Study On The Main Extracellular Hydroxyl Radical Scavengers From Submerged Culture Of Lentinula Edodes On Cornstalk

At present, white rot fungi are considered as one of the most potential microbes which could degrade lignocellulose effectively. During the biodegradation of lignocellulose, white rot fungi could produce lots of activated free radicals such as hydroxyl radicals (·OH), which supported ligninolytic enzymes and made these enzymes degrade lignocellulose easily. However, white rot fungi can protect themselves from the damage of free radicals, the mechanism involved was worth studying.The strain Lentinus edodes A3 was obtained by screening from four white rot fungi, because the strain A3 showed better advantage in growth, secretion of laccase and producing substances which could eliminate free radicals. In addition, the appropriate liquid culture and sampling system was established.The eliminating of free radicals by extracellular substances from strain A3 were studied, the results showed that the component and proportion of extracellular substances, which eliminated free radicals, were different in different media. In the basal medium, crude exopolysaccharides, protein and some usual elements or microelements were the main components of extracellular substances. Furthermore, crude exopolysaccharides and protein were also the main component of extracellular substances in the lignocellulose medium, in addition, there were some other substances eliminating free radicals, which had some relations with lignocellulose biodegradation.Lignocellulose could promote the production of extracellular substances eliminating free radicals, not only the content but also the ability to eliminate hydroxyl radicals. It also showed that the production of extracellular substances eliminating free radicals from strain A3 had some relations with lignocellulose biodegradation.During the process of lignocellulose degradation, the main significance of white rot fungi producing substances eliminating free radicals was that white rot fungi could establish effective defensive system by secreting various extracellular and endocellular substances eliminating free radicals such as polysaccharides and proteins, therefore they could protect themselves from the damage of free radicals during lignocellulose degradation.The paper studied the production of extracellular substances eliminating free radicals during lignocellulose degradation by white rot fungi, ascertained the component, characteristics and dynamic law of extracellular substances eliminating free radicals of white rot fungi, and discussed the defensive mechanism against free radicals of white rot fungi, which provided important theoretic and practical foundation.