BIOS2150 Microbiology Exam 2 Study Guide

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Microbiology Exam 2 Study Guide Chapter 11 – Controlling Microbes 1. Approaches to Control Microbes a. Physical Methods i. Dry 1. incineration or dry oven  sterilization ii. Moist heat ... 1. Boiling water, steam under pressure  sterilization 2. Kills microbes by denaturing enzymes 3. Ex. Autoclaving iii. Radiation 1. Irradiation – bombardment with radiation 2. Ionizing – can penetrate a solid barrier, bombard a cell, enter it, and dislodge electrons form molecules a. x-ray, cathode, gamma  sterilization 3. Nonionizing – enters a cell, strike molecules, and excites them. Results? Mutation of DNA a. Note: non-ionizing radiation cannot penetrate a solid barrier b. UV  disinfection iv. Chemical Methods 1. Antimicrobial chemicals  disinfection or sterilization 2. Gases  disinfection of sterilization v. Mechanical Methods 1. Filtration of air and liquids  decontamination 2. Physical Controls a. Heat i. Moist heat – boiling water (100oC, 30 min) ii. Pasteurization – milk, fruit juices; flash method (~72oC, 15 sec) iii. Pressurized steam – autoclave (121oC, 15psi); used for surgical instruments, commercial canning (clostridium botulinum, problem in canning) b. Radiation i. Gamma radiation – DNA 1. Medical equipment, drugs, food-safe ii. Ultraviolet radiation – DNA iii. Microwave – heat [Show More]

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