Isolation of Phthalic Acid Degrading Pseudomonas Sp. P1 from Soil

Phthalates are common plasticizers used in pPVC (plasticized polyvinyl chloride) products. Phthalates are commonly found in the child rearing products (for teething, toys etc.), blood bags, dialysis tubing, paints, lacquers, cosmetics, coatings of capsules etc. The present study was conducted to explore the potential of new microbial strains for the biodegradation and biotransformation of phthalic acid. A bacterial isolate, Pseudomonas sp. P1, was found to degrade phthalic acid in agar plate assay as evident by the formation of clear zone around the colony. The strain was tested for the growth and tolerance limit on different concentrations (103000 ppm) of phthalic acid in mineral salt medium with and without glucose. On mineral salt agar plates, containing phthalic acid as a sole source of carbon, rich growth along with the hydrolyzing zone was observed upto the maximum concentration of 2800 ppm without glucose and upto the maximum concentration of 2900 ppm of phthalic acid with glucose. Transformational studies were carried out in mineral salt liquid medium containing varying concentrations (100500 ppm) of phthalic acid. Microbial growth was checked at 570 nm at different time intervals and the cell free supernatant was analyzed for the disappearance of phthalic acid at 280 nm. The highest percentage of degradation of phthalic acid was found at 37C and pH 8, i.e. 59% and 64% respectively. In mineral salt medium without glucose, phthalic acid degraded up to 72% at 500 ppm after 48 hours of incubation.