Microbiology Introduction PDF

Microbiology Introduction Microbiology is a branch of biology deals with study of living things , ordinarily too small to be seen without microscope called Microorganisms ( M.O. ) ; which are unicellular or cell-cluster microscopic organisms. Microbiology involves study in numerous areas involvin...

Microbiology Introduction Microbiology is a branch of biology deals with study of living things , ordinarily too small to be seen without microscope called Microorganisms ( M.O. ) ; which are unicellular or cell-cluster microscopic organisms. Microbiology involves study in numerous areas involving : 1- Cell structure 2- Cell function 3- Genetics 4- Immunology 5- Epidemiology 6- Ecology Microorganisms, also called microbes. It is found in every ecosystem and in close association with every type of multicellular organisms.  Microbes are classified into groups according to evolutionary relationships , provided with standard scientific names , and identified by specific characteristics. They found as Normal flora in and on healthy human and animal’s bodies in billions of cells and even participates body functions , like degradation of intestinal contents. M.O includes archaea, bacteria, viruses, fungi, protozoa, algae, and helminths few species of M.O are harmful pathogens to human either by producing toxic compounds and enzymes or direct infection by their virulence factors. Bacteria are unicellular prokaryotic m.o which have a rigid cell wall surrounding the cell membrane that determine the shape of bacteria. Viruses are obligate intracellular parasite that don't have cellular structures. Fungi are non photosynthetic , generally saprophytic eukaryotic m.o some fungi are multicellular filamentous called molds , others are unicellular called yeast. Protozoa are single celled non photosynthetic , eukaryotic , organism that found in different sizes and shapes many protozoa are among the most clinically important parasite of human like Entamoeba and Giardia. Helminths are groups of worms that live as parasites they are multicellular , eukaryotic organisms with complex body organization.  Classification of Bacteria Classification is a method for organizing microorganisms into groups or taxa based on similar morphologic, physiologic, and genetic traits. The hierarchical classification system consists of the following taxa designations : Domains : (Bacteria, Archaea, and Eukarya) Kingdom : (contains similar divisions or phyla; most inclusive taxa) Phylum (contains similar classes; equivalent to the Division taxa in botany) Class (contains similar orders) Order (contains similar families) Family (contains similar genera) Genus (contains similar species) Species (specific epithet; lowercase Latin adjective or noun; most exclusive taxa)  Historically, bacteria or prokaryotes (pre-nucleus) included in a single domain However, with the more detailed analysis using modern techniques, this domain has now been separated into the Bacteria and the Archaea (ancient bacteria). Bacteria includes the environmental prokaryotes (blue green or cyanobacteria) and the heterotrophic medically relevant bacteria. The Archaea are environmental isolates that live in extreme environments such as high salt concentrations, jet fuel, or extreme temperatures. The third domain, Eukarya, eukaryotes (true nucleus), also includes medically relevant organisms, including fungi and parasites. There are several other taxonomic sublevels below the domains, as noted previously; however the typical application of organism classification in the diagnostic microbiology laboratory primarily uses the taxa beginning at the family designation. Family family encompasses a group of organisms that may contain multiple genera and consists of organisms with a common attribute. The name of a family is formed by adding the suffix -aceae to the root name of one of the group’s genera, called the type genus; for example, the Streptococcaceae family type genus is Streptococcus ; this family also includes other genera like Lactococcus Lactovum and peptostreptococcus. One exception to the rule in microbiology is the family Enterobacteriaceae; it is name is derived from the “enteric” group of bacteria. Genus Genus (plural, genera), the next taxon, contains different species that have several important features in common. Each species within a genus differs sufficiently to maintain its status as an individual species. Placement of a species within a particular genus is based on various genetic and phenotypic characteristics shared among the species. Microorganisms do not possess the multitude of physical features exhibited by higher organisms such as plants and animals. Species Species (abbreviated as sp., singular, or spp., plural) is the most basic of the taxonomic groups and can be defined as a collection of bacterial strains that share common physiologic and genetic features and differ notably from other microbial species. Bacterial (prokaryotic)-type species or strains are determined according to guidelines published by the International Committee for the Systematics of Prokaryotes. Species definitions are distinguished using DNA profiling, including a nearly complete 16S rRNA sequence with less than 0% to 5% ambiguity in combination with phenotypic traits. Occasionally, taxonomic subgroups within a species, called subspecies, are recognized. Nomenclature Nomenclature is the naming of microorganisms according to established rules and guidelines set forth in the International Code of Nomenclature of Bacteria (ICNB) or the Bacteriological Code (BC). It provides the accepted labels by which organisms are universally recognized. Because genus and species are commonly used by microbiologists , the discussion of rules governing microbial nomenclature is limited to these two taxa. In this binomial (two name) system of nomenclature, every organism is assigned a genus and a species of Latin or Greek derivation. Each organism has a scientific “label” consisting of two parts: the genus designation, in which the first letter is always capitalized, and the species designation, in which the first letter is always lowercase. The two components are used simultaneously and are printed in italics or underlined in script. For example, the streptococci include Streptococcus pneumonia.