Our Little Friends


Inside everyone there are millions of microbes, George Merrin sets out to explore how they affect us.

THE word microbiome has two meanings; it can mean either the collection of microbes in a community, or it can be the collection of genes within a community of microbes. In the context of the human microbiome, the microbiome can be seen as an equivalent match to the human genome, with one hundred genes for every one in the human genome.

Due to the importance of the microbiomes to humans, the Unites States National Institute of Health (NIH) started the Human Microbiome Project (HMP). The purpose of this study is to identify all the micro-organisms that can be found in both healthy and diseased humans and see how the microbes change between the two. The Project was started in 2008 and had a massive budget of $115 million. In order to make it easier to study, the human body was split into five key areas, which are as different to each other as the Arctic, Sahara, and Amazon are. These areas are the gut, oral cavity, skin, vaginal, and nasal/lung.

“The dirt on our pets exposes us to these beneficial bacteria”

The gut is of particular interest as it plays a large role in our development of certain diseases. Around the world, but especially in the West, there is a rise in immune-mediated diseases. These are diseases that are caused by the immune system negatively affecting the body. This is either through attacking the body’s own tissues or by acting unusually. As our modern lifestyle has altered a lot from the past it is thought that factors such as improved sanitation, caesarean sections, antibiotic usage and immunisation (all of which are factors which change the microbiota) may be the driving forces behind this.

But how does this actually affect us? In a recent study, it was shown that being exposed to pets at a young age is beneficial as it decreases the rates of both childhood allergies and obesity due to the presence of Ruminococcus and Oscillospica, which have been linked to reduced levels of these respectively. This is because the dirt on our pets exposes us to these beneficial bacteria.

Certain strands of probiotic bacteria have been shown to possess efficacy in certain disorders of the Central Nervous System. This includes disorders such as anxiety, depression, autism spectrum disorders and obsessive compulsive disorders. These improve with daily doses of 109 to 1010 colony forming units for one to two months. These bacteria belong to the Bifidobacterium and Lactobacillus genera.

But our gut bacteria don’t only help prevent diseases and disorders, they also are essential to produce many important biochemical building blocks in our bodies. They are involved with fermenting dietary fibre into short-chain fatty acids (SCFAs). These are the main sources of energy for the cells that line the colon, which is a major thing needed for our health.

“But our gut bacteria don’t only help prevent diseases and disorders, they also are essential to produce many important biochemical building blocks in our bodies”

Examples of these SCFAs are acetic acid and butyric acid. These bacteria also synthesise vitamins B and K. Vitamin B12 prevents pernicious anaemia. Vitamin K binds to calcium, which helps build stronger bones and teeth. Vitamin K is also needed for blood coagulation.

Problems begin when dysbiosis occurs. Dysbiosis is when an imbalance between the good and bad bacteria in the gut. There is a particular problem with Clostridium difficile. It can opportunistically take over the gut causing major problems.

When this happens, Faecal Microbiota Transplants (FMTs) becomes an option. This is where the faeces of one person are transplanted into another person with the purpose of reintroducing a normal microbiome. Since the introduction of FMTs the incidence of antibiotic resistance has decreased. As antibiotic resistance becomes a major problem throughout the world, solutions, such as these relating to microbes, are an option to tackle this.