The influence of different submerged cultivation conditions on mycelial biomass and protease production by Lentinus citrinus Walleyn et Rammeloo DPUA 1535 (Agaricomycetideae)

Recovery and partial purification of fibrinolytic protease from Pleurotus ostreatus and P. eryngii and cytotoxic and antioxidant activity of their extracts

Mushrooms are a source of primary and secondary metabolites. Little is known about the most suitable conditions for production of mushrooms by submerged fermentation. This article reports antioxidant and cytotoxic assays, in addition to quantitatively evaluating the content of proteases with fibrinolytic action in the crude extracts of two species of edible mushrooms produced in different formulations, as well as evaluating the recovery of these enzymes by aqueous two-phase systems (ATPS). The mushrooms Pleurotus ostreatus and Pleurotus eryngii, at concentration of 100 µg/mL, displayed inhibition of DPPH and ABTS radicals below 50%. In the cytotoxicity test, the cells human fibroblast cell lines (MRC-5) showed cell viability greater than 80%. Concerning fibrinolytic activity, P. eryngii presented 226.47 ± 7.26 U/mL, therefore being more efficient than P. ostreatus (71.5 ± 0.56 U/mL). In the recovery of the P. eryngii extract by ATPS, the fibrinolytic protease was partitioned in the salt phase (30.25 U/mL). The molecular mass of the proteases was between 75 and 100 kDa. These results prove the low cytotoxicity of the extracts produced and that fermentation in supplemented malt broth favored the excretion of fibrinolytic proteases compared to the other evaluated media.

Optimization of liquid fermentation conditions for biotransformation zein by Cordyceps militaris 202 and characterization of physicochemical and functional properties of fermentative hydrolysates

Cordyceps militaris 202 is a potential fungus for biotransformation zein, due to its various proteases, high tolerance and viability in nature. In this article, single factor experiment and response surface methodology were applied to optimize the liquid fermentation conditions and improve the ability of biotransformation zein. The optimized fermentation conditions were as follows: inoculum concentration of 19%, volume of liquor of 130 mL/500 mL and pH of 4.7. Under this condition, the degree of hydrolysis (DH) was 27.31%. The zein hydrolysates from fungi fermentation maintained a high thermal stability. Compared to the original zein, the zein hydrolysates were found to have high solubility, which most likely results in improved foaming and emulsifying properties. Overall, this research demonstrates that hydrolysis of zein by C. militaris 202 is a potential method for improving the functional properties of zein, and the zein hydrolysates can be used as functional ingredients with an increased antioxidant effect in both food and non-food applications.

Production of mycelial biomass by the Amazonian edible mushroom Pleurotus albidus

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.

Nutritional value and proteases of Lentinus citrinus produced by solid state fermentation of lignocellulosic waste from tropical region

This paper examined the growth and yield performance of Lentinus citrinus on cupuaçu exocarp (Theobroma grandiflorum) mixed with litter (CE + LI) or rice bran (Oryza sativa) (CE + RB) in the ratio of 2:1 (800 g:200 g) to investigate the nutritional composition and proteolytic potential of the fruiting body produced. Significance values of yield were determined on substrate combinations. In CE + LI the biological efficiency of the mushrooms was 93.5% and the content of fat (4.5%), fiber (11.0%), protein (27.0%) and amino acids were higher when compared with CE + RB. Among the amino acids, the amount of glutamic acid, aspartic acid, alanine, arginine and leucine was high. The biological efficiency on CE + RB reduced to 84.2% and based on the nutritional value, carbohydrates (53.59%), energy (324.33 kcal) and minerals such as zinc, iron, copper, potassium and phosphorus were higher in this substrate combination. Protease activity from fruiting body was significant in CE + LI (463.55 U/mL). This protease showed an optimal activity at 50 °C in neutral and alkaline pH with maximum stability at 30 °C at alkaline pH. This is the first report of L. citrinus fruiting body nutritional composition with potential for human food and application in industrial processes.