Evaluating the effect of different substartes on lignin peroxidase and manganese peroxidase production of white rot fungi.

Abstract

The objective of this study was to assess the production of ligninolytic enzymes produced by Flavodon flavus and Pleurotus ostreatus that cultured on five agroindustrial wastes. Flavodon flavus and Pleurotus ostreatus are two fungi that able to completely degrade lignin to CO2 and H2O and produce high amount of lignolytic enzymes (chosen from the previous study). These fungi naturally grow on wood, but they can be artificially cultivated on agroindustrial wastes (sugarcane bagasse, cassava, corn cob, rice straw, sawdust). The degradation of ligninolytic materials involves in enzyme complex including lignin peroxidase (LiP) and manganese peroxidase (MnP). Understanding the production of these enzymes will help to improve the activity of them for industrial application and decrease the pollution that caused by inadequate discharge of agroindustrial wastes. White rot fungi were fermented in solid substrates with 20% rice bran and 60% humidity. Every 5, 10, 20, 30 days after inoculation, enzyme activity was tested, and enzyme activities were determined in U/ml. Enzyme production was different depending on the growth substrate used. The maximum activity of LiP and MnP was recorded at day 10 after incubation. Among five substrates, sugarcane bagasse was the best substrate for LiP and MnP production. Sugarcane bagasse yielded 1.68U/ml LiP, 28.76U/ml MnP of F.flavus and 1.26U/ml LiP, 37.66U/ml MnP of P.ostreatus. Moreover, sawdust is suitable for LiP and corn cob for MnP production. Substrates that fungi can grow well stimulate the production of MnP and substrates that fungi grew slower stimulate the production of LiP. By measuring substrates’ composition including nitrogen, phosphorus, lignin and organic carbon, the results expected to show the influence of substrates’ composition on enzyme activity. However, this result cannot show the correlation between substrates composition and enzyme production. Enzyme production can be affected by the combination of many other physical factors. Highest amount of LiP can be produced on low-nutrient medium such as sawdust and sugarcane bagasse but high carbon content and in contrast of MnP. Keywords: White rot fungi, lignin peroxidase, manganese peroxidase, agroindustrial wastes.