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Flocs vi khuẩn, xảy ra trong nước ngọt và môi trường biển, được xây dựng nhiều loài vi khuẩn phát triển như tế bào duy nhất, sợi, hoặc tập hợp tế bào. Flocs cũng chứa các chất ngoại bào cao phân tử (EPS), được tổng hợp bởi các vi sinh vật, cũng như các hạt vật chất hữu cơ và vô cơ và sâu răng giữa các thành phần này. Keo tụ là thuận lợi cho vi sinh vật: ma trận của flocs dày đặc cung cấp một số bảo vệ từ chăn thả động vật nguyên sinh. Floc vi khuẩn tham gia vào tương tác. | 15 Molecular Analyses of Microbial Community Structure and Function of Flocs Holger Daims CONTENTS 15.1 Introduction. 317 15.2 Molecular Methods for Analyzing Uncultured Bacteria. 318 15.2.1 Phylogenetic Analysis of 16S Ribosomal RNA Gene Sequences . 318 15.2.2 Fluorescence In Situ Hybridization. 319 15.2.3 Quantification and 3D Visualization of Microorganisms by Confocal Laser Scanning Microscopy and Digital Image Analysis. 321 15.2.4 Methods to Determine Ecological Functions of Uncultured Bacteria . 324 15.3 Discovery and Investigation of Nitrospira-Like Bacteria in Wastewater Treatment Plants . 328 15.4 Outlook. 331 References . 332 15.1 INTRODUCTION Microbial flocs which occur in most freshwater and marine environments are built by numerous bacterial species that grow as single cells filaments or cell aggregates. Flocs also contain extracellular polymeric substances EPS which are synthesized by the microorganisms as well as particulate organic and inorganic matter and cavities between these components. Flocculation is advantageous for microorganisms the matrix of dense flocs provides some protection from grazing protozoa. Floc bacteria involved in mutualistic symbiotic interactions benefit from the close proximity to their partners. Changes of the environmental conditions outside of flocs may have attenuated effects inside of flocs where microorganisms to a certain degree create and maintain their own microenvironments. Concentration gradients of soluble nutrients waste compounds and gases form within flocs due to diffusion barriers 1-56670-615-7 05 0.00 1.50 2005 byCRC Press 317 Copyright 2005 by CRC Press 318 Flocculation in Natural and Engineered Environmental Systems and microbial metabolic activity. The combination of a complex physical structure with chemical gradients creates in the same floc microhabitats for different functional groups of microorganisms which may be involved in essential nutrient recycling processes. Flocs also provide niches for .
