Perspectives in biodegradation of alkanes and PCBs

Abstract

Mixtures of indigenous soil bacteria were applied to remediate local ground waters and soil polluted with petroleum derived substances. Implementation of three months remediation protocols resulted in a decline of the amount of petroleum derived contaminants from an initial concentration of 1-10 g.kg-1 soil dry weight to an average of 0.25 g.kg-1 soil dry weight. We also studied genetic and biochemical properties of the bacterial strain Pseudomonas C12B. It was originally isolated for its ability to utilise alkylsulfates and alkylbenzensulfonates as the sole source of carbon and energy. PCB biodegradation was studied using two biological models, bacterial co-cultures and plant cells cultivated in vitro. An industrial mixture of polychlorinated biphenyls (Delor 103) containing about 60 congeners of different degrees of chlorination (an average of three chlorines per biphenyl molecule) was used. Bacterial co-cultures acquired from enrichment protocols were tested in laboratory and semi-pilot experiments. Pilot experiments were performed in a two step process in a ground water decontamination unit (working volume 5m3) which was operated semi-continuously. After 45 days of operation the initial PCB concentration had decreased to 20%. In laboratory experiments PCB degradation using plant cells cultivated in vitro was also performed. Different cultures of various species differing in their growth parameters and morphology (amorphous, differentiated shoot forming or "hairy root"), transformed or nontransformed by Agrobacterium, were used. Differentiated or hairy root cultures exhibited better degradative abilities than undifferentiated amorphous cultures.