Atrazine biodegradation by a monoculture of Raoultella planticola isolated from a herbicides wastewater treatment facility

This research describes indigenous Raoultella planticola bacterial cells which were isolated from the wastewater treatment plant of a herbicide factory. The optimum conditions for degrading atrazine were at pH=7 and 28°C, with a degradation rate of 10mgL^-1h^-1. Biodegradation was observed at temperatures of 45 and 4°C and partial degradation was also observed at extreme pH values (3 and 10). The degradation rates to reach 50% depletion of atrazine were 9.42, 7.42 and 5.42mgL^-1h^-1 in the presence of acetonitrile, phenol or toluene, respectively. Successful inoculation of R.planticola into the original sludge from the herbicide factory led to atrazine degradation within 3h, instead of 3 days without the inoculation. R.planticola developed a massive biofilm when exposed to atrazine. The results indicate that the isolated R.planticola strain can be added to the arsenal of atrazine-degrading bacterial cells that have the ability to degrade this substance under unfavorable conditions, such as those existing in the sludge of herbicide factories. In addition, the isolated strain showed an ability to form a biofilm, which can be utilized for improving the wastewater treatment.