Aerobic and anaerobic bacteria can be identified by growing them in test tubes of thioglycollate broth: 1: Obligate aerobes need oxygen because they cannot ferment or respire anaerobically. They gather at the top of the tube where the oxygen concentration is highest. What device could you use to cultivate anaerobicRead More →
Azotobacter species are free-living, nitrogen-fixing bacteria; in contrast to Rhizobium species, they normally fix molecular nitrogen from the atmosphere without symbiotic relations with plants, although some Azotobacter species are associated with plants. Is Azotobacter anaerobic? Nitrogen Fixing Bacteria: Azotobacter, Beijerinckia and Clostridium (anaerobic) are saprophytic bacteria that perform organic processes.Read More →
Azotobacter species are free-living, nitrogen-fixing bacteria; in contrast to Rhizobium species, they normally fix molecular nitrogen from the atmosphere without symbiotic relations with plants, although some Azotobacter species are associated with plants. What are the examples of nitrogen-fixing bacteria? Nitrogen-fixing bacteria examples comprise Rhizobium (formerly Agrobacterium), Frankia, Azospirillum, Azoarcus, Herbaspirillum,Read More →
At ambient pressure, lysozyme is completely inactive against most gram-negative bacteria because it cannot penetrate the outer membrane to reach its target, the peptidoglycan. … However, pressure apparently stimulates passage of lysozyme through the outer membrane of several gram-negative bacteria. How do bacteria evade lysozyme? Pathogenic bacteria resist the bacteriolyticRead More →
Gram-positive cocci (streptococci and staphylococci) are the most commonly identified organisms in deep neck infection. The retropharyngeal space extends into the thorax. What is found in gram-positive bacteria? Gram-positive organisms have a thicker peptidoglycan cell wall compared with gram-negative bacteria. It is a 20 to 80 nm thick polymer whileRead More →
Bacteria grow most rapidly in the range of temperatures between 40 °F and 140 °F, doubling in number in as little as 20 minutes. This range of temperatures is often called the “Danger Zone.” To learn more about the “Danger Zone” visit the Food Safety and Inspection Service fact sheetRead More →
Why it matters: Bacteria are among the fastest reproducing organisms in the world, doubling every 4 to 20 minutes. How long does it take for germs to get on a surface? Infectious particles have been detected on both surfaces for up to 72 hours. Because virus numbers can’t increase onRead More →
Put 0.5ml bacterial culture in a sterile eppendorf tube. Add 0.5ml of sterile 80% (v/v) glycerol soution. Freeze on dry ice or directly into –70oc . Store at –70oC. Cells are best for about 4-6 months, but will probably work ok for a whole year. How will you prepare glycerol?Read More →
Bacterial endospores. Head of sperm. Cryptosporidium parvum. Isospora belli. Cyclospora cayetanensis. Taenia saginata eggs. Hydatid cysts. Sarcocystis. What color would a gram-negative bacteria be in an acid-fast stain? Gram-negative cells will be stained pink by the safranin. This dye has no effect on Gram-positive cells, which remain purple. Obtain twoRead More →
Antonie van Leeuwenhoek used single-lens microscopes, which he made, to make the first observations of bacteria and protozoa. His extensive research on the growth of small animals such as fleas, mussels, and eels helped disprove the theory of spontaneous generation of life. When did they discover bacteria? Two men areRead More →