Chapter 17: Fermentation: Desirable Effects of Microorganisms
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Define microbiology.
the study of living organisms too small to be seen by the unaided human eye
Define microorganisms.
Organisms that are only visible through a microscope
What are the characteristics of microorganisms?
They multiply rapidly, and transfer easily from one surface to another (cross- contamination)
What is cross-contamination?
transfer easily from one surface to another (cross- contamination)
What are the microorganisms that have positive use in foods?
bacteria, yeasts, and molds
Bacterias are members of what kingdom? Yeasts and molds?
Bacteria: Monera Yeasts + molds: Fungi
What do microorganisms depend on to grow and multiply?
Outside sources
Are bacteria single-celled or multiple-celled?
single-celled organisms
How does bacteria multiply?
Cell division
Describe the cells of bacteria?
Their cells have no nucleus and are filled with a gelatinous liquid called cytoplasm
How long is bacteria?
3 micrometers long
How is bacteria classified?
by shape, cell wall structure, and oxygen needs
Name the 3 basic shapes of bacteria.
– Bacilli have a rod shape – Cocci have a spherical shape – Spirilla have a spiral shape
Name the 2 types of cell wall structures of bacteria.
• Gram-positive bacteria turn violet - Gram-negative turn red
How are the cell wall structures of bacteria identified?
by the ability to be stained by a crystal violet dye, called Gram’s stain
Name the 3 categories of bacteria based on oxygen needs.
– Aerobic bacteria must have oxygen to function – Anaerobic bacteria function best in an oxygen-free environment – Facultative bacteria can function in either type of environment
What kind of bacteria spoils cabbage? What prevents the aerobic bacteria to grow?
• Aerobic bacteria • submerging cabbage in salt water does not allow aerobic bacteria to grow
Aerobic bacteria in cabbage can multiply and develop what?
the flavor and texture of sauerkraut
What do bacterial growth rates depend on?
pH, air, temperature, and nutrients
Define fungus.
a plant that lacks chlorophyll
Are fungi single-celled? Do they have a nucleus?
– are not always single-celled – have a nucleus in their cells
What is the function of fungus in nature?
widely distributed in nature and help organic matter decay
Give examples of fungus.
mushrooms, molds, mildew, rust, and yeast
How is fungi classified?
by their structure and reproduction methods