Industrial production of antibiotics

The first stage of antibiotic production is screening for microorganisms which produce antibiotics. Many such organisms have been useful.

Once an antibiotic has been found, it must be tested to find its optimum production conditions (such as temperature and pH). Chromatography and other techniques can be used to see whether one or more compounds are produced. This method also indicates whether the antibiotic is new and its chemical structure may be determined. Many new antibiotics are discovered every year, but very few are ever marketed because they must satisfy strict safety codes and must be better at killing microorganisms than ones already in use.

Commercial production of antibiotics is by batch or fed-batch culture. The antibiotic-producing microorganism is cultered in a sterile medium in a vast fermenter. It is grown under optimum conditions of temperature and pH so that the organism grows and produces the antibiotic and secretes it into the medium. The medium contains sugar, such as glucose, together with all the other nutrients the organism needs to grow, such as nitrates and sulphates. Fermentation is aerobic, so sterile air must be added to the fermenter. The fermentation is monitored so that the culture is stopped when the maximum level of antibiotic is present. The medium is then filtered off and the antibiotic extracted. The spent microorganisms are sometimes used for animal feed.

A In the laboratory-scale process, the optimum conditions for growth of the microorganism are studied. What kinds of conditions might affect growth?

B In the bulk fermentation stage, these conditions need to be controlled. For each condition you have listed in A state how it might be controlled in the bulk fermenter.

C Suggest how the bulk fermenter, and other equipment used to manufacture antibiotics in bulk, might be sterilized.

D Why is it undesirable to keep a sample of each bulk fermentation to inoculate future fermentation runs?

Summary

• Strict safety precautions are necessary when working with microorganisms. This is even more important in industrial and research laboratories where pathogenic or genetically engineered strains may be used.
• Fermeneters and other equipment must be designed for aseptic operation, easy cleaning and sterilization, and prevention of contamination and escape of organisms.
• Setting up an industrial process involves scaling up from laboratory scale to pilot plant scale, before finally growing the microorganism on industrial plant scale.

Questions

1 Do you think antibiotic production would be more efficient if a continuous fermentation system was used? Explain your answer.

2 Make a table to summarize the features of the different methods of fermentation and their relative advantages and disadvantages.

LESSON 42

VISITING A PLANT (FIRM): COMPUTING EQUIPMENT, TRENDS OF ACTIVITY, PERSONNEL ETC.

THE WORKSHOP

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