**1. Introduction**

About 800 million metric tons (Mt) of plastics were produced worldwide in the last 67 years, and 79% of this production is accumulated in the environment [1]. According to these authors, in 2050 is estimated an accumulation of about 12,000 Mt in landfills or in the natural environment that represent an annual accumulation of ~339 Mt. Therefore, the development of efficient degradation process is very important to avoid this annual accumulation.

The human population on the Earth in 2050 will be about 10 billion people [2]. Thus, adequate disposal of plastics wastes is important for the maintenance of the natural resources to supply this population. Furthermore, the development of degradable plastics is necessary to prevent the accumulation of plastic waste in the ocean [3].

In Brazil, the National Solid Waste Policy [4] establishes the selective collection, separation of solid waste, recycling and the shared responsibility for the appropriate management of these wastes among manufacturers, distributors, consumers and the government. However, in these 7 years of law it has observed satisfactory

results only in selective collection. In 2014, with the deadline for replacing dumps to landfills, new deadlines for 2021 are in discussion in the National Congress [5].

Our results of biotic and fungal degradation of oxo-biodegradable plastics and green polyethylene could contribute for development of a process of degradation of these residues using white rot fungi. These microorganisms can grow under adverse temperature, nutrient and moisture conditions that facilitate composting and fermentation processes.

The plastics polymers degradation is analyzed by alterations in mechanical, optical or electrical characteristics, cracking, fission, corrosion, discoloration, phase separation, chemical transformations and formation of new functional groups after degradation process [6].

Unlike of the petroleum-derived synthetic polymers, the biodegradable plastics polymers, when discarded in the environment, can be degraded by non-biological and biological processes [7]. Exposure to ultraviolet light, thermal heating, and treatment with acidic or basic substances function as term initiators or photooxidation of polyethylene [6]. After this oxidation fragments of polyethylene are degraded by action of microbial enzymes [7].

Oxo-biodegradable or d2W plastics are polymers that contain a pro-oxidant additive to accelerate photo or thermo-oxidation [8, 9]. So, these polymers when exposed to ultraviolet light or at high temperatures are cleaved in low molecular mass compounds that are assimilated by microorganisms [8]. Several studies have shown the biodegradable plastics degradation, after exposed to ultraviolet light or heat, by bacteria and fungi [10–16].

The plastic bags of green polyethylene are produced using low-density polyethylene (LDPE) and green polymers obtain of sugarcane [17]. We have showed the green polyethylene degradation by *Pleurotus ostreatus* PLO6 [15]. However, little information regarding to the biodegradation of these bags is available.

The microbial enzymes, such as depolymerase, esterase and lignolytic ones, that cleave the polymers in small chain compounds, may be involved in the plastics degradation [6, 13, 18, 19]. Thus, white rot fungi have a great potential, because they are enzymes producers and have shown their ability for treatment of industrial waste [20–22].

The white rot, *P. ostreatus*, is a potent degrader of lignin, cellulose and hemicellulose, which lives as saprophyte in wood. This fungus has also been used in the bioconversion of agricultural residues, in biodegradation of organic pollutants, xenobiotics, and industrial effluents, in the cellulose bleaching and production of food and enzymes [23–25]. We showed that *P. ostreatus* PLO6 are capable to degrade oxo-biodegradable plastics and green polyethylene [13–15]. Furthermore, this fungus form edible mushroom that is source of proteins, fibers, minerals and carbohydrates.

Thus, in this chapter described the plastics bags degradation, by abiotic and microbial process, using the exposure to sunlight and *P. ostreatus*.
