Bioresources and their significance

A New Approach for the Production of Selenium-Enriched and Probiotic Yeast Biomass from Agro-Industrial by-Products in a Stirred-Tank Bioreactor

“…In another study, Kieliszek et al [ 45 ] reported a Se content of 1800 μg/g in 15 g d.w. /L of C. utilis biomass and 800 μg/g in 6.7 g d.w. /L of S. cerevisiae biomass after 72 h cultivation. Using agro-industrial by-products as substrate, Martiniano et al [ 31 ] obtained 4.25 g/L biomass containing 167 μg/g Se from corn bran acid hydrolysate supplemented with 15 mg/L Se as Na 2 SeO 3 , and Egressy-Molnár [ 46 ] obtained 42.3 μg/g Se content in Hericium erinaceus mushroom biomass using substrate composed of sawdust, wooden chips, and wheat bran.…”

“…The presence of a high concentration of Se has an inhibitory effect in yeast growth [ 43 , 47 ], but 10 mg Se 4+ /L did not inhibit the growth of the evaluated strain. The higher Se concentration in the medium leads to lower cell growth, but different species exhibit different ranges of tolerance towards this compound [ 31 , 48 ]. Furthermore, when the medium contains nonfermentable carbon sources, cells are more oxygen-demanded, and free radicals are generated during respiration, which can cause oxidative stress to cells, reducing cell growth and viability [ 24 ].…”

“…The use of agro-industrial by-products as feedstock is a low-cost alternative for the biotechnological production of Se-enriched yeast [ 30 ], and assists in the biorefinery implementation, especially for developing countries. The bioresource management is essential for the fulfillment of the needs of humankind and has an important role in the economy; besides, secondary bioresources such as the agro-industrial by-products do not directly compete with food production and enable the use of agricultural lands for other purposes [ 31 ].…”

“…Bran is an agro-industrial by-product from grain manufacturing and, though it is partially used as feed, a large amount remains as a residue. This biomass is rich in macronutrients and micronutrients and can be used as both carbon and nitrogen source for microorganisms during the production of several bioproducts such as Se-enriched yeast, single-cell protein, biopigments, β-glucans, ethanol, xylitol [ 30 , 31 , 32 , 33 ]. Agro-industrial by-products composition may vary depending on the region, however, the basic constituents of each by-product remain in the same range [ 33 , 34 ].…”

“…A biomass pretreatment is necessary to release sugars and nutrients before fermentation, and the acid pretreatment is a low-cost and efficient method for bran such as corn bran [ 35 ]. Besides, the use of agro-industrial by-products for the production of mineral-enriched yeast biomass can be integrated into biorefineries platforms, promoting the simultaneous development of an inexpensive mineral-enriched protein source [ 31 ]. Thereby, their use as carbon and nitrogen sources for Se yeast enrichment is a recent and eco-friendly technology that assists in the development of biorefineries.…”