gut bacteria

Sewage Bacteria Reveal Cities’ Obesity Rates

Urban ‘microbiome’ can offer glimpses into disease trends.

Sampling the waste in a city’s sewage system can be a good way to study the microbes that live in the population’s guts – and could even offer a way to monitor public health issues such as obesity, according to new research.

The community of microbes that live in a person’s gut, known as the microbiome, is intricately tied to that person’s health. The microbiome can influence, and be influenced by, a range of characteristics such as weight, disease, diet, exercise, mood and much more. But it can be difficult to draw large-scale conclusions about what constitutes a “healthy gut” because of the financial and privacy implications of sampling large enough numbers of people.

So a team of researchers led by Sandra McLellan at the University of Wisconsin-Milwaukee and Mitchell Sogin at the Marine Biological Laboratory in Woods Hole, Massachusetts, set out to test whether they would be able to spot human microbes lurking in the soupy mix of municipal sewage systems, and thus sample entire cities at once. Read more at Inside Science.

Bacteria from lean mice prevents obesity in peers

But microbes are only part of the story — the effect also depends on a healthy diet.

Gut bacteria from lean mice can invade the guts of obesity-prone cage-mates and help their new hosts to fight weight gain.

Researchers led by Jeffrey Gordon, a biologist at Washington University in St. Louis, Missouri, set out to find direct evidence that gut bacteria have a role in obesity.

The team took gut bacteria from four sets of human twins in which one of each pair was lean and one was obese, and introduced the microbes into mice bred to be germ-free. Mice given bacteria from a lean twin stayed slim, whereas those given bacteria from an obese twin quickly gained weight, even though all the mice ate about the same amount of food. Read more in Nature.

Gut microbe may fight obesity and diabetes

Bacterium helps to regulate metabolism in mice.

The gut is home to innumerable different bacteria — a complex ecosystem that has an active role in a variety of bodily functions. In a study published this week in Proceedings of the National Academy of Sciences, a team of researchers finds that in mice, just one of those bacterial species plays a major part in controlling obesity and metabolic disorders such as type 2 diabetes.

The bacterium, Akkermansia muciniphila, digests mucus and makes up 3–5% of the microbes in a healthy mammalian gut. But the intestines of obese humans and mice, and those with type 2 diabetes, have much lower levels. A team led by Patrice Cani, who studies the interaction between gut bacteria and metabolism at the Catholic University of Louvain in Belgium, decided to investigate the link. Read more in Nature.