Correct interpretation of actinomycete imagery using scanning electron microscopy

Abstract

Antibiotic discovery was one of the most significant advances in therapeutic medicine following the advances in fermentation technology owing to Howard Florey and his associates. The ‘Golden era’ of antibiotics following the first discoveries in the laboratory of Waksman and his colleagues from a group of microorganisms known as actinomycetes lasted for 34 years (1940–1974). These fascinating microorganisms especially the members of the genus Streptomyces gave us the majority of the known antibiotics we use today, like streptomycin, kanamycin, neomycin, gentamicin, vancomycin and many more. To be able to produce these antibiotics in large-scale, the producer actinomycetes had to be selectively isolated. This resulted in a collaboration of over 40 laboratories from 18 different countries called ‘The International Streptomyces Project (ISP)’. The isolates generated in this project were studied in-depth including their morphologies together with their bioactivity. One of the components of these investigation was the correct interpretation of actinomycete morphology including the use of scanning electron microscopy. At the end of the first European Actinomycete Conference in Bradford University in England (1984), I had the opportunity to be trained by late Professor Cross on actinomycete growth morphologies. Thirty-eight years later when I witness the frequent difficulties students encounter in the interpretation of the actinomycete SEM images, I decided to write this paper and pass the skills given to me by late Professor Cross to the younger generation.