11 things you didn't know about the microbiome

What are some of the fascinating facts and figures about the microbiome that people wouldn’t know about?

• There are over 1000 different bacterial species living on and in the average adult.
• 70% of your immune system can be found in your digestive tract, where most of your bacteria resides.
• Our bacterial fingerprint is even more unique than our DNA.
• Our microbiome, in total, can weigh up to two kilograms.
• Some animals actively alter their microbiome. Young iguanas, for instance, eat soil or faeces to tailor their microbiome to their current diet.

What is it made up of?

The human microbiome consists of bacteria residing in the gut and other body sites, but it also includes an abundant variety of other micro-organisms, from fungi and viruses to less familiar names, such as protists and archaea.

Of the bacteria, which are the most dominant in humans?

The composition of the microbiome can vary greatly from culture to culture, and indeed from person to person and body site to body site, but we know the most about the composition found in the healthy human gut. This community is dominated by bacteria of two phyla – Bacteroidetes and Firmicutes. These make up around 80 to 90 per cent of our total microbiota.

How does bacteria survive in the gastrointestinal system?

You might imagine that the acidic environment of the stomach is an inhospitable place, but acid holds little fear for many types of bacteria. Lactobacillus strains, for instance, create lactic acid as part of their normal operation.

Is the microbiome just in your gut?

While your gut contains the most abundant and diverse population of bacteria, you host a variety of microbial life across your entire body, particularly on the skin, in the mouth and in the urogenital tract.

Who discovered or first reported the microbiome?

The term ‘microbiome’ is a relatively recent invention, but early glimpses of the idea date back to the 1860s, when Antonie van Leeuwenhoek used a specially designed microscope to observe the diversity of bacteria resident in and on his body.

What are some of the things that can have an adverse effect on your microbiome?

Many external factors can influence microbiome diversity. Antibiotics operate by reducing the reproduction of harmful bacteria, but can deplete populations of useful bacteria in the process. Stress can also alter the makeup of the microbiome, lowering numbers of potentially beneficial Lactobacillus bacteria. Fibre provides fuel to the bacteria of the gut, so a diet low in fibre and high in processed foods can be detrimental to microbiome health.