Separation of viable histamine-producing bacteria from yellowtail meat components by density gradient centrifugation.

Quantitative separation of live cells from food samples is essential for non-culture methods to be validated. In this viewpoint, the feasibility of density gradient centrifugation (DGC) was demonstrated for the first time using samples of yellowtail meat to which Morganella morganii, a histamine producing bacterium had been added. Using a Ficoll density gradient from 50 to 10 w/v % with 10 w/v % steps, meat-free fractions of M. morganii cells were collected in 20-50 w/v % layers. The total cell collection rate ranged from 73-86 % irrespective of the cell density in the range 10(2)-10(6) cells/200 microl.