Nester's Microbiology Chapter 4 with complete solutions

biofilm Polymer-encased community of microorganims Chemically defined medium A culture medium composed of exact quantities of pure chemicals; generally used only for specific experiments when nutrients must be precisely controlled 00:02 01:40 complex medium a culture medium that contains protein digests, extracts, or other ingredients that vary in their chemical composition differential medium a culture medium with an ingredient that certain microbes change in a recognizable way; used to differentiate microbes based on their metabolic traits exponential (log) phase Stage in the growth curve during which cells divide at a constant rate; generation time is measured during this period of active multiplication facultative anaerobe organism grows best if O2 is available, but can also grow without it Generation time the time it takes for a population to double in number obligate aerobe organism that requires O2 obligate anaerobe organism that cannot multiply, and is often killed in the presence of O2 plate count method to measure the concentration of viable cells by counting the number of colonies that develop from a sample added to an agar plate pure culture a population descended from a single cell selective medium a culture medium with an ingredient that inhibits the growth of microbes other than the one being sought