Bacillota

Bacillota is a massive phylum of bacteria that plays a vital role in our world. Most members of this group possess a Gram-positive cell wall structure. This term refers to a specific type of thick outer layer. The name "Firmicutes" was used for this group for a long time. That name comes from Latin words meaning "tough skin." This refers to the thick cell walls found in many of these bacteria.

Scientists recently renamed the phylum to Bacillota in 2021. This change was controversial among microbiologists. Many experts still use the older name in their research papers.

These bacteria come in several distinct shapes. Some cells are round, and scientists call these cocci. Other members have a rod-like form known as bacillus. A few specific types have a different structure entirely. Members of the class Negativicutes, like Megasphaera, have a porous pseudo-outer membrane. This special membrane causes them to stain Gram-negative during testing. This is unusual because most Bacillota are Gram-positive.

Some members even use light to survive. The Heliobacteria family performs anoxygenic photosynthesis to produce energy. This means they make power from light without producing oxygen.

To survive in harsh environments, many Bacillota use a clever mechanism. They can produce endospores to protect themselves. An endospore is a highly resistant structure. It helps the bacteria survive desiccation, which is the process of drying out. These spores allow the organisms to endure extreme conditions.

Scientists also divide the phylum into different classes based on how they use oxygen. The Clostridia are anaerobic, meaning they live without oxygen. The Bacilli are either obligate aerobes or optional aerobes. This means they either require oxygen or can live with or without it.

Bacillota are incredibly important to the human gut microbiome. They can make up anywhere from 11% to 95% of the bacteria in your digestive tract. These microbes are involved in energy resorption, which is how the body takes in nutrients. Research shows a connection between Bacillota and body weight. In studies, mice fed a western diet had more Bacillota. This diet is high in fat and sugar. These mice also showed more adiposity, or body fat, than mice on standard diets.

Even transplanting these bacteria into germ-free mice caused them to gain more fat.

Not all Bacillota in the gut are linked to weight gain. Some species actually provide health benefits. For example, the species Faecalibacterium prausnitzii may have anti-inflammatory effects. This means it might help reduce swelling or irritation in the body. It is often found at lower levels in patients with inflammatory bowel disease. Another member, Christensenella, has been found to correlate with a lower body mass index. This suggests that certain Bacillota help maintain a healthy balance in the human body.

However, some members of this phylum are dangerous pathogens. A pathogen is a living thing that causes disease. Examples include Bacillus anthracis and Clostridium botulinum. Other bacteria, like Staphylococcus aureus, are called opportunistic pathogens. These only cause illness in a minority of the people they encounter.

Antibiotic resistance is a growing problem with these infections. One specific type, MRSA, is a very serious concern. It is estimated that MRSA causes about 100,000 deaths every year.

Beyond the human body, Bacillota affect many other systems. They are known to play a role in the spoilage of beer, wine, and cider. This shows how they interact with food production and chemistry. Some scientists even look at the deep history of life to study them. They believe Bacillota might be the source of the archaea. This theory suggests archaea branched from bacteria relatively late in history. This would change how we view the last universal common ancestor, or LUCA.