Cost Reduction of Gray Oyster Mushroom [ Pleurotus sajor-caju (Fr.) Singer] Production Using Lemon Basil ( Ocimum citriodorum Vis.) Straw as a Substrate

Lemon basil straw (LBS) is an agricultural waste comprising approximately 1500 tons every year generated from basil seed production in Thailand. This study demonstrated the application of LBS as an alternative substrate for the cultivation of the gray oyster mushrooms [ Pleurotus sajor-caju (Fr.) Singer] to reduce productions costs. LBS has a high nitrogen content and essential oil as bioactive compounds. LBS was mixed with rubber sawdust (RS), the traditional substrate of mushroom cultivation in Thailand, to estimate the maximum loading of LBS in cylindrical baglog cultivation. Furthermore, total phenolic compounds and antioxidant activities of the fruit body were measured. The optimal mass ratios of RS-to-LBS in the baglogs were in the range of 80:20–50:50. Results showed that the optimal amount of LBS enhanced mycelium growth and the biological efficiency of cultivated mushrooms. At a 50:50 RS-to-LBS mass ratio, the cost of baglog production was reduced by approximately 25% because the cost of LBS was lower than that of RS. Using LBS as replacement substrate at an optimal RS-to-LBS mass ratio not only reduced mushroom production costs but also promoted mycelium growth, biological efficiency, and antioxidant activity of the fruit body. Graphic Abstract