Biochromatogram showing 6-APA in penicillin fermentations

Contact photograph print of the paper strip biochromatogram used in the ‘Synthesis of Penicillin: 6-Aminopenicillanic Acid in Penicillin Fermentations’ by F R Batchelor, F P Doyle, J H C Nayler, G N Rolinson, 'Nature', 183, 24 January 1959 pp257-258, the first scientific publication on the discovery of 6-aminopenicillanic acid by the team at Beecham Research Laboratories

Biochromatograms are an example of chromatographs which show the separation of peptides and proteins. In this example, paper strip chromatograms were laid on sheets of agar on large glass plates seeded with Bacillus sublitis and incubated overnight. The dark zones are areas of inhibited bacterial growth (i.e. clear areas letting light through to a sheet of photographic paper placed underneath and illuminated from above). The third strip shows the presence of 6-APA.

It only became visible as a result of spraying it with phenylacetyl chloride to convert it to antibacterially active benzyl penicillin prior to laying it in contact with the B.subtilis seeded agar. Paper strip no.2 had the same sample applied but no is visible as the 6-APA has very low antibacterial activity prior to conversion to benzylpenicillin.

This research In 1957 by the team at Beecham Research Laboratories led to the development of several semi-synthetic penicillins. By tweaking its chemical structure, scientists created medicines to treat a wider range of bacterial infections, with fewer side effects.

Frank Ralph Batchelor (1931-2021), Frank Doyle (1921-2006), John Nayler and George Rolinson (1928-2016) published their results in the journal Nature. Their careers focused on antibiotics, remaining at Beechams for most of their working lives.