Bacteriological investigation of a case of red discolouration in Dutch salted summer herring

Summary

• 1. An investigation was carried out of a case of reddening in salted herring, caught in August and landed in September 1951.

• 2. Cultivation experiments were started using a fish milk medium, containing 10, 16 and 23 wt% of NaCl; incubation was carried out at 37, 30, 24 and 15°C. and both under aerobic and under anaerobic conditions.

• 3. Growth of red halophiles was observed exclusively in platings on 23 wt% NaCl. Those incubated aerobically at 37°C. showed growth after 1 month and those at 30 and 24°C. after about 2 months. No growth of red halophiles occurred at 15°C.

• 4. The brine and the gonads present in the barrel, containing red herring, and a brine and gonads sampled from a barrel of unspoiled herring, turned out to contain the same red, halophilic sarcinae.

• 5. The numbers of these sarcinae in the red and in the undiscoloured brine both were of the order of 100/ml, being about ten times the numbers found in either the discoloured or the normal tissues.

• 6. The conclusion must be drawn that the type of red discolouration of herring described here is not caused by red halophilic bacteria.