POST GRADUATE PROJECT TOPICS IN BIOLOGY EDUCATION

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POST GRADUATE PROJECT TOPICS IN BIOLOGY EDUCATION ON BIODEGRADATION OF GROUNDNUT SHELLS TO FERMENTABLE SUGAR USING FUNGAL ISOLATES https://emrislot.com/product/post-graduate-project-topics-in-biology-education/

CHAPTER ONE

1.0     INTRODUCTION

There are various types of agricultural residues that are not useful to man and thus constitute a nuisance to the environment. About 147.2 million metric tons of fiber sources are found in the world while the global output of wheat straw residue and rice straw were estimated at 709.2 and 673.3 million metric tons respectively in the 1990’s. Additionally the total global  output of non wood fibers was put at about 2.5 million metric tons. About 61 million metric tons of crop residue available in Nigeria, out of these only 21% are consumed by sheep and goat and only if they are processed into acceptable and digestible forms. POST GRADUATE PROJECT TOPICS IN BIOLOGY EDUCATION

Lignocellulose are the major structural component of woody plant and non woody plant such as grasses and represent a major source of renewable organic matter. Lignocelluloses waste refers to plant biomass wastes that are composed of   cellulose, hemicelluloses and lignin. The chemical properties of   the   component of   lignocellulosics make them a substrate of enormous biotechnological value (Malherbe and Cloete, 2003). Large amounts   of lignocellulosic waste are generated through forestry and agricultural practice and they pose an environmental pollution problem. They may be grouped into different categories such as wood residues (including sawdust and paper mill discards), grasses, waste paper, agricultural residues (including straw, stover, peelings, cobs, stalks, nuts, shells, non-food seeds, bagasse, domestic waste lignocelluloses garbage and sewage), food industry residues, municipal solid waste, (Qi, et al., 2005; Roig, et al., 2006; Rodriguez, et al., 2008). However the huge amount of residual plant biomass considered as waste can potentially be converted into various different value added products. Bioconversion offers a cheap and safe method of not only disposing the agricultural residues but  also  it has the potential to convert lignocellulosic waste into usable forms such as reducing sugars that could be used for the production of other value added products. The   biomass feedstock in Nigeria can provide enough potential of bioconversion of cellulosic materials is frequently considered because of their high availability and low cost. POST GRADUATE PROJECT TOPICS IN BIOLOGY EDUCATION

1.1       Groundnut shells

Groundnut   (Arachis hypogea)   is an important oil seed crop of Nigeria. The pulp or dry pericarp contains about 25-40 percent shell (Dey, et al., 2002).  The chemical composition of groundnut shell is as follows; cellulose 65.7; protein 7.3; mineral, 4.5; and lipids 1.2%. (Masenda et al., 2004).  Groundnut shell is used in mushroom cultivation (Reneau, et al; 1980)   and the production of extracellular enzymes by prodigious cellulolytic fungi. These groundnut shells waste have been insufficiently disposed leading to environmental concern (Fabiyi and Ogunfowora, 2011). Plant lignocellulosics as organic substance are subjects to attacks by biological agents such as fungi, bacteria and insects (Highleey, et al., 1987) breakdown the long chain in cellulose to release the sugar through hydrolysis reaction, but because of their ability, they can achieve higher yield of glucose from cellulose (Wyman, 2004). A portion of pretreated biomass can be used by organisms that produce cellulase that can then be added to pretreated solids to release glucose from cellulose. Filamentous fungi which use cellulose as carbon source possess the unique ability to degrade cellulose molecule. Fungi are the main cellulase producing microorganism though a few bacteria have also been shown to have cellulase activity. Fungal genera like Tricoderma and Aspergillus are known to be cellulase producers. The genus Aspergillus species attack cell wall to free little amount of the cell free cellulase capable of hydrolyzing cellulose to fermentable soluble sugars such as glucose in chemical industries. POST GRADUATE PROJECT TOPICS IN BIOLOGY EDUCATION

Enormous amount of agricultural, industrial and municipal cellulosic waste have been accumulating or used inefficiently due to the high cost of their utilization processes (Lee et al., 2002).

1.2 Statement of problem

One of the limitation to the use of groundnut shells which constitute a nuisance in our environment is the fact that organism that can break the barrier the lignin structure holding up the cellulose content of the groundnut shell to be accessible has not been identified. POST GRADUATE PROJECT TOPICS IN BIOLOGY EDUCATION

1.3 Aim

This work was aimed at biodegradation of groundnut shells to fermentable sugar using fungal isolates.

