+ BACTERIA CLS 311: Basic Microbiology Mrs. Amany Ahmed Niazy

+ Bacteria are the smallest and most versatile independently living cells known.

+ Microorganisms Acellular Cellular ProkaryotesEukaryotes Archaea Bacteria Viruses Protozoae Fungi.

+ History Anton van Leeuwenhoek ( ): He is the father of microbiology. Known for his invention of the single-lens microscope. Bacteria were first observed by him in 1676.

History Louis Pasteur ( ). discoveries helped to formulate “germ theory of disease”. Invention of pasteurization.

+ History Robert Koch ( ): German physician. He confirmed the germ theory of disease. He became famous for isolating Bacillus anthracis, the Tuberculosis bacillus and Vibrio cholerae and for his development of Koch's postulates. He won a Nobel Prize on Monument to Robert Koch in Berlin

Prokaryotes There are two major types of prokaryotes: 1. Bacteria. 2. Archaea (also called archaebacteria) are often found in extreme environments (Oxygen-free environments concentrated salt-water hot, acidic water), and while they are clearly prokaryotic, they have evolved separately from bacteria.  Prokaryotic cells possess simpler structures than eukaryotic cells, since they do not have a nucleus or many cytoplasmic organelles.

+ Bacteriology It is a branch of microbiology that is concerned with bacteria Bacteria – single celled organism that multiply by binary fission Larger and more complex than viruses Viable under light microscope Prokaryotic, has both DNA and RNA

Introduction Bacteria (plural), Bacterium (singular). Bacteriology  The study of bacteria. Bacteria are unicellular microscopic prokaryotes. Bacteria are ubiquitous in every habitat on Earth, growing in soil, acidic hot springs, radioactive waste, water, and deep in the Earth's crust, as well as in organic matter and the live bodies of plants and animals. Bacteria are vital in recycling nutrients such as the fixation of nitrogen from the atmosphere and decomposition of dead organic materials.

Morphological features of bacteria Size Unit of microbial measurement is the micrometer (  m), formerly micron (  ) which is equal to: 1  m = 1/1000 of a millimeter (mm) Average size of the bacteria generally varies from 0.5 – 2  m in diameter and 2 – 8  m in length.

+ Fundamental Shapes Bacilli (bacillus, singular) – rod shaped organisms Cocci (coccus, singular) – spherical or round organisms Spirilla (spirillum, singular) – spiralled or comma- shaped organisms Bacilli Cocci SPIRILLUM

+ Bacterial Arrangements Two factors that affect bacterial arrangements: Plane of division Position taken after cell division

Pairs: – diplococci (e.g. N.gonorrheae) DIPLOCOCCI

Chains – streptococci, STREPTOCOCCI

Grapelike clusters – staphylococci STAPHYLOCOCCI

Groups of four – tetrads (e.g., Peptococcus) TETRADS

Packets of eight – cuboidal (e.g., Sarcinae) PACKETS OF EIGHT

Palisades (slipping) – organisms tend to place themselves side by side (e.g., Corynebacterium) PALISADES

+ CLASSIFICATION and TAXONOMY

+ What is Taxonomy Greek words “taxes” – arrangement, “nomos” – law The science of classification. The branch of biology concerned with the classification of organisms into groups based on similarities of structure, origin, etc.

+ Classification of Organisms Based on the is based on similarities and differences in genotypes and phenotypes Microbiologist traditionally emphasize placement and naming of bacterial species into three categories Family (similar to Human clans) Genus (equivalent to human last name) Species (equivalent to human 1 st name)

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+ Nomenclature Nomenclature provides naming assignments for each organism. Assignment of names for purposes of communication and identification Use a binomial systems of nomenclature Standard rules for bacterial names: The name of the family is CAPITALIZED and has an aceae ending (ex:Enterobacteriaceae) Binomial nomenclature Genus & species Escherichia coli Genus name is always capitalized Species name is never capitalized coli Both names are always either italicized or underlined Abbreviation: E. coli

+ The plural of genus is genera and there are many genera in the family Enterobacteriaceae Ex: Famliy: Enterobacteriaceae Genus: Escherichia Species: coli

The International Committee on Systematic Bacteriology (ICSB) maintains international rules for the naming of bacteria and taxonomic categories and for the ranking of them in the International Code of Nomenclature of Bacteria. Kingdom Bacteria Phylum Proteobacteria Class Gamma Proteobacteria Order Enterobacteriales Family Enterobacteriaceae Genus Escherichia Species Escherichia coli e.g. Escherichia coli

+ Identification Application of classification & nomenclature to assign proper name to unknown organism and place it in its proper position within classification system.