ABSTRACT

The present experiment aims at investigating the growth behaviour of different yeast strains inselected carbon, nitrogen and stress environment to obtain strains with prospects for industrialapplication.   Specifically,   the   study   is   set   to:   isolate   yeast   from   decaying   mango   fruit   anddetermine growth performance of yeast strains in different environments, carbon, nitrogen andstressors. The procedure adopted in the study uses different yeast strains isolated from mangofruit, which were screened in order to determine its ability to utilize different carbon sources(glucose, maltose,  xylose),   nitrogen  sources  (valine,  phenylalanine,   isoleucine)  and  stressors(copper, cyanogen, bromate, calcium carbide) at varying concentrations of 0.05%, 16%, 32% forcarbon sources, 30mg/ml for nitrogenous sources what of the concentrations for the stressors.The result in carbon sources shows that ten colonies (C3. C11, C13, C18, C19, C37, C38, C41,C51 and C52) show growth response in all the selected carbon sources, but with highest growthin glucose. This is followed by 7 colonies (C5, C10, C15, C20, C30, C35, C36 and C44) whichshowed growth response in all the selected carbon sources, except in 0.03% of xylose. The tencolonies previously listed have greater growth response in nitrogen source followed by the sevencolonies following them. The findings also indicate that nine colonies (C3, C11, C15, C20, C36,C37, C44, C51 and C52) show growth response in all the selected stress environments, followedby C35 which showed growth in all except in 1mM of PbSO4  and C5, C10 and C41 whichshowed growth  in  all except in  1mM of CaC2. Then  C18 and  C19 which responded in theselected   carbon   and   nitrogen   sources   show   little   or   no   response   in   all   the   selected   stressenvironments. Finally, the researcher identifies the need for subsequent researchers to study thenature as well as the unique properties of the above listed isolates.

TABLE OF CONTENTS

Title page………………………………………………………………………….i

Approval page……………………………………………………………………ii

Dedication…………………………………………………………………………iii

Acknowledgement…………………………………………………………………iv

Abstract…………………………………………………………………………..v

Table of content………………………………………………………………….vi

CHAPTER ONE1.0 Introduction………………………………………………………………1-2

1.1 Literature review…………………………………………………………2-6

1.2 Objective of the study……………………………………………………6

1.3 Nutrition and growth…………………………………………………….6-7

1.4 Ecology…………………………………………………………………..7

1.5 Reproduction……………………………………………………………7

1.6 Industrial applications of yeast………………………………………..8

CHAPTER TWO2.1 Solvents and Reagents…………………………………………………9

2.2.1 Sample collection………………………………………………………10

2.2.2 Processing of sample……………………………………………………10

2.2.3 Serial dilution……………………………………………………………10

2.2.4 Culture preparation……………………………………………………..11

2.2.5 Screening for utilization of carbon sources using Yeast Peptone DextroseAgar (YPDA)..11

2.2.6 Screening   for   utilization   of   nitrogen   sources   using   Yeast   Carbon   Basemedium (YCB)..11

2.2.7 Screening for utilization of  stressors using  Yeast Nitrogen Base medium(YNB)…11-12

CHAPTER THREE

3.1 Results………………………………………………………………13-19

CHAPTER FOUR

4.1 Discussion……………………………………………………………20

4.2 Conclusion……………………………………………………………21

REFERENCES