ANTIMICROBIAL AND ANTIOXIDANT PROPERTIES OF PLEUROTUS OSTREATUS FORTIFIED WITH SELENIUM

Abstract

This study investigated the antimicrobial and antioxidant properties of Pleurotus spp. fortified with selenium. Pleurotus spp. (fortified with selenium and non-fortified with selenium) were cultivated on corn cobs using standard procedures. The yield/ biological efficiency, selenium absorption level, proximate, mineral, phytochemical and amino acid compositions; antimicrobial activities and antioxidant properties of the cultivated Pleurotus spp. were determined using standard techniques. Non-fortified Pleurotus pulmunarius recorded the highest yield and biological efficiency, while fortified Pleurotus ostreatus had the lowest yields and biological efficiency. Selenium concentration analysis revealed that there was no significant difference (P<0.05) in the selenium absorption level of both species of Pleurotus (51.79 and 59.29 μg/g) but no selenium was detected in the non-fortified samples. The proximate analysis showed that moisture, ash, protein, crude fibre, fat and carbohydrate contents ranged from 14.56-15.77, 5.12-6.29, 18.59-26.35, 0.40-0.82, 0.01-0.40 and 52.01-60.10% respectively. The mineral analysis showed the presence of ten minerals with calcium having the highest value (20.94mg/100g) in Fortified Pleurotus ostreatus, while Nickel had the least value (0.001 mg/100g) in Non-fortified Pleurotus pulmunarius. Phytochemical analysis revealed the presence of 5 phytochemicals viz; saponins, alkaloids, phenols, tannins and flavonoids. Saponin was the highest in value (7.08mg/ml) while tannin had the least value (0.03 mg/ml). The amino acid analysis showed the presence of 18 amino acids with the values ranging from 0.67 mg/100g (Cysteine) to 12.27 mg/100g (Glutamic acid). The ethanolic extracts of Pleurotus spp. inhibited the growth of Gram positive and negative bacteria with Pseudomonas aeruginosa been the most inhibited (25.00±1.00). However, none of the fungal isolates were inhibited. The ethanolic extracts of Pleurotus spp. exhibited high antioxidant properties with the fortified Pleurotus spp. exhibiting the highest antioxidant properties. Based on the findings of this study, it can be concluded that Se-fortification increased the antibacterial activities of Pleurotus spp. These results therefore suggest that Se-enriched mushrooms can be used as potential source of dietary supplements and nutraceuticals.