Activity of bronopol (Pyceze®) against bacteria cultured from eggs of halibut, Hippoglossus hippoglossus and cod, Gadus morhua

Abstract

Bronopol (2-bromo-2-nitro-1,3 propanediol) is a broad spectrum bactericide that is the active ingredient of Pyceze®. To assess the potential of Pyceze® for use in marine fish hatcheries we have determined the Minimum Inhibitory Concentration (MIC) of bronopol for 13 bacteria isolated from eggs of halibut ( Hippoglossus hippoglossus) and Atlantic cod ( Gadus morhua), and Escherichia coli, Staphylococcus aureus and Vibrio anguillarum as control bacteria. Six Vibrio and Moritella spp. had MIC ranging from 1–2 to 8 μg ml − 1 bronopol (mean MIC approximately 3 μg ml − 1 ), but other bacteria tested ( Tenacibacter ovolyticus, Pseudomonas sp., Pseudoalteromonas spp., Colwellia sp., Photobacterium phosphoreum and a Cytophaga/ Flexibacter sp.) were more resistant with MIC in the range 8–16 to 32–64 (mean MIC approximately 25 μg ml − 1 ). E. coli and S. aureus both had MIC of 32 μg ml − 1 . Although the MIC of bronopol for T. ovolyticus was 16–32 μg ml − 1 , a concentration of 100 μg ml − 1 bronopol had no detectable killing effect on this organism within 1 h but at 200 μg ml − 1 bronopol 90% of T. ovolyticus were killed within 30 min and > 99.99% within 2 h.