title: Molybdate reduction to molybdenum blue by an Antarctic bacterium.
abstract: A molybdenum-reducing bacterium from Antarctica has been isolated. The bacterium converts sodium molybdate or Mo⁶⁺ to molybdenum blue (Mo-blue). Electron donors such as glucose, sucrose, fructose, and lactose supported molybdate reduction. Ammonium sulphate was the best nitrogen source for molybdate reduction. Optimal conditions for molybdate reduction were between 30 and 50 mM molybdate, between 15 and 20°C, and initial pH between 6.5 and 7.5. The Mo-blue produced had a unique absorption spectrum with a peak maximum at 865 nm and a shoulder at 710 nm. Respiratory inhibitors such as antimycin A, sodium azide, potassium cyanide, and rotenone failed to inhibit the reducing activity. The Mo-reducing enzyme was partially purified using ion exchange and gel filtration chromatography. The partially purified enzyme showed optimal pH and temperature for activity at 6.0 and 20°C, respectively. Metal ions such as cadmium, chromium, copper, silver, lead, and mercury caused more than 95% inhibition of the molybdenum-reducing activity at 0.1 mM. The isolate was tentatively identified as Pseudomonas sp. strain DRY1 based on partial 16s rDNA molecular phylogenetic assessment and the Biolog microbial identification system. The characteristics of this strain would make it very useful in bioremediation works in the polar and temperate countries.
authors.affiliation: Department of Biochemistry, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia.
authors.forename: S A
authors.initials: SA
authors.lastname: Ahmad
authors.affiliation: Department of Biochemistry, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia.
authors.forename: M Y
authors.initials: MY
authors.lastname: Shukor
authors.affiliation: Faculty of Medicine and Health Sciences, Universiti Sains Islam Malaysia, 13th Floor, Menara B, Persiaran MPAJ, Jalan Pandan Utama, Pandan Indah, 55100 Kuala Lumpur, Malaysia.
authors.forename: N A
authors.initials: NA
authors.lastname: Shamaan
authors.affiliation: lnstituto Antartico Argentino, Cerrito 1248 (1010), Buenos Aires, Argentina.
authors.forename: W P
authors.initials: WP
authors.lastname: Mac Cormack
authors.affiliation: Department of Biochemistry, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia.
authors.forename: M A
authors.initials: MA
authors.lastname: Syed
mesh_terms: D000645:Ammonium Sulfate / Q000378:metabolism; D000864:Antarctic Regions; D002845:Chromatography; D006863:Hydrogen-Ion Concentration; D007477:Ions; D008982:Molybdenum / Q000737:chemistry / Q000378:metabolism*; D009584:Nitrogen / Q000378:metabolism*; D011549:Pseudomonas / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism*; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D013696:Temperature
chemical_list: D007477:Ions; D012336:RNA, Ribosomal, 16S; C044659:molybdate; C017541:molybdenum blue; D008982:Molybdenum; D009584:Nitrogen; D000645:Ammonium Sulfate