Molybdate reduction byPseudomonassp. strain DRY2

Abstract

Aims: To isolate and characterize a potent molybdenum‐reducing bacterium. Methods and Results: A minimal salt medium supplemented with 10 mmol l−1 molybdate, glucose (1·0%, w/v) as a carbon source and ammonium sulfate (0·3%, w/v) as a nitrogen source was used in the screening process. A molybdenum‐reducing bacterium was isolated and tentatively identified as Pseudomonas sp. strain DRY2 based on carbon utilization profiles using Biolog GN plates and partial 16S rDNA molecular phylogeny. Strain DRY2 produced 2·4, 3·2 and 6·2 times more molybdenum blue compared to Serratia marcescens strain DRY6, Enterobacter cloacae strain 48 and Eschericia coli K12, respectively. Molybdate reduction was optimum at 5 mmol l−1 phosphate. The optimum molybdate concentration that supported molybdate reduction at 5 mmol l−1 phosphate was between 15 and 25 mmol l−1. Molybdate reduction was optimum at 40°C and at pH 6·0. Phosphate concentrations higher than 5 mmol l−1 strongly inhibited molybdate reduction. Inhibitors of electron transport system such as antimycin A, rotenone, sodium azide and cyanide did not inhibit the molybdenum‐reducing enzyme activity. Chromium, copper, mercury and lead inhibited the molybdenum‐reducing activity. Conclusions: A novel molybdenum‐reducing bacterium with high molybdenum reduction capacity has been isolated. Significance and Impact of the Study: Molybdenum is an emerging global pollutant that is very toxic to ruminants. The characteristics of this bacterium suggest that it would be useful in the bioremediation of molybdenum pollutant.

ISOLATION AND CHARACTERIZATION OF A MOLYBDENUM-REDUCING AND GLYPHOSATE-DEGRADING Klebsiella oxytoca STRAIN SAW-5 IN SOILS FROM SARAWAK

“…To be precise, the spectrum displayed should demonstrate a maximum absorption in between 860 and 870 nm, and a shoulder at about 700 nm. The Mo-blue spectrum from the PDM generally demonstrated a maximum absorption around 880 to 890 nm, and a shoulder around 700 to 720 nm (Shukor et al, 2010a). It was demonstrated beforehand that all of the molybdenum blue spectra obtained from other molybdenum-reducing bacteria follow this prerequisite (Shukor et al, 2007).…”

“…The determination of phosphate and molybdate concentrations supporting optimal molybdenum reduction is important because both anions have been shown to inhibit Mo-blue production in bacteria (Shukor et al, 2008a;Shukor et al, 2009a;Yunus et al, 2009;Shukor et al, 2009b;Shukor et al, 2010a;Shukor et al, 2010b;Lim et al, 2012;Ahmad et al, 2013;Othman et al, 2013;. The optimum concentration of phosphate occurred at 5 mM with higher concentrations were strongly inhibitory to reduction (Figure 1d).…”

“…Reduction at this high concentration into an insoluble form would allow the strain to reduce high concentration of molybdenum pollution. The lowest optimal concentration of molybdenum reported is 15 mM in Pseudomonas sp strain Dr.Y2 (Shukor et al, 2010a), whilst the highest molybdenum required for optimal reduction was 80 mM in E. coli K12 (Campbell et al, 1985) and K. oxytoca strain hkeem (Lim et al, 2012). Other Mo-reducing bacteria such as EC48 (Ghani et al, 1993), S. marcescens strain Dr.Y6 (Shukor et al, 2008a), S. marcescens.…”

“…Several of the molybdenum-reducing bacteria previously isolated such as Pseudomonas sp. strain DRY2 (Shukor et al, 2010a), Pseudomonas sp. strain DRY1 , Bacillus pumilus strain lbna (Abo-Shakeer et al, 2013) and Bacillus sp.…”

Enhanced caffeine degradation by immobilised cells of <i>Leifsonia</i> sp. strain SIU

“…Comparison between groups was performed using one-way analysis of variance (ANOVA) with posthoc analysis by Turkey's test (Miller and Miller, 2002). p < 0.05 was considered statistically significant (Shukor et al, 2010).…”