CONDUCTANCE METHOD FOR QUANTITATIVE-DETERMINATION OF PHOTOBACTERIUM-PHOSPHOREUM IN FISH PRODUCTS

This paper presents the development of a sensitive and selective condu ctance method for quantitative determination of Photobacterium phospho reum in fresh fish. A calibration curve with a correlation coefficient of -0.981 was established from conductance detection times (DT) for e stimation of cell levels. Less than 50 cells g(-1) of fish could be de tected in less than 45 h. The selectivity of the method in relation to other Photobacteria or other bacteria isolated from spoiled fish was good. DTs for 10-100 cfu ml(-1) of P. phosphoreum were shorter than DT s for 10(6) cells ml(-1) of the other organisms tested. In naturally c ontaminated fresh fish, P. phosphoreum was specifically enumerated whe n it made up 0.1% of the total level of micro-organisms. The repeatabi lity (S.D.%) of the conductance assay ranged from 2.9% to 7.3%.