【正文】 Chapter Overview ? The control of microbes in the environment is a constant concern of health care and industry since microbes are the cause of infection and food spoilage(破壞 ), among other undesirable events. ? Antimicrobial control is acplished using both physical technique and chemical agents to destroy, remove, or reduce microbes in a given area. ? ? Many factors must be contemplated（關(guān)注） when choosing an antimicrobial technique, including the material being treated, the type of microbes involved, the microbial load, and the time available for treatment. ? Antimicrobial agents damage microbes by disrupting the structure of the cell wall or cell membrane ,preventing synthesis of nucleic acids （ DNA and RNA） , or altering the function of cellular proteins . Microbicidal agents kill microbes by inflicting nonreversible（不可逆的） damage to the cell .microbistatic agents temporarily inhibit the reproduction of microbes but do not inflict irreversible damage .Mechanical antimicrobial agents physically remove microbes from materials but do not necessarily kill or inhibit them. ? Heat is the most physical agent in microbial control and can be delivered in both moist (steam sterilization, pasteurization) and dry forms. ? Radiation exposes material to high energy waves that can enter and damage microbes. Examples are ionizing and ultraviolet radiation. ? Chemical antimicrobial are available for every level of microbial treatment, from lowlevel disinfectants to highlevel sterilants. Antimicrobial chemical include halogens, alcohols, phenolics, peroxides, heavy metals, detergents, and aldehydes. Controlling Microanisms ? Controlling our degree of exposure to potentially harmful microbes is a monumental（非常的） concern in our lives, and it has a long and eventful（重大的） history. GENERAL CONSIDERATIONS IN MICROBIAL CONTROL ? The methods of microbial control belong to the general category of decontamination（凈化） procedures, in that they destroy or remove contaminants. Most decontamination methods employ either physical agents, such as heat or radiation, or chemical agents such as disinfectants and antiseptics（無菌的 ） . RELATIVE RESISTANCE OF MICROBIAL FORMS ? The primary targets of microbial control are microanisms capable of causing infection or spoilage that are constantly present in the external environment and on the human body . ? This targeted population is rarely simple or uniform。 in fact, it often contains mixtures of microbes with extreme difference in resistance and harmfulness. ? Contaminants that can have farreaching effects if not adequately controlled include bacterial vegetative cells and endospores, fungal hyphae and spores, yeasts, protozoan trophozoites（滋養(yǎng)體 ） and cysts, worms, insects and their eggs, and viruses. This scheme pares the general resistance these forms have to physical and chemical methods of control: ? Highest resistance ? Bacterial endospores ? Moderate resistance ? Protozoan cysts: some fungal sexual spores (zygospores接合孢子 )。some viruses. In general, naked viruses are more resistant than enveloped forms. ? Least resistance ? Most bacterial vegetative cells。 fungal spores and hyphae。 enveloped viruses。 yeasts。 and protozoan trophozoites. ? Actual parative figures on the requirements for destroying various groups of microanisms are shown in table TERMINOLOGY （術(shù)語） AND METHODS OF MICROBIAL CONTROL ? Through the years, a growing terminology has emerged for describing and defining measures that control microbes. To plicate matters, the everyday use of some of these terms can at times be vague and inexact. ? Sterilization ? Sterilization is a process that destroys or removes all viable microanisms, including viruses. Any material that has been subjected to this process is said to be sterile. ? Sterilized products are essential to human wellbeing. Although most sterilization is performed with a physical agent such as heat, a few chemical called sterilants can be classified as sterilizing agents because of their ability to destroy spores. ? At times, sterilization is neither practicable nor necessary, and only certain groups of microbes need to be controlled. Keep in mind that the destruction of spores is not always a necessity Sterilization High Temperature （高溫） Ultraviolet Rays （紫外線） High temperature can make protein、nucleic acid（核酸） 、 lipid（脂類） and other macromolecules（生物大分子） to degraded （降解）、denaturalized（變性） and destoryed. High Temperature High Temperature Sterilization Dry Heat Sterilization (干熱空氣滅菌法 ) Moist Heat Sterilization (濕熱空氣滅菌法 ) Flame Burn （灼燒） High Temperatue in Oven （干熱空氣 滅菌） Normal Pressure High Pressure Pasteurization (巴氏消毒法 ) Boiling（煮沸法） Tyndallization (間歇滅菌法 ) Continuous Pressure Sterilization（連續(xù)高壓滅菌） Normal Pressure High Pressure Normal Pressure Sterilization（常壓滅菌） Flame Burn Oese(接種環(huán) ) High Temperatue in Oven Oven（烘箱） Culture Dish (培養(yǎng)皿 ) Method: 160 176。 C for 2 Hours. Pasteurization (巴氏消毒法 ) Louis Pasteur (December 27, 1822 – September 28, 1895 ) Louis Pasteur was a French chemist and microbiologist best known for his remarkable breakthroughs in the causes and prevention of disease. Conception of Pasteurization The heating of every particle of milk or milk product to a specific temperature for a specified（特定的） period of time. Aim:Heating liquids