Despite the threat of Fusarium dieback posed due to ambrosia fungi cultured by ambrosia beetles such as Euwallacea spp., the wood-degradation mechanisms utilized by ambrosia fungi are not fully understood. In this study, we analyzed the 16S rRNA and 18S rRNA genes of the microbial community from the Ficus tree tunnel excavated by Euwallacea interjectus and isolated the cellulose-degrading fungus, Fusarium spp. strain EI, by enrichment culture with carboxymethyl cellulose as the sole carbon source. The cellulolytic enzyme secreted by the fungus was identified and expressed in Pichia pastoris, and its enzymatic properties were characterized. The cellulolytic enzyme, termed FsXEG12A, could hydrolyze carboxymethyl cellulose, microcrystalline cellulose, xyloglucan, lichenan, and glucomannan, indicating that the broad substrate specificity of FsXEG12A could be beneficial for degrading complex wood components such as cellulose, xyloglucan, and galactoglucomannan in angiosperms. Inhibition of FsXEG12A function is, thus, an effective target for Fusarium dieback caused by Euwallacea spp.

中文翻译：

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纤维素降解外共生真菌镰刀菌属 FsXEG12A 的表征。由豚草甲虫培养的 EI 菌株。


尽管由豚草甲虫（例如 Euwallacea spp.）培养的豚草真菌造成了镰刀菌顶枯病的威胁，但豚草真菌利用的木材降解机制尚未完全了解。在本研究中，我们分析了由Euwallacea interjectus挖掘的榕树隧道中微生物群落的16S rRNA和18S rRNA基因，并分离了纤维素降解真菌Fusarium spp。菌株EI，以羧甲基纤维素为唯一碳源富集培养。鉴定了该真菌分泌的纤维素分解酶并在毕赤酵母中表达，并表征了其酶学特性。这种纤维素分解酶，称为FsXEG12A，可以水解羧甲基纤维素、微晶纤维素、木葡聚糖、地衣聚糖和葡甘露聚糖，这表明FsXEG12A广泛的底物特异性可能有利于降解被子植物中复杂的木材成分，如纤维素、木葡聚糖和半乳葡甘聚糖。因此，抑制 FsXEG12A 功能是由真鞭毛菌引起的镰刀菌顶枯病的有效靶标。