School of Engineering and Physical Sciences, James Cook University, Townsville, QLD, 4811, Australia.
Adv Exp Med Biol. 2011;715:213-26. doi: 10.1007/978-94-007-0940-9_13.
Extracellular polysaccharides are as structurally and functionally diverse as the bacteria that synthesise them. They can be present in many forms, including cell-bound capsular polysaccharides, unbound "slime", and as O-antigen component of lipopolysaccharide, with an equally wide range of biological functions. These include resistance to desiccation, protection against nonspecific and specific host immunity, and adherence. Unsurprisingly then, much effort has been made to catalogue the enormous structural complexity of the extracellular polysaccharides made possible by the wide assortment of available monosaccharide combinations, non-carbohydrate residues, and linkage types, and to elucidate their biosynthesis and export. In addition, the work is driven by the commercial potential of these microbial substances in food, pharmaceutics and biomedical industries. Most recently, bacteria-mediated environmental restoration and bioleaching have been attracting much attention owing to their potential to remediate environmental effluents produced by the mining and metallurgy industries. In spite of technological advances in chemistry, molecular biology and imaging techniques that allowed for considerable expansion of knowledge pertaining to the bacterial surface polysaccharides, current understanding of the mechanisms of synthesis and regulation of extracellular polysaccharides is yet to fully explain their structural intricacy and functional variability.
胞外多糖与合成它们的细菌一样，在结构和功能上具有多样性。它们可以以多种形式存在，包括细胞结合的荚膜多糖、未结合的“粘液”以及脂多糖的 O-抗原成分，具有同样广泛的生物学功能。这些功能包括抵抗干燥、保护免受非特异性和特异性宿主免疫以及粘附。因此，人们付出了巨大的努力来对胞外多糖的巨大结构复杂性进行编目，这些多糖是由各种可用的单糖组合、非碳水化合物残基和连接类型所带来的，并且阐明了它们的生物合成和输出。此外，这些微生物物质在食品、制药和生物医学工业中的商业潜力也推动了这项工作的开展。最近，由于细菌介导的环境修复和生物浸出具有修复采矿业和冶金业产生的环境废水的潜力，因此引起了广泛关注。尽管在化学、分子生物学和成像技术方面取得了技术进步，使与细菌表面多糖相关的知识得到了极大的扩展，但对胞外多糖合成和调控机制的理解尚未完全解释其结构复杂性和功能变异性。
