Effect of glucose and ribose on microbial degradation of the herbicide bromoxynil continuously added to soil.

Bromoxynil (3,5-dibromo-4-hydroxybenzonitrile) was continuously added to chernozem (Haplic typic) soil inoculated with a suspension of Pseudomonas putida capable of cometabolic decomposition of the compound in a hetero-continuous-flow cultivation setup. In the steady state, when glucose or ribose were simultaneously added, 90 and 47% of the added herbicide was degraded per day, respectively. If the saccharides were absent, only 10-27% of the herbicide was decomposed. Addition and removal of glucose feeding resulted in an increase and decrease, respectively, of the degradation intensity, irrespective of the amount of the bacterial decomposers present. Two degradation products, 3,5-dibromo-4-hydroxy-benzamide and 3,5-dibromo-4-hydroxybenzoic acid, were formed during cultivation. The total amount of bromine-containing compounds was reduced only in the presence of glucose.