25 - Methods of Anaerobic Cultivation of Bacteria

Abstract

This chapter discusses the methods for anaerobic cultivation of bacteria. Oxygen is required for the growth of many, but not all, microorganisms. Those that will grow only in the presence of free oxygen are called obligatory or strict aerobes, those that can grow only in the absence of free oxygen are called obligate or strict anaerobes, and those organisms that can grow in either state are termed facultative anaerobes. Most organisms of medical importance fall into this last group and generally grow more luxuriously under aerobic conditions. Those organisms which grow best in an atmosphere containing a reduced level of oxygen are termed microaerophilic. The best general method of anaerobic cultivation is the use of the anaerobic jar. One advantage of this type of jar is that the process of evacuation causes oxygen dissolved in liquid media to be displaced by the reduced pressure, thereby ensuring correct anaerobic conditions within the tubes. To test that anaerobic conditions have been achieved, jars are commonly fitted with side arms to which are attached tubes containing chemical redox indicators. The chapter also discusses the use of an anaerobic jar for CO2 cultivation.