Microbiology and Mathematics: microbiological meaning from mathematical models.

Mathematical modelling has traditionally been a normal part of microbiological research. It was not considered to warrant any special mention in the title and abstract and then require burying in the supplementary material. Models were simply used when useful and researchers had the skills to use them. Describing growth and death of populations is probably the first area where models were used as a matter of course. Then came the molecular biology revolution. While pioneered by scientists with strong theoretical skills and mind-set, experiments soon trumped theory in the elucidation of the genetic code. Moreover, molecular biology had been enormously successful in revealing the function of myriads of genes without any theory, not even statistics. This side-lined modelling and the skills it required although quantitative reasoning survived in some areas of microbial sciences such as predicting bacterial growth in food stuffs. The effects of the molecular revolution are still felt today despite the increasing recognition that mere qualitative understanding of the interactions of genes and gene products and products of gene products cannot deal with the complexity and dynamical nature of these interactions, giving rise to systems biology and the need for biologists to have quantitative skills. As Schnell, Grima and Maini put it in 2007, "Molecular Biology took Humpty Dumpty apart; mathematical modelling is required to put him back together again".