Bacteroidota

Bacteroides biacutis 01

Bacteroidota is a phylum of Gram-negative bacteria that play a significant role in the environment, human health, and disease. This phylum was previously known as Bacteroidetes. Members of Bacteroidota are widely distributed in various habitats, including soil, sediments, sea water, and the gastrointestinal tracts of animals, including humans. They are involved in complex carbohydrate degradation, an essential process in the decomposition of organic matter and in the human gut, where they help in digesting polysaccharides that are not digested by the host.

Characteristics

Bacteroidota are typically rod-shaped, and they can be anaerobic or aerotolerant anaerobes. They are distinguished by their unique cell wall structure, which lacks a typical Gram-positive thick peptidoglycan layer, making them Gram-negative. Despite this, their cell walls are more complex than those of many other Gram-negative bacteria, containing sphingolipids and other unique components.

Ecology

In the environment, Bacteroidota play a crucial role in the breakdown of complex carbohydrates, such as cellulose and xylan, contributing to the carbon cycle and the production of biogas. In the human gut, they are a major component of the microbiota, contributing to the digestion of dietary fibers, the production of short-chain fatty acids (SCFAs) like acetate, propionate, and butyrate, which are important for colon health and have systemic effects on the host's metabolism.

Clinical Significance

Some species within the Bacteroidota phylum are pathogenic to humans, causing infections such as bacteremia, peritonitis, and abscesses. However, the majority of the Bacteroidota in the human gut are commensal or beneficial. Alterations in the composition of gut Bacteroidota have been associated with various diseases, including obesity, inflammatory bowel disease (IBD), and diabetes.

Genomics

The genomic study of Bacteroidota has revealed a high degree of genetic diversity within this phylum, with a large number of genes dedicated to carbohydrate metabolism, reflecting their specialization in polysaccharide degradation. Comparative genomics has also highlighted the adaptability of Bacteroidota to different environments, including the ability to acquire resistance to antibiotics and metals, which is of concern in clinical settings.

Classification

The classification of Bacteroidota has evolved with advances in molecular techniques, particularly 16S rRNA gene sequencing, which has led to the identification of new species and genera within this phylum. The phylum Bacteroidota includes several classes, with Bacteroidia and Flavobacteriia being among the most well-known. These classes encompass a variety of genera, including Bacteroides, Prevotella, and Flavobacterium, each with distinct ecological and physiological characteristics.

Conclusion

Bacteroidota are a diverse group of bacteria with significant ecological roles and impacts on human health. Their ability to degrade complex carbohydrates is crucial in both natural and human-associated environments. While some members of this phylum are pathogenic, the majority contribute to the health of the ecosystems they inhabit and the hosts they colonize. Ongoing research into the Bacteroidota will continue to reveal their complexities and the ways in which they influence their surroundings.