The versatility of microbial biosynthesis is enormous. The most industrially important primary metabolites are the amino acids, nucleotides, vitamins, solvents, and organic acids. Millions of tons of amino acids are produced each year with a total multibillion dollar market. Many synthetic vitamin production processes are being replaced by microbial fermentations. In addition to the multiple reaction sequences of fermentations, microorganisms are extremely useful in carrying out biotransformation processes. These are becoming essential to the fine chemical industry in the production of single-isomer intermediates. Microbially produced secondary metabolites are extremely important to our health and nutrition. As a group, they have tremendous economic importance. The antibiotic market amounts to almost 30 billion dollars and includes about 160 antibiotics and derivatives such as the beta-lactam peptide antibiotics, the macrolide polyketide erythromycin, tetracyclines, aminoglycosides and others. Other important pharmaceutical products produced by microrganisms are hypocholesterolemic agents, enzyme inhibitors, immunosuppressants and antitumor compounds, some having markets of over 1 billion dollars per year. Agriculturally important secondary metabolites include coccidiostats, animal growth promotants, antihelmintics and biopesticides. The modern biotechnology industry has made a major impact in the business world, biopharmaceuticals (recombinant protein drugs, vaccines and monoclonal antibodies) having a market of 15 billion dollars. Recombinant DNA technology has also produced a revolution in agriculture and has markedly increased markets for microbial enzymes. Molecular manipulations have been added to mutational techniques as means of increasing titers and yields of microbial procresses and in discovery of new drugs. Today, microbiology is a major participant in global industry. The best is yet to come as microbes move into the environmental and energy sectors.