Molecular detection of a histamine former, Morganella morganii, in albacore, mackerel, sardine, and a processing plant

Testing for Morganella morganii, a prolific histamine former, was carried out in fish and processing plant to determine its origin and contamination source using PCR assay coupled with Southern hybridization. M. morganii was mostly found in mackerel and sardines but rarely in albacore. It was most frequently present in the gill followed by the skin but rarely in the intestine and cavity. No M. morganii was found in the processing plant but was detected on the surfaces of conveyer belts and plastic totes during processing. The compiled results indicated that histamine-forming bacteria are endogenous to fish and pointed out the importance of sanitation in the processing plant to prevent cross-contamination.