SCREENING OF SOME LACTIC ACID BACTERIA ISOLATED FROM SELECTED NIGERIAN FERMENTED FOODS FOR VITAMIN PRODUCTION

ABSTRACT

Thiamine, riboflavin and niacin are among the essential vitamins required for normal physiological function that cannot be synthesized by the body, and thus must be obtained from dietary source.  Five lactic acid bacteria were isolated from selected Nigerian fermented foods (Yoghurt, ogi, ogiri, ugba). The isolates were identified based on cultural and biochemical characteristics. All the isolates were screened for thiamine, riboflavin and niacin production. Thiamine, riboflavin and niacin produced were quantified. The five lactic acid bacteria isolated were Lactobacillus plantarum,Lactobacillus brevis, Lactobacillus fermentum, Lactobacillus casei and Lactococcuslactis. The most frequent isolate was Lactobacillus plantarum (100%) followed by Lactobacillus caesi (75%). Lactobacillus brevis, Lactobacillus fermentum and Lactobacillus lactis were the least isolates having (50%) occurrence each. Lactobacillus plantarum produced the highest amount of thiamine (5.8833µg/100ml) and riboflavin (5.0400µg/100ml) while Lactobacillus lactis had the least thiamine (5.2267µg/100ml) and Lactobacillus caesi had the least riboflavin (4.8300µg/100ml). Lactobacillus casei produced the highest niacin (1.6433µg/100ml) while Lactobacillus fermentum had the least (1.2900µg/100ml). This study revelsLactobacillus plantarum as the most efficient thiamine and riboflavin producer. Lactobacillus caseiproduced the most niacin. 

TABLE OF CONTENTS

Title page                                                                                                                    i

Certification                                                                                                               ii

Dedication                                                                                                                  iii

Acknowledgement                                                                                                      iv

Tables of contents                                                                                                       v

List of tables                                                                                                               vi

Abstract                                                                                                                       vii

Chapter One

1.0  Introduction                                                                                                    1

1.1       Aim                                                                                                                 2

1.2  Objectives                                                                                                       2

Chapter Two

2.1       Lactic Acid Bacteria (LAB)                                                                          3

2.2       What are Lactic Acid Bacteria?                                                                     3

2.3.      Physiology and Morphology                                                                          5

2.4       General Description                                                                                        7

2.5       Genetics                                                                                                          9

2.6.      Application of Lactic Acid Bacteria                                                               10

2.7.      Lactic Acid Bacteria as Source of Probiotics                                                 11

2.7.1    Probiotics and Health                                                                                     13

2.8       Lactic Acid Bacteria as Source of Starter Cultures                                        14

2.8.1    Starter Culture and Functional Starter Cultures in Fermentation of Foods  14

2.8.2    Probiotics as Functional Starter Culture                                                        14

2.8.3    Functional Starter Cultures in Fermented Dairy Products                             17

2.8.4    Functional Starter Cultures in Fermented Non Dairy Products.                        17

2.8.4.1. Fermented Meat and Meat Products                                                              17

2.8.4.3. Starter Culture in Silage                                                                                17

2.9       Lactic Acid Bacteria as Source of Antimicrobial Agents.                             18

2.9.1    Bacteriocins                                                                                                    19

2.10.    Lactic Acid Bacteria as a Source of Vitamins                                              19

2.10.1 Folate                                                                                                              20

2.10.2. Vitamin B₁₂                                                                                                                                                       21

2.10.3 Vitamin K                                                                                                        21

2.10.4 Riboflavin                                                                                                        22

