• Nutritional requirements of bacteriaare much like ours - including sugars, amino acids, vitamins and minerals;
• Bacteria are 80-90% water - too much water flowing into or out of the cell can kill it
• Most bacteria require organic material as food - parasites feed on living organisms, saprophytes feed on non-living organic material
• Some bacteria obtain their energy from inorganic substances (e.g. many soil bacteria) - called autotrophic (self-nourishing).
• Most bacteria thrive aroundhuman body temperature ( 97°- 99°F) - Although some prefer cold (even freezing) temperatures, others need very hot temperatures (even up to 660°F at cracks in the ocean floor). Each has its own narrow range of temperature in which it can survive.
• Most bacteria thrive in a pH range that is slightly more and less than water (pH 6.5-7.5) - but others can live in a pH more acidic than battery acid
| Terms used to describe O2 ReQUIREMENTS for Microorganism GROWTH/REPRODUCTION | |||
|---|---|---|---|
| Group | Environment | Oxygen (O2) Effect | |
| Aerobic | Anaerobic | ||
|
Obligate Aerobe |
Growth |
No growth |
Required (utilized for aerobic respiration). E.g. bacillus; humans are also obligate anaerobes |
|
Microaerophile |
Growth if level not too high |
No growth |
Required but at levels below 0.2 atm; E.g. H. Pylori, Lactobacilli, Camphylobacter |
|
Aerotolerant Anaerobe |
Growth |
Growth |
Not required and not utilized. Lactobacillus natural gut flora |
|
Facultative Anaerobe (Facultative Aerobe) |
Growth |
Growth |
Not required for growth but prefer to use oxygen when available (for efficiency). E.g. E. Coli, Staphylococcus |
|
Obligate Anaerobe |
No growth |
Growth |
Die in presence of oxygen (and other oxidants). E.g. Clostridium (however, C. tetani, C. botulinum, C. Perfringens, C. difficile can produce endospores, allowing dormancy/safety); inefficient energy producers; infect areas of body devoid of oxygen; some use nitrogen compounds to obtain energy; most intestinal bacteria are anaerobes |
