Investigating the Biodegradation of Low-Density Polyethylene by Proteus and Serratia spp.

Plastics are gradually replacing ceramics, glasses and other materials in their day to day use, their short term application and release to the environment has made them a waste burden on cities and municipalities, where they cause environmental pollution and esthetic damage. There is therefore, a need to develop an eco-friendly protocol to manage plastic wastes. The role of microbes in bioremediation has been established, although, there is paucity of information on the use of Proteus and Serratia spp. to degrade plastics. Hence, the ability of Proteus and Serratia spp. to degrade low-density polyethylene was investigated. The microorganisms were isolated from waste dumpsites in Owerri Municipality and its immediate environs. 100ml enrichment cultures were dispensed into 10 labeled conical flasks, 1ml aliquot of 10^-1 microbial dilutions of each organism were seeded each into 5 sets of the conical flasks and 0.5g of polyethylene powder was added as the sole source of carbon to each set of flasks, the set-up was incubated in a rotary shaker at 30⁰c and 150rpm for 60 days. The optical density (OD₆₀₀), temperature and P^H changes were measured at 10 days interval, while enumeration of viable colonies in (cfu/ml) during incubation period was also carried out. Results obtained showed progressive but gradual increase in optical density, temperature and P^H values and appearance of air bubbles in the test media indicating microbial activities and ability of the organisms to utilize the substrate as energy source. The viability count of the isolates during and at the end of the incubation period also showed gradual increase in viable colonies (cfu/ml). It is concluded that both Proteus and Serratia spp. were able to utilize the low-density polyethylene as sole carbon source, hence suggesting their ability to degrade the polymer.