Abstract:
Pleurotus species are an extensively cultivated type of mushroom and are consumed as a
nutritious, healthy source of food all over the world. Numerous agricultural wastes can be used
to grow these mushrooms, such as sawdust, paddy straw, coconut coir, etc., which further
contributes to the prevention of environmental pollution. In this study, two commonly cultivated
oyster mushroom species; Pleurotus ostreatus (American oyster) and Pleurotus eous (Bhutan
oyster) were grown separately on paper waste and paddy straw and the yield, nutritional
composition, levels of bioactive compounds, and antioxidant activity were evaluated. The main
objectives of this study were to determine the most nutritious oyster mushroom variety with
health benefits and to investigate the best substrate to cultivate it. Various tests including the
protein analysis using the Lowry assay, phenol sulfuric assay to determine total carbohydrates,
qualitative tests for bioactive compounds, antioxidant capacity using DPPH assay, and total
phenolic content assay were performed. Bhutan oyster cultivated on paddy straw showed
significant results in the number of fruiting bodies (7.3±2.3) and fastest growth (9.7±6.7 days)
compared to other groups. However, American oyster cultivated on paddy straw and paper waste
had the highest protein (5.5±1.5g/100g) and carbohydrate contents (8.2±0.9g/100g)
respectively. The bioactive compounds, terpenoids and polyphenols were present in all the
samples. Furthermore, there was no significant difference in the total phenolic values although
all the study groups exhibited substantial phenolic levels. Bhutan oyster cultivated on paper
waste displayed a significantly low IC50 or half-maximal inhibitory concentration
(23.4±26.2μg/mL) compared to Bhutan oyster cultivated on paddy straw (93.9±26.2μg/mL),
showing higher antioxidant properties. When considering the substrates, although paper waste
took less number of days for the mycelium growth to complete, both substrates did not have any
significant difference with respect to the water holding capacity. In conclusion, the outcomes for
nutritional properties and antioxidant activity of both species grown on the two substrates were
remarkably similar and showed promising results. Therefore, both Bhutan and American oyster
mushrooms grown on the substrates of paper waste and paddy straw can be consumed as an
affordable and good food source with many nutrients, antioxidants, and bioactive compounds.
