ABSTRACT
Probiotics are microbial food supplements containing live microorganisms which confers health benefits to the host. These live microorganisms are found in fermented food where the release or production of their compounds are very important to the consumers. Locally fermented foods consists of tuber (cassava), cereal (maize, millet, and sorghum), etc. Examples of some locally fermented foods include fufu, garri, ogi, yoghurt, and burukutu. The aim of this study is to examine some locally fermented foods with Probiotic Potentials. The total of 3 samples (fufu, ogi and garri) used in this study were purchased from Amaba, Ndoru and Ahieke market and then taken to the laboratory for analysis. The standard serial dilution and spread plate method was employed. The samples were cultured on deMan Rogosa Sharpe (MRS) agar, MRS broth and then subcultured in Nutrient agar. The mean counts of microorganisms identified ranged from 1.03×10^5 - 1.12×10^5 cfu|ml. The bacterial isolates were identified by morphological characteristics, pigmentation of media, microscopy, biochemical and sugar fermentation methods. The predominate bacterial isolates obtained are Lactobacillus plantarium, Lactococcus brevis and Leuconostoc mesenteroides. Lactobacillus plantarium, Lactococcus brevis and Leuconostoc mesenteroides showed lower viability in MRS broth at pH 2.0 than at pH 2.5 and 3.5 after 2h of incubation. Addition of Sodium chloride up to 1.5g in MRS broth did not affect the viability of the cells in comparison to culture in their absence. Addition of 2g Sodium chloride into MRS broth results in significant decrease in cell viability compared to control. The Antimicrobial activity of the strains against important pathogenic bacteria showed a clear zone of inhibition against Escherichia coli, Staphylococcus aurues and Candida albicans. The inhibitory ability of the Lactic acid bacteria is associated with the production of bacteriocin- like metabolites.
TABLE
OF CONTENTS
Title page i
Certification ii
Dedication iii
Acknowledgment iv
Table of content v
List of Tables vii
List of figures.
viii
Abstract ix
CHAPTER ONE
1.0 Introduction
1
1.1 Objectives
of the study 2
1.2 Aim
of the study 2
CHAPTER TWO
2.0 Literature review.
3
2.1 Fermented foods 3
2.2 Example of locally fermented food 3
2.3 Benefits of fermented foods 4
2.4 Probiotics 6
2.4.1 Benefits of probiotic microorganisms 6
2.4.2 Selection criteria of probiotics potential 6
2.4.3 Potential benefits of probiotics 7
CHAPTER THREE
3.0. Materials and
Methods 9
3.1 Source of materials 9
3.2 Sterilization of materials 9
3.3 Media preparation 9
3.4 Microbiological analysis 9
3.5 Identification and characterization of isolates 10
3.5.1 Gram staining 10
3.5.2 Catalase test 10
3.5.3 Oxidase test 10
3.5.4 Indole test 11
3.5.5 Citrate utilization test 11
3.5.6 Carbohydrate fermentation test 11
3.6 Probiotic attribute of lactic acid bacteria 11
3.6.1 Acid tolerance test 11
3.6.2 Bile-salt tolerance test 12
3.6.3 Antimicrobial activity of lactic acid bacteria on some pathogens 12
CHAPTER FOUR
4.0. Results and
discussion 13
4.1 Results 13
4.2 Discussion
18
4.3 Conclusion 20
References
LIST
OF TABLES
Table 1 Probiotics potential
attributes 7
Table 4.1 Morphological
and biochemical characterization of isolated lactic acid
bacteria 14
Table 4.2 Acid tolerance of
the LAB isolated 15
Table 4.3 Bile salt
tolerance of the LAB isolated 16
Table 4.4 The inhibition
zones of the LAB on the pathogens 17
LIST
OF FIGURES
Figure 1 Traditional
method of fufu processing 4
Figure 2 Traditional
methods of ogi processing 4
CHAPTER ONE
1.0 INTRODUCTION
Fermented foods are consumed throughout the world and
traditional fermentation processes such as those involved in the production of
fermented dairy products and alcoholic beverages have been performed for
thousands of years. These food products result from the activities of microorganisms
which modify the flavour and texture and increase long term product stability.
Lactic acid bacteria (LAB) are a group of
Gram-positive, non-sporulating, anaerobic or facultative aerobic cocci or rods,
which produce lactic acid as one of the main fermentation products of the
metabolism of carbohydrates. The monograph published by Orla-Jensen is the base
of the present classification of lactic acid bacteria (LAB) using the following
criteria: cellular morphology, mode of glucose fermentation, range of growth
temperature, and sugar utilization patterns. Four genera were recognized as
LAB: Lactobacillus, Leuconostoc, Pediococcus, and Streptococcus.
Molecular biological methods have increased the number of genera included in
this group. The current taxonomic classification includes the LAB group in the
phylum Firmicutes, class Bacilli, and order Lactobacillales.
Lactic acid bacteria constitute an important group of
these organisms and have been associated with production of fermented foods and
feeds for many centuries. They are important in the production of many
fermented foods such as sauerkraut, silage, sourdough, dry fermented sausages
and cheeses. Some of the reasons for their widespread use are the ability to
retard spoilage, preserve food as well as improve flavour and texture of foods.
They also play fundamental role in microbial ecology of foods by synthesizing a
variety of antimicrobial compounds such as organic acids, hydrogen peroxide,
diacetyl and bacteriocins. They are thus able to inhibit many microorganisms
including spoilage and pathogenic organisms. They are increasingly being
recognized for their health and nutritional benefits hence some strains are
used as probiotics.
1.1 Objective of the Study
The objective of this research was therefore to
isolate and characterize predominant lactic acid bacteria species during the
course of traditional fufu and Ogi fermentations.
1.2 Aim of the Study
1)
Isolation and characteristics of lactic acid bacteria from
locally fermented food for probiotics.
2)
To ascertain that the organism isolated is a probiotic
organism
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