Related Experiment Video
Updated: Jun 23, 2026
06:08
Design of Solid-State Fermentation Systems for Polymer Hydrolytic Extracellular Enzyme Production by Filamentous Fungi
Published on: June 6, 2025
Citric acid production by Aspergillus niger ATCC 9142 from a treated ethanol fermentation co-product using
1Department of Chemistry and Biochemistry, South Dakota State University, Brookings, SD 57007, USA.
Letters in Applied Microbiology
|May 7, 2009
Summary
Aspergillus niger ATCC 9142 can produce citric acid using corn distillers dried grains with solubles. Phosphate treatment of these grains enhances citric acid production, indicating commercial potential.
Area of Science:
- Biotechnology
- Industrial Microbiology
Background:
- Corn distillers dried grains with solubles (DDGS) are a co-product of ethanol fermentation.
- DDGS presents a potential low-cost substrate for microbial fermentation processes.
Purpose of the Study:
- To evaluate the suitability of DDGS as a substrate for citric acid production by Aspergillus niger ATCC 9142.
- To investigate the effects of various pre-treatments and supplementation on citric acid yield.
Main Methods:
- Citric acid and biomass production were quantified using enzyme assays and gravimetric methods.
- DDGS were subjected to untreated, autoclaved, and acid-hydrolysed treatments.
- Phosphate and methanol supplementation were tested, and optimal fermentation parameters (temperature, moisture, time) were determined.
Main Results:
- Citric acid production was highest on untreated DDGS compared to treated grains.
- Autoclaving and acid hydrolysis enhanced fungal biomass but reduced citric acid yield.
- Phosphate supplementation slightly increased citric acid production, while methanol inhibited it.
- Optimal conditions for citric acid production were 25°C, 82% moisture, and 240 h fermentation time with phosphate-supplemented DDGS.
Conclusions:
- Aspergillus niger ATCC 9142 can effectively produce citric acid using DDGS as a substrate.
- Phosphate supplementation of DDGS improves citric acid yield.
- DDGS is a viable and potentially commercial substrate for citric acid biosynthesis.
Related Concept Videos
01:25Production of Organic Acids
Lactic acid, an important organic acid extensively applied in food, pharmaceutical, and biodegradable polymer industries, is primarily produced via microbial fermentation. This method is favored over chemical synthesis due to its environmental sustainability and capacity for enantiomerically pure product formation. Among various microbial processes, the fermentation of starch-based substrates stands out due to the abundance and renewability of raw materials like corn and potatoes.Hydrolysis of...
01:27Production of Alcohol
Continuous fermentation is a key strategy in industrial ethanol production, particularly when efficiency, scalability, and high yields are essential. This approach allows for uninterrupted operation and optimized resource utilization. The primary feedstock, corn starch, undergoes enzymatic hydrolysis facilitated by α-amylase and glucoamylase. These enzymes break down the starch into fermentable sugars such as glucose, which are readily assimilated by fermentative microorganisms.Fermentation...
00:53Products of the Citric Acid Cycle
The cells of most organisms—including plants and animals—obtain usable energy through aerobic respiration, the oxygen-requiring version of cellular respiration. Aerobic respiration consists of four major stages: glycolysis, pyruvate oxidation, the citric acid cycle, and oxidative phosphorylation. The third major stage, the citric acid cycle, is also known as the Krebs cycle or tricarboxylic acid (TCA) cycle.
01:37The Citric Acid Cycle: Overview
In aerobic organisms, the citric acid cycle is the second stage of cellular respiration wherein molecules derived from the breakdown of carbohydrates, proteins, and fats are oxidized into carbon dioxide and energy. This process is also known as the tricarboxylic acid (TCA) cycle as the first product of the cycle, citric acid, contains three carboxyl groups in its structure. Alternatively, this cycle is also referred to as the Krebs cycle, in honor of its discoverer Sir Hans Krebs.
The citric...
The citric...
01:20Fates of Pyruvate
Pyruvate is the end product of glycolysis, where glucose is oxidized to pyruvate, simultaneously reducing NAD+ to NADH. Two molecules of ATP are also produced by substrate-level phosphorylation.
In aerobic organisms, pyruvate is metabolized via the citric acid cycle to produce reduced coenzymes NADH and FADH2. These coenzymes are then oxidized in the electron transport chain to produce ATP and, in the process, regenerate the NAD+ and FAD. As seen in some cell types and organisms, fermentation...
In aerobic organisms, pyruvate is metabolized via the citric acid cycle to produce reduced coenzymes NADH and FADH2. These coenzymes are then oxidized in the electron transport chain to produce ATP and, in the process, regenerate the NAD+ and FAD. As seen in some cell types and organisms, fermentation...
02:36The Citric Acid Cycle
The citric acid cycle, also known as the Krebs cycle or TCA cycle, consists of several energy-generating reactions that yield one ATP molecule, three NADH molecules, one FADH2 molecule, and two CO2 molecules.