Related Experiment Video
Updated: Jun 26, 2026
15:19
Development of Sulfidogenic Sludge from Marine Sediments and Trichloroethylene Reduction in an Upflow Anaerobic Sludge Blanket Reactor
Published on: October 15, 2015
Reduction of molybdate by sulfate-reducing bacteria.
Keka C Biswas1, Nicole A Woodards, Huifang Xu
1Department of Science, Wesley College, Dover, DE 19901, USA. kekacbiswas@gmail.com
Summary
Sulfate-reducing bacteria (SRB) can reduce molybdate, forming a molybdate-sulfide complex. This microbial process may explain the presence of molybdenum sulfides in ancient marine sediments.
Area of Science:
- Environmental microbiology
- Geochemistry
- Biogeochemical cycling
Background:
- Molybdate is an essential trace element for anaerobic sulfate-reducing bacteria (SRB).
- High environmental concentrations of molybdate can be detrimental.
- Molybdate, a sulfate analog, inhibits SRB sulfate respiration, but its effect on pure cultures is poorly understood.
Purpose of the Study:
- To investigate the effects of sub-lethal molybdate concentrations on pure cultures of SRB.
- To characterize the interaction between molybdate and SRB metabolism.
- To explore the potential role of SRB in the formation of molybdenum sulfides in geological settings.
Main Methods:
- Cultivation of four SRB species (Desulfovibrio gigas, Desulfovibrio vulgaris, and two strains of Desulfovibrio desulfuricans) in media with sub-lethal molybdate levels.
- Observation of culture fluid color changes.
- Spectral analysis (UV-Vis spectrophotometry) of culture fluids.
- Localization of molybdate reduction within bacterial cells.
Main Results:
- A distinct red-brown color developed in culture fluids containing molybdate.
- Spectral analysis identified absorption peaks characteristic of a molybdate-sulfide complex.
- Molybdate reduction to molybdate disulfide was observed in the periplasm of Desulfovibrio gigas and Desulfovibrio desulfuricans DSM 642.
- Sub-lethal molybdate levels did not inhibit bacterial growth.
Conclusions:
- SRB can metabolize molybdate, forming molybdate-sulfide complexes.
- The periplasmic reduction of molybdate by SRB leads to the formation of Mo-sulfides.
- SRB activity is a potential mechanism for the selective enrichment and formation of molybdenum sulfides in ancient marine environments, such as black shales.
More Related Videos
06:52Experimental Column Setup for Studying Anaerobic Biogeochemical Interactions Between Iron (Oxy)Hydroxides, Trace Elements, and Bacteria
Published on: December 19, 2017
08:21Optimized Procedure for Determining the Adsorption of Phosphonates onto Granular Ferric Hydroxide using a Miniaturized Phosphorus Determination Method
Published on: May 18, 2018
Related Concept Videos
01:24Microbes and Other Elemental Cycles
Microbial activity plays a pivotal role in the biogeochemical cycling of iron and manganese, especially at the redox gradients characteristic of stratified aquatic environments. These cycles are driven by microbial transformations between oxidized and reduced forms of the metals, allowing organisms to exploit them for metabolic energy and structural purposes.Iron Cycling Across Redox GradientsIn neutral, oxygen-rich surface waters, iron is predominantly found in its oxidized, insoluble ferric...
01:25Microbial Bioremediation of Uranium
Microorganisms play a critical role in the transformation and immobilization of uranium in contaminated environments through four main pathways: bioreduction, biosorption, bioaccumulation, and biomineralization. These mechanisms reduce uranium’s toxicity and prevent its migration through groundwater systems, offering sustainable approaches for in situ bioremediation.Bioreduction of UraniumBioreduction is driven by anaerobic bacteria such as certain strains of Geobacter and Shewanella, which use...
01:29Microbes and the Sulfur Cycle
Sulfur is a vital element in Earth's biogeochemical systems. It transitions through various inorganic states, including sulfate (SO₄²⁻), elemental sulfur (S⁰), and sulfide (S²⁻). Abiotic and biological mechanisms across oxic and anoxic environments intricately mediate these transformations. Sulfate, the most oxidized form of sulfur, is predominantly stored in rocks, marine sediments, and oceanic waters, acting as a long-term reservoir in the global sulfur cycle.In oxic environments,...
01:26Redox Titration: Other Oxidizing and Reducing Agents
Besides iodine, other oxidizing or reducing agents can serve as titrants in redox titrations. Common oxidizing titrants include KMnO4, cerium(IV), and K2Cr2O7. The choice of oxidizing titrants depends on factors like stability, cost, analyte strength, and reaction rate between the analyte and titrant. KMnO4 is a strong oxidizing titrant that reduces from Mn(VII) to Mn(II) in a highly acidic solution, simultaneously oxidizing the analyte to a higher oxidation state. In this case, KMnO4 acts as a...
01:20Sulfur Assimilation
Sulfur is an essential element in biological systems, contributing to synthesizing key biomolecules, including amino acids such as cysteine and methionine, and cofactors such as coenzyme A and biotin. Microorganisms primarily assimilate sulfur as sulfate (SO₄²⁻) from the environment, which must undergo a series of biochemical transformations before it can be incorporated into cellular components. As sulfate is highly oxidized, it must undergo assimilatory sulfate reduction to become...
01:27Microbial Leaching
Microbial leaching, also known as bioleaching, is an environmentally favorable method for extracting metals from low-grade ores using specific microorganisms. This biotechnological approach is particularly valuable for mining operations targeting copper, gold, and uranium, where traditional extraction methods may be economically or environmentally impractical.Copper Leaching and Microbial CatalysisIn copper bioleaching, crushed ore is arranged into heaps and irrigated with a dilute sulfuric...