ABSTRACT 

Biofilms are aggregates of microbial cells embedded in self –produced matrix of extracellular polymeric substance (EPS) and adhering to non-living or living surfaces. The purpose of this research on microbial communities developing biofilms in drinking water sources in MOUAU was to determine the presence of pathogenic organisms that are present in the water which causes the contamination of the water system and to know their tendency in biofilm formation. The morphological characteristics, Gram reaction and Biochemical tests were carried out to characterize them. The study reveals the percentage of occurrence E. coli as 10 (38.5%), P. aeruginosa - 8 (30.8%), P. vulgaris - 6 (23.0%) and S. aureus – 2(7.7%) and biofilm detection test was carried out using qualitative biofilm detection method (tube method). The screening for the biofilm forming organisms using the tube method revealed E. coli, P. aeruginosa and P. vulgaris to have strong biofilm formation while S. aureus gave moderate positive result. 

TABLE OF CONTENTS

Title i

Certification ii

Dedication iii

Acknowledgement iv

Table of Contents v

List of Tables viii

List of Figure ix

Abstract x

CHAPTER ONE 

INTRODUCTION 

1.1 Background of the Study 1

1.2 Objectives of the Study 3

1.3 Problem Statement 3

CHAPTER TWO

LITERATURE REVIEW 

2.1 Definition of Biofilm 4

2.2. Biofilms Formation and Development 5

2.2.1  Factors Affecting Biofilm Formation 6

2.2.1.1 Substratum Effect 7

2.2.1.2 Conditioning Film 7

2.2.1.3 Hydrodynamics 7

2.2.1.4 Characteristics of Aqueous Medium 7

2.2.1.5 Horizontal Gene Transfer 8

2.2.1.6 Quorum Sensing 8

2.3. Biofilm Structure and Function 9

2.3.1 Extracellular Polymeric Substances 9

2.3.2 Protein 10

2.3.2 Interaction of Particles 11

2.4.3 Community: biofilms and communal behavior 11

2.4.3.1 Biofilms as multicellular organisms 11

2.4.3.2 Division of the metabolic burden 13

2.4.3.3  Selfless behavior 13

2.5 Environmental factors influencing biofilm development 14

2.5.1 Effect of pH 14

2.5.2 Rheological and adhesive properties of biofilms 15

2.5.3 Effect of temperature 16

2.6 Water 17

2.6.1 Sources of Water 17

2.6.1.1 Surface Water 17

2.6.1.2 Ground Water 17

2.6.2 Sources of Contamination Water 18

2.7 Biofilms of Drinking Water Distribution Systems 18

2.8 Effect of long storage of water on Biofilm Formation 19

CHAPTER THREE

MATERIALS AND METHODS

3.1 Sample Collection 20

3.2 Preparation of Media and Sterilization 20

3.3 Sample Inoculation 20

3.3.1 Isolation of Bacteria 20

3.4 Identification of the Isolates 21

3.4.1 Macroscopic Examination 21

3.4.2 Microscopic Examination (Gram Staining) 21

3.5 Biochemical Tests 21

3.5.1 Catalase test 21

3.5.2 Citrate Utilization Test 22

3.5.3 Coagulase Test 22

3.5.4 Oxidase Test 22

3.5.5 Motility, Urease and Indole (MUI) Tests 22

3.5.6 Methyl Red- Vogus Proskauer Test 23

3.5.7 Sugar Fermentation Test 23

3.6 Detection of Biofilm using Tube Method 24

CHAPTER FOUR

RESULTS 25

CHAPTER FIVE

DISCUSSION, CONCLUSION AND RECOMMENDATION

5.1 Discussion 30

5.2 Conclusion 33

5.3 Recommendations 33

References 34