform-ellipsoidal. DNA was extracted and t...

RESISTANCE OF HELMINTHOSPORIUM SOLANI STRAINS TO SELECTED FUNGICIDES APPLIED FOR TUBER TREATMENT

Helminthosporium solani strains were isolated from potato tubers collected in Russia or taken from imported German and Dutch seed tubers. Sequences of the nuclear ribosomal genes and internal transcribed spacers (ITS) for all 24 tested strains were identical and had 100% similarity to the sequences from GenBank identified as Helminthosporium solani. The obtained molecular data confirmed the morphological identification based on the width and length of conidia, the shape of conidiophores and the colony morphology. Screening for resistance to the fungicides Score 250 SC (active ingredient difenoconazole 250 g/l), Quadris (azoxystrobin 250 g/l), Tecto 500 SC (thiabendazole 500g/l), Zeroxxe (colloidal silver particles (3 g/l) stabilized with amphoteric surfactant) was done. Agar blocks with pure cultures of the fungal strains were placed in the centre of Petri dishes containing malt agar amended with fungicide concentrations of 0.1, 1, 10, 100 and 1000 mg/l (accounted for the concentration of the active ingredient). Malt agar free of fungicide was used as the control. 2 Growth inhibition of 50% (EC50) compared to the control was detected based on the doseresponse curves. Difenoconazole (EC50 100 mg/l). Thiabendazole appears to be effective against the sensitive strains of H. solani (EC50 1000 mg/l). The sequence of their β-tubulin gene contained a SNP mutation in the 198 codon or 200 codon, translating to Gln (CAG) instead of Glu (GAG) or Tyr (TAC) instead of Phe (TTC), respectively. Thus, the resistance to thiabendazole of the Russian, European, and American strains had the same genetic background and was conferred by the same mutations.

GREEN SYNTHESIS AND CHARACTERIZATION OF MARINE YEAST-MEDIATED SILVER AND ZINC OXIDE NANOPARTICLES AND ASSESSMENT OF THEIR ANTIOXIDANT ACTIVITY

Objective: The present study focuses on the synthesis of silver and zinc oxide (ZnO) nanoparticles from marine yeasts, isolated from the sediments of the Bay of Bengal, Bakkhali coast, West Bengal, and India.Methods: The marine sediment samples were diluted through serial diution and cultured onto yeast malt agar medium by the spread plate method. The selected yeast isolates were screened for the biosynthesis of silver and ZnO nanoparticles. Characterization of both the nanoparticles was done by applying ultraviolet (UV)-visible spectroscopy, atomic force microscopy, scanning electron microscopy, and Fourier transform infrared spectroscopy.Results: A total of five marine yeasts isolates were able to synthesize silver and ZnO nanoparticles as evidence of the color change. Optical density was measured in UV-spectrometer at different time interval for the conformation of production of nanoparticles. The size of silver nanoparticle was 31.78 nm and ZnO nanoparticle was 86.27 nm. The synthesized nanoparticles are then used for antioxidant assays.Conclusions: We are concluding that marine yeast isolates SAG1 and SAG2 both are potential marine yeast isolates which can synthesize both the silver and ZnO nanoparticles. They also showed good antioxidant activity.

Cancro europeu da macieira: variabilidade morfofisiológicas e patogenicidade de isolados de Neonectria ditissima no sul do Brasil

European apple canker (EC) is caused by Neonectria ditissima, a pathogen officially registered as a quarantine pest in 2012. Thirty-five isolates of N. ditissima of different geographical regions of southern Brazil from apple branches showing symptoms of EC were identified by the specific pair primers Ch1 and Ch2 and analyzed concerning the virulence on Gala apple cultivar and morphophysiological characteristics. The disease symptoms were characterized and the isolates compared based on average mycelium growth (AMG), mycelium growth index (MGI), colony color, conidia type, dimensions and growth on potato dextrose agar (PDA), malt agar (AM), and synthetic SNAY (SN) culture media. Nineteen isolates showed the greatest AMG on PDA, forming three growth groups of 35.56 (GI), 52.71 (GII), and 62.67mm (GIII). Seven isolates showed MGI greater than 4.0mm diameter on PDA compared with that on AM and SN. The highest conidia production was on SN, and the predominant colony color in all media was white to beige with central pigmentation of brown and borders colored in shades of beige. There were significant differences among the average dimensions of micro- and macroconidia on PDA, AM, and SN. The pathogenicity was confirmed for all isolates despite of different morphophysiological characteristics. There was no correlation among isolates morphophysiological variability, virulence, and geographical origin.

