ABSTRACT
In this work, dry and wet peels derived from watermelon waste as alternative substrate for Single Cell Protein production from Saccharomyces cerevisiae (from palm wine), Aspergillus niger and Saccharomyces cerevisiae (from baker’s yeast) were investigated. Submerged method was employed to culture them in batches. A glucose solution (monosaccharide) was used as a control for the experiment. Batch 1 represent 4-day culture of the three microorganisms grown on dry, wet and control substrates respectively. Batch 1 gave rise to the following biomass in grams; for palm wine yeast – 0.10, 0.08 and 0.07; for baker’s yeast; 0.15, 0.35 and 0.32; for A. niger – 0.24, 0.30 and 0.21. Batch II represent 6-day culture of the microorganisms grown on dry, wet and control substrates respectively giving rise to the following biomass yield in grams; for palm wine yeast; 0.14, 0.35 and 0.15; for baker’s yeast – 0.33, 0.45 and 0.41; for A. niger – 0.26, 0.43 and 0.28. Batch III represent 8-day culture of the microorganisms grown on dry, wet and control substrates respectively which gave rise to the following biomass yield; for palm wine yeast – 0.10, 0.15 and 0.08; for baker’s yeast – 0.32, 0.43 and 0.29; A. niger – 0.13, 0.32 and 0.25. Nutritional compositions of the raw dry and wet watermelon waste prior to their use as substrates were determined. Proximate composition of the fungal biomass was also determined. Present investigation revealed that baker’s yeast grown on the wet watermelon substrate cultured for 6-day produced the highest quantity of single cell protein, suggesting that wet watermelon peel is more suitable for the production of SCP. The findings from this study support the need for SCP production from cheap, inexpensive agro-waste materials.
TABLE OF CONTENTS
Certification . . . . . . . . . . i
Declaration . . . . . . . . . . ii
Dedication . . . . . . . . . . iii
Acknowledgement . . . . . . . . . iv
Table
of contents . . . . . . . . . v
List
of Tables and Figures . . . . . . . . vii
Abstract . . . . . . . . . . viii
CHAPTER ONE
1.0 Introduction . . . . . . . . . 1
1.1 Fungi . . . . . . . . . . 2
1.2 Botany of Watermelon [Citrullus lanatus (Thumb.)
Matsum
and Nakai] . . . . . . . . . 3
1.3 Aims and Objectives . . . . . . . 4
1.4 Justification . . . . . . . . . 4
CHAPTER TWO
2.0 Literature Review . . . . . . . . 6
2.1 Choice of Microorganism for SCP
Production . . . . 8
2.2 Potential Substrates for Single Cell
Protein Production . . . 11
2.3 Cultivation Methods in SCP Production . . . . . 12
2.4 Nutritional Value of SCP . . . . . . . 15
2.5 The Biotechnology of SCP Production . . . . . 16
2.5.1 The Biochemistry and Physiology of Biomass
Production . . 16
2.5.2 Process Design and Control . . . . . . 18
2.6 The Economics of SCP Production and
Marketing . . . 20
2.7 Drawbacks of Single Cell Protein
Technology . . . . 20
2.8 Future
Prospects . . . . . . . . 22
CHAPTER THREE
3.0 Materials and Methods . . . . . . . 23
3.1 Collection of the Plant Material . . . . . . 23
3.2 Preparation of the Plant Sample . . . . . . 23
3.2.1 Dry Sample . . . . . . . . . 23
3.2.2 Wet Sample . . . . . . . . . 23
3.
