<P> Bacteria are economically important as these microorganisms are used by humans for many purposes and are harmful in causing disease and spoiling food . The beneficial uses of bacteria include the production of traditional foods such as yoghurt, cheese, and vinegar; biotechnology and genetic engineering, producing substances such as drugs and vitamins; agriculture; fibre retting; human and animal digestion; and biological control of pests . </P> <P> Sourdough bread is made to rise by fermentation, with a leaven that consists of bacteria, often combined with wild yeasts . </P> <P> The milk - souring bacterium Lactobacillus bulgaricus is used to make yoghurt and cheese . Bacteria are used, too, to form organic acids in pickles and vinegar . </P> <P> Biotechnology is the use of microorganisms including bacteria and fungi in the manufacturing and services industries . These include chemical manufacturing such as ethanol, acetone, organic acid, enzymes, and perfumes . In the chemical industry, bacteria are most important in the production of pharmaceuticals . Clostridium butyclicum is used for commercial preparation of riboflavin and vitamin K . </P>

Explain examples of the importance of bacteria in society