Detoxification of Mercury by Bacteria Using Crude Glycerol from Biodiesel as a Carbon Source

Abstract

Bacteria that harbor the mer operon in their genome are able to enzymatically reduce mercury (II) to the volatile form of mercury Hg (0). Detoxification of contaminated waste by using these bacteria may be an alternative to conventional methods for mercury removal. Residual glycerol from the biodiesel industry can be used as a carbon source to accelerate the process. This work shows for the first time the feasibility of using residual glycerol as a carbon source for Hg removal by bacteria prospected from contaminated environments. Eight bacterial isolates were able to remove mercury and degrade glycerol in mineral medium and residual glycerol. Mercury removal was monitored by atomic absorption spectroscopy and glycerol degradation by high performance liquid chromatography. The best results of mercury removal and glycerol degradation were obtained using isolates of Serratia marcescens M25C (85 and 100 %), Klebsiella pneumoniae PLB (90 and 100 %), Klebsiella oxytoca (90 and 100 %), and Arthrobacter sp. U3 (80 and 75 %), with addition of 0.5 g L −1 yeast extract. The Arthrobacter sp. U3 isolate is common in soils and has proven to be a promising candidate for environment applications due to its low pathogenicity and higher Hg removal and glycerol degradation rates.

Latent Benefits and Toxicity Risks Transmission Chain of High Dietary Copper along the Livestock–Environment–Plant–Human Health Axis and Microbial Homeostasis: A Review

“…224 In addition, copY and copZ (Cu chaperone) can also regulate the expression of cop. 225 Bacteria can also convert Cu from high-toxicity to lowtoxicity products through redox and methylation reactions inside the cell to achieve detoxification, 226 which is called internal transformation. The intracellular periplasm of the bacterial cell is the main site of Cu transformation in which the cuproenzyme CueO (a multicopper oxidase) can oxidize Cu + to Cu 2+ to reduce its toxicity (Figure 1C).…”