CHAPTER ONE
INTRODUCTION
1.1 Background of the Study
Environment is a comprehensive term, which comprises of all the factors which make up the surroundings. The air that one breathes, the land on which one lives, the water one drinks and all the living and non-living things that are part of the surroundings are referred to as the environment1. Environments are components of ecosystems. An ecosystem is a community of micro-organisms and their physical and chemical environment that functions as an ecological unit. The ecosphere or biosphere, organise the entirety of living organisms on Earth and the abiotic surroundings they occupy. It can be divided into atmosphere, hydrosphere and litho-ecosphere to define the shares of the global expense inhabited by living things in air, water and soil environments respectively. The environment has rendered a significant contribution in the evolution of the biological spectrum by the process of natural selection and elimination. The environment has influenced and structured the lives of the individuals since ancient past.
Notably, within the environment, there are presence of micro-organisms. Micro-organisms lives within the habitats of the ecospheres. The habitat is one component of a comprehensive concept of the ecological niche, which includes not only where an organism lives but also the functions it performs. The niche is the functional role of an organism within an ecosystem. Micro-organisms may be autochthonous or indigenous or allochthonous or foreign. Micro-organisms, by their omnipresence, have an influence upon the entire biosphere. They are present in essentially all of the planet's environments, including some of the most extreme, from acidic lakes to the deepest ocean, and from frozen environments to hydrothermal vents. Microorganisms are found in each of the three domains of life: Archaea, Bacteria, and Eukarya2.
Bacteria and their phages are the oldest and most abundant life forms on the planet. Bacteria are single-celled, or simple, organisms. Though small, bacteria are powerful and complex, and they can survive in extreme conditions. Bacteria are also instrumental for understanding fundamental life processes that are required by all organisms, including central metabolism, replication, transcription, translation, protein targeting, assembly and structure of macromolecular complexes, protein folding, stress responses, error correction mechanisms, signal transduction, and developmental programs. These processes are more easily characterized in model bacteria and their phages than in other organisms because microbes provide such tractable experimental systems. The large repertoire of genetic and biochemical tools and data that have been acquired from basic research on bacteria is crucial for dissecting the complex metabolic and regulatory networks that control these processes3. Although we also live in an environment replete with bacteria that can cause a wide variety of human diseases, bacteria have been proven to be of environmental benefit this is because they make possible the continued existence of green plants and therefore of animals because the plants are the only source of food for animals.