Isolamento e caracterização de microrganismos do solo degradadores de polietileno

Abstract

Polyethylene is one of the plastic materials with the highest commercial production. In its family, LDPE (low density polyethylene) represents 60% of the total production of plastic bags, the main component of municipal solid waste. Considering the above, and these materials have a long life time extended, the work seeks to find possible degraders and track indigenous bacterial isolates with potential to break down these molecules through the state of Paran´ a. The process for the isolation of microorganisms, was started by selecting a collection point in relation to the time of exposure of the soil, with the materials poured. Then, in the laboratory, a serial dilution was carried out in saline 0.9% (w/v), followed by a Pour plate. Therefore, the colonies were applied in Minimum Medium, containing 1 g of polyethylene powder. After sample growth, the media were stained with a mixture of 0.1% (w/v) Comassie R-250 Blue, 40% (v/v) methanol and 10% (v/v) acetic acid, obtaining three possible degraders: A.R.B, B.D.A and T.B.I that presented halos in the environment of their colonies, positive factor to the degradation of polyethylene. By a second methodology, using mineral liquid medium and pieces of LDPE (2 cm), the 3 samples were exposed to a study process, again regarding their degradations, in which through analysis in the FTIR, we sought to observe conformational changes in their chemical structures, through the appearance of characteristic bands. Finally, a gram staining was performed in the samples of positive isolates and soon after, the sequencing of amplified DNA structures was carried out, in which the species of the positive organisms to degradation was determined, in which they can be designated as: Paenibacillus alvei for B.D.A and Rhodanobacter spathiphyilli for A.R.B. As for the sample T.B.I, during sequencing it was noted that two reading bands appeared, inferring a cons´orcio of two microorganisms, for analysis and verification of the observed was necessary to perform an isolation of the sample, in which it was identified the joint growth of two distinct species. With the results obtained, this work highlights that bacterial isolates found, can actively contribute to the biodegradation of polyethylene and be an option for this degradative process.