使用生物燃料替代石油和煤炭等化石燃料的想法,看上去很美,但落实起来困难很多。其中重要挑战之一是,至今没有找到经济的生物燃料制造方法。
从植物中提取生物燃料是当前的热门领域。一些国家已经把生物燃料的产量写入国策,比如美国政府决定,在2022年前美国生物燃料的年产量要达到360亿加仑(约1.36亿立方米)。
转化纤维素,需要生物催化剂——酶来帮忙,酶的来源是真菌。但问题是,目前所使用的真菌的活跃温度在40摄氏度至50摄氏度之间。在这个温度区间,转化效率不高,结果是生物燃料的成本居高不下。
为此,不少国家的政府和公司正在联合开展一场科研竞赛,研究嗜热型真菌和其所产生的酶,以求尽快开辟一条高效制造生物燃料的道路。
据英国《自然—生物技术》杂志报道,由丹麦诺维信公司科学家兰迪·贝尔卡领导的一个国际科研团队近日破解了两种重要嗜热型真菌的基因组,为未来研究打下坚实基础。
这两种真菌分别名为“太瑞斯梭孢壳霉”和“耐热性毁丝霉”,其所产生的酶的活跃温度在70摄氏度至80摄氏度之间。基因测序结果表明,这两种真菌分别含有3870万和3690万个碱基对。
贝尔卡说:“这些嗜热真菌是提炼生物燃料的最佳场所,它们可以替代炼油厂,制造人类所需的燃料。”(生物谷 Bioon.com)
doi:10.1038/nbt.1976
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Comparative genomic analysis of the thermophilic biomass-degrading fungi Myceliophthora thermophila and Thielavia terrestris
Randy M Berka, Igor V Grigoriev, Robert Otillar, Asaf Salamov, Jane Grimwood, Ian Reid, Nadeeza Ishmael, Tricia John, Corinne Darmond, Marie-Claude Moisan, Bernard Henrissat, Pedro M Coutinho, Vincent Lombard, Donald O Natvig, Erika Lindquist, Jeremy Schmutz, Susan Lucas, Paul Harris, Justin Powlowski, Annie Bellemare, David Taylor, Gregory Butler, Ronald P de Vries, Iris E Allijn, Joost van den Brink et al.
Thermostable enzymes and thermophilic cell factories may afford economic advantages in the production of many chemicals and biomass-based fuels. Here we describe and compare the genomes of two thermophilic fungi, Myceliophthora thermophila and Thielavia terrestris. To our knowledge, these genomes are the first described for thermophilic eukaryotes and the first complete telomere-to-telomere genomes for filamentous fungi. Genome analyses and experimental data suggest that both thermophiles are capable of hydrolyzing all major polysaccharides found in biomass. Examination of transcriptome data and secreted proteins suggests that the two fungi use shared approaches in the hydrolysis of cellulose and xylan but distinct mechanisms in pectin degradation. Characterization of the biomass-hydrolyzing activity of recombinant enzymes suggests that these organisms are highly efficient in biomass decomposition at both moderate and high temperatures. Furthermore, we present evidence suggesting that aside from representing a potential reservoir of thermostable enzymes, thermophilic fungi are amenable to manipulation using classical and molecular genetics.