Experience with microbiological assay for folate using a chloramphenicol-resistant L. casei strain

Area of Science:

• Microbiology
• Clinical Chemistry
• Nutritional Science

Background:

• Folate (vitamin B9) is essential for DNA synthesis and cell growth.
• Accurate measurement of folate levels in serum and red blood cells is critical for diagnosing deficiencies and related health conditions.

Purpose of the Study:

• To describe the implementation and performance of a semi-automated assay for folate determination.
• To establish reference ranges for serum and red blood cell folate using the described method.

Main Methods:

• Utilized a semi-automated assay employing a chloramphenicol-resistant strain of *Lactobacillus casei*.
• Required precise control over medium pH and incubation time for assay reliability.
• Measured folate concentrations in both serum and red blood cell samples.

Main Results:

• The assay demonstrated the need for controlled pH and incubation time.
• Established a normal reference range for serum folate as 2 to 16 ng/ml.
• Established a normal reference range for red blood cell folate as 200 to 600 ng/ml.

Conclusions:

• The semi-automated *L. casei* folate assay provides a viable method for folate level determination.
• The established reference ranges are valuable for clinical interpretation of folate status.
• Methodological controls (pH, incubation time) are essential for assay accuracy.