Preliminary Studies on the Microbial Degradation of Plastic Waste Using <i>Aspergillus niger</i> and <i>Pseudomonas</i> sp.

Abstract

The possibility of microbial degradation of plastic waste was investigated by isolating microorganisms present in dumpsite containing low-density polyethylene (LDP). Aspergillus niger (fungi) and Pseudomonas sp. (bacteria) were identified and subsequently used to biodegrade plastic waste. The medium was made up of 0.2 g of MgSO 4 , 1.0 g of KH 2 PO 4 , 1.0 g of K 2 HPO 4 , 1.0 g of NH 4 NO 3 , 0.02 g of CaCl 2 , 0.05 g of FeCl 3 in 1000 ml water. 10 ml of the medium containing the bacteria and/or fungi was poured into test tubes and 0.1 g of the plastic sample (Pure water sachet) pre-treated with ethanol was introduced into the tubes. The pH of the medium was adjusted to 7.2, 5.4 and 6.0 for Pseudomonas sp . , Aspergillus niger and the mixed culture respectively. Each experiment was carried out aerobically at room temperature and incubated on a rotary shaker at 120 rpm. The weight loss in each experiment was monitored at 10 days interval for 60 days. The total weight loss after 60 days was 7.2%, 12.4%, 15% for degradation with Pseudomonas sp ., Aspergillus niger and the mixed culture respectively. From this study it can be inferred that Pseudomonas sp . and Aspergillus niger have the ability to degrade plastics. It can also be inferred that Aspergillus niger degraded plastics better than Pseudomonas sp . and there was synergy between the two microorganisms since the mixed culture gave a higher degradation.