African Journal of Biotechnology Vol. 2 (1), pp. 8-12, January 2003

ISSN 1684-5315  © 2003 Academic Journals  

Effects of mixed nitrogen sources on biodegradation of phenol by immobilized Acinetobacter sp. strain W-17

Desouky Abd-El-Haleem¹*, Usama Beshay¹, Abdou O. Abdelhamid ², Hassan Moawad³ and Sahar Zaki¹

¹Environmental Biotechnology Department & Bioprocess Development Department, Genetic Engineering and Biotechnology Research Institute (GEBRI), Mubarak City for Scientific Research and Technology Applications, New Burg-Elarab City, Alexandria, Egypt.

²Chemistry Department, Faculty of Science, Cairo University, Cairo, Egypt.

*Corresponding author; e-mail: phone: (00203) 459-3421; fax: (00203) 459-3423; e-mail: abdelhaleemm@yahoo.de

Accepted 11 December 2002

Using Ca-alginate immobilized cells of Acinetobacter sp. strain W-17, the effects of ammonium-N and nitrate-N on the biodegradation of phenol were investigated. Degradation experiments in three different culture media; minimal salts medium (MSM), simulated (SW) and modified simulated wastewater (MSW) were performed. With the freely suspended cells (cell dry weight 0.2 g/l), complete phenol (500 mg/l) degradation was achieved after incubation for 120 h. Using the immobilized cells, the time was reduced to 24 h in MSM medium, and 15 h in the MSW. The results also indicate that strain W-17 can tolerate to high concentrations of NH₄⁺-N (63 mg/l) and NO₃^--N (1000 mg/l) without a significant loss in the phenol biodegradation rate. Moreover, the presence of 500 mg/l phenol in the MSW had no considerable effect on the removal of both ammonium-N and nitrate-N. Repeated use of immobilized cells revealed that they could be used as much as five times without loss of activity. Our findings could be extended to enhance biotreatment of phenol contamination in a variety of biological treatment processes.

Key words: Phenol, biodegradation, immobilization, Acinetobacter, Ca-alginate, ammonium, nitrate.