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Exploring Microscopic World: Bacteria Characteristics, Shapes, and Economic Importance

Learn about the characteristics, shapes, and economic significance of bacteria. Discover how they obtain energy, respire, and their role in food production and biowarfare. Understand methods to prevent food spoilage.

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Exploring Microscopic World: Bacteria Characteristics, Shapes, and Economic Importance

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  1. Bacteria Domain: Bacteria and Archaea Kingdom Eubacteria and Archaebacteria (previously Monera) Crash Course: Bacteria Video

  2. Characteristics • Lack nucleus and organelles (prokaryotic) • Usually smaller than eukaryotic cells • Single cells but can form strands or clumps • Single circular piece of DNA • Reproduce by binary fission • Can divide every 20 minutes • Limited food source reduces actual rate of division

  3. Characteristics • Flagella that spins for movement • Some have pili • Shorter and thicker than flagella • Used for attachment www.ou.edu/class/pheidole/bacteria.html • Aerobic or anaerobic metabolism

  4. Classification of Bacteria • Ways Bacteria are classified • Shape – most common way to classify • Arrangement (Number/ size) • Food requirements • Oxygen requirements • How they move/number of flagella • Cell wall composition (gram staining) • Method of reproduction – rarely used

  5. Bacterial Shapes • Bacillus = rod • Coccus = round • Spirillum = spiral

  6. Bacterial Arrangement • Diplococcus = 2 round bacteria cells • Streptococcus = chains of round bacteria • Staphylococcus = cluster of round bacteria • Tetrad = 4 round bacteria in a square

  7. Bacterial Arrangement • Diplobacillus = pairs of rod shaped bacteria • Streptobacillus = chains of rod shaped bacteria

  8. Bacteria Facts • Bacteria is everywhere • The number of bacteria in the human mouth is greater than the number of people who ever lived on the earth. • Bacteriologist is a scientist who studies bacteria. • Bacteria is grown in a lab as a culture with nutrient agar (food source).

  9. Gram Staining • Used to identify the type of bacteria present • Used to determine the best antibiotic needed to kill the bacteria • Antibiotic = interferes with the life processes of bacteria • Alexander Fleming – penicillin inventor

  10. Why are bacteria so resistant? • Endospores = thick walls around bacteria during harsh conditions • Ex- low nutrients, drought, high temperatures, low temperature, etc. • Endospores will open up when conditions become more favorable.

  11. Capsule = purple outer layer Bacteria Structure • Draw a bacterial cell. Label cytoplasm, DNA, ribosomes, flagella, pili, capsule, cell wall, cell membrane

  12. Obtaining Energy (nutrition) • Photosynthetic = makes own food • Heterotrophs = obtain food from another source • Saprophytes = Eat dead organisms • Symbiotic relationships = live in close association with another organism • Mutualism = both organisms are helped • Example= sheep & cows have bacteria in stomach to aid in grass digestion • Parasitism = one is helped; other is harmed • Host = organism that is harmed

  13. Obtaining energy (nutrition) • Chemoautotrophs • Use inorganic compounds such as ammonia and hydrogen sulfide to make food • Use organic compounds such as methane to make food

  14. Respiration • Obligate aerobes - require oxygen • Obligate anaerobes – require no oxygen; oxygen will poison the bacteria and kill it • Botulism – produces toxins in improperly canned foods • Facultative anaerobes – can function with or without oxygen but will not be poisoned by the presence of oxygen

  15. Economic Importance • Pathogenic – disease causing • Examples: tuberculosis, anthrax, bubonic plague, cholera, dental cavities, lyme disease, typhus, strep throat, acne, tetanus, stomach ulcers • Food Poisoning • Botulism • E. coli (ground beef) • Food spoilage

  16. Economic Importance • Biowarfare • Food Production • Pickles, buttermilk, cheese, sauerkraut, olives, vinegar, sourdough bread, sausage • Make chemicals • Acetone, butane, medicines • Mining • Extracts minerals from impure sources • Clean up petroleum and chemical spills

  17. Preventing Food Spoilage • Refrigeration • Freezing • Drying • Salting • Canning • Heating thoroughly

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