Milk-clotting proteases from Pleurotus albidus: an innovative alternative for the production of Minas frescal cheese

Pleurotus albidus, a naturally growing species in the Amazon region, has been considered a promising source of milk-clotting proteases. The production of such enzymes using lignocellulosic residues is a sustainable alternative to replace mammalian rennet. The application of P. albidus milk-clotting proteases in cheese making has not yet been reported in the scientific literature. The aim of this study was to characterize the milk-clotting proteases of P. albidus and use these enzymes in the production of Minas frescal cheese. For the production of coagulating proteases, the mushroom was grown in açaí seeds supplemented with rice bran (10%, w/w). The parameters affecting the production of coagulant, such as inoculum size, fermentation time, initial pH of cultivation medium and age of the inoculum were evaluated. The coagulant extract obtained under optimal production conditions was evaluated for optimal pH and temperature, pH and temperature stability, effect of ions and inhibitors. Significant production of coagulating proteases was obtained under the following conditions: inoculum size (2.5%), fermentation time (10 days), initial pH of the cultivation medium (6), and inoculum age (10 days). The coagulant exhibited significant catalytic activity in pH 5.0 at 55°C, with stability at 45°C and was completely inhibited by iodoacetic acid. The milk-clotting proteases of P. albidus were efficient for making Minas frescal cheese that presented 55.0% of moisture, 20.0% of lipids and 17.20% of protein. Pleurotus albidus is a potential source of milk-clotting proteases that can be applied in dairy industry for production of fresh Minas frescal cheese.

Production of mycelial biomass by the Amazonian edible mushroom Pleurotus albidus

ABSTRACT Edible mushroom species are considered as an adequate source of food in a healthy diet due to high content of protein, fiber, vitamins, and a variety of minerals. The representatives of Pleurotus genus are characterized by distinct gastronomic, nutritional, and medicinal properties among the edible mushrooms commercialized worldwide. In the present study, the growth of mycelial biomass of Pleurotus albidus cultivated in submerged fermentation was evaluated. Saccharose, fructose, and maltose were the three main carbon sources for mycelial biomass formation with corresponding yields of 7.28 g L−1, 7.07 g L−1, and 6.99 g L−1. Inorganic nitrogen sources did not stimulate growth and the optimal yield was significantly higher with yeast extract (7.98 g L−1). The factorial design used to evaluate the influence of saccharose and yeast extract concentration, agitation speed, and initial pH indicated that all variables significantly influenced the production of biomass, especially the concentration of saccharose. The greater amount of saccharose resulted in the production of significantly more biomass. The highest mycelial biomass production (9.81 g L−1) was reached in the medium formulated with 30.0 g L−1 saccharose, 2.5 g L−1 yeast extract, pH 7.0, and a speed of agitation at 180 rpm. Furthermore, P. albidus manifested different aspects of morphology and physiology under the growth conditions employed. Media composition affected mycelial biomass production indicating that the diversification of carbon sources promoted its improvement and can be used as food or supplement.

Improvement of submerged culture conditions to produce colorants by Penicillium purpurogenum

Safety issues related to the employment of synthetic colorants in different industrial segments have increased the interest in the production of colorants from natural sources, such as microorganisms. Improved cultivation technologies have allowed the use of microorganisms as an alternative source of natural colorants. The objective of this work was to evaluate the influence of some factors on natural colorants production by a recently isolated from Amazon Forest, Penicillium purpurogenum DPUA 1275 employing statistical tools. To this purpose the following variables: orbital stirring speed, pH, temperature, sucrose and yeast extract concentrations and incubation time were studied through two fractional factorial, one full factorial and a central composite factorial designs. The regression analysis pointed out that sucrose and yeast extract concentrations were the variables that influenced more in colorants production. Under the best conditions (yeast extract concentration around 10 g/L and sucrose concentration of 50 g/L) an increase of 10, 33 and 23% respectively to yellow, orange and red colorants absorbance was achieved. These results show that P. purpurogenum is an alternative colorants producer and the production of these biocompounds can be improved employing statistical tool.

