Thiol-tolerant assay for quantitative colorimetric determination of chloride released from whole-cell biodehalogenations.

Determination of inorganic chloride released from a chloro-organic compound by whole-cell or enzymatic dehalogenation can be affected by free thiols, phosphate, sugars, pH, the chloro-organic substrate, and its dehalogenation product. For these reasons a highly sensitive, colorimetric chloride assay on the basis of [FeCl]2+ (lambda(max) = 340 nm) formed in highly acidic medium which is insensitive to composition of culture medium, free thiols, substrate, and dehalogenation product was developed. It is applicable to both fungal and bacterial high-cell-density cultures. The [FeCl]2+ method provides reliable data and is convenient for the rapid and facile determination of dehalogenation kinetics.