687
• Requirement for 0.1 % (w/v) L-cysteine hydrochloride
This is essentially a requirement for the growth of Ren. salmoninarum. Inoculated
media should be incubated at 15 °C, and examined at weekly intervals for up to
16 weeks.
• Oxidation-fermentation test
This involves the measurement of acid production from glucose metabolism
under aerobic and/or anaerobic conditions in the basal medium of Hugh and Leifson
( 1953 ). The production of an alkaline reaction is indicated by a deep blue colour
which develops, usually in the open tube. For marine organisms, it is necessary to
use the modifi ed medium of Leifson ( 1963 ). The presence of acid, indicated by a
colour change to yellow, should be recorded after incubation for 1, 2 and 7 days.
• Indole production
This is recorded after 7 days incubation in 1 % (w/v) peptone water. For marine
organisms, this should be prepared MSS (2.4 % (w/v) NaCl; 0.7 % (w/v)
MgSO 4 .7H 2 0; 0.075 % (w/v) KCl; after Austin et al. 1979 ). A positive response is
indicated by a red coloration following the addition of a few drops of Kovacs
reagent.
• α-galactosidase production
One of the most reproducible methods is to record α-galactosidase production
from the API zym system after incubation for 48 h at 15 or 25 °C.
• β-galactosidase production
This involves use of the medium of Lowe ( 1962 ). Inoculated medium is incubated for 7 days, whereupon a positive response is indicated by a yellow coloration.
For marine organisms, the medium should be prepared in MSS.
• Production of arginine dihydrolase and lysine decarboxylase
We recommend use of the medium described by Møller ( 1955 ). Essentially inoculated medium is incubated for 7 days, when a positive reaction is indicated by a
purple coloration. With marine organisms, the medium should be prepared in MSS.
• Urease production
Using the medium of Stuart et al. ( 1945 ), a positive response develops as a reddish coloration, within 28 days. For marine organisms, it is suggested that the
medium is supplemented with 2.4 % (w/v) sodium chloride.
• Methyl red test and Voges-Proskauer reaction
These may be recorded after 7 days incubation in MRVP broth (Difco). Following
the addition of a few drops of methyl red, a bright red coloration indicates a positive
methyl red test. The Voges Proskauer reaction is recorded after use of commercially
available reagents. A positive reaction is indicated by a red coloration which
Phenotypic Tests
• Requirement for 0.1 % (w/v) L-cysteine hydrochloride
This is essentially a requirement for the growth of Ren. salmoninarum. Inoculated
media should be incubated at 15 °C, and examined at weekly intervals for up to
16 weeks.
• Oxidation-fermentation test
This involves the measurement of acid production from glucose metabolism
under aerobic and/or anaerobic conditions in the basal medium of Hugh and Leifson
( 1953 ). The production of an alkaline reaction is indicated by a deep blue colour
which develops, usually in the open tube. For marine organisms, it is necessary to
use the modifi ed medium of Leifson ( 1963 ). The presence of acid, indicated by a
colour change to yellow, should be recorded after incubation for 1, 2 and 7 days.
• Indole production
This is recorded after 7 days incubation in 1 % (w/v) peptone water. For marine
organisms, this should be prepared MSS (2.4 % (w/v) NaCl; 0.7 % (w/v)
MgSO 4 .7H 2 0; 0.075 % (w/v) KCl; after Austin et al. 1979 ). A positive response is
indicated by a red coloration following the addition of a few drops of Kovacs
reagent.
• α-galactosidase production
One of the most reproducible methods is to record α-galactosidase production
from the API zym system after incubation for 48 h at 15 or 25 °C.
• β-galactosidase production
This involves use of the medium of Lowe ( 1962 ). Inoculated medium is incubated for 7 days, whereupon a positive response is indicated by a yellow coloration.
For marine organisms, the medium should be prepared in MSS.
• Production of arginine dihydrolase and lysine decarboxylase
We recommend use of the medium described by Møller ( 1955 ). Essentially inoculated medium is incubated for 7 days, when a positive reaction is indicated by a
purple coloration. With marine organisms, the medium should be prepared in MSS.
• Urease production
Using the medium of Stuart et al. ( 1945 ), a positive response develops as a reddish coloration, within 28 days. For marine organisms, it is suggested that the
medium is supplemented with 2.4 % (w/v) sodium chloride.
• Methyl red test and Voges-Proskauer reaction
These may be recorded after 7 days incubation in MRVP broth (Difco). Following
the addition of a few drops of methyl red, a bright red coloration indicates a positive
methyl red test. The Voges Proskauer reaction is recorded after use of commercially
available reagents. A positive reaction is indicated by a red coloration which
Phenotypic Tests