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Published on: October 18, 2010
Detection and identification of histamine-producing bacteria associated with harvesting and processing mahimahi and
D Grey Allen1, David P Green, Gregory E Bolton
1Center for Marine Sciences and Technology, Department of Food Science, North Carolina State University, 303 College Circle, Morehead City, North Carolina 28557, USA.
Abstract:
Histamine poisoning is one of the most common chemically induced seafoodborne illnesses reported in the United States today. The causative agents are biogenic amines, commonly produced by gram-negative bacteria. The purpose of this study was to detect and identify histamine-producing bacteria associated with standard industry practices during the harvesting, receiving, and processing of mahimahi and yellowfin tuna in North Carolina. Twenty-nine composite samples were obtained from 18 mahimahi and 11 yellowfin tuna and analyzed for their histamine content. No sample analyzed exceeded 2 ppm histamine, the lower detection limit. Composite fish muscle and environmental samples were screened (n = 386) for the presence of histamine-producing bacteria. Twenty-six percent (145) of 549 isolates selected on the basis of their morphological characteristics tested positive on Niven's media. Sixty-three Niven-positive isolates were gram negative, and 58 were gram positive. Of the 43 isolates tested further, 5 were confirmed as histamine producers, and all 5 produced at low levels (< 250 ppm in 48 h at > 15 degrees C). Three gram-negative and two gram-positive isolates were identified as Enterobacter cloacae and Staphylococcus kloosii, respectively. This study revealed that gram-negative bacteria might not be solely responsible for histamine production in at-risk fish. The confirmation of histamine-producing bacteria demonstrates the potential risk for histamine production. However, no detectable levels were found in the composite fish muscle samples analyzed even though 60% of the yellowfin tuna harvested did not meet the U.S. Food and Drug Administration's regulatory hazard analysis critical control point guidelines for temperature reduction. Therefore, no seafood safety risks were found under the standard industry practices observed in this study.
Insights
Histamine poisoning from seafood is common, but this study found no detectable histamine in North Carolina mahimahi and yellowfin tuna. Researchers identified some histamine-producing bacteria, including gram-positive types, challenging the notion that only gram-negative bacteria are responsible.
Area of Science:
- Food Science
- Microbiology
- Seafood Safety
Background:
- Histamine poisoning is a frequent chemically induced seafoodborne illness in the U.S.
- Biogenic amines, like histamine, are typically produced by gram-negative bacteria.
- Understanding the sources of histamine production in seafood is crucial for public health.
Purpose of the Study:
- To detect and identify histamine-producing bacteria in mahimahi and yellowfin tuna.
- To assess histamine production associated with North Carolina's seafood industry practices.
- To evaluate potential seafood safety risks related to histamine.
Main Methods:
- Analysis of 29 composite mahimahi and yellowfin tuna samples for histamine content.
- Screening of 386 bacterial isolates from fish and environmental samples for histamine production using Niven's media.
- Identification of confirmed histamine-producing isolates using biochemical and Gram staining methods.
Main Results:
- No analyzed fish samples exceeded the 2 ppm histamine detection limit.
- Twenty-six percent of isolates tested positive for histamine production on Niven's media.
- Five isolates confirmed as histamine producers, including both gram-negative and gram-positive bacteria (Enterobacter cloacae, Staphylococcus kloosii), producing low levels.
Conclusions:
- Histamine-producing bacteria, including gram-positive species, were identified in association with tuna harvesting and processing.
- Despite the presence of histamine-producing bacteria, no detectable histamine levels were found in the analyzed fish.
- Observed industry practices did not result in detectable histamine levels, indicating no seafood safety risk in this study.
