2. Materials and methods
2.1. Preparation of starter culture
The starter culture used in this study was Bacillus polymyxa
D05-1, which was isolated from salted fish products of Taiwan
[20]. It has high ability to degrade histamine and lesser ability
to degrade putrescine and cadaverine in trypticase soy broth
(TSB; Difco, Detroit, MI, USA) supplemented with 0.1% histamine
(histamine TSB broth). Samples (100 mL) of the 20-hourold
bacterial cultures in 5 mL of histamine TSB broth at 30C
were inoculated into fresh 100 mL histamine TSB broth and
incubated at 30C for another 24 hours. The culture was
centrifuged at 10,000g for 10 minutes at 4C and the cell pellet
was washed and resuspended in sterile saline solution,
adjusted to approximately 1 107 cells/mL.