Microbiology Trapped in the 19th Century
When the science of microbiology was in its early stages of development, scientists used liquid media for the cultivation of microorganisms. For those who were in need of a method to segregate individual types of organisms, the use of liquid media proved to be a significant disadvantage. This was the case for Dr. Robert Koch, who, in 1881, was determined to find an alternative method for his experiments. His laboratory first used aseptically cut slices of potato as a solid culture medium, and later turned to liquid culture supplemented with gelatin, which was subsequently poured into glass plates and allowed to solidify. This technique permitted the scientists to obtain pure cultures of the bacteria that were found to be growing in the form of discreet colonies on the surface of the plates.
Unfortunately, on hot summer days, the gelatin medium would liquefy, rendering it useless for its intended application. Furthermore, this phenomenon was accelerated when certain types of bacteria growing on the surface would produce enzymes capable of digesting the gelatin medium. One of the scientists, Dr. Walther Hesse, was frustrated by these events, and he turned to his wife and laboratory assistant, Angelina for help. Walther recalled that his wife's jellies and puddings remained solid, even in the heat of the day, and when he inquired as to what her secret was, she provided an unusual but simple answer. Angelina was previously made aware of a cooking ingredient called Agar-Agar, which had been used as a gelling agent by Asian chefs for many centuries, and as a result, used the material in many of her recipes. Dr. and Mrs. Hesse discussed the possibility of using Agar-Agar as the basis for a stable, solid microbiological medium, and subsequent experiments showed that this worked magnificently.
This simple kitchen ingredient revolutionized the science of microbiology as it made what had been a difficult task of separating and culturing microorganisms on solid surfaces a routine procedure. Interestingly, more than 125 years later, all microbiology laboratories, in every industry sector, continue to use agar as the most important and widely accepted material for growing microorganisms today. Angelina would be proud...but should we be proud as well?
Although the growth of microbial cells on agar surfaces provides the laboratory with critical information about the amount and the type of organisms that may be present in a sample under evaluation, the time to result is usually longer than what is desired. Days and even weeks may elapse before microbial colonies are visually detected, and in most cases, confluent growth prevents individual organisms from being isolated, necessitating sub-culture onto additional agar media, delaying the time to result even further. Additionally, many laboratories are discovering that microorganisms, when stressed due to nutrient deprivation, or following exposure to sub-lethal concentrations of antimicrobial agents, such as preservatives, disinfectants, heat or decontaminating gases, may not replicate when cultured on artificial media, because the environment is not truly optimal for the resuscitation and subsequent proliferation of organisms that may be present. For these reasons, the modern microbiological laboratory should look toward developing innovative approaches to the detection, quantification and identification of microorganisms. From a quality risk management perspective, this direction is critical for the pharmaceutical and biopharmaceutical industries.