3 Preparation of Watermelon Extracts . . . . . 23
3.4 Microorganisms Used . . . . . . . 25
3.5 Analysis of the Raw Substrate . . . . . . 25
3.6 Production and Harvesting of Single Cell
Protein (SCP) . . . 25
3.7 Analysis of Fungal Biomass and Procedures
for
Proximate
Composition . . . . . . . 26
3.7.1 Moisture Content . . . . . . . . 26
3.7.2 Determination of Ash Content . . . . . . 26
3.7.3 Determination of Crude Fat Content (Dry
Extraction) . . . 27
3.7.4 Determination of Crude Fat Content (Wet
Extraction) . . . 28
3.7.5 Determination of Crude Protein . . . . . . 28
3.8 Procedure for Total Sugar using Anthrone
Reagent . . . 29
CHAPTER FOUR
4.0 Results . . . . . . . . . 31
CHAPTER
FIVE
5.0 Discussion and Conclusion . . . . . . . 40
5.1 Discussion . . . . . . . . . 40
5.2 Conclusion
. . . . . . . . . 42
REFERENCES . . . . . . . . . 43
LIST OF TABLES AND
FIGURES
Figure 1: Proximate composition of the raw dry and
wet watermelon peels prior
to Fermentation . . 33
Figure
2: Biomass (g) growth of fungi
grown on two different substrates (dry and wet watermelon and glucose sugar
as control) harvested at 4, 6 and 8 days after inoculation. . . . 34
Figure
3: Ash content of fungal biomass . . . . 35
Figure 4: Crude fat content of fungal biomass . . . . 36
Figure 5: Moisture content of fungal biomass . . . . 37
Figure 6: Crude protein content of fungal biomass . . . . 38
Table 1: Comparism of Microorganisms for Mean
Biomass
Yield
and Proximate Composition . . . . . 39
Table
2: Correlation Coefficient (r) of
Biomass and Proximate Compositions
of Microorganisms
Inoculated on Different Media . . 39
Table
3: Comparison of Means of Raw Wet
and Dry Watermelon Peel
Substrate used for
Proximate Analysis . . . . 39
CHAPTER ONE
INTRODUCTION
The rapidly
increasing world population necessitates the challenge of providing necessary
food sources. The increasing global protein deficiency in food consumed by many
people is becoming a major problem for mankind (Gour et al., 2015). Single Cell Protein (SCP) is one of the most
important steps for this goal and is an alternative and an innovative way to
successfully solving the global protein-rich food problem (Najafpur and Ghasem,
2007). With the world population reaching 9 billion by 2050, there is strong
evidence that agriculture alone will not be able to meet the world’s food
demand (Challinor et al., 2014).
Proteins are mainly called as building blocks of all living organisms. Proteins
are necessary for the growth and development of living organisms and carryout a
number of different biochemical reactions in the form of enzyme (Khan et al., 2010). As compared to other
macromolecules, our body requires abundant quantity of proteins and its
destruction is sometimes lethal (Solomons, 1983).
The protein comes from a number of vegetables, cereals and fruits, often not
affordable by a common man and therefore microbial proteins can be an
alternative source to make proteinous food available to the down trodden
communities in the world in general and Nigeria in particular (Mahnaaz et al., 2010).
The term Single
Cell Protein (SCP) refers to dead, dry microbial cells or total proteins
extracted from pure microbial cell culture and is produced using a number of
different microorganisms including bacteria. Fungi and algae (Anupama and
Ravindra, 2000). Single Cell Protein can also be referred to as edible
unicellular microorganisms. The biomass or protein extract from pure or mixed
cultures of algae, yeasts, fungi or bacteria, may be used as an ingredient or a
substitute for protein-rich foods and is suitable for human consumption or as
animal feeds (https://wikipedia/single-cell-protein).
The benefits of
Single Cell Protein were thus extended from the production of food to the
preservation of the environment. It is an established fact that despite
manifold increase in organization and industrialization, majority of our people
live below poverty line and are malnourished and deserve immediate attention of
the relevant government authorities in general and scientists in particular for
ensuring that these people are with balanced food and nutritive diet, which
comprises of all necessary ingredients including proteins which comprises of
all necessary ingredients including proteins which are desperately needed for
their healthy growth and development (Khan et
al., 2010). Moreover, there is problem of disposal of organic wastes mainly
consisting of vegetable and fruit residues. It is therefore considered
imperative to make use of these affordable cheap substrates for culturing
fungal species which can be harvested as a source of Single Cell Protein to be
used for human and animal consumption or as supplement in the food and fodder.
This will enable at least to some extent to help malnourished and to minimize
the load of pollution. Thus, if the waste is utilized regularly and
systematically for the production of SCP, it will be a source of protein at
affordable cost (Mahnaaz et al., 2010).
Single Cell Protein appears to be the only feasible approach to bridge the gap
between requirement and supply of proteins (Singh, 1998).
Single Cell
Protein was introduced by Carl
Wilson in 1944 for the first time.
Single Cell Protein in terms called cells or proteins is derived from
microorganisms “microbial protein”, resulting from the growth of microorganisms
on different sources of protein and carbohydrates was produced and used as an
alternative or supplementary source of food in
the diet of
animals and humans (Jamel et al., 2007;
Adedayo et al., 2011).
1.1 FUNGI
Saccharomyces
cerevisiae is a
species of yeast. It has been instrumental to winemaking, baking, and brewing since ancient times (Walker et al.,
2004). Many proteins important in human biology were first
discovered by studying their homologs in yeast; these proteins include cell cycle proteins, signaling proteins, and
protein-processing enzymes. S. cerevisiae is currently the only yeast
cell known to have Berkeley bodies present, which are involved in particular secretary
pathways (Moyad, 2008).