English

The actinobacteria are the most abundant bacterial group in the soil, where they present different characteristics and antagonistic effects on other microorganisms. The objectives of this study were to characterize and evaluate the antagonistic effect of actinobacteria from the semiarid region on rhizobia from the same climatic region. Tests were performed to observe chromogenic and micro-morphological characteristics, tolerance to pH levels of melanin production, and use of carbon sources. This occurred due to the use of modified CDA culture media and basal medium supplemented with specific carbon sources, as well as the use of Ral color chat to observe the colonies. The in vitro antagonism on rhizobia was evaluated in yeast malt agar (YMA) culture medium for the observation of inhibition halo by actinobacteria. We observed different characteristics in relation to the color of aerial mycelium and reverse pigments; tolerance to media with acid and alkaline pH; and production of melanoid pigment occurred only in three strains. The morphological characteristics were described for genera Streptomyces and Saccharothrix, later confirmed by molecular sequencing. These genera were generalists in use of carbon sources, showing their physiological versatility. Regarding antagonism, nine strains of the genus Streptomyces were able to inhibit in vitro strains of Rhizobium tropici and Bradyrhizobium yuanmingense also coming from semiarid soils. The antagonism between actinobacteria and rhizobia can directly affect the symbiosis between nitrogen-fixing bacteria and leguminous plants. These results are pioneering in observing antagonism of these species of rhizobia under the climate condition of the semiarid region, and may contribute to agricultural biotechnology. Key words: Streptomyces, soil, microbe interactions, Brazil, agricultural biotechnology, actinobacteria, antagonistic effect.

European apple canker: morphophysiological variability and pathogenicity in isolates of Neonectria ditissima in southern Brazil

ABSTRACT: European apple canker (EC) is caused by Neonectria ditissima, a pathogen officially registered as a quarantine pest in 2012. Thirty-five isolates of N. ditissima of different geographical regions of southern Brazil from apple branches showing symptoms of EC were identified by the specific pair primers Ch1 and Ch2 and analyzed concerning the virulence on Gala apple cultivar and morphophysiological characteristics. The disease symptoms were characterized and the isolates compared based on average mycelium growth (AMG), mycelium growth index (MGI), colony color, conidia type, dimensions and growth on potato dextrose agar (PDA), malt agar (AM), and synthetic SNAY (SN) culture media. Nineteen isolates showed the greatest AMG on PDA, forming three growth groups of 35.56 (GI), 52.71 (GII), and 62.67mm (GIII). Seven isolates showed MGI greater than 4.0mm diameter on PDA compared with that on AM and SN. The highest conidia production was on SN, and the predominant colony color in all media was white to beige with central pigmentation of brown and borders colored in shades of beige. There were significant differences among the average dimensions of micro- and macroconidia on PDA, AM, and SN. The pathogenicity was confirmed for all isolates despite of different morphophysiological characteristics. There was no correlation among isolates morphophysiological variability, virulence, and geographical origin.

Antifungal and antioxidant activities of Coleonema album and C. pulchellum against skin diseases

Context: Coleonema album (Thunb) Bart. & H. L. Wendl (Rutaceae) has been used in the formulation of skincare products, and the Khoisan people rub it on their skin to add luster. Coleonema pulchellum I. Williams has received less attention in the South African traditional medicine. Objective: This study investigates the antifungal and antioxidant activities of C. album and C. pulchellum essential oil (EO) and leaf extracts; and analyzes the chemical components of their EOs. Materials and methods: Antifungal activity of leaf extracts was determined using the microdilution method with griseofulvin and ketoconazole as controls. Antifungal capacity of EO was investigated using the ‘Volatile release plate method’. Trichophyton rubrum (ATCC 28188) and T. mentagrophytes (ATCC 9533) mycelia (0.3 cm diameter) were placed on fresh yeast malt agar in Petri dishes with filter paper (impregnated with 20 μL of EO) on the lid for direct exposure to EO volatiles while plates without EO were used as controls. The incubation time was seven days. Antioxidant activities of the leaf extracts were determined. Results: Methanol leaf extract of C. pulchellum inhibited the growth of three fungi tested with MIC values of 195, 391 and 49 μg/mL for Trichophyton rubrum, Trichophyton mentagrophytes and Microsporum gypseum, respectively. Terpenes formed the major components of the EO. The EO from both plants inhibited the growth of T. rubrum in vitro. Discussion and conclusion: This study revealed the therapeutic value of C. pulchellum. Coleonema album and C. pulchellum should be considered as potential plants for skin ointment from natural origin.

INHIBITION OF PATHOGENS BY SPOROGENIC BACTERIA ISOLATED FROM HONEY OF Melipona sp. (APIDAE: APINAE: MELIPONINI)

ABSTRACT The aim of this study was to isolate sporogenic bacteria from the honey of stingless bees Melipona sp., in dry forest, and to evaluate their antagonistic potential for medicinal employment purposes and animal production. The honey samples were collected in Serra Talhada-PE, where honey was taken from four different hives (in triplicate), totaling 12 samples. The samples were diluted and subjected to 80 ºC for 20 minutes to eliminate vegetative cells. The dilutions were plated onto nutrient agar and incubated at 30 ºC for 72 hours. Then the colony forming units (CFU) were quantified. The samples were also plated onto malt agar and Sabouraud agar, and incubated at 30 ºC for 14 days for the growth of yeast and molds. Total and fecal coliforms were quantified by the most probable number method (MPN). Seven isolates (I) of sporogenic bacteria (Bacillus) were obtained, however only four showed probiotic potential. Isolate I-5 showed the greatest probiotic potential and inhibited the growth of Escherichia coli, Klebsiella sp., Pseudomonas aeruginosa, Salmonella sp., and Staphylococcus aureus. The growth of the Sarcina sp. was not inhibited by any isolate. No yeast, molds or coliforms were found. The Melipona sp. honey is a source of spore-forming bacteria and is antagonistic to microorganisms that contaminate honey. It has good microbiological quality.