{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

chapt08 - 8 Control of Microorganisms in the Environment...

Info icon This preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
8 Control of Microorganisms in the Environment CHAPTER OVERVIEW This chapter focuses on the control and the destruction of microorganisms by physical and chemical agents. This is a topic of great importance, because microorganisms may have deleterious effects, such as food spoilage and disease. It is therefore essential to be able to kill or remove microorganisms from certain environments in order to minimize their harmful effects. CHAPTER OBJECTIVES After reading this chapter you should be able to: compare and contrast the processes of disinfection, sanitization, antisepsis, and sterilization compare the difficulties encountered when trying to kill endospores with those encountered when trying to kill vegetative cells discuss the exponential pattern of microbial death discuss the influence of environmental factors on the effectiveness of various agents used to control microbial populations discuss the uses and limitations of various physical and chemical agents used to control microbial populations describe the procedures used to evaluate the effectiveness of various antimicrobial agents discuss biological agents used to control microorganisms CHAPTER OUTLINE I.Definition of Frequently Used Terms A. Sterilization is the destruction or removal of all viable organisms (vegetative cells and endospores) from an object or from a particular environment B. Disinfection is the killing, inhibition, or removal of pathogenic microorganisms (usually on inanimate objects) C. Sanitization is the reduction of microbial populations to a safe level as determined by public health standards D. Antisepsis is the prevention of infection of living tissue by microorganisms E. Antimicrobial agents fall into one of two broad categories denoted by suffixes indicating effect 1. -cide is a suffix indicating that the agent will kill the kind of organism in question (e.g., viricide, fungicide) 2. -static is a suffix indicating that the agent will prevent the growth of the type of organism in question (e.g., bacteriostatic, fungistatic) II.The Pattern of Microbial Death A. Microorganisms are not killed instantly when exposed to a lethal agent; rather, the population generally decreases by a constant fraction at constant intervals (exponential killing) B. Efficiency of killing agent a. The decimal reduction time ( D, or D value) is the time required to kill 90% of the microorganisms or spores in a sample at a specific temperature b. The Z value is the increase in temperature required to reduce D to 1/10 of its previous value C. A microorganism is usually considered dead when it is unable to grow in conditions that would normally support its growth and reproduction; however, the issue is confounded by organisms that are in a viable but nonculturable (VBNC) state 78
Image of page 1

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
III. Conditions Influencing the Effectiveness of Antimicrobial Agents A.
Image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern