CHAPTER ONE
1.0 INTRODUCTION
Proteins play key roles in cell structure, physiology, and metabolism, and the amino acids that build up proteins are therefore nutritionally important compounds for all living organisms. Together, the twenty common protein-forming L-amino acids represent a variety of different characteristics and chemical properties, and almost all of them have commercial interest (Kumagai, 2000). The importance of amino acids cannot be over emphasized, as the primary metabolites do not only play the role of building blocks of proteins, cells, tissues, intermediate of the genetic pathway, animal feed additives (lysine, methionine, threonine), flavor enhancers (aspartic acid, monosodium glutamate, serine), ingredients in cosmetic and medicinal products and as specialty nutrients in the medical field (Kalin et al.,2013), but also form antibodies to resist foreign antigens such as bacteria and viruses that could be pathogenic to host cell (Ali, 2008). Amino acids are part of the enzyme, hormonal system and of nucleoproteins (RNA and DNA), carry oxygen throughout the body and participate in muscle activity (Uchefuna et al., 2016).
Out of the twenty naturally occurring amino acids, nine of the amino acids cannot be synthesized by higher animals and humans and must therefore be supplied in food or feed. These are the so-called essential amino acids, and lysine belongs to this class. Its major commercial form is L-lysine Monohydrochloride (L-lysine-HCL). Good sources of lysine are foods rich in protein like meats, cheese, certain fish, nuts, eggs, soyabeans (Ezemba et al., 2014a). In addition to the worldwide demand for L-lysine as a feed supplement for the pig and poultry industries, there is an ongoing exploitation of new applications for this amino acid, including in pharmaceuticals and cosmetics. L-Lysine has also been used for preventing atherosclerosis and to treat certain viral infections (Sanchez and Demain, 2008).
L-Lysine is nutritionally important to man and animals and can be used to supplement food and food materials especially cereal products to improve protein quality (Dutta and Ottaway, 1976). Tosaka et al. (1993) reported that since these cereal products contain only small quantities of lysine, poultry, cattle and other livestock unable to synthesize this amino acids must have lysine added to their feed stuff to provide adequate diet. Children and growing animals require high levels of lysine, for bone formation, adequate milk production and proper growth. Lysine also has some pharmaceutical application in the formulation of diets with balanced amino acid composition and in amino acid infusion (Shan et al., 2002). L-Lysine is the common protein-forming form of lysine and has, by far, the highest commercial value of the different lysine forms (Ezemba et al., 2014a). L-Lysine is one of the essential amino acids for higher animals and is widely used as a feed additive for swine and poultry. The protein in traditional feedstuffs such as corn, wheat, and barley has low lysine content, and in order to increase feed efficiency, pure L-lysine is added.
Since L-lysine is of great importance and the worldwide market is growing, there is constant effort aimed at improving the L-lysine fermentation processes, including development of better production strains, better fermentation processes, media optimization and downstream processing (product separation and purification) (Ezemba et al., 2014b). Accordingly, the bulk of research has focused on development of efficient methods for production of L-lysine, in particular on understanding and improving production capacities of L-lysine-producing bacteria, as well as development of efficient fermentation and downstream processes (Schrumpf et al., 1992; Ekwealor and Orafu, 2003).
Aim of the Research Work
- Bacteria organisms producing lysine from soil and fruit samples.
Specific Objectives of the Research Include:
- Isolation and characterization of bacteria from soil and fruits.
- Screening for lysine producers on solid agar medium.
- Identification of the organisms using biochemical tests.
