This chapter discusses the uses of microorganisms in processes that are grouped under the heading of industrial microbiology and biotechnology. The use of genetically engineered microorganisms to increase the efficiency of the processes and to produce new or modified products is discussed, as is the integration of biological and chemical processes to achieve a desired objective. The chapter concludes with discussions of biodegradation, some recent biotechnological applications, and the impact of microbial biotechnology on ecology and human society.