Isolation and identification of phenol degrading bacteria from Kor river and their growth kinetics assay

Abstract

Background : Phenol and it’s derivatives were removed by physicochemical methods in the past but nowadays biological treatment has priority. Bacteria with the rapid proliferation in the presence of phenol and it’s derivatives can remove them in a good manner. The aim of this project is isolation and identification of bacteria that degrade phenol from water and sediment of Kor river and also investigation of their growth kinetics in the presence of this toxic matrer. Materials and Methods: 60 samples from water and sediment of different area in Kor river were collected. Then collected samples were cultivated in the salt base phenol broth medium for isolation of phenol degrading bacteria. For screening of phenol degrading bacteria bromothymol blue was added to culture medium. Bacteria were cultivated in different concentrations of phenol (0.2-0.9 g/L), so bacterial ability in degrading of different concentrations of phenol was measured. Investigation of growth kinetics of bacteria was done by continuously recorded of optical absorption in 600 nm (OD600). In this method after primary record of OD, culture media were placed in incubator for 24 hours and in 30ºC with round of 100 rpm. After that optical absorption was recorded for 300 hours. Results: Pseudomonas sp were amongst the most important phenol degrading bacteria which were isolated from Kor river. They have a wide frequency in different area of this river. Acinetobacter also was important after Pseudomonas. The most of isolated bacteria had special ability in degrading phenol .For example Pseudomonas up to 0.9 g/L, Acinetobacter up to 0.8 g/L, Shigella, Salmonella, Klebsiella, and Citrobacter up to 0.6 g/L and other bacteria up to 0.2-0.3 g/L removed phenol from culture medium. Investigation of OD600 also confirmed acquired data because Pseudomonas had the most value of OD and maximum optical absorption for each bacterium was observed in the maximum degradation concentration. Conclusion: Kor river has many phenol degrading bacteria that have high ability in phenol degrading. Pseudomonas and Acinetobacter can be referred to as the most important ones.