Biodegradation of low-density polyethylene (IDPE) by bacteria isolated from dump sites in some metropolitan cities in north central Nigeria

Abstract

In this study, biodegradation of Low-Density Polyethylene (LDPE) by bacteria isolated from dump sites was evaluated in a liquid Basal Salts Medium. The bacteria, including Psuedomonas aeruginosa, Bacillus megaterium, Providencia stuarti, Alcaligenes faecalis, Enterobacter hormaechei, Klebsiella pneumonia and Proteus vulgaris were isolated from soil samples taken from municipal dump sites in some metropolitan cities in North Central Nigeria, namely, Abuja, Makurdi and Jos and screened for their ability to utilize LDPE using the clear zone method. 0.500 gram waste LPDE strips (1 cm x 5 cm) were placed into a 500 milliliter flask containing sterilized liquid medium at 30 °C and incubated in a rotary shaker for eight (8) weeks. Each bacterium was added to a separate flask. Biodegradation was measured by pH changes of the media and gravimetrically by weight loss of the waste LDPE strips two weekly during the incubation period. The results obtained showed a gradual decrease in the pH of the media originally set at 7.05 with incubation time for all isolated bacteria. Psuedomonas aeruginosa and Providencia stuarti recorded the highest weight loss of the LDPE strips after eight (8) weeks at 19.80±0.04 %, with a final pH of 3.75±0.01 and 19.20±0.42 %, and final pH 4.85±0.01 respectively followed by Bacillus megaterium at 13.40±0.10% and final pH of 3.95±0.01. Klebsiella pnuemonia and Proteus vulgaris recorded the least gravimetric weight loss at 1.40±0.02 %, with a final pH of 4.75±0.01 and 0.80±0.01 %, pH 4.85±0.01 respectively. This work reveals that bacteria play a vital role in the degradation of low-density polyethylene waste in the natural environment. This can be applied to the development of commercial bioreactors in the future for the degradation of polyethylene wastes.