Selenized non-Saccharomyces yeasts and their potential use in fish feed.

Selenium (Se) is a vital trace element, essential for growth and other biological functions in fish. Its significance lies in its role as a fundamental component of selenoproteins, which are crucial for optimal functioning of the organism. The inclusion of Se in the diets of farmed animals, including fish, has proved invaluable in mitigating the challenges arising from elemental deficiencies experienced in captivity conditions due to limitations in the content of fishmeal. Supplementing diets with Se enhances physiological responses, particularly mitigates the effects of the continuous presence of environmental stress factors. Organic Se has been shown to have higher absorption rates and a greater impact on bioavailability and overall health than inorganic forms. A characteristic feature of yeasts is their rapid proliferation and growth, marked by efficient mineral assimilation. Most of the selenized yeasts currently available in the market, and used predominantly in animal production and aquaculture, are based on Saccharomyces cerevisiae, which contains selenomethionine (Se-Met). The object of this review is to highlight the importance of selenized yeasts. In addition, it presents metabolic and productive aspects of other yeast genera that are important potential sources of organic selenium. Some yeast strains discussed produce metabolites of interest such as lipids, pigments, and amino acids, which could have applications in aquaculture and further enrich their usefulness.

Genetic variability and physiological traits of Saccharomyces cerevisiae strains isolated from "Vale dos Vinhedos" vineyards reflect agricultural practices and history of this Brazilian wet subtropical area.

Vale dos Vinhedos appellation of origin has a very recent history as industrial wine making region. In this study we investigated the genetic and phenotypic variability of Saccharomyces cerevisiae strains isolated from South-Brazilian vineyards in order to evaluate strain fermentation aptitude and copper and sulphites tolerance. Merlot grape bunches were collected from three vineyards and yeast isolation was performed after single bunch fermentation. High genotypic variability was found and most of the genotypes revealed to be vine-specific. No industrial strain dissemination was present in the sampled vineyards, although it has been wildly reported in traditional winemaking countries. From the phenotypic traits analysis these Brazilian native strains showed good fermentation performances, good tolerance to sulphites and, in particular, a high copper tolerance level. Copper is the most important metal in the formulation of fungicides against downy mildew (Plasmopara viticola), one of the most harmful disease of the vines, and other fungal pests. The high tolerance to copper suggests an environmental adaptation to the strong use of copper-based fungicides, requested by the wet subtropical climate.

Schizophyllan from Schizophyllum commune BRM 060008: Potential application as an inhibitor of lipase.

ß-D-glucan has significant implications in regulating lipid metabolism and preventing diseases associated with lipid accumulation. Schizophyllan (SPG) from Schizophyllum commune fungus is a commercially important ß-glucan with applications in the health food industry, pharmacy, and cosmetics. However, SPG was obtained by submerged culture of the wood-rotting and filamentous fungus S. commune BRM 060008, which may have been isolated from the Cerrado Biome of Brazil. In this study, to confirm that the polysaccharide produced by BRM 060008 strain fermentation was indeed (1→3)(1→6)-ß-D-glucan, it was purified and characterized using Fourier transform infrared spectroscopy, thermogravimetric analysis, high-performance size exclusion chromatography, nuclear magnetic resonance, and methylation analysis. The polysaccharide produced was identified as the ß-D-glucan expected with a high molecular weight (1.093 × 106 g/mol) and the thermogravimetric analysis indicated a maximum degradation temperature of ~324 °C and a 60 % residual weight, lower than commercial SPG. The molecular structure and thermal properties of the ß-D-glucan were similar to the commercial sample. Additionally, the in vitro pancreatic lipase inhibitory activity was evaluated, investigating anti-obesity and anti-lipidemic properties. The results showed unprecedented lipase inhibition activity to SPG prepared using the S. commune strain BRM 060008, making it promising for food and pharmaceutical applications.

Biogenic silver nanoparticles production and characterization from native stain of Corynebacterium species and its antimicrobial activity.

In the present study, synthesis, characterization, and the antibacterial activity of silver nanoparticles from native isolate of Corynebacterium glutamicum has been reported. Silver nanoparticles were synthesized by challenging the dried biomass of C. glutamicum with aqueous diamine silver ([Ag (NH3)2]+) containing 1 mM AgNO3. Synthesized silver nanoparticles (AgNPs) were characterized by ultraviolet-visible spectroscopy and energy-dispersive X-ray (EDX) spectroscopy analysis. Morphological study of silver nanoparticles was carried out using transmission electron microscopy (TEM) and scanning electron microscope (SEM). The spherical morphology of silver nanoparticles was confirmed from SEM image. The TEM image showed the average particle size of silver nanoparticles was about 15 nm. Silver nanoparticles synthesized from C. glutamicum were found to have enhanced antimicrobial activity against selected pathogenic strains. Silver nanoparticles from pure strains of Corynebacterium species was done by many investigators, but as per the present literature, this is the first report on the production of silver nanoparticles using a native strain of Corynebacterium.

