DEGRADATION OF LDPE PLASTIC BY Pseudomonas aeruginosa nmp1 IDENTIFIED BY BIOCHEMICAL AND 16S rDNA ANALYSIS

Plastic bags from agricultural soils were collected and bacteria were isolated Out of three bacterial isolates (B1, B2 and B3), B1 isolate was most potent for degradation of LDPE plastic. Its potentiality was measured by some methods such as weight loss methods, molecular weight loss by viscosity meter, biofilm growth, surface morphology by SEM, CO2evolution method. Both pretreated by ethanol or preuntreated sample of LDPE were employed. Alcohol pretreated LDPE was degraded (percentage 51.14±4.24 wt loss) and preuntreated LDPE was degraded (percentage 49.90 ± 3.90 wt loss) by B1 isolate after 150 days. Surface morphology analysis under SEM showed distortion area and degraded areas on bacteria (B1) treated LDPE. CO2 evolution was measured. Biofilm by this isolate was distinct (+++). Molecular weight loss of ethanol pretreated LDPE by this isolate was slightly larger than preuntreated. All data indicate that B1 is very potent LDPE degrader. Other two isolates (B2 and B3) were not able to degrade both alcohol pretreated and preuntreated LDPE and consequently they don’t form biofilm on plastic. The phenotypical and biochemical identification of the B1 isolate (small rod and Gram+) were done. For molecular identification (16 S rDNA), genomic DNA was isolated and a nucleotide portion of 16S rDNA was amplified using specific primer by thermocycler. The amplified portion was sequenced by gene sequencer. The nucleotide sequence was blast in NCBI data base and it was identical to Pseudomonas aeruginosa 1683 (EU53441). The gene sequence has published as Pseudomonas aeruginosa strain mmp1 (Accession No: KM491554.1) in NCBI.