Mathematical modelling of molybdenum reduction to mo-blue by a cyanide-degrading bacterium

Abstract

Molybdenum, an emerging pollutant, has being demonstrated recently to be toxic to spermatogenesis in several animal model systems. Metal mines especially gold mine often use cyanide and hence isolation of metal-reducing and cyanide-degrading bacteria can be useful for the bioremediation of these pollutants. Preliminary screening shows that three cyanide-degrading bacteria were able to reduce molybdenum to molybdenum blue (Mo-blue) when grown on a molybdate low phosphate minimal salts media. Phylogenetic analyses of the 16S rRNA gene of the best reducer indicates that it belongs to the Serratia genus. A variety of mathematical models such as logistic, Gompertz, Richards, Schnute, Baranyi-Roberts, von Bertalanffy, Buchanan three-phase and Huang were used to model molybdenum reduction, and the best model based on statistical analysis was modified Gompertz with lowest values for RMSE and AICc, highest adjusted R2 values, with Bias Factor and Accuracy Factor nearest to unity (1.0). The reduction constants obtained from the model will be used to carry out secondary modelling to study the effect of various parameters such as substrate, pH and temperature to molybdenum reduction.

Modelling the Effect of Copper on the Mo-reduction Rate of the Antarctic Bacterium Pseudomonas sp. strain DRY1

“…A concentration of copper at 1.0 mg/L leads to a complete cessation of reduction. This was also observed in many Mo-reduction works [32][33][34][35][36][37][38][39][40][41].…”

“…Molybdenum reduction by the bacterium exhibits a sigmoidal profile, which is a common theme seen in many Mo-reducing bacteria [29][30][31]. As the concentration of copper was increased a significant decrease in the maximum Mo reduction was observed together with the increase in lag periods (Fig.…”

Immobilization of Bacillus sp. Strain Neni-8 in Dialysis Tubing Reduced Copper Toxicity to the Molybdenum Reduction Process

“…One of them is the enzymatic transformation of metals into precipitable forms in which they pose less risk. Reducing the toxicity of soluble molybdenum can result in the formation of molybdenum blue (Mo-blue), a precipitable substance with a beautiful blue color [23][24][25][26][27][28][29][30][31][32][33].…”

Entrapment of Mo-reducing Bacterium Increase its Resistance towards Mercury

“…The first known instance of molybdenum bioremediation utilizing microorganisms and plants occurred in this region. As a byproduct of copper mining, molybdenum in the form of molybdenite is extracted in Malaysia [14][15][16][17][18][19][20][21][22]. However, there have been several incidents of contamination due to the inadvertent leaking of pipes carrying the metal.…”

“…Enzymatic reduction of metal into a less hazardous precipitable state is one of them. One particularly eye-catching instance is the reduction of molybdenum to molybdenum blue (Mo-blue), a precipitable material with a stunning blue color [3,[20][21][22][23][24][25][26][27][28][29]. It has been known for at least the last century that some microorganisms can convert molybdate into Mo-blue.…”