ABSTRACT
CONTENTS 4.1 Introduction ......................................................................................................................... 98
4.1.1 Diversity and Uses of Aquatic Environments ................................................... 98 4.1.2 Diversity of Aquatic Bacteria................................................................................ 98
4.2 Aquatic Pathogenic Bacteria and Indicators of Pathogenic Organisms in Water ................................................................................................................................ 99 4.2.1 Aquatic Pathogenic Bacteria ................................................................................. 99 4.2.2 Use of Bacteria as Indicators of Pathogenic Organisms in Water ................ 101
4.2.2.1 Total Coliforms....................................................................................... 102 4.2.2.2 Fecal Coliforms....................................................................................... 102 4.2.2.3 Escherichia Coli ........................................................................................ 103 4.2.2.4 Fecal Streptococci................................................................................... 103 4.2.2.5 Enterococci .............................................................................................. 104 4.2.2.6 Clostridium perfringens ........................................................................... 104
4.3 Dynamics of Indicator Bacteria in Surface Waters and Problems Associated with Using Fecal Coliforms as Indicators of Pathogenic Organisms ...................... 104 4.3.1 Dynamics of Fecal Coliforms in Surface Waters in
Relation to Environmental Factors: Implications for Assessing Fecal Coliform Levels in Surface Waters ....................................... 104
4.3.2 Problems Associated with Using Fecal Coliforms as Indicators of Pathogenic Organisms.................................................................. 105
4.4 Bacterial Source Tracking and Other Indicators of Fecal Contamination and Measures of Water Quality ......................................................... 106 4.4.1 Bacterial Source Tracking .................................................................................... 106 4.4.2 Other Indicators of Fecal Contamination ......................................................... 107 4.4.3 Prevotella-Bacteroides Detection........................................................................... 107 4.4.4 Use of Heterotrophic Plate Count as a Measure of Water Quality.............. 108
4.5 Bacteriological Water Quality Standards...................................................................... 108 4.6 Collection, Handling, Dilution of Samples, and Data Analysis ............................... 110 4.7 Methods for Detection and Enumeration of Bacteria in Water ................................ 111
4.7.1 Plating/Culturing Method .................................................................................. 111 4.7.1.1 Viable Plate-Count Procedure ............................................................. 111 4.7.1.2 Most Probable Number Method (Multiple Tube Technique) ........ 112 4.7.1.3 Presence-Absence Test ......................................................................... 112
4.7.2 Direct Epifluorescent Microscopy...................................................................... 112
4.7.3 Gene Probes in Water Analysis.......................................................................... 113 4.7.4 DNA Fingerprinting............................................................................................. 114
4.8 Detection and Enumeration of Bacteria in Water ....................................................... 115 4.8.1 Heterotrophic Plate Count .................................................................................. 115
4.8.1.1 Pour-Plate and Spread-Plate Techniques........................................... 115 4.8.1.2 Membrane Filtration Method .............................................................. 116
4.8.2 Enumeration of Total Coliforms, Fecal Coliforms, and E. coli ...................... 116 4.8.2.1 Multiple Tube Fermentation Method (MPN Method) .................... 117 4.8.2.2 Multiple Tube Fermentation Method (MPN Method) for
Detecting Fecal Coliforms .................................................................... 118 4.8.2.3 Membrane Filtration Technique.......................................................... 119 4.8.2.4 Determination and Enumeration of Bacteria Using
Chromogenic and Fluorogenic Media-Based Methods................... 121 4.8.3 Enumeration of Fecal Streptococci/Enterococci.............................................. 123
4.8.3.1 Membrane Filtration Method .............................................................. 123 4.8.3.2 An Alternative Method of Determining Fecal
Streptococci in Water ............................................................................ 124 4.8.3.3 Determination of Fecal Streptococci/Enterococci
Using the Most Probable Number Method....................................... 124 4.8.3.4 Detection of Fecal Streptococci/Enterococci Using
Enzyme Substrate Method ................................................................... 125 4.8.4 Enumeration of Staphylococcus aureus................................................................ 126
4.8.4.1 Membrane Filtration Method .............................................................. 126 4.8.4.2 Most Probable Number Method for the
Detection of Staphylococcus ................................................................... 126 References ................................................................................................................................... 127
4.1.1 Diversity and Uses of Aquatic Environments
About 70% of the Earth’s surface is covered by water much of which occurs in the oceans, estuaries, and freshwaters (ponds, streams, rivers, and lakes). These waters are used for many purposes such as recreation and transportation, as sources of drinking water (sometimes without any form of treatment, particularly in developing countries), and for industrial activities and irrigation on farmlands. Surface waters are also important ecosystems from which finfish, shellfish, and macroalgae are harvested, and in which a variety of organisms are cultured.
