Isolation and identification of haloalkaliphilic phenol degrading bacteria and evaluating their applicability

Abstract

 Introduction: Phenolic compounds are toxic environmental pollutants. Removal of phenol from wastewaters is very important. Phenol biodegradation is generally preferred to common physico- chemical methods. The aim of this study is to enrich and isolate haloalkaliphilic phenol-degrading bacteria and evaluate their potential for caustic wastewater treatment in consortium and pure cultures. Materials and methods: Soil and water samples were collected from hydrocarbon polluted areas. Samples were enriched in the mineral medium with phenol as the only carbon and energy source. Phenol degrading strains were isolated and identified using morphological and phylogenic techniques. Isolates were screened based on phenol removal ability and key parameters such as pH, temperature and various salt (NaCl, NaNO3, NH4Cl and KCl) and phenol concentration were evaluated for optimizing biodegradation activity of the selected strain. Results: Three phenol-degrading strains were isolated from Yadavaran oilfield sample, which belong to bacterial genera Halomonas, Janibacter and Pseudomonas. The strain Janibacter sp.YF3 was selected due to its high phenol-degrading rate. The strain was gram positive coccus whose optimal growth condition was 30 ºC, Nacl 5 % (w/v), pH 8.5 and phenol 400 ppm. The results showed that this strain could thrive in highly saline conditions and preferred NaNO3 among other salts. Discussion and conclusion: Isolate entitled Janibacter sp. strain YF3 was a polyextremophile which could tolerate harsh conditions (NaCl concentration up to 10 % and pH 9.5) and could utilize phenol at high concentration up to 1000 ppm. These results showed that this strain could be potentially applicable for phenol removal from haloalkaline industrial wastewaters such as spent caustic. 

Keywords

• Industrial wastewaters
• Biodegradation
• Phenolic compounds
• Haloalkaliphile
• Janibacter