MICROBIAL COMMUNITIES DEVELOPING BIOFILMS IN DRINKING WATER SOURCES IN MOUAU

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 ﾿