Screening of Amazonian plants from the Adolpho Ducke forest reserve, Manaus, state of Amazonas, Brazil, for antimicrobial activity

Tropical forests are species-rich reserves for the discovery and development of antimicrobial drugs. The aim of this work is to investigate the in vitro antimicrobial potential of Amazon plants found within the National Institute on Amazon Research's Adolpho Ducke forest reserve, located in Manaus, state of Amazonas, Brazil. 75 methanol, chloroform and water extracts representing 12 plant species were tested for antimicrobial activity towards strains of Mycobacterium smegmatis, Escherichia coli, Streptococcus sanguis, Streptococcus oralis, Staphylococcus aureus and Candida albicans using the gel-diffusion method. Active extracts were further evaluated to establish minimum inhibitory concentrations (MIC) and antimicrobial profiles using bioautography on normal-phase thin-layer chromatography plates. Diclinanona calycina presented extracts with good antimicrobial activity and S. oralis and M. smegmatis were the most sensitive bacteria. D. calycina and Lacmellea gracilis presented extracts with the lowest MIC (48.8 µg/ml). D. calycina methanol and chloroform leaf extracts presented the best overall antimicrobial activity. All test organisms were sensitive to D. calycina branch chloroform extract in the bioautography assay. This is the first evaluation of the biological activity of these plant species and significant in vitro antimicrobial activity was detected in extracts and components from two species, D. calycina and L. gracilis.

Seleção de leveduras da Região Amazônica para produção de protease extracelular / Screening of yeasts from Amazon Region for extracellular protease production

O objetivo deste trabalho foi identificar 50 leveduras isoladas a partir de diferentes substratos da Região Amazônica e selecionar uma espécie de maior atividade proteolítica. Entre as 26 espécies identificadas predominaram Candida aquatica (12 por cento) e Candida tropicalis (10 por cento). A fermentação submersa foi realizada em Extrato de Malte suplementado com gelatina 1 por cento, Candida intermedia foi a que expressou maior atividade proteolítica, halo = 25 mm e 273 U/mL, crescimento máximo a 30 °C, viabilidade celular 6,2 x 10(6) UFC, em 48 horas, não demonstrou características de patogenicidade e a melhor densidade do inóculo foi 3 por cento, utilizando-se culturas com 24 horas de crescimento em ágar Malte.

The objective of this work was to identify 50 yeasts isolates obtained from differents substracts from Amazon Region and to select one species of higher proteolytic activity. Among the 26 identified species it had predominance of Candida aquatica (12 percent) and Candida tropicalis (10 percent). The submerged fermentation was carried out in Malt Extract supplemented with gelatin 1 percent, Candida intermedia exhibited higher proteolytic activity, halo = 25 mm and 273U/mL, the maximum growth 30 °C, the cellular viability 6.2 x 10(6) UFC, in 48 hours, did not demonstrate pathogenicity characteristics and the best inoculum density tested was 3 percent, using 24 hours Malt agar cultures.

Micobiota presente em pescado processado, comercializado na cidade de Manaus, Amazonas / Present micobiota in fished processing, commercialized in the city of Manaus, Amazonas

Fungos em alimentos podem produzir micotoxinas, que causam intoxicações e, até mesmo, câncer. Na região amazônica, há vários fatores favoráveis ao desenvolvimento e deterioração por fungos, principalmente a alta umidade. Neste estudo, a ocorrência de fungos, a viabilidade do processamento e eficiência no estoque de pescado regional congelao vendido em supermercado de Manaus – Amazonas – Brasil foram verificadas. Para o isolamento das colônicas fúngicas, 0,2 mL das diluições sucessivas foram incorporadas em agar Sabouraud suplementado com cloranfenicol (0,01 por cento) e rosa bengala (0,005 por cento), em triplicata. As culturas foram incubadas à 28ºC, durante 8 dias, com observações diárias. Apesar das boas condições higiênicas nos locais de venda, todos os exemplares estavam estocados em temperaturas inadequadas, com médias de -4.6±1ºC sobre os produtos e -3.5±2ºC entre os produtos. Os índices de contaminação foram 2,3x10³ e 1,4x10³ UFC/g, acima do limite máximo estabelecido pela legislação para produtos congelados (10³UFC/g). Somente um local apresentou índice menor que o limite máximo (5x10² UFC/g). Os índices de pH (média de 4,5±0,5) provavelmente favoreceram o desenvolvimento de leveduras. Os gêneros de fungos identificados nas amostras foram Candida, Rhodotorula, Sccharomyces, Torulopsis e Trichosporon, comumente encontrados em produtos refrigerados. As espécies identificadas foram Candida melinii e Trichosporon aquatile, leveduras naturais de águas frias. Os resultados sugerem que as condições de processamento e estocagem do peixe congelado comercializado nos supermercados amostrados não obedecem à legislação em vigor e apontam riscos à saúde pública, originados do consumo de pescado congelado e seus derivados contaminados por microrganismos.

Onicomicose por Microsporum gypseum. Registro de um caso / Onychomycosis ddue to Microsporum gypseum. One recorded case

Registra-se um caso de Onicomicose por Microsporum gypseum em mulher de 27 anos, residente em Manaus. O diagnóstico foi estabelecido após cultura em Agar-Sabouraud e Mycosel, após 10 dias de observaçäo