Protection of rainbow trout (Oncorhynchus mykiss) from furunculosis by Lactobacillus rhamnosus

The present study aimed to investigate the potential probiotic properties i n fish of a lactic acid bacterium intended for human use: Lactobacillus rha mnosus (ATCC 53103). A probiotic for human use was specifically chosen sinc e it is known to be safe for human use, which is of major importance becaus e the fish are meant for human consumption. The bacterium was administered at two different doses (10(9) and 10(12) CFU/g feed) to rainbow trout for 5 1 days. Sixteen days after the start of the Lactobacillus feeding, the fish were challenged with Aeromonas salmonicida ssp. salmonicida, which causes furunculosis. During the challenge trial the mortality was monitored. L. rh amnosus reduced the fish mortality significantly, from 52.6% in the control to 18.9% and 46.3% in the 10(9) CFU/g feed and the 10(12) CFU/g feed group s, respectively. From this, it was concluded that the tested strain may be a promising probiotic for fish without subsequent risk for human consumptio n. (C) 2001 Elsevier Science B.V. All rights reserved.