ABSTRACT
This study investigated the determination of probiotic potential of Lactic Acid Bacteria from traditional fermented foods. A total of 34 Lactic Acid Bacteria were identified, characterized and isolated. The study found out that LAB count were 9 Lactobacillus plantarum and Streptococcus species, having the highest and the lowest counts respectively. Most isolates (5) were present in Ogi, tomatoes and Ugba and Lactococcus lactis was the most tolerant to the heat treatment at 10, 30 and 60 minutes respectively while Streptococcus species have the lowest bile salt tolerance after exposure for 3 and 4 hours respectively. These results proved that lactobacillus which can be isolated from fermented foods are good sources of probiotics and thus recommend the uses of probiotic LAB and their application because probiotics can be of many health benefits to humans.
TABLE OF CONTENTS
Title Page
Title
Page ii
Certification iii
Dedication iv
Acknowledgements v
Table
of Contents vi
List of Figures ix
List
of Tables x
Abstract xi
CHAPTER ONE: INTRODUCTION
1
1.1. The History of
Probiotics 2
1.2. Aims and
Objectives 3
CHAPTER
2: LITERATURE REVIEW 5
2.1.
Raw Material Development 5
2.2.
Development OF Fermentation Processes 6
2.3
Purpose and Benefits Of Food Fermentation 8
2.3.1
Health Benefits Of Fermented Foods 8
2.4
Food and Beverage Fermentation by LAB
10
2.5
Role and Importance of LAB in Traditional Fermented Foods 12
2.6
LAB as Probiotics 12
2.6.1
The Role Of LAB in Immune System Modulation And Mental Health 13
2.7
LAB as a Source of Antimicrobial Agents 14
2.7.1
Antifungal Agents and Other Antimicrobial Agents from LAB 14
2.7.2
Antimicrobial Activity and Safety 14
2.7.3.
Other Selection Criteria for Probiotic LAB 15
CHAPTER
3. MATERIALS AND METHODS
3.1. Sample
Collection 16
3.2.
Sterilization of Materials 16
3.3.
Media Preparation for Isolation of Lactic Acid Bacteria 16
3.4.
Microbiological Analysis 17
3.5.
Identification of Isolates 17
3.6.
Gram Staining 17
3.7.
Motility Test (Hanging Drop Method) 18
3.8.
Biochemical Tests 18
3.8.1.
Catalase Test 18
3.8.2.
Coagulase Test (Slide Test) 18
3.8.3.
Oxidase Test 19
3.8.4
Citrate Utilization Test 19
3.8.5.
Indole Test 20
3.8.6.
Voges-Proskauer Test 20
3.8.7.
Methyl Red Test 20
3.8.8. Sugar Utilization Test 21
3.9
Food Pathogen Indicator Bacteria 21
3.10.
Determination Of Probiotic Characteristics Of The Lactic Acid Bacteria
Isolates 21
3.10.1.
Production Of Crude Bacteriocin 21
3.10.2.
Antibacterial Activity of Lactic Acid Bacteria 22
3.10.3.
Acid Tolerance 22
3.10.4. Tolerance to Bile Salts 23
3.10.5.
Thermo Tolerance 23
3.10.6.
Antibiotic Activities of the LAB Isolates 24
CHAPTER
4: RESULT
Result 25
CHAPTER 5:
DISCUSSION, CONCLUSION AND RECOMMENDATION
Discussion 44
Conclusion 49
Recommendation 49
References 50
LIST OF FIGURES
Figure1. Flow Chart of Cassava Processing 6
Figure 2
Packaging Of Iru By Traditional And Modern Industrial Methods 8
LIST OF TABLES
Table 4.1: Average Total Lactic Acid Bacteria
(LAB) Count From Fermented Food Sample
30
Table 4.2: Identification And Characterization
Of Lactic Acid Bacteria (LAB) Isolates 33
Table
4.3: Distribution of Lactic Acid Bacteria (LAB) Isolates from Traditional
Fermented Food 34
Table 4.4: Percentage Occurrence of Lactic Acid
Bacteria (LAB) Isolates From Traditional
Fermented Food 35
Table 4.5: Antibacterial Activity of the Lactic
Acid Bacteria (LAB) Isolates 36
Table 4.6: Activities of Acid Tolerance of the
Lactic Acid Bacteria (LAB) Isolates 37
Table 4.7: Activities of Bile Salt Tolerance of
the Lactic Acid Bacteria (LAB) Isolates 38
Table
4.8a: Activities of Thermo Tolerance of the Lactic Acid Bacteria (LAB) Isolates
at 10
minutes
39
Table
4.8b: Activities of Thermo Tolerance of the Lactic Acid Bacteria (LAB) Isolates
at 30
minutes 40
Table
4.8c: Activities of Thermo Tolerance of the Lactic Acid Bacteria (LAB) Isolates
at 60
minutes 41
Table
4.9a: Antibiotic Susceptibility Patterns of the Lactic Acid Bacteria (LAB)
Isolates from
Fermented Food 42
Table 4.9b:
Antibiotic Susceptibility Patterns Of The Lactic Acid Bacteria (LAB) Isolates
From
Fermented Food 43
CHAPTER ONE
1.0 Introduction
Probiotic
bacteria may produce various compounds, which are inhibitory to the pathogen’s
growth, which include organic acids (lactic and Acid acids), bacteriocins, and
reuterin. The organic acids not only lower the pH, thereby affecting the growth
of the pathogen, but they can also be toxic to the microbes (Tambekar and
Bhutada, 2010). There is increasing evidence that probiotics are beneficial in
gastrointestinal disturbances, such as diarrhoea, dysentery, typhoid etc
(Tambekar and Bhutada, 2010). It is important to underline when considering the
effectiveness and biological activity of probiotics, prebiotics or their
combination (synbiotics) that they are food products and not drugs.
