In this study, starch metabolites and enzymes were determined during starch-based plastic polymer biodegradation by the white rot fungus Phanerochaete chrysosporium, grown in sugarcane bagasse pith in tubular reactors. Various metabolites, amylase, ligninase and cellulase production were measured during P. chrysosporium growth on sugarcane bagasse pith with added glucose and starch polymer. Online respirometric analyses followed during 32 days confirmed the P. chrysosporium capability of growing on sugarcane bagasse pith with starch polymer degradation. Enzyme activity during secondary metabolism increased, and a 70% and 74% starch degradation was reached with and without glucose addition, generating low molecular weight metabolites (e.g.) dextrin, maltotriose, maltose and glucose that were detected by high performance liquid chromatography.

Introduction

One of the most successful materials currently used as protective loose-fill is a starch-based polymer (Lim et al., 1998). Starch is an inexpensive, easily available and re- newable raw material. Several million tons of starch are annually produced in the United States (Swanson et al., 1993). Corn starch is a natural farming product, which can replace petroleum-based plastics (Swanson et al., 1993), mainly in the form of polystyrene foams that are widely used as cushioning material (Bhatnagar and Handa, 1996). Other materials have been developed, specifically, starch-based materials with biodegradable properties (Bhatnagar and Handa, 1996). Disposal of this type of polymers could be easier than synthetic polymers, using solid-state culture and lignocellulosic materials(Rodríguez-Vázquezetal., 1999a,b; Mendoza et al., 2000). This would enable degradation of starch- based polymers in soils by landfill or other composting system conditions. White rot fungi, such as Phanerochaete chrysosporium are able to degrade a wide variety of aromatic compounds (Reddy, 1995), through the production of lignin peroxidases (LiP), manganese peroxidases (MnP), and cellulases. In addition, some white rot fungi can produce amylases (Dey et al., 1991; Se- thuraman et al., 1998) together with other ligninolytic enzymes, that support the degradation of a wide range of aromatic compounds.