Odour of Microbes

One of the pillars of diagnostic microbiology is the initial examination of colonies for the preliminary identification of bacteria.

Despite being challenging to describe in detail, the odours emitted by some bacteria in solid and liquid media can be highly useful in the tentative identification of the microorganisms involved. Bacteria produce numerous odours, most of which we would prefer not to think about. Understanding the characteristics of volatile chemicals, can indicate a variety of factors. This distinctive volatile residue were once crucial for microbiological diagnosis and for the production of microbe-based consumables like wine, beer and cheese. Until very recently, however, the odours that bacteria make were not known to have much of a significance.

It is crucial to keep in mind that when sniffing plate media, you should always proceed with extreme caution and raise the lid of the petri dish just slightly in order to identify the odour. Several species have shown the propensity to infect laboratory personnel, thus workers are advised not to sniff them at all. If there is a possibility that the culture plate contains Bacillus anthracis, Francisella tularensis, Burkholderia pseudomallei, Brucella spp., or Neisseria meningitides, it should never be smelled for odour. Such cultures ought to be taken out of the environment and placed in a biological safety cabinet, where all following work can be completed without risk of worker exposure. When there are moulds present in the mycology laboratory or when mycobacteria is present, plates should never be opened.

In the current era of artificial intelligence and automation, where machines perform much of the job. Has anyone ever smelled bacterial odours?