Tolerance of various plant seeds to different concentrations of phenol, and growth of bacteria on phenol as a sole carbon source has been investigated. Three different types of bacterial colonies have been recovered on the agar plates. Biochemical and culture morphology examination of the recovered bacteria revealed that they mainly belonged to the genus Pseudomonas, Micrococcus and Streptomyces. O.D. reading at 600 nm and UV absorbance at 273 nm determined the growth and/or phenol degradation by the tested bacteria. Incubation of 4 tested Pseudomonas spp. and 1 Streptomyces sp. in mineral salts medium (MSM) supplemented with 0.2% (w/v) of phenol for 14 days and at 28 °C indicated the removal of 124 mg/l of phenol by Streptomyces sp. (strain 3A13) as compared to 42, 84, 90 and 102 mg/l by P. putrefaciense, P. fluorescense, P. cepacia and P. acidovorans, respectively. Streptomyces sp. (strain 3A13) seems to play a significant role in decomposition of toxic compounds such as phenol. A noticeable decline in Jew's mallow (Cochorus olitorius) and Alfaalfa (Medicago sativa) seed germination of 62.5% and 86.4% was shown at 500 and 1000 mg/kg phenol or higher, respectively. Seeds of barley (Hordeum vulgare) showed more resistant to phenol with a decline of 40 and 76% at 1000 and 1500 mg/kg phenol, respectively. However, seeds of solid Horani wheat (Triticum durum) were the most resistant to phenol which showed a percentage decline of 43.5% at 1500 mg/kg phenol. The effect of different phenol concentrations was also reflected on the length of sprouts of the tested plants with severe decline (> 75%) of C. olitorius sprouts' length at 500 mg/kg phenol as compared to the most resistant plant sprouts (T. durum) that showed < 45% decline of sprouts' length. It appears that the local seed plants (T. durum and Hordeum vulgare) have the ability to germinate with 40 % or more at 1500 mg/kg phenol. Careful selection of plant species to be used at a particular polluted sites should be cautiously approached based on the actual soil and climate conditions and other characteristics of the site.

United Arab Emirates

Papers

Selection of Bacteria and Plant Seeds to Grow on Phenol to be Used in Remediation of Phenol Contaminated Soils