EXAM 3 STUDY GUIDE MICRO - 7.1 7.3-7.4,7.6-7.7 Microbial...

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7.1, 7.3-7.4,7.6-7.7 Microbial Growth in Natural Environments o microbial environments are complex constantly changing often contain low nutrient concentrations and exposes microbes to many overlapping gradients of nutrients and other environmental factors o microbial growth depends on Nutrient supply tolerance of environment Inhibitory substances most microbes grow attached to surfaces as biofilms Dynamic community o metabolic differences location provide resistance microbial interactions o metabolic exchange o DNA uptake o microbes reversibly attach to conditioned surface and release polysaccharides, proteins, and DNA to form the extracellular polymeric substances (EPS) 8.1-8.4, 8.6 8.1 Biocide- a chemical or physical agent, usually broad spectrum, that inactivates microorganisms Sterilization- the process in which all living cell, spores, and acellular entities are either destroyed or removed from an object or habitat Bactericide- agent that kills bacteria Fungicide- agent that kills fungi Viricide- agent that inactivates viruses so that they cannot reproduce within host cells Bacteriostatic- inhibits growth and reproduction in bacteria Fungistatic- inhibits growth and reproduction of fungi Disinfection- killing, inhibition or removal of microorganisms that may cause disease; it is the substantial reduction of the total microbial population and the destruction of potential pathogens Disinfectants- agents, usually chemical, used to carry out disinfection and are normally used on inanimate objects Does not sterilize because an object because viable spores and a few microorganisms may still remain Sanitization- microbial population is reduced to levels that are considered safe by public health standards Antisepsis (“against putrefaction”)- the destruction or inhibition of microorganisms on living tissue; it is the prevention of sepsis Antiseptics- chemical agents applied to tissue to prevent infection by killing or inhibiting pathogen growth; they reduce the total microbial population Not as toxic as disinfectants
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Chemotherapy – use of chemical agents to kill or inhibit the growth of microorganism w/in host tissue Decimal reduction time (d-value)- the time required to kill 90% of the microorganisms or spores in a sample under specified conditions; precise measure of an agents killing efficiency Anti-microbial agent- agent that kills microorganisms or inhibits their growth Autoclave- used to destroy bacterial endospores, moist heat sterilization must be carried out at temperatures above 100C, in which requires the steam sterilization of this Pasteurization- heat sensitive substances are treated with controlled heating at temperature below well boiling Tyndallization- technique used to destroy heat-resistant microorganisms in dust; also uses steam (30-60minutes) to destroy vegetative bacteria Depth filters- consist of fibrous or granular materials that have been bonded into a thick layer filled with twisting channels of small diameters; Membrane filters- have porous membranes, a little over 0.1 mm thick, made of cellulose acetate, cellulose nitrate,
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