Lange L, Grell M N
Department of Biotechnology, Chemistry and Environmental Engineering, Aalborg University, A.C. Meyers Vænge 15, 2450, Copenhagen, SV, Denmark,
Appl Microbiol Biotechnol. 2014 Jun;98(11):4839-51. doi: 10.1007/s00253-014-5708-5. Epub 2014 Apr 15.
Molecular studies have added significantly to understanding of the role of fungi and fungal enzymes in the efficient biomass conversion, which takes place in the fungus garden of leaf-cutting ants. It is now clear that the fungal symbiont expresses the full spectrum of genes for degrading cellulose and other plant cell wall polysaccharides. Since the start of the genomics era, numerous interesting studies have especially focused on evolutionary, molecular, and organismal aspects of the biological and biochemical functions of the symbiosis between leaf-cutting ants (Atta spp. and Acromyrmex spp.) and their fungal symbiont Leucoagaricus gongylophorus. Macroscopic observations of the fungus-farming ant colony inherently depict the ants as the leading part of the symbiosis (the myrmicocentric approach, overshadowing the mycocentric aspects). However, at the molecular level, it is fungal enzymes that enable the ants to access the nutrition embedded in recalcitrant plant biomass. Our hypothesis is that the evolutionary events that established fungus-farming practice were predisposed by a fascinating fungal evolution toward increasing attractiveness to ants. This resulted in the ants allowing the fungus to grow in the nests and began to supply plant materials for more fungal growth. Molecular studies also confirm that specialized fungal structures, the gongylidia, with high levels of proteins and rich blend of enzymes, are essential for symbiosis. Harvested and used as ant feed, the gongylidia are the key factor for sustaining the highly complex leaf-cutting ant colony. This microbial upgrade of fresh leaves to protein-enriched animal feed can serve as inspiration for modern biorefinery technology.
分子研究极大地增进了我们对真菌及真菌酶在高效生物质转化中所起作用的理解，这种转化发生在切叶蚁的菌圃中。现在已经清楚，真菌共生体表达了降解纤维素和其他植物细胞壁多糖的全套基因。自基因组学时代开始以来，众多有趣的研究特别聚焦于切叶蚁（Atta属和Acromyrmex属）与其真菌共生体白环柄菇（Leucoagaricus gongylophorus）之间共生关系的生物学和生化功能的进化、分子及生物体方面。对真菌养殖蚁群的宏观观察本质上把蚂蚁描绘为共生关系的主导部分（蚁中心论方法，掩盖了菌中心的方面）。然而，在分子层面，正是真菌酶使蚂蚁能够获取顽固植物生物质中所含的营养。我们的假设是，确立真菌养殖行为的进化事件是由真菌朝着对蚂蚁吸引力增加的迷人进化所预先决定的。这导致蚂蚁允许真菌在巢中生长，并开始为真菌的更多生长提供植物材料。分子研究还证实，具有高水平蛋白质和丰富酶混合物的特殊真菌结构——菌丝球，对于共生至关重要。菌丝球被采集并用作蚂蚁饲料，是维持高度复杂的切叶蚁群体的关键因素。这种将新鲜树叶微生物转化为富含蛋白质的动物饲料的过程可为现代生物精炼技术提供灵感。
