Microbiology Research Journal International

Aim: Polycyclic aromatic hydrocarbons (PAHs) are categorised as potentially harmful chemicals of environmental and health apprehension. Microbial degradation is the principle practice for effective elimination and abolition of PAHs from polluted environment. Phenanthrene, a PAH compound, recalcitrant xenobiotic causes severe damage to kidney, liver, fat tissues and causes cancer. Removal of this from environmental pollutants is expensive by existing methods. To overcome this, an attempt has been made for the degradation of phenanthrene by using microorganisms.

Materials and Methods: Seven organisms were isolated from thirty six soil samples using M9 media with phenanthrene. One organism that shows highest degradation was identified by morphological and molecular (16S rRNA sequencing) analysis. Physical parameters such as incubation period, concentration, pH and temperature and chemical parameters like carbon, nitrogen and metal ion sources were used for efficient degradation of phenanthrene.

Results: Results revealed that, among the seven organisms, one organism was significantly effective in degradation and was identified as Pseudomonas aeruginosa by 16S rRNA sequence and strain kar5, accession No KT225506 was registered in National Centre for Biotechnology Information (NCBI). Maximum degradation was noticed using 100 ppm concentration at 37°C with pH 7 and 96 hr. Starch showed slightly high degradation compared to other carbon sources such as sucrose, lactose, maltose and cellulose. In nitrogen sources, tryptone revealed more degradation than casein, gelatin, egg albumin and bovine serum albumin. Metal ions like MgCl₂ and ZnCl₂ recoded significant degradation measured by spectrophotometer at 340 nm and confirmed by HPLC. Maximum growth of microorganism measured by spectrophotometer at 600 nm and reached to OD 0.851 ± 0.7.

Conclusion: Study confirms that, physico-chemical parameters play a significant role in degrading soil with high PAHs concentration.