All strains of S. cerevisiae can grow aerobically on glucose, maltose, and trehalose and fail to grow on lactose and cellobiose. However, growth on other sugars is variable. Galactose and fructose are
shown to be two of the best fermenting sugars. The ability of yeasts to use
different sugars can differ depending on whether they are grown aerobically or
anaerobically (Feldmann, 2010).
Baker’s yeast (Saccharomyces cerevisiae) was the first
microorganism to be produced in aerobic stirred fermentation on molasses as it
is still produced today (White, 1954; Chen and Chinger, 1985).
Aspergillus niger is a fungus and one of the most common species of the genus Aspergillus (Samson et al., 2001). A. niger is cultured for the
industrial production of many substances. Various strains of A. niger
are used in the industrial preparation of citric acid (E330) and gluconic acid (E574) and have been assessed as acceptable for daily
intake by the World Health Organization. A. niger fermentation is
"generally recognized as safe" (GRAS) by the United States Food
and Drug Administration
under the Federal
Food, Drug, and Cosmetic
Act ("Inventory
of GRAS Notices: Summary of all GRAS Notices",
2008).
1.2 BOTANY
OF WATERMELON [Citrullus lanatus (Thumb.) Matsum and Nakai]
Many raw materials
have been considered as substrate (carbon and energy sources) for single cell
protein production (Nasseri et al.,
2011).
Scientific
Classification:
Domain - Eukarya
Kingdom - Plantae
Division - Magnoliophyta
Class - Magnoliopsida
Order - Cucurbitales
Family - Cucurbitaceae
Genus - Citrullus
Species - C.
lanatus Thumb.
Generic Group - Gourd Source:
(https://wikipedia.org)
Watermelon (Citrullus lanatus var. Lanatus, family; Cucurbitaceae) is a
vine like flowering plant that originated from Southern Africa. It is large
annual plant with coarse, hairy pinnately-lobed leaves with white to yellow
flowers. It is grown for its edible fruit. Watermelon is a special kind of berry
botanically called as “pepo”. The fruit has a smooth hard rind, usually green
with dark green stripes or yellow spots and juicy, sweet interior flesh,
usually deep red to pink but sometime orange, yellow or white, with many seeds.
The fruit can be eaten raw or cooked (https://wikipedia.org).
A variety of
microorganisms and substrates are used to produce SCP. Yeast is suitable for
single cell protein production because of its superior nutritional quality (Miller and Litsky,
1976).
1.3 AIMS
AND OBJECTIVES
1. To
determine the growth of selected microorganism (fungi) on waste watermelon peel
(wet and dry forms) as carbon source (substrate) for SCP production.
2. To
determine which of the state of the substrate’s (watermelon) forms that will
promote the growth of the organism better for the production of SCP.
3. To
determine at what period the highest yield will be obtained as well as the
microorganisms
that will give the highest biomass yield.
1.4 JUSTIFICATION
Increasing human’s
search for nutrition has led to increase in consumption of fruits and
vegetables thereby leaving the environment polluted with agro-wastes from these
fruits and vegetables. These wastes are found dumped on road sides, in the
drains and water bodies proper. Disposal of wastes especially those from these
fruits and vegetables (agro-wastes) has been a serious problem and their
deposition poses health hazards for humans. Hence, there is urgent need for proper
exploitation of these wastes as a substrate for the production of cellular
biomass of edible protein (single cell protein) to supplement the scarce
protein needed to serve as animal feed and food for human consumption. This
single cell protein serves as suitable alternative to scanty protein sources
through recycling of these wastes. The process of production is also cheap or
inexpensive and environmentally friendly.
The present
economic crisis in Nigeria today is posing a tremendous threat on livelihood of
many citizens. The burgeoning population is faced with the challenge of proper
feeding as majority become victim of malnutrition. Protein being one of the
essential components of human and animal diet, the sources is very expensive
for an average citizen of Nigeria and other under developed countries of the
world. The innovation of single cell protein production as a means of obtaining
a protein source from waste agricultural produce is a welcome development to
help address the problem of protein need to humans and animals. Therefore, single
cell protein becomes the only feasible approach to bridge the gap between
requirement and supply of protein.
It is to this end
that this research study is aimed at investigating the possibility of using dry
and wet forms of watermelon peels as substrate/carbon source for production of
single cell protein using three selected fungal organisms.
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