Composition and Function of a Novel Consortial Endosymbiosis in the Shipworm Lyrodus pedicellatus.

环境中每年产生大量的木材和其他木本植物材料(包括树叶、树皮、树枝、茎和坚果)。事实上，木质材料的主要成分纤维素被认为是地球上最丰富的生物材料。这种非常强大和持久的分子是葡萄糖(糖)的聚合物，通过一种化学键将其连接在一起，使其无法被大多数生物消化。因此，这种丰富的食物能量来源只有几种动物(如白蚁和反刍动物)可以在肠道微生物的帮助下消化纤维素。令人惊讶的是，一些海洋动物也能消化木材。最重要的一类是钻木蚌，俗称船虫。与白蚁和反刍动物不同，这些动物的肠道中没有微生物，而是在它们的鳃细胞中藏匿着大量的共生细菌。根据DNA分析，这些细菌至少属于四个密切相关的家族。PI提出，这些细菌产生的纤维素酶从鳃运输到肠道。本研究的目的是探索鞭虫鳃中共生菌类型的多样性和分布，确定每种共生菌类型是否贡献了不同的纤维素酶，并发现宿主如何利用这些细菌产物来利用纤维素作为食物来源。这些研究将导致发现新的纤维素酶，这些酶可能在造纸和纺织加工以及通过农业废物的生物转化生产燃料(乙醇)等领域具有工业应用。这些努力还将帮助PI了解共生细菌感染的生理学，这些感染对宿主有益而不是有害。

Enormous quantities of wood and other woody plant materials(including leaves, bark, shoots, stems and nuts) are produced annually inthe environment. In fact, cellulose, the major component of woodymaterials, is thought to be the most abundant biological material on earth.This remarkably strong and enduring molecule is a polymer of glucose(sugar) linked by a type of chemical bond that makes it indigestible tomost living organisms. Therefore, this rich source of food energy isavailable to only a few animals (e.g., termites and ruminants) that candigest cellulose with the aid of microbes living in their guts. Surprisingly, some marine animals can also digest wood. The mostimportant group is the wood-boring clams, commonly known as shipworms. Unliketermites and ruminants, these animals lack microorganisms in their gut.Instead they harbor enormous numbers of symbiotic bacteria inside the cellsof their gills. These bacteria fall into at least four closely relatedfamilies based on DNA analyses. The PIs have proposed that these bacteriaproduce cellulolytic enzymes that are transported from the gills to thegut. The purpose of this investigation is to explore the diversity anddistribution of symbiont types in the shipworm gills, to determine if eachsymbiont type contributes different cellulolytic enzymes, and to discoverhow the host uses these bacterial products to exploit cellulose as a foodsource. These investigations should result in the discovery of newcellulolytic enzymes that may have industrial applications in such areas aspaper and textile processing and fuel (ethanol) production via biomassconversion of agricultural wastes. These efforts will also help the PIs tounderstand the physiology of symbiotic bacterial infections that arebeneficial rather than harmful to their hosts.