Everything about The Firmicutes totally explained
The
Firmicutes (
Latin:
firmus, strong, and
cutis, skin, referring to the cell wall) are a division of
bacteria, most of which have
Gram-positive cell wall structure. A few, the
Mollicutes or mycoplasmas, lack
cell walls altogether and so don't respond to Gram staining, but still lack the second membrane found in other
Gram-negative forms. Others, such as Megasphaera, Pectinatus, Selenomonas, and Zymophilus have a porous pseudo-outer-membrane that causes them to stain Gram-negative. Originally the Firmicutes were taken to include all Gram-positive bacteria, but more recently they tend to be restricted to 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-shaped forms.
Many
Firmicutes produce
endospores, which are resistant to
desiccation and can survive extreme conditions. They are found in various environments, and some notable pathogens. Those in one family, the
heliobacteria, produce energy through
photosynthesis. Firmicutes play an important role in beer, wine, and cider spoilage.
There is currently no way of detecting a bacterium as belonging to Firmicutes as the phylum is highly diverse in phenotypic characteristics due to promiscusious
plasmid exchange across species and genera of this phyla.
The division
Firmicutes as part of the
gut flora has been shown to be involved in energy resorption and obesity.
The presence of
Firmicutes can now be detected by real-time PCR using the methodologies described by Haakensen et al (Int J Food Microbiol, In Press).
Classes
The group is typically divided into the Clostridia, which are
anaerobic, the Bacilli, which are obligate or facultative
aerobes, and the Mollicutes. On
phylogenetic trees the first two groups show up as
paraphyletic or
polyphyletic, as do their main genera,
Clostridium and
Bacillus. It is likely these groups will undergo revision.
Genera
While there are currently more than 274 genera within the Firmicutes phylum, notable genera of Firmicutes include:
Bacilli, order Bacillales
Further Information
Get more info on 'Firmicutes'.
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