Isolation And Characterization Of Micro-Organisms

Project and Seminar Material for Public Health

Isolation And Characterization Of Micro-Organisms


The microbial changes which took place during the steeping and storage of pan (ogi) was studied. The steeped water had an initial PH of 6.8 which latter reduced to 4.9 at the end of steeping. The bacterial number for the steeped water ranged from 4.7×104 to 3.2 x 107 cfu/ml while the fungal number ranged from 1.5 x103 to 5.7 x 106 cfu/ml. In the stored pap, pap I had higher count which range from 7.2×104 to 6.0×107 cfu/g while 6.0×107 to 1.6×1011. The fungal count for pap I and II ranged from 8.2 x 105 to 2.5×1012 and 8.2×106 to 3.6×1010 respectively. The bacteria isolated from stee pingwere Lactabacillus species Bacillus specie, Corynebacterium, streptococcus specie and clostridium species.

The fungi were Aspergillus species fusrarium specie, pencillium specie sachanomyces specie and candida specie. The bacteria spp isolated from stored pap were lactobacillus species, streptococcus specie Eubacterium specie, Pseudomonas specie, Baccillus specie, streptococcus specie, Lactobacillus specie, Leucomostoc specie for pap I and II respectively. The fungi isolated were Aspergillus specie, Pensillum specie, fusarium specie, sacharomyces specie, candida specie, Debaryomyces specie for pap I and II respectively. The pap stored without changing water developed an off flavour after 48 hours and is not fit for consumption. On the other hand, the pap stored while changing water is fit and better for consumption.

List of Tables

  • Table I: The percentage chemical composition of maize grain
  • Table 2: changes in PH value during the steeping of maize for pop production
  • Table 3: Bacterial count of steeped water during the steeping of maize for pap production
  • Table 4: Fungal counts of steeped water during the steeping of maize for pap production
  • Table 5: Bacterial count for pap samples I and II during storage at room temperature
  • Table 6: Fungal count for pap samples I and II during storage at room temperature
  • Table 7: Predominant bacteria isolated from steeped water
  • Table 8: Fungi isolated from steeped water
  • Table 9: Predominant bacteria isolated from stored pap I
  • Table 10: Predominant bacteria isolated from pap II
  • Table 11: Fungal isolated from samples Pap I
  • Table 12: Fungal isolated from sample Pap II

List of Figures

  • Figure 1: Structure of maize grain
  • Figure 2: Steps in preparation of pap (Oge)
  • Figure 3: Changes in PH value during the steeping of maize for pap production

Table of Contents

  • Title page
  • Certification
  • Dedication
  • Acknowledgement
  • Abstract
  • List of tables
  • List of figures
  • Table of contents

Chapter One


  • 1.1 Background of the study
  • 1.2 Statement of problem
  • 1.3 Aim and objectives of the study
  • 1.4 Hypothesis
  • 1.5 Justification of the study
  • 1.6 Significance of study
  • 1.7 Limitation of the study

Chapter Two


  • 2.1 Origin of maize pad
  • 2.2 Structure of maize grain
  • 2.3 Chemical composition of maize grain
  • 2.4 Uses of maize pap
  • 2.5 Chemical changes in stored pap (ogi)
  • 2.6 Nutrition changes in stored pap
  • 2.7 Microorganisms associated with stored pap

Chapter Three

Materials and Method

  • 3.1 Collection of sample
  • 3.2 Materials and equipments used
  • 3.3 Media and reagents used
  • 3.4 Preparation of pap (ogi)
  • 3.5 Quantitative analysis of microorganisms
  • 3.5.1 Serial dilution
  • 3.5.2 Culturing technique
  • 3.6 Isolation of bactria
  • 3.7 Characterization of isolate
  • 3.8 Biochemical test for identification of microorganisms
  • 3.9 Identification of fungi

