Finegoldia magna

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Classification

Figure 1. FESEM micrograph of mono-species biofilm of F. magna strain FmBs12. [1]

Figure 2. Image of two distinct morphs of F. magna; top row is a biofilm-producing morph with unique surface proteins. Brüggemman et al. believe these differences warrant a refined subspecies or new species classification. [2]

Domain: Bacteria

Phylum: Firmicutes

Class: Clostridia

Order: Eubacteriales

Family: Peptoniphilaceae

Genus: Finegoldia

Species

Finegoldia magna

F. magna was previously classified as Peptostreptococcus anaerobius, and it was recognized as a unique species as recently as 1998. [4]

NCBI: Taxonomy [5]

Figure 3. F. magna high-resolution images (B with overlay of A) with assisted advanced sof-touch method with Z scale bars up to 0.3 μm and XY bars indicating 500 nm. [2]

Description and Significance

Describe the appearance, habitat, etc. of the organism, and why you think it is important.

"Finegoldia magna" is a slow-growing, non-spore-forming, Gram-positive anaerobic coccus (GPAC) bacteria.

F. magna is a major part of healthy skin and mucosal surface microflora. It has been shown to be the most commonly-isolated anaerobe from skin specimens [6] , and it is prevalent in chronic wounds, such as diabetic and pressure ulcers. [7] It is also commonly found as the culprit of secondary infections following prosthetic joint replacement or cardiac valve replacement surgeries. [8] ] The importance of F. magna as a human pathogen is insufficiently recognized, especially as it has been recently implicated in a case of toxic shock syndrome.

The color of the colonies is usually translucent, but it can appear whitish to yellow or gray. [9]

The Genus namesake is in remembrance of the American microbiologist Sydney Martin Finegold.

Genome Structure

Describe the size and content of the genome. How many chromosomes? Circular or linear? Other interesting features? What is known about its sequence?

Cell Structure, Metabolism and Life Cycle

Figure 4. Electron microscopy images of F. magna strains ALB8 (top row) and 505 (bottom row). Bar represents 10 µm (left) and 5 µm (right). [3]

Interesting features of cell structure; how it gains energy; what important molecules it produces.

Cell Structure

Finegoldia magna is a Gram-positive anaerobic coccus (GPAC) bacteria, in which "coccus" indicates a spherical cell shape. Gram-positive indicates a bacterium with thick petidoglycan cell walls.
It has a cell size that varies from 0.8 µm and 1.6 µm in diameter, and cells occur predominantly in masses or clusters but occasionally in short chains or pairs, as in Figure 4.
This bacteria has sortase-dependent pilli, which are hair-like structures important for bacterial adhesion and colonization (i.e., important for biofilm formation) as well as host infection. [10] Sortases are enzymes that modify surface proteins of the cell wall.

Metabolism

As an anaerobe, F. magna requires an oxygen-free environment to grow. However, in a 1998 experiment by Murdoch et al., F. magna isolates were plated on agar and exposed to air. After 48 hours, some clusters survived, indicating some level of oxygen tolerance. [11]

F. magna produces acetic acid as a major fermentation product. It produces weak acid utilizing fructose, while a few strains use glucose as a carbon source. Peptones and amino acids are also used an energy sources. It can produce ammonia from glycine, threonine, and serine. [12]

Aminopeptidases (i.e. catalyze cleavage of amino acids) have been reported but are not well-studied. [13]

Survival and Life Cycle

F. magna is susceptible to antibiotics used to treat anaerobic infections. However, it shows some resistance (10-20%) to clindamycin, metronidazole, penicillin, while even higher resistance (>20%) to erythromycin and tetracycline. Its ability to form mono-species and dual-species biofilms may lend greater protection against host immune defenses and antibiotics. [1]

The nutritional requirements of cultured GPAC organisms, including F. magna are understudied. Commercial media tend to vary in their ability to support growth. However, Fastidious Anaerobe Agar has consistently proved most successful. Sodium oleate, vitamin K, and hemin supplements are not necessary. [11]

Cocci bacteria, including F. magna, replicate asexually through binary fission and can divide from different planes to form a variety of arrangements (as compared to bacilli, which divide from the horizontal axis).

Ecology and Pathogenesis

Habitat; symbiosis; biogeochemical significance; contributions to environment. If relevant, how does this organism cause disease? Human, animal, plant hosts? Virulence factors, as well as patient symptoms.