163
Box 4.1: Aeromonas allosaccharophila
Cultures comprise Gram-negative, motile fermentative rods, which produce
catalase, ß-galactosidase, indole, lysine decarboxylase and oxidase but not
H 2 S, reduce nitrates, degrade casein, DNA, egg yolk, gelatin, starch and
Tween 80 but not elastin, sodium dodecyl sulphate or urea, and grow in 0–3 %
(w/v) sodium chloride, at 4–42 °C and at pH 9.0. The Voges Proskauer reaction is negative. Acid is produced from D-cellobiose, D-galactose, glucose
(plus gas), glycerol, maltose, D-mannitol, D-mannose and D-trehalose, but
not from adonitol, arbutin, dulcitol, m -erythritol, m -inositol, lactose, salicin,
D-sorbitol or D-xylose. A wide range of compounds are utilized as sole
sources of carbon for energy and growth, including L-arabinose, L-arginine,
D-cellobiose, fumarate, D-galactose, D-gluconate, L-glutamate, glycerol,
L-histidine, maltose, D-mannitol, D-mannose, L-proline, succinate, sucrose
and D-trehalose, but not L-alanine, γ − aminobutyrate, L-citrulline, dulcitol,
m -erythritol, ethanol, D-glucuronate, L-glutamine, glycine, DL-3hydroxybutyrate, m -inositol, α-ketoglutarate, lactose, L-leucine, propionate,
putrescine, salicin or L-serine. Susceptibility has been recorded to chloramphenicol, erythromycin, fosfomicin, gentamicin, kanamycin, nalidixic acid,
nitrofurantoin, oxolinic acid, polymyxin B and rifampicin, but not to ampicillin, streptomycin, sulphadimethoxine or trimethoprim. The G + C content of
the DNA is 59.6 moles % (Martinez-Murcia et al. 1992 ).
The basis of allocating the isolates to a new species stemmed from the examination of 16S rRNA sequences, where homology values of >97.7 % were exhibited to
other validly described Aeromonas species (Martinez-Murcia et al. 1992 ). Three
isolates were found to be highly related, i.e. 70–100 %, by DNA:DNA hybridisation
(Esteve et al. 1995a ). On the basis of AFLP fi ngerprinting, Aer. allosaccharophila
has been determined to be genetically related to Aeromonas HG 8/10 (Huys et al.
1996 ).
Diagnosis
Phenotypic Methods
Aer. allosaccharophila isolates may be identifi ed by the examination of key phenotypic characters. In particular, the utilisation of L-arabinose and L-histidine as sole
carbon sources, acid production from D-mannitol, D-melibiose, D-raffi nose,
L-rhamnose, salicin and sucrose, and the Voges Proskauer reaction were considered
differential (Martinez-Murcia et al. 1992 ). However, a word of caution is necessary,
insofar as the organisms which clearly demonstrated genetic homogeneity were
markedly heterogeneous phenotypically. This would complicate diagnoses.
Aeromonas allosaccharophila
Box 4.1: Aeromonas allosaccharophila
Cultures comprise Gram-negative, motile fermentative rods, which produce
catalase, ß-galactosidase, indole, lysine decarboxylase and oxidase but not
H 2 S, reduce nitrates, degrade casein, DNA, egg yolk, gelatin, starch and
Tween 80 but not elastin, sodium dodecyl sulphate or urea, and grow in 0–3 %
(w/v) sodium chloride, at 4–42 °C and at pH 9.0. The Voges Proskauer reaction is negative. Acid is produced from D-cellobiose, D-galactose, glucose
(plus gas), glycerol, maltose, D-mannitol, D-mannose and D-trehalose, but
not from adonitol, arbutin, dulcitol, m -erythritol, m -inositol, lactose, salicin,
D-sorbitol or D-xylose. A wide range of compounds are utilized as sole
sources of carbon for energy and growth, including L-arabinose, L-arginine,
D-cellobiose, fumarate, D-galactose, D-gluconate, L-glutamate, glycerol,
L-histidine, maltose, D-mannitol, D-mannose, L-proline, succinate, sucrose
and D-trehalose, but not L-alanine, γ − aminobutyrate, L-citrulline, dulcitol,
m -erythritol, ethanol, D-glucuronate, L-glutamine, glycine, DL-3hydroxybutyrate, m -inositol, α-ketoglutarate, lactose, L-leucine, propionate,
putrescine, salicin or L-serine. Susceptibility has been recorded to chloramphenicol, erythromycin, fosfomicin, gentamicin, kanamycin, nalidixic acid,
nitrofurantoin, oxolinic acid, polymyxin B and rifampicin, but not to ampicillin, streptomycin, sulphadimethoxine or trimethoprim. The G + C content of
the DNA is 59.6 moles % (Martinez-Murcia et al. 1992 ).
The basis of allocating the isolates to a new species stemmed from the examination of 16S rRNA sequences, where homology values of >97.7 % were exhibited to
other validly described Aeromonas species (Martinez-Murcia et al. 1992 ). Three
isolates were found to be highly related, i.e. 70–100 %, by DNA:DNA hybridisation
(Esteve et al. 1995a ). On the basis of AFLP fi ngerprinting, Aer. allosaccharophila
has been determined to be genetically related to Aeromonas HG 8/10 (Huys et al.
1996 ).
Diagnosis
Phenotypic Methods
Aer. allosaccharophila isolates may be identifi ed by the examination of key phenotypic characters. In particular, the utilisation of L-arabinose and L-histidine as sole
carbon sources, acid production from D-mannitol, D-melibiose, D-raffi nose,
L-rhamnose, salicin and sucrose, and the Voges Proskauer reaction were considered
differential (Martinez-Murcia et al. 1992 ). However, a word of caution is necessary,
insofar as the organisms which clearly demonstrated genetic homogeneity were
markedly heterogeneous phenotypically. This would complicate diagnoses.
Aeromonas allosaccharophila