Isolation and identification of phenol degrading bacteria from Lake Parishan and their growth kinetic assay

Abstract

Phenol and its components are extremely toxic and can easily be isolated from different industrial sewage such as oil refinery, petrochemical industry and mines, especially collier and chemical factories. Hence the presence of these compounds in the environment could cause environmental pollution, especially in water resources. In the past, physicochemical method was used for the elimination of phenol and its compounds, but today, bioremediation is preferable. The aim of this study is to isolate and identify phenol degrading bacteria from Lake Parishan and to assay their kinetic growth. Sixty samples of water and sedimentation of different area of Lake Parishan were collected. In order to isolate phenol degrading bacteria, samples were cultured on salt base phenol broth media. For screening of degrading bacteria, bromothymole blue indicator was added to media, which formed green color in it. Finally, the ability of bacteria to degrade different concentration of phenol was measured using culturing bacteria in different concentration of phenol from 0.2 to 0.9 g/l. Cultivated bacteria on the salt base phenol broth containing indicator changed the color of the media from green to yellow by using the phenol and decreasing the pH. These bacteria were, chiefly, gram negative and they belong to Pseudomonaceae and Acinetobacteraceae Family. Psuodomonas spp. are the most important phenol degrading bacteria in Lake Parishan which showed vast diversity in different parts of this lake. Species of Acinetobacter and other species such as Kelibsiella, Citrobacter and Shigella were found as well. Most of the isolated bacteria showed a good ability of degradation of phenol, where Pseudomonas and Acinetobacter showed 0.8 - 0.9 g/l, and Kelibsiella, Citrobacter and Shigella showed 0.6 - 0.7 g/l and the rest showed 0.2 - 0.3 g/l of phenol degradation. Findings show that the Lake Parishan has a lot of high ability phenol degrading bacteria. The most important species belong to Psuodomonas and Acinetobacter.

Key words: Phenol, degrading, Pseudomonas, Acinetobacter, Lake Parishan.