Optimization and Screening of Extracellular Enzymes produced by Pseudomonas Aeruginosa during LDPE degradation

ABSTRACT

Plastics are synthetic polymers made by chains of carbon atoms with hydrogen, oxygen, nitrogen, Sulphur built around the carbon chains (Shah et al., 2008). These polymers are involved in every domain of our lives ever since its production began from the year 1950’s, plastics have been produced at an augmented rate to meet day to day demands of the entire world. Accumulation of plastic waste in the environment causes chemical pollution when methods like incineration are used to get rid of waste. Chemicals used during the production stage of plastic like ethylene, vinyl chloride, terephthalic acid and bisphenol which are most commonly employed in consumer based plastic products, have harmful effects on human health causing diseases like cancer, endocrine diseases, birth defects and many other health issues.

The effect of temperature has been seen to contribute immensely to the ability and rate of microbial degradation of plastics and related materials. Montazer et al., (2018) have similar result reported when they subjected pretreated low density polyethene to some of these bacteria at various temperature. This had been reported earlier by Mahalashimi et al., (2012) for Pseudomonas and Klebsiella, in which temperature was a major factor in their rate degradation of plastics and related materials.

The results obtained in this research has establish that bacteria such as Pseudomonas, Klebsiella, Salmonella, Rhizobium and Streptococcus are actively involved in the degradation of bioplastics and they produced enzymes such as cutinase, esterase, laccase, manganese, peroxidase and lipase. These enzymes are actually the ones that soften these plastics resulting in their eventual decay and putrefaction. Temperature may also play a role in the rate of the plastic degradation.

TABLE OF CONTENTS

COVER PAGEi

TITLE PAGEii

CERTIFICATIONiii

DEDICATIONiv

ACKNOWLEDGEMENTv

ABSTRACTvi

TABLE OF CONTENTSvii

LIST OF FIGURESxii

LIST OF TABLESxiii

LIST OF PLATESxiv

ABBREVIATIONSxv

CHAPTER ONE1

INTRODUCTION1

1.1. Background Study1

1.2. Problem Statement3

1.3. Aim of Study4

1.4. Objectives of the Study4

CHAPTER TWO6

LITERATURE REVIEW6

  2.1 Concept of Biodegradation.........................................................................6

  2.2 Polyethylene...............................................................................................7

2.2.1 Types of Polyethylene...............................................................................8

2.2.2 Methods of Degradation..........................................................................14

2.3 Mechanism of Polyethylene Degradation..................................................16

CHAPTER THREE21

METHODOLOGY21

3.0 Preparation of Seed culture...................................................................20

3.1 Procedure for Enzyme Assay................................................................20

3.1.1 PETase assay......................................................................................21

CHAPTER FOUR....................................................................................................23

RESULT..................................................................................................................23

4.0 Temperature optimization..........................................................23

4.1 Enzyme Activity.........................................................................25

CHAPTER FIVE....................................................................................................52

DISCUSSION, CONCLUSION AND RECOMMENDATIONS......................52

5.1. Discussion........................................................................................................52

5.2. Conclusion.......................................................................................................54

5.3. Recommendation............................................................................................54

REFERENCES......................................................................................................55

APPENDIX............................................................................................................55