Implication of storage conditions on luminescence response from Photobacterium phosphoreum in free and immobilized...

Bioluminescent bacteria in the form of a cell suspension for on-site hazard analysis are not suitable as in vivo luminescence in free cells fluctuates and may lead to erroneous results. Furthermore, the culture broth cannot be stored for long durations to continue sensing analytes as the luminescence ceases over time. Factors that affect luminescence response include growth dynamism, and ambient environmental conditions. The present study investigated the effect of storage conditions such as temperature (25 ± 2°C, room temperature; 4°C; and -20°C) and ambient aqueous environment (M1: sucrose, 1.02 M; M2, bioluminescent media [tryptone, 10 g L^-1 ; NaCl, 28.5 g L^-1 ; MgCl₂ .7H₂ O, 4.5 g L^-1 ; CaCl₂ , 0.5 g L^-1 ; KCl 0.5 g L^-1 ; yeast extract, 1 g L^-1 ; H₂ O, 1 L]; M3, bioluminescent media and 95% glycerol, 1:1 ratio) on the luminescence emission from the calcium alginate-immobilized Photobacterium phosphoreum (S_b ) against the cells in free suspension for an extended period. The results indicated that both the parameters that were undertaken markedly affected the luminescence. In the study, S_b showed an enhanced luminescence emission than the control up to 18.5-fold and for a prolonged period which can be efficiently utilized for rapid biosensing of hazardous materials.