Aerococcus viridans colonies on Sheep Blood Agar
Aerococcus viridans
Cultural characteristics
Biochemical characters
Phylum Firmicutes, Class Bacilli, Order Lactobacillales, Family Aerococcaceae, Genus Aerococcus, Aerococcus viridans Williams et
al. 1953, species - type species of the genus.
No reaction with Lancefield group antisera.
Gaffkya homari Hitchner and Snieszko 1947, Pediococcus homari
Deibel and Niven 1960.
Gram-positive cocci, 1-2 μm in diameter, non-motile, grouped in pairs or small
groups. Chains are not formed on solid or in fluid media and the paired cocci do not
show elongation along the axis joining their centres. Non-spore-forming.
Colonies on blood agar are 0.5-2.0 mm in diameter, semi-transparent, white or grey,
and surrounded by a wide or narrow zone of greening (alpha-hemolytic). Rarely,
strains that produce a yellow pigment may be encountered.
Grows well on nutrient agar with or without 0.5% glucose, and on serum agar,
chocolate agar and blood agar. Good growth on serum agar containing 40% bile and
on agar containing 1/400,000 crystal violet and 1/100,000 potassium tellurite. The
colonies are larger on blood agar than on the other media.  Pantothenic acid, nicotinic
acid, and biotin are either required or stimulatory for the growth.
Facultatively anaerobic. Growth is not enhanced, and may be slightly decreased, by
incubation anaerobically or in air with 30% carbon dioxide. The green discoloration
round colonies on blood agar or chocolate agar is much decreased in depth and area
when the cultures are incubated anaerobically. Grows at 22 and 37 ºC. No growth at
45 ºC. Acid is produced, but no clot in litmus milk. Survive heating to 60 ºC for 30
minutes. Can grow at pH 9-6 and in 6.5% (w/v) NaCl.
Acid but no gas is produced from glucose and other sugars.
Isolated from air, dust, vegetation, meat-curing brines, soil, and marine sources. It may also be found in small numbers in the upper
respiratory tract and on the skin of normal persons. Isolated from animals: dairy cows, goats (admin note), lobsters.
Usually is considered to be a contaminant.
May be found in small numbers as part of the indigenous flora in the upper respiratory tract and on the skin of normal persons. Rarely
is associated with human infections (endocarditis, urinary tract infections, septic arthritis and acute childhood meningitis.
In animals may be responsible for subclinical intramammary infections in ruminants and a fatal disease (gaffkemia) of lobsters.
  1. R. E. O. Williams, Ann Hirch, S. T. Cowan: Aerococcus, a New Bacterial Genus. Microbiology, June 1953 8: 475-480.
  2. Masanori Tohno, Maki Kitahara, Shuichi Matsuyama, Koji Kimura, Moriya Ohkuma, Kiyoshi Tajima: Aerococcus vaginalis sp. nov.,
    isolated from the vaginal mucosa of a beef cow, and emended descriptions of Aerococcus suis, Aerococcus viridans, Aerococcus
    urinaeequi, Aerococcus urinaehominis, Aerococcus urinae, Aerococcus christensenii and Aerococcus sanguinicola. Int J Syst Evol
    Microbiol, April 2014 64: 1229-1236.
  3. Matthew D. Collins and Enevold Falsen, 2009. Genus I. Aerococcus Williams, Hirch and Cowan 1953, 475AL. In: (Eds.) P.D. Vos,
    G. Garrity, D. Jones, N.R. Krieg, W. Ludwig, F.A. Rainey, K.-H. Schleifer, W.B. Whitman. Bergey’s Manual of Systematic
    Bacteriology, Volume 3: The Firmicutes, Springer, 655-711.
Description is based mostly on API 50 CH, API ZYM, API ID 32 Strep and API Strep.

Positive results for alkaline phosphatase, hippurate hydrolysis, aesculin hydrolysis, C4 esterase, C8 esterase, naphthol-AS-BI-

phosphohydrolase, acid production (after 7 days incubation at 30 ºC)  from: cellobiose, D-fructose, D-galactose, D-glucose, glycerol,
lactose, maltose, D-mannose, D-mannitol, methyl alpha-D-glucopyranoside, N-acetylglucosamine, D-ribose, sucrose & turanose.

Negative results for arginine hydrolysis, acetoin production, catalase, C14 lipase, leucine aminopeptidase, valine aminopeptidase,
cystine aminopeptidase, trypsin, chymotrypsin, acid phosphatase, alpha- and beta-galactosidase, beta-glucuronidase, alpha and
beta-glucosidase, N-acetyl-beta-glucosaminidase, alpha-mannosidase, alpha-fucosidase, pyrrolidonyl arylamidase,
alanine-phenylalanine-proline arylamidase, glycine-tryptophan arylamidase, beta-mannosidase, urease, acid production from:
D-adonitol, aesculin ferric citrate, amygdalin, D- and L-arabinose, D- and L-arabitol, arbutin, dulcitol, erythritol, D- and L-fucose,
gentiobiose, gluconate, glycogen, inositol, inulin, 2- and 5-ketogluconate, D-lyxose, melezitose, melibiose, methyl
alpha-D-mannopyranoside, raffinose, L-rhamnose, salicin, L-sorbose, D-sorbitol, starch, D-tagatose, trehalose, methyl
beta-D-xylopyranoside, xylitol, D- and L-xylose.
(c) Costin Stoica
Culture media
Biochemical tests
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