Rapid monitoring of the biodegradation of phenol-like compounds by the yeast Candida maltosa using BOD measurements

Since phenol-like compounds can have serious environmental effects, microbiological and biochemical features of their aerobic degradation are of great interest, and monitoring oxygen uptake can give valuable data about the processes involved. It is shown here that the AQUALYTIC® Sensomat System can provide reliable, continuous measurement of biological oxygen demand (BOD), and is suitable for small-scale studies of the degradation of phenol-like compounds by the soil-borne yeast Candida maltosa. It was found that C. maltosa can use phenol and catechol as sole sources of carbon and energy at concentrations up to 1.7 g l−1 and 1.5 g l−1, respectively, and it is unaffected by resorcinol, even at 2 g l−1. It can also co-metabolise p-cresol, but cannot utilise benzoate or salicylate. These results may have practical implications for the use of C. maltosa in soil bioremediation, e.g. in bioventing. Enzyme tests were also performed to help interpret the data. Phenol hydroxylase activity reached maximum levels at the beginning of the exponential phase during cultivation on phenol. After the phenol had been completely utilised, the enzyme was slowly degraded.