The present innovation deals with construction of immobilized robust biophotonic bead using p. leiognathi, a marine luminescent bacterium isolated from indian coast for their application in monitoring of environmental toxicants. these biophotonic beads were used as a rapid and reliable optical biosensing tool for the detection of heavy metals [hg(ii), as(v) or cd(ii)] and pesticide [2,4-dichlorophenoxyacetic acid (2,4-d)] in water systems. the concentration range for the detection of hg (ii), as(v), cd(ii) and 2,4-d was 232 ppm, 4128 ppm, 16512 ppm and 100600 ppm, respectively, while corresponding sensitivity threshold was 2.0 ppm, 4.0 ppm, 16.0 ppm and 100 ppm. the time taken for the detection of heavy metals and pesticide was less than 30 min. a highly sensitive and portable bioluminometer was also developed for the determination of microbial contamination in food and water.