Abstract
Both inorganic and organic selenium (Se) can prevent and treat various diseases caused by Se deficiency. However, organic Se has less toxicity and a higher absorption rate than inorganic Se. In this study, inorganic Se (Na2SeO3) was bio-transformed into Se-enriched discarded beer yeast (Se-enriched DB-yeast) through fermentation accumulation by re-using discarded Saccharomyces cerevisiae from the beer industry for Se-enriched fodder application. Through a single-factor experiment and L9(34)-orthogonal test for optimization of fermentation conditions, the Se content and biomass of Se-enriched DB-yeast were calculated as 14.95 mg/L and 7.3 g/L, respectively, under the optimized condition. The total amino-acid content of Se-enriched DB-yeast was increased by 9.9% compared with that from DB yeast. Additionally, alkaline amino-acid content was increased, whereas acidic amino-acid and sulfur-containing amino-acid contents were decreased. Reducing capacity, hydroxyl radical removal capacity, and sulfhydryl content after treatment with H2O2 of the Se-enriched DB-yeast extracted protein were obviously increased compared with those of the DB-yeast extracted protein. Mouse and genetically improved farmed tilapia (Oreochromis niloticus) (GIFT) bioassays showed that the Se sedimentation of organs and serum indexes after feeding Se-enriched DB-yeast-containing fodder were higher than those of DB-yeast-containing fodder. The half lethal dose (LD50) of Se-enriched DB-yeast (9260.0 mg/kg body weight (BW), 18.97 mg/kg of Se content, non-toxic level) was considerably higher than that of Na2SeO3 (20.0 mg/kg BW, 5.08 mg/kg of Se content, highly toxic level) against mouse. Therefore, Se-enriched yeast prepared by re-using discarded S. cerevisiae from beer industry fermentation accumulation has the potential to be a safe and effective Se-enriched fodder additive.
Highlights
Selenium (Se) is recognized as a nutritional trace element that is essential for the proper functioning of humans and animals with antioxidant functions
Se-enriched yeast prepared by re-using discarded S. cerevisiae from beer industry fermentation accumulation has the potential to be a safe and effective Se-enriched fodder additive
The growth performance of mice and Genetically Improved Farmed Tilapia (GIFT) treated with Se-enriched DB-yeast was not significantly increased compared with those treated with Na2 SeO3, which was slightly different from the results reported by Yoon et al [32], where organic Se supplementation improved growth compared with inorganic Se supplementation in broiler chickens; this may because of variations in the growth performance of different species in the presence of Se
Summary
Selenium (Se) is recognized as a nutritional trace element that is essential for the proper functioning of humans and animals with antioxidant functions. The recommended dietary dose of Se for humans is 55 μg per day [1,2]. This trace element is a component of a number of important selenoproteins, as well as enzymes including glutathione peroxidases (GSH-Px), iodothyronine deiodinases, selenophosphate synthetases, thioredoxin reductases, etc., which play critical roles in reproduction, thyroid hormone. Sci. 2019, 9, 3777 metabolism, DNA synthesis, and protection from oxidative damage and infection [3,4,5,6]. There are approximately 0.5 to 1.0 billion people in 40 countries around the world facing potential adverse health impacts because of Se deficiency [7]. Se deficiency is associated with the loss of hair pigment and macrocytosis in intravenously fed children, and is the cause of other human diseases, such as Keshan disease (an endemic cardiomyopathy) and Kashin–Beck disease (a type of osteoarthritis) in
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