tailieunhanh - Oceanography and Marine Biology: An Annual Review (Volume 42) - Chapter 3

Exopolymers trừu tượng (EPS) được tiết ra bởi những sinh vật đơn bào và đa bào. Chúng bao gồm chủ yếu là carbohydrate hydrate khi tiếp xúc với nước và EPS được hấp thụ và thường thixotropic. Những kết quả bất động sản ở một số lượng lớn sử dụng: cho file đính kèm, như một trợ giúp để tuyển nổi, trong vận động, trong chăn nuôi, cho các cấu trúc xây dựng, làm cơ sở của các màng sinh học, bảo vệ chống lại một số điều kiện môi trường khắc nghiệt, như là một rào cản chống lại. | THE ESSENTIAL ROLE OF EXOPOLYMERS EPS IN AQUATIC SYSTEMS ROGER S. WOTTON Department of Biology University College London Darwin Building Gower Street London wCiE 6BT . E-mail Abstract Exopolymers EPS are exuded by single-celled and multicellular organisms. They consist mainly of carbohydrates that hydrate on contact with water and EPS are adsorbent and often thixotropic. These properties result in a large number of uses for attachment as an aid to flotation in locomotion in feeding for building structures as the basis of biofilms for protection against a number of harsh environmental conditions as a barrier against attack by pathogens parasitic organisms and predators and in communication. In addition EPS are found free in the water column where they form readily into gels and then into larger aggregates that are foci for biological activity and the breakdown of organic matter to provide nutrients. EPS are truly ubiquitous and are essential to the functioning of all aquatic ecosystems. Introduction What are exopolymers Exopolymers EPS are produced by both single-cell and multicellular organisms. They are also found free in all water bodies and are found abundantly in aggregates. Although the chemical composition of EPS from different sources varies a common feature is the dominance of carbohydrates that give EPS many of their properties they are adsorptive and their hydration results in large bulk for little organic matter. In this review developing ideas presented in articles by Astley Ratcliffe 1989 Denny 1989 Decho 1990 and Wotton 2004 the uses made of EPS by organisms and their role in processes within the water column are discussed. The review uses a selection of papers from a wide and disparate literature and it is not the intention to provide indepth coverage of all aspects of the subject. Rather the review provides a broad and novel synthesis bringing together descriptions of the uses made of EPS by organisms with information from the