MCB 3020C Lecture Notes - Lecture 21: Kjeldahl Method, Quorum Sensing, Dental Caries
Document Summary
When the cells are no longer able to find the nutrients needed, the cells can die. The death phase is also exponential, but is slower than the growth exponential rate. Note: the terms lag phase, exponential phase, stationary phase and death phase do not apply to individual cells, but only to populations of cells. Microorganisms rarely live in single species isolates: most live in biofilms, can include single species, multiple, and even fungi, coordinated community with protective layer (hydrogel, synergistic relationship. Cell-to-cell communication (quorum sensing) occurs: share nutrients and are sheltered from the environment, might assist on sharing genetic information. Attached to hard places or mucous: starts with a free-swimming bacteria attaching to the surface, form pillar-like structures with channels between them for water, nutrients and waste management. Page 2: microbes in a cow"s gi track to break down cellulose, sewage treatment systems. Downsides: out 70% of human infections involve biofilm. Dental caries, contact lenses, cystic fibrosis: resistance to microbicides.