2.11.    Lactic Acid Bacteria as Source of Enzymes                                                 22

2.12.    Lactic Acid Bacteria as Source of Exopolysaccharides                                 23

2.13.    Lactic Acid Bacteria as Source of Low-Calories Sweeteners.                        24

Chapter Three

3.0       Materials and Method                                                                                     25

3.1       Source of Materials                                                                                        25

3.2       Sample Preparation                                                                                        25

3.3       Media Preparation                                                                                         25

3.4       Isolation of Lactic Acid Bacteria                                                                   26

3.5.      Morphological Identification of Bacterial Isolates.                                        26

3.5.1    Gram Staining                                                                                                26

3.5.2    Biochemical Parameters.                                                                                27

3.6.1.   Determination of Thiamine (Vitamin B₁)                                                      29

3.6.2    Determination of Riboflavin (Vitamin B_2­)                                                     31

3.6.3.   Determination of Niacin (Vitamin B₃)                                                           31

3.7       Statistical Analysis                                                                                         32

Chapter Four

Results                                                                                                                        33

Chapter Five

5.1       Discussion                                                                                                       38

5.2       Conclusion                                                                                                      40

References

Appendix

LIST OF TABLES

Table                          Title                                                             page

1          Some of the Beneficial Effects of Probiotics                                                 13

2          Lactic Acid Bacteria Used as Starter Culture in Fermented Foods                        16

3          Morphological and Biochemical Characteristics of Bacterial

Isolates from Selected Food Sample.                                                             35

4          Percentage Occurrence of Lactic Acid Bacteria Isolated

from Different Food Samples.                                                                        36

5          Determination of the Vitamin Produced                                                        37

LIST OF FIGURES

Figure                         Title                                                                 page

1                      Uses and functional Ingredients of LAB                       10

CHAPTER ONE

1.0    INTRODUCTION

Food is any substance consumed to provide nutritional support for the body. It is usually of plants and animal origin and contains essential nutrients, such as fats, proteins, vitamins or minerals. The substance is ingested by the organism and assimilated by the organism’s cells to provide energy, maintain life or stimulate growth (Aguilera and David, 1999).

Campbell-Platt (1987) has defined fermentation as those foods which have been subjected to the action of microorganisms or enzymes so that desirable biochemical changes cause significant modification to the food. However, to the microbiologist, the term ‘fermentation’ describes a form of energy-yielding microbial metabolism in which an organic substrate, usually a carbohydrate, is incompletely oxidized and an organic carbohydrate act as the electron acceptor (Adams 1990).

The primary benefit of fermentation is the conversion of sugars and other carbohydrates to usable end products. The traditional fermentation of foods serves several functions, which includes; enhancement of diet through development of flavor, aroma and texture in food substrates, preservation and shelf-life extension through lactic acid, alcohol, acetic acid and alkaline fermentation, enhancement of food quality with protein, essential amino acids, essential fatty acids and vitamins, improving digestibility and nutrient availability, detoxification and anti-nutrient through food fermentation processes, and a decrease in cooking time and fuel requirement (Steinkraus, 1995).

Fermented foods are generally produced using plants or animal ingredients in combination with fungi or bacteria which are either sourced from the environment or carefully kept in cultures maintained by humans. Just as living organisms cover the surface of the earth, fermentation microbes cover the surface of the organisms. Wild yeasts are found living on grapes and bacteria line the human digestive tract (Chamberlain et al; 1997).

Fermented foods, whether from plants or animal Origen are an intricate of the diet of people in all parts of the world. It makes major contributions to the protein requirements of the rural population. The preparation of many indigenous or ‘traditional’ fermented foods and beverages such as gari, fufu, lafun, ogi, masa, pito, burukutu, kunuun-zaki, ogiri, dadawa/ iru, ugba, afiyo (Okpehe), nono, cheese, kilisho,etc. remains a househood art today (Ijabadeniyi, 2007; Achi, 2005; Agarry, et al., 2010; Osho et al., 2010.)

1.1       AIM

The broad aim of this work is to screen some Lactic Acid Bacteria isolated from selected Nigerian fermented foods for vitamin (Thiamine, Riboflavin and Niacin) production.

1.1   OBJECTIVES

-       To isolate Lactic Acid Bacteria from selected Nigerian fermented foods.

-       To characterize and identify the isolates.

-       To screen these Lactic Acid Bacteria isolates for vitamin (Thiamine, Riboflavin and Niacin) production.

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