Biodegradation effect of some Pseudomonas species on 2,4-dichlorophenoxyacetic acid and trifluralin herbicides

Herbicides have been widely used to increase productivity of agricultural products and in weed killing. Such use has caused environmental pollution and started to threaten living creatures (mutagenesis and cancer) with time. Biological struggles carried out with algae and particular bacteria species to remove herbicides contamination hava become one of the popular attempts within the last ten years.Certain species from pseudomonas genera degrade compounds which have hydrocarbons. This study has been carried out with 4 different types of pseudomonas isolated from the environment (soil and water) and clinical samples to degrade widely used 2,4-D and trifluralin in our country. 4 environmental and 4 clinical samples of P. aeruginosa, B. cepacia, P. fluorescens and P. putida species were chosen from a total of 110 environmental samples and 11 clinical samples and the study was carried out using 8 samples. Isolation and identification was made by classic and automaticity systems. Bacteria; 2,4-D (25, 50 and 100 ppm) and trifluralin (100, 250 and 500 ppm) were left in the pipetted experiment set-up (microplate) for 3 days. Colony forming units counts were carried out on the samples collected daily. The results were transformed to lethal concentration values by Probit analysis. The most resistant bacteria to 2,4-D was P4 bacteria ( from clinical sample) Burkholderia cepacia (LC90 = 27 ppm) and the one most resistant to trifluraline was P11 bacteria (from environment sample) Pseudomonas aeruginosa (LC90 = 360 ppm). The biodegradation capacity of the two resistant bacteria was determined by HPLC method. For determination of the biodegradation capacity of the bacteria in most active media multi-factor (23) experiment design experiment set-up was established. The HPLC biodegradation results taken from the experiments carried out for three days were transformed into percents and interpreted with Yates algorithm statistic method using the experiment results of the 3rd day. (Significance P= 0,01 and 0,05)A degradation of 33.3% was observed in B. cepacia 2,4-D in the absence of active carbons in the media while a degradation of 99,7 % was observed in the presence of active carbons in the media. A degradation of 58,4% was observed in P. aeruginosa trifluralin in the absence of active carbons in the media while a degradation of 99,3% was observed in the presence of active carbons in the media. Presence of active carbons and succinic acide in the media increased the effect of the bacteria on herbicides biodegradation.Finally; it is thought that the herbicides (2,4-D and trifluralin) used widely in our country will facilitate the biological struggle on environmental pollution. New large-scale experiments made on different types of bacteria and pesticides will throw a light on the issue.