An interdisciplinary and engaging practical is detailed which offers great versatility in the study of a qualitative and quantitative metabolism of azo-dyes by "Staphylococcus aureus". This practical has broad scope for adaptation in the number and depth of variables to allow a focused practical experiment or small research project. Azo-dyes are an important group of dyes characterised by the presence of an azo-bond within the molecule. Many bacteria are able to produce azoreductases--enzymes which cleave the azo-bond of such dyes, decolourising them. This visual representation of metabolism offers a simple and inexpensive method to study bacterial metabolism and the variables which may affect this. The practical experiment combines basic microbiological and biochemical techniques whereby broth cultures are incubated with an azo-dye, and dye degradation is photometrically monitored. Microbiological methods may also be employed to monitor the resulting microbial growth. Example results are shown from student data to highlight the effects of differing broth media and how metabolism and growth may change over a 24-hour incubation period. The performance, analysis and interpretation of the findings may prove beneficial to test a variety of skills and aptitudes within both secondary and tertiary biological education. (Contains 1 table and 4 figures.)