Introduction to Bacteria

Transcription

1 Introduction to Bacteria USDA NIFSI Food Safety in the Classroom University of Tennessee, Knoxville 2006

2 A quick clip deos/28824/chp937402_700k.asf

3 Bacteria

4 What are bacteria? Single celled organisms Very small E. Coli O157:H7 can make you very sick. Need a microscope to see Can be found on most materials and surfaces Billions on and in your body right now Streptococcus can cause strep throat. USDA NIFSI Food Safety in the Classroom University of Tennessee, Knoxville 2006 This E. coli helps you digest food.

5 Bacteria are ALIVE! Bacteria fit all the criteria to be alive. This is in contrast to the virus. USDA NIFSI Food Safety in the Classroom University of Tennessee, Knoxville 2006

6 KINGDOMS ARCHAEBACTERIA & EUBACTERIA Most numerous organisms on earth Earliest life forms (fossils date 2.5 billion years old) Microscopic prokaryotes (no nucleus nor membrane-bound organelles)

7 Kingdom Archaebacteria Found in harsh environments (undersea volcanic vents, acidic hot springs, salty water) Cell walls without peptidoglycan Subdivided into 3 groups based on their habitat --- methanogens, thermoacidophiles, & extreme halophiles

8 Kingdom Eubacteria (true bacteria) Most bacteria in this kingdom Come in 3 basic shapes --- cocci (spheres), bacilli (rod shaped), spirilla (corkscrew shape)

9 A Good Comparison BACTERIA Cell walls that have peptidoglycan No introns Live in a wide variety of environments Lipids in cell membranes ARCHAEA No peptidoglycan in cell walls introns Live in extreme environments Unusual lipids in cell membranes. rrna that is unlike rrna of eukaryotes rrna that resembles rrna of eukaryotes Genes that are unlike eukaryotic genes Genes that resemble eukaryotic genes

10 What do they look like? Some exist as single cells, others cluster together Bacilli Cocci Spiral Cluster of cocci USDA NIFSI Food Safety in the Classroom University of Tennessee, Knoxville 2006

11 Bacteria can occur in pairs ( diplo- bacilli or cocci) Streptococcus cause infections such as strep throat Bacteria occurring in chains are called strepto- bacilli or cocci Staphylo- in clusters

12 Gram + or Gram - Staining includes: Gram positive- Have more peptidoglycan and take up the purple dye and appear purple. Gram negative-takes up red dye and appears pinkish

13 Bacteria Structure Most are made up of a cell wall, cell membrane, cytoplasm, ribosomes, DNA, small molecules, and ions. Bacterial cell walls are composed of Peptidoglycan and not cellulose like plants.

14 Some bacteria have a tough outer coating that helps to keep it from dying and it can withstand drying out. It is revived when conditions are good. Once type is C. botulinum or botulism found in foods. Food poisoning is fatal if not treated properly.

15 How do bacteria reproduce? Grow in number not in size Humans grow in size from child to adult Make copies of themselves by dividing in half Human parents create a child USDA NIFSI Food Safety in the Classroom University of Tennessee, Knoxville 2006

16 Reproduction in Bacteria Reproduction is by an asexual process called binary fission. During this process, the DNA replicates and attaches to the plasma membrane. Then the cell divides and a bacterial cell wall forms. Although there is no true sexual reproduction in bacteria, there are processes including transformation, conjugation, and transduction which allow for the exchange of genetic information

17 Recombination- They share DNA by either Transformation (DNA comes from outside), Conjugation (Use pili to share DNA in a sexual repro.) Transduction (Using Viral DNA)

18 No true sexual form of reproduction however Bacteria use pili for attachment to substates and conjugation, as shown here

19 Binary Fission- asexual reproduction Where DNA replicates and DNA molecules are pulled to different ends and the cell pinches in two. Pg 471 Sketch

20 How do bacteria eat? Some make their own food from sunlight like plants Photosynthetic bacteria Some are scavengers Share the environment around them Example: The bacteria in your stomach are now eating what you ate for breakfast Some are warriors (pathogens) USDA NIFSI Food Safety in the Classroom University of Tennessee, Knoxville 2006 They attack other living things Example: The bacteria on your face can attack skin causing infection and acne Harmless bacteria on the stomach lining E. Coli O157:H7 is a pathogen

21 End Day 1

22 Movement Some bacteria move about their environment by means of long, whiplike structures called flagella.

23 Spiral Motion: In helix shaped bacteria. Moves similar to a cork screw.

24 Slime gliding: Cells secrete slimy threads that anchor to the host. As the cell continues to secrete a slime layers build up and the bacteria is able to glide around. Others have no movement

25 Some Terms. Pathology is the study of diseases. Exotoxins are toxins that bacteria secrete. EX: Tetanus Endotoxins are toxins that the outer membrane of E.coli releases once the cell dies. These cause fever, aches, diarrhea, weakness, hemorrhage.

26 Where do you get a pathogen? Indirect contact Foods that could be contaminated Contact with people who are sick Direct or indirect Food, Water, or other Surfaces that are contaminated USDA NIFSI Food Safety in the Classroom University of Tennessee, Knoxville 2006 Direct contact

27 A Closer Look Where do you get a pathogen Indirect Contact Direct Contact Foods and water may be contaminated USDA NIFSI Food Safety in the Classroom University of Tennessee, Knoxville 2006

28 Are all bacteria pathogens? No, most are harmless Some are even helpful Examples of helpful bacteria: Lactobacillus: makes cheese, yogurt, & buttermilk and produces vitamins in your intestine Leuconostoc: makes pickles & sauerkraut Pediococcus: makes pepperoni, salami, & summer sausage USDA NIFSI Food Safety in the Classroom University of Tennessee, Knoxville 2006

29 A Closer Look Helpful Bacteria Pediococcus - used in production of fermented meats Lactobacillus casei found in human intestines and mouth to improve digestion Leuconostoc cremoris used in the production of buttermilk and USDA NIFSI Food Safety in the Classroom University of Tennessee, Knoxville 2006 sour cream Lactobacillus bulgaricus used in the production of yogurt

30 What are some common pathogens? Pathogenic E. coli (like O157:H7) Found in ground beef, contaminated fruits and vegetables E. coli O157:H7 Salmonella Found in raw meats, poultry, eggs, sprouts, fruit and vegetables Salmonella Listeria Found in deli foods, lunch meats, smoked fish and vegetables USDA NIFSI Food Safety in the Classroom University of Tennessee, Knoxville 2006 Listeria

31 Bacteria can also destroy body tissues. Antibiotics affect a bacteria cell s normal functions. Penicillin blocks the ability to make new cell wall Tetracycline blocks proteins synthesis Overused antibiotics has lead to Antibiotic Resistance. Why must you always finish your WHOLE cycle of antibiotics? FYI: A disease that can go from animal to human is a Zoonosis.

32 What are biological weapons? Journal Entry Pg 39 Brief History and Definition. What are examples? Future of weapons? What do you think about them? List at least two sources o4/kortepeter.htm

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