The challenges of investigating bacterial populations
Microbial communities are multicultural. Many populations live together in the same environment, so scientists studying bacteria will often report on the number of different species, their relatedness to one another and their shared characteristics. One way to recognise the different populations is to study their genes.
It is now possible to sequence an entire bacterial genome – every letter of its DNA – in a matter of days, or even hours. This can be done for bacteria taken straight from the soil or ocean, for example, or grown in the lab.
However, to compare different species, it may only be necessary to look for a few well-recognised genes. A gene known as the 16S rRNA gene has a slightly different DNA sequence in every species, so scientists can use it to tell different species apart, or to work out if they have discovered a new species.
Microbes are so diverse and widespread because they can reproduce extremely quickly, forming large populations. They also have the ability to adapt rapidly to new environments and changing conditions. In hospitals the adaptability of bacterial populations poses a major threat to human health – see our case study on antibiotic resistance for more information.