Microorganisms Chapter 24 Bacteria

Microorganisms Defined Microorganisms can be defined as those unicellular and multi-cellular organisms too small to be seen with the naked eye. Microorganisms are thought to be the descendants of the first living organisms on earth. Microorganisms are thought to have started life as ocean dwellers that utilized organic nutrients gathered from the ocean for their existence.

Microorganisms Defined Evidence suggests that these first organisms were small, uncomplicated, lacked membrane bound organelles and did not have a nucleus.

Classification of Microorganisms In the 6 kingdom system the prokaryotes called bacteria are grouped in 2 kingdoms Eubacteria and Archaebacteria The kingdom Protista are composed of two major types of organisms Monerans and Algae The kingdom Fungi are made up of Molds, Yeasts and Lichens

Science of Microbiology Dedicated to the study of the organisms, their relationship to other organisms and the environment and the impact microbes have on the health and well being of the human population.

Microbiologists Scientists who study ‘Microbes” and enable us to develop an understanding of how microbes effect our world. Specialized by the type of microbe they study Bacteriologist-Bacteria Virologist-Viruses Mycologists-Fungi

Tools of the Microbiologist The main tools of the microbiologist are The light microscope Electron microscope Instruments used to grow microorganisms for study Incubators Petri Dishes Nutrient Agar Stains to locate and identify microorganisms

Kingdom Archaebacteria Make up group of bacteria called “Extremeophiles. Archaebacteria lack peptidoglycan in their cell walls and posses unusual lipids in their cell walls. Methanogens-acquire energy from the conversion of H2 and CO2 into methane gas. Halophiles-salt loving bacteria, use salt to generate ATP. Thermoacidophiles-live in extreme acidic/hot environments. (temperatures up to 230 F)

Kingdom Eubacteria 3 Basic Shapes Bacilli-bacteria that have rod shapes Cocci-Bacteria that are spherical in shape Spirilla-Bacteria that are spiral in shape Cocci that occur in chains are called Streptococci and those that occur in bunches are called Staphylococci

Kingdom Eubacteria Divided into 2 groups based on their response to a technique called the Gram Stain. Bacteria that stain purple are called Gram Positive. Bacteria that do not take up the stain and appear pink are called Gram Negative. These bacteria can also be differentiated by how they respond to antibiotics.

Bacteria Groups -4 Phylum Cyanobacteria-Cyanobacteria use photosynthesis to produce the energy that they need the by product is oxygen. Spirochetes-Spiral Shaped bacterium Treponema pallidum responsible for the sexually transmitted disease Syphilis Gram Positive Bacteria-Actinomycetes grow in soil and produce antibiotics that inhibit or kill other organisms Proteobacteria-Enteric (Escherichia coli) Chemoautotroph-extract energy from minerals and gases Example Rhizobium-Nitrogen fixing bacteria, get energy from nitrogen gas in the atmosphere.

Bacterial Structure 1. Cell Wall-made up of peptidoglycan Cell Membrane and Cytoplasm Capsules and Pili Capsule- outer covering that protect it from drying and harsh chemicals Pili-hair like surface structure that help the bacterium adhere to the cells of the host. Also use to transfer genetic information from one bacterium to another. Endospore-thick outer covering that protects the bacteria when exposed to harsh environmental conditions.

Movement Flagella are use to move bacteria. Bacteria may have 1 or a tuft of flagella Spiral shaped bacteria use corkscrew movements Some bacteria secrete a slime coat to glide through

Nutrition and Growth Bacteria may be heterotrophic or autotrophic. Autotrophs-Photoautotrophs obtain energy from the sun. Chemoautotroph-obtain energy from minerals in the environment. Heterotrophs Saprophytes-obtain energy from dead and decaying material.

Oxygen Requirements Obligate Anaerobes-cannot live in the presence of oxygen-Ex. Clostridium tetani Facultative anaerobes-can live with or without oxygen. Obligate Aerobes-cannot survive without oxygen. Ex. Mycobacterium tuberculosis

Genetic Recombination A. Transformation-DNA taken in from the external environment. B. Conjugation-Pilus connects two bacterium forming Conjugation bridge for the exchange of genetic material. C. Transduction-Replication of DNA fragments within a virus inside a bacterium.

Bacteria and Disease The study of diseases is called Pathology Bacteria cause disease by the release of poisons called Toxins.

Bacterial Toxins-2 kinds Exotoxins-bacterial excretions into the surrounding environment-Tetanus Endotoxins-toxins released as result of the death and disintegration of bacteria. Cause of body ache, weakness and fever.

Antibiotics Antibiotics are drugs that destroy bacteria by interfering with either the structure or function of the bacterium Two common antibiotics are Penicillin-bacterial cell wall synthesis Tetracycline-bacterial protein synthesis

Useful Bacteria Bacteria are used beneficially in Sewage treatment The recycling of dead organisms Processing foods Yogurt, Cheeses, Sour Cream, Alcoholic Beverages Pesticides Clean up of environmental disasters