Furthermore,
in many cases, their effects are mainly prophylactic in nature, rather than
therapeutic, i.e. preventive rather than curative (Suskovic et al., 2001). Lactic acid bacteria were
referred to as probiotics in scientific literature by Lilley and Stillwell.
Lactic acid bacteria (LAB) are a group of Gram positive, non-spore forming,
cocci or rods which produce lactic acid as major end product from fermentation
of carbohydrates. Majority of microorganisms used as probiotics are the Lactic acid bacteria and bifidobacteria. Within the group of LAB,
Lactobacillus species are most
commonly utilized group of microorganisms for their potential beneficiary
properties as probiotics. The antagonistic activity of such bacteria is known
to inhibit a large number of enteric and urinary pathogenic bacteria (Hutt et al., 2006). Lactic acid bacteria
including Lactobacillus, leuconostoc,
Lactococcus, pediococcus and Bifidobacterium are found throughout the
gastrointestinal tract. Lactobacillus and
Bifidobacterium spp. are prominent
members of the intestinal flora and are the commonly studied probiotics
bacteria. They cause reduced lactose intolerance alleviation of some
diarrhoeas, lowered blood cholesterol, increased immune response and prevention
of cancer.
The
selection criteria for probiotic LAB include: safety, viability/activity in
delivery vehicles, resistance to acid and bile, adherence to gut epithelial
tissue ability to colonise the gastro intestinal tract, production of
antimicrobial substances, ability to stimulate a host immune response and the
ability to influence metabolic activities such as vitamin production,
cholesterol assimilation and lactose activity (Savodago et al., 2006).
1.1 THEHISTORYOFPROBIOTICS
The
word ‘probiotic’ comes from Greek language ‘pro bios’ which means ‘for life’
opposed to ‘antibiotics’ which means ‘against life’. The history of probiotics
began with the history of man by consuming fermented foods that is well known
Greek and Romans consume very much (Guarneret
al., 2005).
In
1908 a Russian researcher Ellie Metchnikoff, who has a nobel prize, firstly
proposed the beneficial effects of probiotic microorganisms on human health.
Metchnikoff hypothesized that Bulgarians are healthy and long lived people
because of the consumption of fermented milk products which consists of rod
shaped bacteria (Lactobacillus spp.). Therefore, these bacteria affect the gut
microflora positively and decrease the microbial toxic activity (Chuayana et al., 2003).
The
term ‘probiotic’ firstly used in 1965 by Lilly and Stillwell to describe
substances which stimulate the growth of other microorganisms. After this year
the word ‘probiotic’ was used in different meaning according to its mechanism
and the effects on human health. The meaning was improved to the closest one we
use today by Parker in 1974. Parker defined ‘probiotic’ as ‘substances and
organisms which contribute to intestinal microbial balance’. In 1989, the
meaning use today was improved by Fuller. Thus, probiotic is a live microbial
supplement which affects host’s health positively by improving its intestinal
microbial balance (Sanders 2003).
In the following years lots of researchers
studied on probiotics and made so much definition.
Ø ‘Living
microorganisms, which upon ingestion in certain numbers, exert health benefits
beyond inherent basic nutrition(Shaafasma, 1996).
Ø ‘A
microbial dietary adjuvant that beneficially affects the host physiology by
modulating mucosal and systemic immunity, as well as improving nutritional and
microbial balance in the intestinal tract(Naidu et al., 1999).
Ø ‘A
live microbial food ingredient that is beneficial to health’ (Salminen et al., 1998).
Ø ‘A
preparation of or a product containing viable, defined microorganisms in sufficient
numbers, which alter the microflora (by implantation or colonization) in a
compartment of the host and by that exert beneficial health effects in this
host’ (Schrezenmeir and de Vrese, 2001).
Ø ‘Live
microorganisms which when administered in adequate amounts confer a health
benefit on the host’ is accepted by FAO/WHO (Guarner, et al., 2005).
1.2 AIMS AND OBJECTIVES
1.2.1 Aim
The
aim of this project is to determine the probiotic potential of lactic acid
bacteria isolated from traditional fermented foods.
1.2.2 Objectives
The
specific objectives are,
i.
To determine Lactic Acid
Bacteria (LAB) count from the fermented food sample
ii.
To identify and
characterize Lactic Acid Bacteria isolates from the fermented foods
iii.
To determine the survival
rates of the Lactic Acid Bacteria from the fermented foods
iv.
The antibiotics
susceptibility pattern of the Lactic Acid Bacteria from the fermented foods.
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