A robust high-throughput fungal biosensor assay for the detection of estrogen activity.

The researchers validated a biosensor assay that uses a genetically modified strain of Aspergillus nidulans fungus to detect estrogen activity in cattle samples. This biosensor provides a fast, reliable way to test a wide variety of matrices and has potential clinical applications in pregnancy diagnosis.

Understanding the Research

• Estrogenic active compounds can alter biological functions in vertebrates. Therefore, the development of innovative analytical systems that could rapidly and accurately identify the presence of these compounds in various substances or matrices is important.
• The research team adapted and tested a fungal biosensor’s effectiveness in detecting estrogen activity in samples obtained from cows. They further assessed its potential in diagnosing pregnancy in mares and cows.

The Biosensor

• The biosensor is a genetically modified strain of a filamentous fungus called Aspergillus nidulans. This fungus was engineered to contain the human estrogen receptor alpha and a reporter construct.
• The reporter construct involves the β-galactosidase gene expression being controlled by an estrogen-responsive-element. This means that the presence and activity of estrogen can be tracked by measuring the activity of the β-galactosidase enzyme.

Testing and Validation

• The researchers validated the estrogen response of the fungal biosensor with different sample matrices including blood, urine, feces, milk, and saliva. The biosensor’s results were then compared to an enzyme immunoassay (EIA).
• Notable findings were that the biosensor provided consistent results with milk, urine, and feces samples that were comparable to those from the EIA. Also noteworthy was the lack of requirement for any sample pre-treatment by chemical extraction, which is an economic advantage.
• The biosensor demonstrated a detection limit for 17β-estradiol, one of the most potent and prevalent estrogens, of 1ng/L.

Results and Potential Applications

• The validation of the biosensor for pregnancy diagnosis showed a 100% specificity and a more than 97% sensitivity. Specificity relates to the test’s ability correctly identify non-pregnant animals, and sensitivity is the ability to correctly identify pregnant animals.
• The fungal biosensor represents a robust and sensitive tool for detecting estrogen activity. Due to its high-throughput capacity and abstinence from the need for organic solvents, this biosensor could also have significant implications on cost and resources in testing processes.