Toxicity monitoring of solvents, hydrocarbons, and heavy metals using statistically optimized model of luminous Vibrio sp. 6HFE.

BACKGROUND

The utilization of bioluminescent bacteria in environmental monitoring of water contaminates considers being a vital and powerful approach. This study aimed to isolate, optimize, and apply luminescent bacteria for toxicity monitoring of various toxicants in wastewater.

RESULTS

On the basis of light intensity, strain Vibrio sp. 6HFE was initially selected, physiologically/morphologically characterized, and identified using the 16SrDNA gene. The luminescence production was further optimized by employing statistical approaches (Plackett-Burman design and central composite design). The maximum bioluminescence intensity recorded 1.53 × 106 CPS using optimized medium containing (g/L), yeast extract (0.2g), CaCl2 (4.0), MgSO4 (0.1), and K2HPO4 (0.1) by 2.3-fold increase within 1h. The harnessing of Vibrio sp. 6HFE as a bioluminescent reporter for toxicity of organic solvents was examined using a bioluminescence inhibition assay. According to IC50 results, the toxicity order of such pollutants was chloroform > isoamyl > acetic acid > formamide > ethyl acetate > acetonitrile > DMSO > acetone > methanol. However, among eight heavy metals tested, the bioluminescence was most sensitive to Ag+ and Hg+ and least sensitive to Co2+ and Ni2+. Additionally, the bioluminescence was inhibited by benzene, catechol, phenol, and penta-chlorophenol at 443.1, 500, 535.1, and 537.4 ppm.

CONCLUSION

Vibrio sp. 6HFE succeeded in pollution detection at four different environmental and wastewater samples revealing its efficiency in ecotoxicity monitoring.