Firmicutes

Firmicutes (fir-mi-kyoo-teez, from Latin firmus, strong, and cutis, skin, referring to the cell wall) are a phylum of bacteria, most of which have Gram-positive cell wall structure. A few, however, such as Megasphaera, Pectinatus, Selenomonas and Zymophilus, have a porous pseudo-outer-membrane that causes them to stain Gram-negative. Scientists once classified the Firmicutes to include all Gram-positive bacteria, but have recently defined them to be of a core group of related forms called the low-G+C group, in contrast to the Actinobacteria. They have round cells, called cocci (singular coccus), or rod-like forms (bacillus).

Etymology

The name Firmicutes is derived from the Latin firmus, meaning strong, and cutis, meaning skin. This refers to the strong cell wall that characterizes bacteria in this phylum.

Characteristics

Firmicutes consist of both Gram-positive and Gram-negative species. They are generally non-motile and have a thick cell wall. Many Firmicutes produce endospores, which are resistant to desiccation and can survive extreme conditions. They are found in various environments and some species are important pathogens, causing disease in humans and other animals.

Classification

The phylum Firmicutes is part of the domain Bacteria, and it is divided into several classes including Bacilli, Clostridia, and Negativicutes. These classes are further subdivided into orders, families, genera, and species.

Medical relevance

Some Firmicutes are significant in medical science as they are involved in various human diseases such as staphylococcus, streptococcus, and Clostridium difficile infections. They are also involved in conditions like obesity and colon cancer.

See also

• Bacteria
• Gram-positive bacteria
• Gram-negative bacteria
• Endospore
• Staphylococcus
• Streptococcus
• Clostridium difficile
• Obesity
• Colon cancer

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