KiB® Stool Reports - How it is identified
Determination of the bacterial composition of your sample
As soon as the sample arrives at our labs, we start with assessing the composition of the bacteria in the sample. The classic style for determination of this would be by cultivation methods using petri dishes and taking up to 4 days for results but, nowadays, ‘molecular’ techniques are employed for this purpose and are much quicker, being based on DNA analysis. DNA consists of two chains that are wrapped around each other in two opposing spirals. Each chain consists of 4 different units (nucleotides) that are repeated along the chain in a specific order, called the sequence. Like you can form words using letters from the alphabet, you can form genes with the nucleotide sequence.
The sequence of the nucleotides determines which proteins can be made in the bacterial cells. The protein constructing factories are called ‘ribosomes’. Considering that these protein factories are incredibly important for the bacterial cells, all bacterial cells carry the genes that code for the ribosomes.
One of these genes is the ‘16S rRNA gene’. Although all bacteria carry this gene, its sequence differs between bacterial species.
To study the DNA of bacteria, we first of all extract the DNA from the sample that you send us, followed by amplification of the 16S rRNA genes in the DNA using the Polymerase Chain Reaction (PCR). The latter is performed to obtain enough material for the subsequent steps of the analysis. When enough material has been collected the sequence of the 16S rRNA gene is determined.
These sequences are subsequently used for identification and enumeration of the bacteria in your sample. The number of specific sequences indicates how many of the different bacteria are represented in the sample. With these data we can construct graphs that give you a clear view on the composition of the bacteria in your sample.