Chapter Four

Result and Discussion

Chapter Five

Conclusion and Recommendation

  • 5.1 Conclusion
  • 5.2 Recommendation
  • References
  • Appendix

Chapter One


1.1 Background of the Study

Cereals have been known to man from the earliest times porridge prepared from cereals are eaten in different parts o the world, especially in developing countries where they may present the basic diet. This porridge could be baked to enhance the taste, quality and improve digestibility (Oke 1967, Adeniyi and Potter 1978, Uno and field 1981).
Corn (zea mays) is one of cereals which is an important raw material in human diet. In Nigeria, maize is grown mainly in the southern part of Nigeria while sorghum (Sorghum bicolor) and millet (perinisetum typhoideum) are grown in the northern part of the country. A fermented cereal product is known as paplogi). Corn is processed into traditional food such as paplogi) Umo and fields 1981).

Pap is a fermented non-alcoholic starchy food and is a major staple food widely consumed in west Africa. It is a sour fine past beverage which when cooked produces a thin semi solid porridge. Pap (Ogi) porridge has a smooth texture and a sour taste resembling that of yoghurt,. In Nigeria, some states such as Anambra, Imo, Enugu and Abia refer to it as Akamu but Ogi is a Yoruba name but most state of Nigeria, it refers to maize pap. On the other hand, sorghum pap is known as Ogi baba while millet pap is known as Ogi gero in Yoruba (Banigi 1977, Onyekwere and Akinrele 1977).

Pap logi) can be consumed with variety of other product including with bread, steamed been cake (moi-moi), fried bean cake (Akara), fried yam and plantain etc. it is used as a main meal for adult and sick patients and it is suitable for breakfast, lunch and dinner. Pap is widely used as the first native food given to babies at wearing to supplement breast milk and is a major breakfast cereal for pre-school children and adults. It is consumed as a main meal for convalescing patients because it can easily be digested. As a wearing food, it is utilized mainly by low income earners category, it is estimated that about 25 million or more adults eat it about 4-5 days weakly (Banigo 1972).

Milk and sugar may be added to improved the taske and nutritional quality. Pap is cooked and turned into a stiff gel called Agidi which is similar to kenkey, a fermented shanian product (Muller 1988, withby 1968). Some Yoruba indigens beliwved that pap is capable of stimulating the production of breast milk in Nursing mother (Bassir 1962). However, there has been no qualitative evidence of support of this belief.

In spite of it’s important in the Nigeria diet, pap manufacture is essential a home based industry. There are at present no large scale factory operation for the production of pap. The manufacture is carried out on a small scale by some house wives as a commercial venture in many parts of the country. The cleaned grain free of dirt and impurities steeped in eastern ware, plastic or enamel pot for 1-3 days at room temperature, this is followed by wet milling and sieving.

Twenty-four (24) hours of sleeping leads to a greater depletion of the fermentable carbohydrate. After sieving, the coarse material obtained is wash with water to separate more of the starch. The filtered slurry is allowed to sediment and undergo further fermentation for 1-2 days at room temperature. The coarse matter which is separated is used ad animal feed while the sediment (Pap) is boiled to obtain.

1.2 Statement of Problem

Microorganisms are involved in the processing of pap especially during fermentation and equally during storage. Few organisms are found in the pap, if it is properly stored. Their presence in pap during storage leads to irregular of flavour and loss of nutrients (van veen and steinkrans 1990). This is the result of their metabolic activity in the stored pap.

The tradiitonal method of pap production using various grains encourage significant nutrient losses, Losses m,ay occur during steeping, milling and sieving. Large parts of the protein in the grain is located in the testa and germ that are shifted off during processing.

Losses of fibre, protein, ash as well as some vitamins have been reported by Banigo and Muller (1972). Losses in nutrients could be minimized by using an improved wet milling method devised by Banigo and Muller (1972). At the end of this work, the microorganisms found in stored pap was isolated and characterized.

1.3 Aim and Objectives of the Study

The aim of this study is to isolate and characterize micro-organisms from stored pap.

