BACTERIA

Natural Variation and Speciation in Bacteria

Natural Variation and Speciation in Bacteria

Introduction

Bacteria are microorganisms with an extraordinary ability to adapt to different environmental conditions. To understand the essence of this capability is important to know its genetic basis, i.e. as genetic information is organized as performed, and regulates their expression and mechanisms of genetic variation have. The infectivity of pathogenic bacteria lies in that possess the information gene required to colonize host tissues, invade and / or produce substances toxic that will cause the disease. Other hand, knowledge of genetic functioning of bacteria, added to that are easy to handle in the laboratory and have rapid growth, has permitted use to synthesize products useful in medicine for both diagnosis and for the prevention and treatment of some diseases. These possibilities have been increased with the development of genetic engineering and the availability of techniques molecular biology.

Discussion

Bacteria are microorganisms unicellular which have a size of a few micrometers (0.5 to 5 microns, usually) and various shapes including spheres (cocci), rods (bacilli) and helices (spirilla). Bacteria are prokaryotes and, therefore, unlike the cells eukaryotes (of animals, plants, and fungi), have not the nucleus defined nor present, in general, organelles membranous inmates. Generally possess a cell wall composed of peptidoglycan. Many bacteria have flagella or other displacement systems and are mobile. The study of bacteria is responsible for the bacteriology, a branch of microbiology.

Bacteria are the most abundant organisms on the planet. Are ubiquitous, found in all habitats and aquatic, grow up in the most extreme as in the hot springs and acidic in radioactive waste in the depths of both Tues and the earth's crust . Some bacteria can even survive in extreme conditions of outer space. It is estimated that there can be found around 40 million bacterial cells in a gram of land and a million bacterial cells in a millilitre of fresh water. In total, there are approximately 5 × 10 30 bacteria in the world.

Bacteria is a taxonomic kingdom comprising of sub kingdoms including “Archaea” and “Eubacteria" or, in the three-domain classification, the only kingdom in the domain Eubacteria. Bacteria are prokaryotes, most of which are single-celled and most having a rigid cell wall. They are almost universal in distribution and play many important roles as agents of decay and mineralization and in the recycling of elements such as nitrogen. Some species cause illness in animals. There are eleven principal groups: Gram-positive bacteria; purple bacteria; cyanobacteria; green non-sulphur bacteria; spirochaetes; flavobacteria; green sulphur bacteria; Planctomyces; Chlamydiales; Deinococci; and Thermatogales (Rajan, 2003, pp. 48). Bacteria grow by binary fissions. May of the bacteria reproduced by simple sexual processes called binary fissions. The bacteria are bigger in the size of all micro organisms. It could be understood by an example that the biggest virus in the smallest bacterium.

The use of antibiotics selects bacteria insensitive to the drug. Once again a rare genetic character without any adaptive advantage becomes a favourable character by the presence of a factor in the environment (in ...