1.3.1 Objectives of the study

The objective of this study includes:

  1. To isolate fungal from steeped groundnut shell.
  2. To determine the best suited culture conditions for degradation of the groundnut shells to fermentable sugar.
  3. To determine the fungal isolate best suited for the degradation.
  4. To compare the action of the fungal in monoculture and in co-culture

1.4 Literature Review

1.4.1   Lignin

Lignin is a complex cross-linked  polymers of aromatic rings (phenolic monomers). A  highly branched macromolecule composed of several types of aromatic acids that has an important role in the physical characteristics of wood as well as in preventing lignocellulosic materials against biological attacks, e.g. against cellulose degrading microorganisms. The term lignin was introduced in 1819 and derived from latin word lignum ( Sjostrom, 1993). POST GRADUATE PROJECT TOPICS IN BIOLOGY EDUCATION

1.4.2   Cellulose

Cellulose a polymer of glucose residues connected by 1-4 linkage being the primary structural materials of plant cell wall is most abundant carbohydrate in nature (Saha, et al; 2005). Cellulose, a widely distributed long-chain polymeric and skeletal polysaccharide carbohydrate, of beta-glucose, is the most abundant renewable natural product that can be obtained in the biosphere. It forms the primary structural component of green plant, and represent about 50% of cell wall material of plants. The primary cell wall of plant is made of cellulose, the secondary wall contains cellulose with variable amount of ligin.  Cellulose has been used by man for ages. However, its enormous potential as a renewable energy source was recognized only after cellulose degrading enzymes (Cellulases) had been identified (Bhat and Bhat, 1997). The cellulose molecules composed of longer slander bundles of long chains of β-D-glucopyranose residues liniked by β-1,4-glycosidic bonds, called elementary fibrils, by condensation.  This is in contrast to the α-1, 4- glycosidic bonds present in starch: cellulose is a straight chain polymer. The molecule adopts an extended rod like conformation. In microfibrils, the multiple hydroxyl group on the glucose residues hydrogen bond with each other, holding the chains firmly together and contributing to their high tensile strength. This strength is important in cell wall, where they are meshed into a carbohydrate matrix, helping keep plant cells rigid (Lee, et al.,2002) POST GRADUATE PROJECT TOPICS IN BIOLOGY EDUCATION

The molecule have two regions; one of this which is called crystalline cellulose’ is composed of highly-oriented molecules and another is called amorphous cellulose’ which comprise less oriented molecules. Many of this elementary fibrils form together in microfibril, and furthermore several microfibrils  joined together form a macro fibril (Zarnea, 1994).

Compared to starch, cellulose is also much more crystalline. Given a cellulose material, the portion that does not dissolve in 17.5% solution of sodium hydroxide at 20 c is a-cellulose, which is true cellulose; the portion that dissolves and then precipitates upon acidification is B-cellulose; and the proportion that dissolves but does not precipitate is y-cellulose. The crystalline region is very difficult to break or hydrolyze because of strong bonds and also the tight packing of the cellulose structure. The region is always in orderly arrangement and waterproof. The amorphous region is solid and randomly arranged (Spano, et al.,1975).

The hydroxyl groups of cellulose can be partially or fully reacted with various chemicals to provide derivates with useful properties. Cellulose esters and cellulose ethers are the most important commercial materials. In principles, though not always in current industrial practice, cellulosic polymers are renewable resources. Among the esters are cellulose acetate and cellulose triacetate, which are film-forming and fiber-forming materials that find a variety of uses. The inorganic ester nitrocellulose was initially used as an explosive and was an early film forming material.

Annual cellulose production is estimated to be 1.5×10   tonnes. Proportion of cellulose in plant tissues  are about 20 to 40% dry weight and about 90% in cotton fiber. Most cellulose in the nature exist as waste paper. Its potential as an alternative energy source has stimulated researches on converting cellulose to soluble sugars. One of the methods is pyrolysis to biological methods such as the application of cellulase enzyme (Bharadwaj, et al., 2004).     Therefore, it has become considerable interest to develop processes for effective utilization of cellulosic waste as inexpensive carbon source. Cellulose, a widely distributed long-chain polymeric and skeletal polysaccharide carbohydrate, of beta-glucose, is the most abundant renewable natural product that can be obtained in the biosphere. It forms the primary structural component of green plant, and represents about 50% of cell wall material of plants. The primary cell wall of green plants is made of cellulose; the secondary wall contains cellulose with variable amounts of lignin. Cellulose has been used by man for ages. However, its enormous potential as a renewable energy source was recognized only after cellulose grading enzymes (Cellulases) had been identified (Bhat and Bhat,1997)                                                                                                                                        The cellulose molecules composed of longer slander bundles of long chains of ß-D-glucopyranose residues linked by β-1, 4-glycosidic bonds, called ‘elementary fibrils’ by condensation. This is in contrast to the α-1, 4-glycosidic bonds present in starch, Cellulose is a straight chain polymer. The molecule adopts an extended rod-like conformation. In microfibrils, the multiple hydroxyl groups on the glucose residues hydrogen bond with each other, holding the chains firmly together and contributing to their high tensile strength. This strength is important in cell walls, where they are meshed into a carbohydrate matrix, helping keep plant cells rigid. (Lee et al., 2002).

The cellulose molecules composed of longer slander bundles of long chains of ß-D-glucopyranose residues linked by β-1, 4-glycosidic bonds, called ‘elementary fibrils’ by condensation. This is in contrast to the α-1, 4-glycosidic bonds present in starch, Cellulose is a straight chain polymer. The molecule adopts an extended rod-like conformation. In microfibrils, the multiple hydroxyl groups on the glucose residues hydrogen bond with each other, holding the chains firmly together and contributing to their high tensile strength. This strength is important in cell walls, where they are meshed into a carbohydrate matrix, helping keep plant cells rigid. (Lee et al., 2002)

RESEARCH TOPICS IN BIOLOGY FOR UNDERGRADUATES

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