Studies on the maintenance of bioluminescence from stored Photobacterium phosphoreum

摘要

The object of this work is to improve the maintenance of bioluminescence from stored Photobacterium phosphoreum in a view of developing continuous monitoring system for pollutants. The long-term experiments were performed to determine the effect of storage temperature and immobilization on the maintenance of bioluminescence and viability of P. phosphoreum. A naturally luminescent bacterium, P. phosphoreum was starved in 2.5 percent NaCl solution at 20 deg C, 4 deg C, -20 deg C and -700 deg C for 30 days. In vivo luminescence was measured by luminometry, and total cell concentrations and concentrations of culturable and viable cells were determined by acridine orange staining, dilution plate counting, and direct viable counting, respectively. The bioluminescence emission from cells stored at 4 deg C was maintained up to 10 days while those with starved cells at other temperature ranges decreased to background level within 3 days. In terms of viability of cells, concentrations of cells stored at 20 deg C were rapidly decreased as a result of cell lysis, leading to a drop in culturable and viable counts while cells stored at 4 deg C was shown viable but nonculturable state during starvation. With immobilized cells on strontium alginate, the bioluminescence showed higher maintenance than free cells and decreased with count number of nonculturable cells.