The firmicutes phylum includes members like Staphylococcus, Streptococcus, Enterococcus, Lactobacillus, Listeria, Clostridium, Bacillus, and Micrococcus just to name a few. I’m sure you’ve heard of some of these before.
Most of these bacteria can tolerate oxygen but prefer not to have any and they can produce endospores which give them the ability to survive harsh environments (it’s a bit like being able to hibernate from danger). Firmicutes produce lactic acid, are generally gram-positive (that’s just a way we stain the cells so we know who they are) and are cocci or round in shape. But…..there’s always some that just don’t follow suit in this phylum and they can have diverse shapes, physiology and gram-staining which makes them difficult to recognise and identify sometimes. They are clever and they are generally good for us and will be on your side if we feed them right.
How do they help you with your health?
If you are obese or overweight you probably have a higher number of Firmicutes which has been shown in a number of different studies. But as usual with research, there is a few studies that will show the opposite but it all depends on the participants themselves and many other external factors such as diet, environment, geography and general health (Barlow, Yu, & Mathur, 2015; Dugas, Fuller, Gilbert, & Layden, 2016). The table below gives you a snapshot of the changes in your microbiota between health and disease (Chakraborti, 2015).
Firmicutes produce something called butyrate (a short chain fatty acid) which our body uses as an energy source for colonic epithelium to keep your colon healthy. Experiments in mice have shown that butyrate can increase insulin sensitivity and can contribute towards obesity-related anti-inflammatory action in humans. Butyrate is also suggested to protect us against gaining weight which can’t be a bad thing (Chakraborti, 2015).
If they are so good why do they increase when we are obese? Too much of a good thing? Diets high in fat and ultra-processed foods usually cause obesity. It’s not just one thing as you all know. That is why moderation is a great thing and fresh food with lots of fibre is perfect to keep a slim and happy microbiota community.