Related Experiment Video
Updated: May 19, 2026
06:52
Experimental Column Setup for Studying Anaerobic Biogeochemical Interactions Between Iron (Oxy)Hydroxides, Trace Elements, and Bacteria
Published on: December 19, 2017
Biotic factor does not limit operational pH in packed-bed bioreactor for ferrous iron biooxidation
Alfonso Mazuelos1, José María Moreno, Francisco Carranza
1Departamento de Ingeniería Química, Universidad de Sevilla, c/Profesor García González. Edificio Química, 41012 Seville, Spain. mazuelos@us.es
Journal of Industrial Microbiology & Biotechnology
|August 23, 2012
Summary
Ferrous ion biooxidation in flooded packed-bed bioreactors (FPBs) is optimized by controlling pH. Microbial populations shift, with Acidithiobacillus ferrooxidans dominating above pH 1.3 and Leptospirillum ferrooxidans below it.
Area of Science:
- Environmental Microbiology
- Biotechnology
- Industrial Bioprocessing
Background:
- Ferrous ion biooxidation is crucial for industrial applications like bioleaching and acid mine drainage treatment.
- Flooded packed-bed bioreactors (FPBs) offer the highest biooxidation rates due to immobilized biomass in a ferric compound matrix.
- pH significantly impacts FPB operation by affecting the stability of the ferric matrix and microbial activity.
Purpose of the Study:
- To investigate the effect of pH on flooded packed-bed bioreactor (FPB) operation.
- To analyze the behavior of microbial populations within FPBs across a range of pH conditions.
- To determine the optimal pH range for stable FPB performance and microbial community structure.
Main Methods:
- Assaying FPBs with mixed inocula across a pH range of 0.8 to 2.3.
- Characterizing the microbial population dynamics in response to varying pH levels.
- Monitoring bioreactor performance and microbial community shifts under continuous operation.
Main Results:
- The microbial consortium in FPBs is significantly influenced by pH.
- Acidithiobacillus ferrooxidans is the dominant species at pH above 1.3.
- Leptospirillum ferrooxidans becomes dominant at pH below 1.3.
- Bioreactor performance is not compromised by the biotic factor within the pH range of 1 to 2.3 when the inoculum is adapted to acidity.
Conclusions:
- pH is a critical operational parameter for flooded packed-bed bioreactors (FPBs).
- Microbial community composition, specifically the dominance of Acidithiobacillus ferrooxidans or Leptospirillum ferrooxidans, is determined by pH.
- Adapting the inoculum to decreasing pH allows for stable bioreactor performance across a broad acidic range (pH 1-2.3).
Related Concept Videos
01:29Bioreactor Design and Operational System
Bioreactors are engineered vessels designed to cultivate microorganisms under controlled conditions for industrial bioprocessing. They maintain sterility and allow precise regulation of pH, temperature, oxygen, and nutrient levels to optimize microbial growth and metabolite production. Bioreactors range from small laboratory units of 1 liter to industrial systems holding up to 500,000 liters, though only about 75% of their volume is actively used for fermentation. The remaining headspace...
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...
01:27Microbial 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...
01:18Bioreactor Controls-II
In aerobic fermentations, oxygen is vital for microbial growth and metabolite production. Since air comprises only about 20% oxygen and the gas is poorly soluble in water—just 9 ppm at 20°C—supplying sufficient oxygen becomes a critical challenge, especially in high-demand processes like yeast growth or citric acid production. Even a fully saturated broth may offer only a few seconds of oxygen availability.To address this, sterile or scrubbed air is introduced into the fermentor via a sparger...
01:28Microbial Nutrition
Organisms exhibit remarkable metabolic diversity, categorized based on how they acquire energy and carbon. These strategies enable survival in various ecological niches and are essential for maintaining energy flow and nutrient cycling within ecosystems.Energy and Carbon SourcesOrganisms are classified as phototrophs or chemotrophs based on energy acquisition. Phototrophs use light as their energy source, while chemotrophs rely on oxidizing chemical compounds. Further differentiation arises...
01:15Metabolism of Chemolithotrophs
Chemolithotrophs are microorganisms that obtain energy by oxidizing inorganic molecules such as hydrogen gas (H₂), ammonia (NH₃), reduced sulfur compounds (H₂S, S²⁻), and ferrous iron (Fe²⁺). Unlike heterotrophic organisms that rely on organic carbon, chemolithotrophs transfer electrons from these inorganic donors to the electron transport chain (ETC), generating a proton motive force (PMF) that drives ATP synthesis through oxidative phosphorylation. However, because inorganic electron donors...