Regulation of Respiratory and Ligninolytic Enzyme Activity of Lentinula edodes by Selenium

The production of mushrooms enriched with essential elements, e.g. selenium, for human health is an interesting strategy to improve the functional foods supply. The selenium is an essential mineral and makes part of structure of enzymes involved in the oxidative metabolism. However, the selenium effect on the activity of respiratory and lignocellulolytic enzymes has not been considered. The understanding of this effect is important to determine the selenium concentration that increases the mushroom productivity and the degradation rate of the substrate. In this study, it was observed reduction of the respiratory activity of Lentinula edodes (Berk.) Pegler, the shiitake mushroom, in function of the increasing of the sodium selenite concentration in the substrate (p < 0.05). Selenium did not inhibit the activity of the hydrolytic enzymes (cellulase and xylanase), but it increased the activity of the oxidative enzyme (laccase). Respiratory activity of L. edodes has a negative correlation with sodium selenite concentration added in substrate. Thus is important to define the ideal dose of selenium to be added to the substrate for increasing lignocellulosic residues degradation and, consequently, guarantee a higher production of Se-enriched mushrooms.

Microbial lipases:Propitious biocatalysts for the food industry

Lipases(triacylglycerol acylhydrolases,EC 3.1.1.3)are one of the largest groups of enzymes and are used in various industrial processes.Lipases of microbial origin are currently receiving increased attention for industrial application as microorganisms grow quickly and are easily genetically manipulated.Furthermore,they offer several advantages,such as catalysis of diverse reactions,high specificity,high yields,low energy consumption and reduced processing time and production costs.There is a relentless ongoing effort to optimise the production of microbial lipases for potential application in the food industry.In this context,this review highlights the most promising techniques for producing microbial lipases and the recent applications of these lipases in dairy,oils and fats,bakery and confectionery,meat,flavours and aromas and other food industries.Microbial lipases are normally obtained by fermentation,but the high costs of carbon and nitrogen sources limit the process.To overcome this problem,low-cost agro-industrial residues in the lipase production process are explored.To obtain lipases with high yields and improved characteristics,the technique of protein engineering is described as promising,and the immobilization method that allows the recycling of lipases to improve their catalytic performance is focused.Due to their catalytic properties and versatility,lipases of microbial origin are considered extremely important catalysts in the food industry,meeting the demand for tastier foods with pleasant aromas and textures.Therefore,microbial lipases are considered safe and sustainable biocatalysts.