Classification of Microorganisms PDF

Classification of Microorganisms B Y M R. A LT A Y I B Z A K A R I A MSC IN MEDICAL MICROBIOLOGY By the end of this presentation every one should understand the following characteristic : 1. Classification of microorganisms 2. Classification of Bacteria 3. Classification of Fungi 4...

Classification of Microorganisms B Y M R. A LT A Y I B Z A K A R I A MSC IN MEDICAL MICROBIOLOGY By the end of this presentation every one should understand the following characteristic : 1. Classification of microorganisms 2. Classification of Bacteria 3. Classification of Fungi 4. Classification of viruses The five main types of microorganisms are: Bacteria: Archaea: Fungi: Protists: Viruses: Classification of Microorganisms : Microorganisms are classified based on a variety of characteristics as : 1. Cell structure 2. Metabolism 3. Genetics. 1. Classification of microorganisms is by their cell structure. A. Prokaryotes: Prokaryotes do not have a nucleus or other membrane-bound organelles. Their DNA is located in a region of the cytoplasm called the nucleoid. Bacteria and archaea are both prokaryotes. B. Eukaryotes: Eukaryotes have a nucleus and other membrane-bound organelles. Their DNA is enclosed within the nucleus. Fungi, protists, and animals are all eukaryotes. 2. Classification of microorganisms is by their metabolism:  Metabolism is the process of converting food into energy and building new cell materials. 1. Autotrophs:  Autotrophs can produce their own food using sunlight or chemicals.  Plants and algae are both autotrophs. 2. Heterotrophs:  Heterotrophs must consume other organisms or their products for food.  Animals, fungi, and bacteria are all heterotrophs. 3. Classification of microorganisms based on their genetics :  Genetics is the study of how genes are passed from one generation to the next. 1. Domain:  The highest level of taxonomic classification is the domain.  There are three domains of life: 1. Archaea 2. Bacteria 3. Eukarya. 2. Kingdom: The kingdom is the next level of taxonomic classification. There are six kingdoms of life: I. Archaea II. Bacteria III. Fungi IV. Plantae V. Animalia VI. Protista. 3. Phylum:  The phylum is the next level of taxonomic classification. 4. Class:  The class is the next level of taxonomic classification. 5. Order:  The order is the next level of taxonomic classification. 6. Family:  The family is the next level of taxonomic classification. 7. Genus:  The genus is the next level of taxonomic classification. 8. Species:  The species is the lowest level of taxonomic classification.  For example, the scientific name of the bacterium that causes Escherichia coli (E. coli) is Escherichia coli.  Escherichia coli is a member of the genus Escherichia, the family Enterobacteriaceae, and the kingdom Bacteria  Classification of Bacteria Bacteria are classified according to a variety of criteria, including: 1. Shape: A. Spherical (cocci) B. Rod-shaped (bacilli) C. Spiral (spirilla), or comma-shaped (vibrios). 2. Cell wall composition: I. Gram-positive : have a thick cell wall made of peptidoglycan II. Gram-negative : have a thinner cell wall with an outer membrane. 3. Mode of respiration: A. Aerobic (require oxygen to breathe) or B. Anaerobic (can breathe without oxygen). 4. Mode of nutrition: A. Autotrophs (make their own food) B. Heterotrophs (consume other organisms for food).  Classification of fungi: Morphologically we have three types of fungi: 1. Filamentous fungi. 2. Yeast and yeast - like fungi. 3. Dimorphic fungi. 1. Filamentous fungi: e.g. moulds Are tube like structure know as hyphae they grow by enlongation of terminal part of hypha. 2- Yeast: Are unicellular organisms that are round to oval. range in size from 2-60 µm, consist of one cell.  some are capsulated while another not. 3- Dimorphic fungi: Group of fungi  appear filamentous at 22-26 oc  or yeast 37oc. Depend upon temp.  (Thermally diamorphism) e.g: Histoplasma capsulatum.  Blastomyces dermatitids. Classification of Virses : Viruses can be classifies according to : 1. Virion morphology: including size, shape, type of symmetry presence or absent of envelope. 2. Virus genome properties. 3. Virus protein properties. 4. Biological properties. 5. Genome organization & Replication properties. 6. Antigenic properties  According to ICTV more than 30,000 different virus isolated and grouped in more than 3,600 species, in 164 genera and 71 families.  A virus family may consist of members that replicate only in vertebrates, only in invertebrates, only in plants, or only in bacteria. Families (viridae) based on virion morphology genome structure, & strategies of replication. Genera:  (virus) based on physiochemical or serologic deference. Order (-virales)  Family (-viridae) - Subfamily (-virinae) - Genus (-virus) - Species Exa: Order Mononegavirales - Family Filoviridae - Genus Filovirus - Species: Ebola virus Zaire Classification of viruses by Nucleic acid : 1. Major DNA viruses : ssDNA 1- Parvoviridae dsDNA 2- Papovaviridae. 3- Adenoviriade. 4- Herpesviridae 5- Iridoviriade 6- Poxviridae 2. Major RNA viruses: dsRNA 1- Reoviridae ssRNA 2- Picornaviridae 3- Togaviridae 4- Orthomyxoviridae 5- Paramyxoviridae 6- Rhabdoviridae 7- Retroviridea. 8- Coronaviriade. 9- Arenaviridae THANK YOU