ABSTRACT

A  biofilm is a complex aggregation of microorganism growing on a solid substrate. It act as defensive role for microorganism during various stress conditions. The proposed work was carried out to study the biofilm forming ability of microorganisms specifically  Escherichia coli, Staphylococcus aures, Streptococcous spp, Bacillus,  Pseudomonas,  Enterobacter,  Salmonella  and Listeria from fish pond in MOUAU. The bacteria were isolated using selective media morphological and biochemical characterization of isolates were carried out. All eight (8) isolates were found to be Gram positive and Gram negative pathogens bacteria. Biofilm forming ability was studied by Congo red agar method (CRA) Staphylococcus aureus, Bacillus and Pseudomonas occurrence at 100% (6) each are strong biofilm producer based on black colonies appearance on (CRA) While Streptococcus, Escherichia coli and Listeria spp are moderate biofilm producers occurrence at 66.7% (4) each and non-biofilm producers are Enterobacter and Salmonella spp. Occurrence at 50%(3) each. This present study will help to understand the biofilm formation of fish pond.

TABLE OF CONTENTS

Title page i

Dedication ii

Acknowledgement iii

Certification iv

Declaration

Table of contents v

List of tables vii

Abstract x

CHAPTER ONE

1.0 Introduction  1-2

1.1 Background of study 2

1.2 Aim and objective of the study 3

CHAPTER TWO

2.0 Literature review 4

2.1 General concept of biofilms 4

2.2Mechanism for the formation of biofilms  4

2.3 Different places where biofilms can be formed        5                   

2.4 Biofilms and infectious diseases 6

2.5 Biofilms in the food industry 7 2.6 Bacteria associated with farmed fish 8

2.6.1 Vibrio Paraheamotyticus and other vibrios: 9-10

2.6.2 Escherichia coli 10-11

2.6.3 Salmonella Spp: 11

2.6.4 Staphylococcus Aureus: 11

2.6.5 Listeria Monocytogenes: 12

2.6.6 Clostridium botulinum: 13

2.6.7 Pseudomonas Aeruginosa: 13

26.8 Aeromonas Species: 14  

2.6.9 Citrobacter Freundii: 14-15

2.7 Factors contributing to fish contamination 16-17

CHAPTER THREE

3.0 Materials and methods 18 3.1 Collection and preparation of the fish pond water sample 18

3.2 Preparation of media 18

3.3 Isolation of biofilm producing bacteria 18

3.4 Characterization and identification of isolates 19

3.4.1 Gram Staining 19

3. Biochemical Tests 20

3.5.1 Catalase Test 20

3.5.2 Urease Test  20

3.5.3 Indole Test

3.5.4 Methyl Red-Voges Proskauer Test      20-21                                                                                             

3.5.5 Citrate Utilization Test 21

3.5.6 Sugar Fermentation Tests 21

CHAPTER FOUR

4.0 Results 22-24

CHAPTER FIVE

5.1 Discussion 25

5.2 Conclusions 26

Reference 28-29