Week 3 - Bacterial growth and replication, including yield and responses to nutrient availability Flashcards
Energy source = light
Carbon source = carbon dioxide
= photoautotroph
• plants, algae, and cyanobacteria
• use H2O to reduce CO2, producing O2 as a side product
• photosynthetic green sulfur and purple sulfur bacteria do not use H20 nor produce O2
Energy source = chemical compounds
Carbon source = carbon dioxide
= chemoautotrophs
• hydrogen, sulfur, and nitrifying bacteria
Energy source = light
Carbon source = organic compounds
= photoheterotrophs
• green nonsulfur and purple nonsulfur bacteria
Energy source = chemical compounds
Carbon source = organic compounds
= chemoheterotrophs
• aerobic respiration - most animals, fungi, and protozoa, and many bacteria
• anaerobic respiration - some animals, protozoa, and bacteria
• fermentation - some bacteria and yeasts
Growth
increase the number of cells
Binary fission
cell division following enlargement of a cell to twice its minimum size
• duplicates that are identical
Generation time
time required for microbial cells to double in number
• depends on many factors
During cell division, each daughter cell
receives a chromosome and sufficient copies of all other cell constituents to exist as an independent cell
Reproduction in prokaryotes
- binary fission
- budding
- conidiospores (actinomycetes)
- fragmentation of filaments
Growth requirements
- physical
* chemical
Physical growth requirements
- temperature
- light (energy)
- pH
- osmotic pressure
Chemical growth requirements
• gases (CO2) -not all breathe oxygen (eg sulfur dioxide) • chemicals - organic (solids) - inorganic
Physical requirements - temperature
- maximum growth temperature
- optimum growth temperature
- minimum growth temperature
Hyperthermophiles
65 - 110 C
Thermophiles
40 - 70 C
Mesophiles
10-50 C
• environmental pathogens of humans
Psychrotrophs
0 - 30 C
Psychrophiles
-10 - 20 C
Temperatures in this range destroy most microbes, although most temperatures take more time
~62 to 130 C
Very slow bacterial growth
~52 - 62C
Rapid growth of bacteria
some may produce toxins
15 - 52 C
Many bacteria survive, some may grow
~5 - 15 C
Refrigerator temperatures
may allow slow growth of spoilage bacteria, very low pathogens
0 - 5 C
No significant growth below freezing
-30 - 0 C