Over the last decade, resistance to antibioties antihintice ha BACTERA BACTERIA

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Over the last decade, resistance to antibioties antihintice ha BACTERA BACTERIA LABORATORY 2B Bacteria have a very simple structure yet are a diverse group of organisms capable of performing amazing tasks. Many are beneficial, most are harmless. Working with a partner, prepare wet mounts of bacteria from the various live culures available. View these using a compound microscope removed from the microscope cabinet and set up at your desk. Industrial Applications: Throughout the ages, humans have utilized the metabolic machinery of heterotrophic bacteria to ferment foods as a means of preserving them for later use (eg, sauerkraut kimchi, pickles). Several nutritious products including yogurt result from the fermentation of milk. To make yogurt, several species of bacteria are added to a sealed container of milk. In this nutrient-rich, but oxygen-poor environment, bacteria obtain the energy they need to survive and reproduce by breaking down the sugars (lactose) found in milk. As a byproduct of that activity, lactic acid is formed and the pH of the environment drops (becomes acidic). In response to increasing acidity, the solution sours (producing a tart taste) and thickens as milk proteins change shape (denature). Not only is yogurt an excellent source of protein, vitamins and calcium; as a probiotic, it supplies your digestive system with beneficial bacteria. To examine bacteria used in fermenting milk, (1) scoop out a small amount of yogurt with a toothpick and spread it thinly onto a microscope slide, (2) add a drop of water (or drop of methylene blue if you are unable to see any bacteria on the first go-round) followed by a cover slip, and (3) view the sample using the lowest magnification to start with and then work your way up to the 40x objective. Draw, label and describe what you see in Figure 2B.2. Be sure to indicate total magnification. Figure 2B.2 Heterotrophic Bacteria in Yogurt Bacteria Found in Yogurt (magnification x) Bacteria speciesCell Shape(s)*Description S, thermo phavs, and L Csp coccus, spiriliomActive bacteria cultures as indicated on the yogurt label Do the names of the bacteria found on the yogurt label fit with the cell shapes that you observed? Okbhartney

Explanation / Answer

Fig 2B.2 Answer

-bacteria found in yoghurt - streptococcus thermophilous, lactobacillus belgaricus

- cell shape - round ( dots )

- description- spread out small dots

- magnification-40 x

Fig 2B.3 answer

- cells are arranged in chain pattern or beads pattern

-shape - barrel shaped

- pigmented ( red-green i.e. brown color)

- cells are of different in size . Some are small and some are larger

Fig 2B.4 answer

- cells are arranged diffusely and parallely

- cells are spiral in shape

- pigmented- blue color

- they are different in length .

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