CHAPTER ONE
INTRODUCTION
Investigative bacteriology and mycology requires microorganisms to be studied within the laboratory environment. Many bacteria and fungi can be grown on culture media: a substance designed to create nutritional conditions similar to the natural environment in which the microorganism commonly survives and reproduces (Collins, 2007). Culture media is a term used to describe a complex or synthetic substance (chemically defined) found in one of two states of matter: either the liquid (broth) or solid (such as agar in a Petri dish) (Denyer, et al., 2004).
The cultivation of microorganisms on culture media is dependent upon a number of important factors including an optimal array of nutrients, oxygen or other gases, moisture, pH and temperature. Important nutrients include sources of carbon, nitrogen, inorganic phosphates and sulphur, trace metals, water and vitamins. Each nutrient is, in varying combinations, a key ingredient of microbiological culture media (Stainer et al., 2007). The nutrients function as ‘growth factors’. A growth factor is a naturally occurring substance, like an amino acid, which is capable of stimulating cellular growth, proliferation and cellular differentiation.
Microbial culture media can be of different type, depending on the nutritional growth requirements of the microorganisms. Microorganisms require about 10 macro-elements namely Carbon(C), Oxygen (O), Hydrogen (H), Nitrogen (N), Sulfur (S), Phosphorous (P), Potassium (K), Calcium (Ca), Magnesium (Mg), Iron (Fe) (Srijoni et al., 2015). The first six components are used in the synthesis of Carbohydrates, Lipids, Proteins and Nucleic acids and the remaining four exist in the cell as cations and play a variety of roles. In addition to macroelements, all microorganisms require several microelements like Manganese (Mn), Zinc (Zn), Cobalt (Co), Molybdenum (Mo), Nickel (Ni), and Copper (Cu). These are generally part of enzymes and cofactors. Microorganisms also require growth factors, which are organic compounds (Srijoni et al., 2015).
Detection and identification of the infectious agent causing disease is a highly relevant issue in microbiological diagnostics (Anjum et al., 2012). Several conventional tools (microscopy, serology, culturing of microbes and sometimes X-rays) are used to diagnose the disease. With the outcome of new pathogens and need to screen large number of clinical samples within time, these conventional techniques are not at par with time and need. Therefore, it is necessary to develop technologies which is more specific, sensitive, accurate and fast as well as can detect very small amount of pathogens in the sample. In the last twenty years, technologies based on nucleic acid amplification techniques (NAATs) have taken an irreversible position in the diagnostic field of infectious diseases.
Recent developments in modern diagnostic tools have opened a new era for a vast improvement in parasite detection. Molecular based approaches such as Qualitative Nucleic Acid Sequence Based Amplification (QT-NASBA), Loop-Mediated Isothermal Amplification (LAMP) Real-Time Polymerase Chain Reaction (RT-PCR), luminex, microarrays, metagenomics and DNA-based biosensors have shown a high potential for use in disease diagnosis with increased specificity and sensitivity (Muldrew, 2009; Petrosino et al., 2009).
Molecular techniques are major tools for the analysis of microorganisms from food and other biological substances. The techniques provide ways to screen for a broad range of agents in a single test. It has truly come of age and its range of application is perceived to broaden in the near future. The food industries, water processors, and analytical laboratories have taken up the latter method; for rapid differentiation of species, strain identification and definition of strain relatedness from infected samples. Molecular methods varies with respect to discriminatory power, reproducibility, ease of use, and ease of interpretation (Lasker, 2002).
Whilst microbiological techniques remains important in any microbiology laboratory, innovations continue to arise with new techniques recipes being formulated for the selection of new strains to the application of media in conjunction with rapid microbiological methods.
