Abstract
The objective of this work was to improve bioluminescence stability of Photobacterium phosphoreum when it stored in view of developing continuous on-line monitoring system for pullutants. Long-term experiments were made to determine the effect of immobilization and storage temperature on the maintenance and stability of bioluminescence from luminescent bacteria. The immobilized cells of P. phosphoreum were compared with free cells in terms of maintenance of bioluminescence at room temperature. The bioluminescence of cells immobilized showed higher bioluminescence intensity that free and strontium bioluminescence stability was investigated with free and immobilized cells stored at $20^{\circ}C,\; 4^{\circ}C,\; -20^{\circ}C\;and\;-70^{\circ}C$for 20 days. Both free and immobilized cells stored at $4^{\circ}C$ emitted a stable bioluminescence while the bioluminescence markedly decreased with those stored at $20^{\circ}C,\;-20^{\circ}C\;and\; -70^{\circ}C$.
P. phosphoreum의 고정화에 있어 중요한 것은 Matrix의 선택이며, Matrix로서 sodium algnate만을 사용하여 고정화하는 것보다는 strontnum chloride를 첨가하였을 때 세포의 bio-iummescence 유지도가 증가하였다. 저장 온도에 따른 bio-iummescence 유지도와 관련하여 -$70^{\circ}C,\;-20^{\circ}C,\;20^{\circ}C$에서 저장한 세포의 경우 저장 1일 후에 급격한 bioluminescence의 감소를 보였으나 $4^{\circ}C$ 에서 저장한 세포는 bioluminescence의 유지도가 15일 이상 이어졌다. 따라서 P. phosphoreum의 bioluminescence 안정성에 있어 가장 좋은 결과를 나타낸 것은 2.5%(W/W)sodium alginate와 0.3M(W/V)strontnum chloride 를 사용하여 고정화한 세포였으며 저장 온도는 $4^{\circ}C$였다.