厌氧真菌生态作用及其分子生物学研究进展

Ecological Functions and Advances in Molecular Biology of Anaerobic Fungi

厌氧真菌是瘤胃内重要的纤维降解菌,在瘤胃功能的发挥中起重要作用。目前对厌氧真菌纤维降解能力的研究较多,主要集中于对厌氧真菌纤维降解酶如纤维素酶、木聚糖酶等的研究。在瘤胃中,厌氧真菌对粗纤维的降解是其和瘤胃内其他微生物共同作用的结果,因此,瘤胃内厌氧真菌与他微生物之间相互关系的研究越来越受到重视。现代分子生物学技术的发展有利于更深入和透彻的研究厌氧真菌,利用18S rRNA、RFLPI、TS1等分子生物学方法对厌氧真菌进行系统学及进化研究成为热点。

The obligate anaerobic nature of the gut indigenous fungi distinguishes them from other fungi. Gut anaerobic fungi are distributed widely in large herbivores,both in the foregut of ruminant and ruminant-like animals and in the hindgut of hindgut fermenters. These fungi have been assigned to the NeocaUimasticales within the chytridiomycete. The anaerobic fungi of domestic ruminants have been studied most extensively. Plant materials entering the rumen are rapidly colonized by zoospores that attach and develop into thalli. The anaerobic fungi have been shown to produce high active ceUulases and xylanases and preferentially colonize and grow on plant vascular tissues. Large populations of anaerobic fungi colonize plant fragments in the rumens of cattle and sheep on high-fiber diets. The properties of the anaerobic fungi together with the extent of their populations on plant fragments in animals on high-fiber diets indicate their significant role in fiber digestion. Meanwhile,the fiber digestion in the rumen is the result of the co-operation of anaerobic fungi and other microorganisms which excrete ceUulases and xylanases breaking down the fiber or use the end fermentation products such as CO2,H2,formate,acetate . Therefore,more attentions have been focused on the relationship between anaerobic fungi and other rumen microorganisms. Modem molecular biology techniques provide effective methods to study anaerobic fungi intensively. Methods such as 18S rRNA,RFLP,ITS1 have been used for the classification of anaerobic fungi. But it＇s still difficult to distinguish different species within the same genera due to the high similarity between their genes. Thus,gut anaerobic fungi have been attracting increasingly interests from nutritionists as wells as biologists.