Fungal Community Associated with the Leaf-Cutting Ant Acromyrmex crassispinus (Hymenoptera: Formicidae) Colonies: a Search for Potential Biocontrol Agents.

The leaf-cutting ant Acromyrmex crassispinus is considered an important pest in forest plantations in southern Brazil. This work aimed to study the fungal community associated with A. crassispinus colonies, subjected to treatments with subdoses of granulated baits (sulfluramid), which might reduce the ability of the ants to care for their symbiotic fungus and other fungi (maybe biocontrol fungi) would take over, to prospect for potential biological control agents. Samplings of fungus gardens and dead ants allowed the identification of 195 fungal isolates, distributed in 29 families, 36 genera, and 53 species. The most frequent genera were Trichoderma (49.2%), Penicillium (13.8%), Chaetomium (6.2%), and Fusarium (3.6%). This is the first study that conducted a survey of antagonistic and entomopathogenic fungi to A. crassispinus and its symbiotic fungus, reporting for the first time the occurrence of potential biological control agents. Escovopsis weberi, Fusarium oxysporum, Rhizomucor variabilis, Trichoderma atroviride, Trichoderma harzianum, Trichoderma koningiopsis, and Trichoderma spirale are considered some of the potential biocontrol organisms.

Evaluation of the nutritional composition and antioxidant activity of Bjerkandera adusta

Abstract Bjerkandera adusta, a globally distributed fungus, is commonly used in the nutritional practices of the East Asian population. In this study, we evaluated the nutritional composition of the lyophilized mycelium of B. adusta as well as the phenolic composition and antioxidant activity of its extracts. The mycelium exhibited moisture (7.97 %), ash (3.27 %), and fiber (5.31 %) content values similar to the established values reported in the available literature. In addition, a high protein (9.32 %) and carbohydrate (63.45 %) content was shown, with a low lipid (1.36 %) content. The energy value per 100 g sample of mycelium was 1445.85 kJ. The results obtained indicated a statistically significant variation (p < 0.05) in the phenolic composition (81.84-110.96 mg gallic acid equivalents (GAE) per g of extract), free radical 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging activity (IC50 29.05-340.46 µg·mL-1), phosphomolybdenum antioxidant content (34.89-55.64 %), reduction of ferricyanide ion (66.55-69.4 %), and thiobarbituric acid reactive substance (TBARS) values (44.66-133.03 %). These results are unprecedented for this species and emphasize its nutraceutical potential.

Optimisation of Bjerkandera adusta culture conditions for the production of α-α-trehalose.

Several factors affect the vegetative growth of fungi, such as temperature, pH, and culture medium. In addition to mycelial growth, these factors affect metabolite production. There are limited studies that have identified the metabolites produced by the fungus Bjerkandera adusta, which have potential biotechnological applications. Here, we evaluated the effects of temperature, culture medium, and incubation time on the production of mycelial mass and metabolites of B. adusta isolated from Pinus taeda. The highest mycelial mass was obtained at 24 °C, in the potato dextrose and malt extract media, upon incubation for 28 and 35 days. The disaccharide α-α-trehalose was for the first time isolated and identified by X-ray diffraction in this fungal genus.

Morphophysiological characterization of Ceratocystis fimbriata isolates from yerba mate / Caracterização morfofisiológica de isolados de Ceratocystis fimbriata de erva-mate

ABSTRACT: This study aimed to morphologically characterize the isolates of Ceratocystis fimbriata from yerba mate and to evaluate the effect of culture medium and temperature on mycelial growth and sporulation of C. fimbriata. For the morphological characterization of the 11 monosporic isolates of the fungus, slides were prepared to determine the dimensions of the sexual and asexual structures of the fungus. Four experiments were conducted to evaluate the mycelial growth and to evaluate the sporulation of C. fimbriata in different culture mediums and temperatures. The isolates of C. fimbriata from yerba mate showed perithecia with brown to black necks, divergent ostiolar hyphae, hatshaped hyaline ascospores, single-celled, cylindrical endoconidia, and globular to ovoid aleurioconidia. PDA and V8-agar media showed the highest mycelial growth. The average optimum temperature for mycelial growth and sporulation of isolates of C. fimbriata of yerba mate were 22.5 and 22.4 ºC, respectively.

RESUMO: Este estudo teve como objetivo caracterizar morfologicamente os isolados de Ceratocystis fimbriata e avaliar o efeito do meio de cultura e da temperatura no crescimento micelial e na esporulação de C. fimbriata. Para a caracterização morfológica dos 11 isolados monospóricos do fungo foram preparadas lâminas para determinar as dimensões das estruturas sexuadas e assexuadas do fungo. Quatro experimentos foram conduzidos para avaliar o crescimento micelial e esporulação of C. fimbriata em diferentes meios de culturae temperaturas. Os isolados de C. fimbriata de erva-mate apresentaram peritécios com pescoço de marrom a preto, hifa ostiolar divergente, ascósporos hialinos em formato de chapéu, endoconídios unicelulares, cilíndricos, e aleuroconídios com formato globoso a ovoide. Os meios de cultura PDA e V8-ágar apresentaram os maiores crescimentos miceliais. A temperatura ótima média para crescimento micelial e esporulação dos isolados de C. fimbriata de erva-mate foram de 22,5 e 22,4 ºC, respectivamente.

