Microbial Growth “ Because individual cells grow larger only to divide into new individuals, microbial growth is defined not in terms of cell size but as the increase in the number of cells, which occurs by cell division."
Temperature Optima Also Psychrotrophs & Thermodurics
Thermophiles A large channel draining from a hot pool, containing carotenoid-rich microorganisms. The temperature of this channel in the foreground is about 60 o C. Layers of white-coloured limestone (forming a rock deposit known as travertine) can also be seen. Note the footprints of buffalo in the foreground. These animals often seek the warmth of thermal areas in the winter months. limestone terraces formed by precipitation from calcium-rich water flowing from a raised hot pool. Pink, green and brown-coloured microorganisms occupy the thermal gradients in the flowing water (60-100 o C)
Growing Obligate Anaerobes <ul><li>Fluid Thioglycolate Medium </li></ul><ul><li>Peptones, Yeast Extracts, Glucose </li></ul><ul><li>Thioglycolate binds O 2 </li></ul><ul><li>Agar slows diffusion of O 2 </li></ul><ul><li>Resazurin is O 2 indicator (red) </li></ul>
Winogradsky Column Allows for the development of a redox gradient in a sample, from anaerobic through to H 2 S-rich Consists of water over sediment and substrate (sometimes with sand) Other components (e.g.., carbon sources, inorganic elements) often added. (these can be manipulated to select for different populations) AIR SAND Sediment Cellulose CaSO 4 + CaCO 3 Water
Winogradsky Column Example Winogradsky column (from Atlas and Bartha 1999) Microbial Zones reactions Algae, cyanobacteria CO 2 > CH 2 O, H 2 O > O 2 H 2 S - oxidizers H 2 S > S 0 , CO 2 > CH 2 O Facultative anaerobes CH 2 O > C0 2 + H 2 Purple non-sulfur CH 2 O > H 2 , CO 2 > CH 2 0 photoheterotrophs Purple Sulfur Bacteria H 2 S > S 0 , CO 2 > CH 2 O Green Sulfur bacteria H 2 S > S 0 , CO 2 > CH 2 O Sulfate reducers SO 4 2- > H 2 S, CH 2 O > CO 2 Fermentative heterotrophs CH 2 O > CO 2 + H 2 H 2 O AIR SAND Sediment Cellulose CaSO 4 + CaCO 3 Aerobic Microaerophilic Anaerobic H 2 S Redox Gradient