The effect of rhizodeposition from helophytes on bacterial degradation of phenolic compounds

The effect of rhizodeposition from helophytes (aquatic plants) on the bacterial degradation of toxic compounds such as phenolic substances was tested. Investigations were carried out as batch experiments with rhizodeposition products obtained from helophytes. DOC concentrations, which were used as points of reference for rhizodeposition, were between 2.5 and 12 mg per litre. Rhizodeposition was found to advance the biodegradation of 4-chlorophenol when using a mixed bacterial culture and pure cultures of bacteria previously isolated from Phalaris arundinacea roots. This stimulation is a result of rhizodeposition products serving as growth substrates for the bacteria. Investigations with Ralstonia eutropha (DSMZ Braunschweig, strain 5536) confirmed the function of rhizodeposition products as growth substrates. Degradation by Acinetobacter baumannii and Ralstonia sp. obtained from Phalaris arundinacea was'accompanied by the dechlorination of 4-chlorophenol. There was no enhancing impact on the degradation of the substances phenol and 2,6-dimethylphenol by rhizodeposition products.