Rhizobial inoculation in black wattle plantation (Acacia mearnsii De Wild.) in production systems of southern Brazil.

Black wattle (Acacia mearnsii De Wild.) is a tree legume native to southeast Australia, but present in all continents. Today it covers about 142,400 ha in Brazil, with plantations concentrated in the southern region of the country. Black wattle may form nodules and establish rhizobial symbiosis capable of fixing N2, but rhizobial inoculation is not done in commercial plantations. About 40 kg ha-1 of urea is applied during seedling transplantation. In this review, evidences by which rhizobial inoculation affects monoculture, mixed cultivation, and agroforestry black wattle production systems were searched in literature. Previous measurements in cultivated forests have indicated that biological nitrogen fixation in black wattle may provide up to 200 kg of N ha-1 year-1 to the soil. Therefore, rhizobia inoculation may bring several opportunities to improve black wattle production systems. Black wattle is not a very selective partner in the rhizobial symbiosis, but the genus Bradyrhizobium dominates the rhizobial diversity of black wattle nodules. Investigation on rhizobial diversity in soils where the crop is cultivated may represent an opportunity to find more effective rhizobia strains for inoculants. The successful history of biological nitrogen fixation in grain legumes must inspire the history of tree legumes. Microbiology applied to forestry must overcome challenges on the lack of trained professionals and the development of new application technologies.

Antagonistic activity of Diplodia pinea against phytopathogenic fungi.

The ability of Diplodia pinea to inhibit Armillaria sp., Bjerkandera adusta, Botrytis cinerea, and Rhizoctonia sp. mycelium growth was analyzed using the double-culture method. Wild-type fungal strains were incubated in a biochemical oxygen demand incubator using potato agar dextrose medium at 24 ± 2 °C for 35 days in darkness. D. pinea significantly inhibited the growth of all fungi species tested (30.75 to 98.37% inhibition) and showed moderate antagonistic activity (antagonistic index, 14.5). Chemical analysis of D. pinea culture broth extracts revealed steroids, triterpenes, and phenolic compounds. Alkaloids were qualitatively detected in the mycelium crude extract. The presence of these compounds may be related to the antagonistic activity observed. The inhibition ability of D. pinea is due to competition with the tested fungi for substrate and space.

Bioautography to assess antibacterial activity of Ottonia martiana Miq. (Piperaceae) on the human oral microbiota

Ottonia martiana Miq. (Piperaceae), planta conhecida popularmente por "anestésia" e empregada no tratamento de odontalgias devido à sua ação anestésica sobre a mucosa oral, foi investigada por meio de ensaios antibacterianos de difusão em disco de papel e de bioautografia frente a microorganismos presentes na microbiota oral humana [Streptococcus mutans (ATCC 25175), Streptococcus mitis (ATCC 49456), Streptococcus pyogenes (ATCC 19615), Streptococcus salivarius (ATCC 25975), Escherichia coli (ATCC 11229 e 25922), Pseudomonas aeruginosa (ATCC 27853), Enterobacter aerogenes (ATCC 27853). Os resultados dos bioensaios mostraram que o extrato bruto de O. martiana (32.9 mg mL-1) apresenta potencial antibacteriano frente às bactérias Gram-positivas testadas. Dentre as substâncias bioativas detectadas foram identificadas a piperovatina (Rf 0.35), piperlonguminina (Rf 0.52) e a isopiperlonguminina (Rf 0.52). A piperovatina e isopiperlonguminina foram isoladadas do extrato das raízes de O. martiana, guiadas pelo teste de bioautografia.

Ottonia martiana Miq. (Piperaceae), a plant known popularly in southern Brazil as "anestésia" and used in the treatment of odontalgia for its anesthetic action on the oral mucosa, was investigated for antibacterial activity by paper disc agar diffusion and bioautographic methods, against microorganisms present in the human oral cavity [Streptococcus mutans (ATCC 25175), Streptococcus mitis (ATCC 49456), Streptococcus pyogenes (ATCC 19615), Streptococcus salivarius (ATCC 25975), Escherichia coli (ATCC 11229 and 25922), Pseudomonas aeruginosa (ATCC 27853) and Enterobacter aerogenes (ATCC 27853).The crude extract of O. martiana (32.9 mg mL-1) had antibacterial potential against all Gram-positive bacteria tested. Analysis of the bioautograms led to the detection of bioactive substances, among which it was possible to identify piperovatine (Rf 0.35), piperlonguminine (Rf 0.52) and isopiperlonguminine (Rf 0.52). The piperovatine and isopiperlonguminine were isolated from the roots of O. martiana, guided by a bioautographic antibacterial bioassay.