The Functional Starter and its Genomic Insights for Histamine Degradation in Fish Sauce

Histamine is a biogenic amine significantly formed in fish sauce leading to a major concern in consumers. This study aimed to identify a halophilic culture for histamine degradation in fish sauce, and understand its genomic insights to enhance the histamine degradation activity. We discovered the novel halophilic bacterium, Bacillus piscicola FBU1786, degrading histamine and other biogenic amines. Its histamine breakdown was growth-associated in a wide range of NaCl concentrations, pH, and temperature from 4% to 18%, 6.0 to 9.0, and 30 to 45ºC, respectively. Genome sequencing revealed the presence of Cu 2+ -binding oxidase-encoding genes and their heterologous expression with Cu 2+ supplementation triggered histamine degradation in E. coli . The degree of histamine breakdown in B . piscicola FBU1786 could be enhanced by Cu 2+ addition. Histamine degradation of the culture was evaluated in raw fish sauce mixtures to partially mimic the condition during fish sauce fermentation. Histamine degradation was suppressed to the extent of raw fish sauce. However, the degradation activity could be restored by Cu 2+ supplementation. Together, this study disclosed B. piscicola FBU1786 with the potent histamine degradation activity, identified Cu 2+ -binding oxidases responsible for histamine breakdown, and enhanced histamine degradation of the culture using Cu 2+ supplementation.