Asian Journal of Microbiology, Biotechnology & Environmental Sciences Paper

PHENOL DEGRADATION BY PURE AND MIXED CULTURES OF ARTHOBACTER, MYCOBACTERILIIVI AND PSUEDOMONAS IN FLASK CULTURES AND SPIKED SOIL SAMPLES

M. VASANTHA LAXMI, K.SUBBA REDDY, V.HIMABINDU, S.S. VUTUKURU ANDY. ANJANEYULU

Abstract

Biodegradation of phenol, a common Pollutant in several industrial effluents in Hyderabad city was studied with a few indigenous strains of bacteria provisionally identified by morphological and biochemical parameters as species of Art hobacter, Mycobacterium and Pseudonzonas (S S 2 and S 3, respectively). These strains were collected from soils contaminated with pharmaceutical and textile dye industrial effluents. Phenol itself being a carbon source for these bacteria, it is doubly advantageous to study its biodegradation to nullify its pollutant effects. A series of phenol concentrations viz., 20, 50,100, 500 and 1000 mg/L are used in the current investigation to examine their prospective degradation by pure strains and mixed consortia in flask cultures. Phenol was completely degraded by all the three strains and mixed consortia within 3-8 h in lower concentrations used (20 and 50 mg/L). In higher concentrations of phenol (100, 500 and 1000 mg/L) maximum degradation (95 'A) was observed in all the concentrations within 4 to 11 days. From flask culture studies, it is evident that the maximum concentration of phenol that could be degraded by these three strains was 1000 mg/L. Hence, garden soil samples were spiked with 1000 mg/L of phenol (worst case scenario) and the above three strains I'ere examined for their efficiency to degrade phenol in soil matrix. At the end of 4 weeks, maximum growth in terms of CFU was observed in mixed culture with a corresponding degradation of phenol by 88.7% followed by Mycobacterium (87.2%) while the degradation of phenol by Pseudomonas (76.4%) and Arthobacter (69.5%) was achieved at the end of 5 weeks. Of the three strains used, Mycobacterium showed maximum growth and degradation efficiency at the end of 4"' week. However, interestingly all the strains including the mixed consortia completely degraded phenol at the end of 10" week by 98.8 to 99.7%. Though the maximum time taken for the complete degradation of phenol is 10 weeks it, however, is significantly degraded by the end of 4-5 weeks by all the strains and mixed cultures in spiked soil samples