Ovicidal Efficacy of Metarhizium anisopliae (Hypocreales: Clavicipitaceae) towards Rhipicephalus sanguineus (Acari: Ixodidae) Eggs

@#Rhipicephalus sanguineus, commonly known as brown dog tick is a widespread species with considerable public health and economic importance. Tremendous efforts were performed to control the tick populations with the concern of resistance build-up and environmental issues. Alternative towards microbial control thus emerged as one option to reduce tick populations. In this study, the ovicidal efficacy of a native isolate entomopathogenic hyphomycetes fungi, Metarhizium anisopliae strain HSAH5 was evaluated against eggs of R. sanguineus. Spray applications with three different conidial concentrations of 105, 106 and 107 conidia mL-1; 40 ppm of Flumethrin and a negative control. The M. anisopliae strain was found highly virulent to R. sanguineus eggs by reducing the hatching percentages to ≈30% compared with 8.9% in Flumethrin eggs. The result showed a significantly higher mortality in M. anisopliae group than those of the control groups (F = 42.08, df = 32, P < 0.001) at 30 days post-infection. However, there are no significant differences within the M. anisopliae group, in which the mortality between different conidial concentrations is almost the same. The estimated LC50 of M. anisopliae against eggs of R. sanguineus is 1.36 × 103 conidia ml-1. Thus, these results suggest M. anisopliae strain HSAH5 could be a potential biocontrol agent of R. sanguineus in the integrated approach to managing ticks in the residential landscape by targeting on the eggs.

Presence and significance of Bacillus thuringiensis Cry proteins associated with the Andean weevil Premnotrypes vorax (Coleoptera: Curculionidae)

The Andean weevil Premnotrypes vorax represents an important cause of damage to Colombian potato crops. Due to the impact of this plague on the economy of the country, we searched for new alternatives for its biological control, based on the entomopathogenic bacteria Bacillus thuringiensis. A total of 300 B. thuringiensis strains obtained from potato plantations infested with P. vorax were analyzed through crystal morphology, SDS-PAGE, PCR and bioassays. We used site- directed mutagenesis to modify the Cry3Aa protein. Most of the B. thuringiensis isolates had a bipyramidal crystal morphology. SDS-PAGE analyses had seven strains groups with σ-endotoxins from 35 to 135 kDa. The genes cry 2 and cry 1 were significantly more frequent in the P. vorax habitat (PCR analyses). Three mutant toxins, 1 (D354E), 2 (R345A, ∆Y350, ∆Y351), and 3 (Q482A, S484A, R485A), were analyzed to assess their activity against P. vorax larvae. Toxicity was low, or absent, against P. vorax for isolates, wild type cry 3Aa and cry 3Aa mutants. The genetic characterization of the collection provides opportunities for the selection of strains to be tested in bioassays against other insect pests of agricultural importance, and for designing Cry proteins with improved insecticidal toxicity. Rev. Biol. Trop. 57 (4): 1235-1243. Epub 2009 December 01.

El gorgojo andino Premnotrypes vorax es una causa importante de daño en los cultivos colombianos de este tubérculo. Debido al impacto que esta plaga tiene sobre la economía del país, nos interesamos en buscar alternativas nuevas para el control biológico de P. vorax, basadas en la bacteria entomopatógena Bacillus thuringiensis. Se recolectaron un total de 300 cepas de B. thuringiensis a partir de plantaciones de papa infestadas con P. vorax, las cuales fueron analizadas por medio de la morfología del cristal, SDS-PAGE, PCR y ensayos biológicos. La mayoría de los aislamientos de B. thuringiensis presentaron cristales bipiramidales. Los análisis de SDS-PAGE indicaron la presencia de siete grupos de cepas con σ- endotoxinas que variaban entre 35 a 135 kDa. Las pruebas con PCR demostraron que los genes cry 2 y cry 1 fueron significativamente más frecuentes en el medioambiente de P. vorax. Además, se utilizó la mutagénesis sitio-dirigida para modificar la proteína Cry3Aa. Se analizaron tres toxinas mutantes, 1 (D354E), 2 (R345A, ∆Y350, ∆Y351), y 3 (Q482A, S484A, R485A), para determinar su actividad contra larvas de P. vorax. Los ensayos de toxicidad señalaron escasa, o nula, actividad hacia P. vorax tanto para las cepas, la toxina Cry3Aa de referencia y las proteínas Cry3Aa mutantes. La caracterización genética de la colección puede proveer oportunidades para la selección de cepas que pueden evaluarse por medio de bioensayos contra otros insectos-plaga de importancia agrícola, y para el diseño de proteínas Cry con actividad toxica mejorada.