Specific Objectives Are
  1. To isolate and characterize bacterial contaminants from stored pap
  2. To isolate and characterize fungal contaminants from stored pap

1.4 Hypothesis

HI; Bacteria and fungi are involved in the fermentation and storage of maize pap.

1.5 Justification of the Study

Not very much work has been done in this in recent times, with reference to the microbiology of the process. Some of the earliest workdone in this include those of Akiurele (1970-1977) and Barigo (1969, 1970, 1972, 1977).

1.6 Significance of Study

Pap stored improperly for a relatively length of time is likely to develop microorganisms. Therefore, the study is carried-out to identify this organisms and properly advice on the proper way of storing pap.

1.7 Limitation of the Study

This work is limited to viable microorganism present in the corn (zea mays) only which will be purchased from Ogbete in the Enugu Area.

Chapter Five

Conclusion and Recommendation

5.1 Conclusion

The pH and microbial changes which occurred during the steeping and storage of pap (Ogi) at room temperature were studied. The pH at the initial time of steeping was 6.8. at 24 hours of steeping, the pH had reduced to 6.0 and at the end of 72 hours, the pH was 4.9. the decrease in pH during the steeping period could be as result of the activities of Lactic acid bacteria. These bacteria are responsible for the production of lactic acid and acetic acid which reduce, the pH of the medium during pap production (odunya and Adeyele 1984).

During the steeping, the bacterial counts were higher than the fungal counts. This indicates the predominance of bacteria in maize fermentation. The increase could be as a result of increase in acidity of the medium which favours the growth and proliferation of lactic acid bacteria. The initial bacterial count of the pap sample was 6.0 x 107 Cfu/g. all through the storage period of sample pap I, there was an increase in bacterial number. This is unlike the bacterial count for papII which initially was 6.0×104 cfu/g. this is due to microbial build up in a sample pap I water that was not changed. The reduction could waster used for the immersion of the pap.

During storage of sample pap I, a steady increase in fungal count all through the storage period was observed. From an initial count of 8.2×106, it increased to 2.5 x 1012 cfu/g. this shows that pap can be contaminated with both bacteria and fungi (including mold and yeast). The bacteria isolated at the initial time of steeping were corynebaterium specie, Lactobacillus specie. At 24 hours of steeping, Bacillus specie, clostridium specie, lactobacillus specie and streptococcus specie were isolated. The presence of corynebacterium is due to its ability to hydrolyze the starch in maize to form organic acids. The fungi isolated were Aspergillus specie and fusarium specie. No yeast was isolated was isolated. When steeping had proceeded for one (1) day, fusarium, penicillum and Aspergillus was isolated as well as steeping period along with spores of Aspergillus specie.

The number of molds reduced drastically after 24 hours of steeping probably due to the low oxygen tension in the steeped water (Odunga and Adeyele, 1984). The molds isolated from the steeped water are believed t be from the steeped water are between to be from the unfermented maize grain (Akinrele 1970). Christian (1970) isolated Rhodotorula, candida and saccharomyces specie from fermenting maize grain.

During storage of sample pap I at 0 day, spores of Aspergillus specie were isolated along with the yeast saccharomyces and candida specie. After two day, fusarium, Aspergillus, Rhizopus and mucor were isolated in increasing number. The mold isolated at the initial state of storage of sample pap II was spore of Aspergillus along with the yeat saccharomyces and candida. At the second day of storage, yeast Debarmyces was isolated in addition to saccharomyces and candida species. These remained even up to the forth day of storage but started decreasing in number at the sixth day. As off flavour developed in sample pap I after 48 hours of storage, this was not detected in samplepap II where the water used for storage was changed daily.

5.2 Recommendation

The presence of undersirable organisms such as proteins clostridium, psedomonas and E. Coli in sample Pap I indicated the need for better storage methods. The microorganisms were absent in sample pap II showing the changing of water during storage of pap at room temperature extends the keeping quality of pap partly through the reduction of microbial load. Adequate cooking of pap (ogi) before consumption is important because of the rapid increase in bacteria and fungi counts during storage at room temperature.

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