Histidine decarboxylase bacterial production

Amine build-up in fish muscle usually results from decarboxylation of amino acids in the muscle by enzymes of bacterial origin. This review will present information on the activity of bacterial decarboxylases and the formation of amines in fish. Mechanisms of decarboxylase action and production of bacterial decarboxylases in fish muscle are discussed. Emphasis is placed upon studies dealing with formation of histidine decarboxylase and histamine. Histamine, because of its involvement in Scombroid food poisoning, has been extensively studied with regard to its formation in fish and fishery products. 

Because amine formation in fish muscle and other foods usually results from bacterial growth with concomitant production of a bacterial decarboxylase, this paper will concentrate on the mechanisms of bacterial decarboxylation and factors influencing the production and activity of the enzymes. Also, because of the overall scope of the subject, the availability of excellent reviews on bacterial decarboxylation (2, 3) and the public health importance of histamine in fish and fishery products, this paper will primarily be limited to a discussion of histidine decarboxylase (EC 4.1.1.22) and the formation of histamine in fish muscle. 

Relationship of Bacterial Histidine Decarboxylase Production to Histamine Formation. Many studies have been completed with the objective of understanding factors such as storage time and temperature that influence production of histamine in fish. The majority of the investigations have considered only the histamine content of the product, and, consequently, only limited information is available concerning the relationship of histidine decarboxylase formation by the microflora to histamine build-up. 

Holland et al. (1978) suggested that a second enzyme may be required for histamine synthesis and/or stability (histidine decarboxylase was shown to be unstable). Histamine production can have a significant effect on the course of acne vulgaris. If the pH inside the follicle drops to 4.5, approaching the first pH-optimum, histamine production in vivo will increase, serving as a metabolic response to the bacterial environment since amines reduce the acidity, histamine production creates more favorable... 

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