Isolation and characterization of molybdenum-reducing and PEG-degrading Enterobacter cloacae strain KIK-14 in agricultural soil from Nigeria

Abstract

Today, numerous researches have demonstrated the cost-effectiveness of bioremediation to waste removal from agricultural and industrial sectors particularly at lower levels of the toxicants, where other physicochemical techniques are ineffective. Multiple toxicant remediation by a single microorganism is important for remediation of sites contaminated with numerous toxicants. In this work, a molybdenum-reducing bacterium was screened for its ability to use the xenobiotic polyethylene glycol (PEG) as the sole source of carbon for growth and as electron donor source for molybdate reduction. Biochemical analysis results in the tentative identification of the isolate as Enterobacter cloacae strain KIK-14. The use of PEGs as an electron donor in this bacterium did not support molybdenum-blue production, even though the bacterium grew well on PEGs 200, 300, 600 and 1000 independent of molybdate reduction. Reduction of molybdate to Mo-blue was optimal at pH between 6.0 and 6.3, the temperature between 25 and 37 oC, molybdate and phosphate concentrations between 15 and 20 mM and between 5.0 and 7.5 mM respectively. The best electron donor source supporting the reduction process was glucose. The Mo-blue absorption spectrum resembles reduced phosphomolybdate and is similar to that of the previous Mo-reducing bacterium. At 2 ppm of silver, mercury and copper, molybdenum reduction was inhibited by 41.5, 57.1 and 40.5%, respectively. The ability of this bacterium to detoxify mixed toxicants makes it an important tool for bioremediation.

Isolation and Characterization of a Molybdenum-reducing and the Congo Red Dye-decolorizing Pseudomonas putida strain Neni-3 in soils from West Sumatera, Indonesia

“…To monitor Mo-blue production, the plate was first incubated at room temperature or designated temperatures when the temperature was optimized and then read at 750 nm using a microplate reader with the specific extinction coefficient of 11.69 mM. -1 .cm -1 at 750 nm [31].…”

Rapid Biomonitoring of Heavy Metals in Polluted Sites Using Xenoassay®-Metal

“…In a short time, 12phosphomolybdate is turned into molybdenum blue by the enzyme. As an overview, 50 mM of phosphomolybdic acid, or 12-phoshomolybdate, (sodium phosphomolybdate hydrate, Sigma, St. Louis, USA) was produced as an initial stock solution in 10 mM of phosphate buffer pH 5.8 and added to a 1-milliliter enzyme reaction mixture at a final concentration of 3-milliliters [33,34]. Finally, NADH is added to bring the final concentration up to 2.5mM.…”

Mathematical Modeling of Molybdenum Blue Production from Bacillus sp. Strain Khayat

“…680). Mo-blue production was quantified by measuring the specific extinction coefficient of the medium at 750 nm, which was the longest wavelength for which a filter was available for the microplate unit [40]. This was done since 750 nm was the longest wavelength for which a filter was available.…”