Degradation of biodegradable plastic mulch films in soil environment by phylloplane fungi isolated from gramineous plants

Abstract

To improve the biodegradation of biodegradable plastic (BP) mulch films, 1227 fungal strains were isolated from plant surface (phylloplane) and evaluated for BP-degrading ability. Among them, B47-9 a strain isolated from the leaf surface of barley showed the strongest ability to degrade poly-(butylene succinate-co-butylene adipate) (PBSA) and poly-(butylene succinate) (PBS) films. The strain grew on the surface of soil-mounted BP films, produced breaks along the direction of hyphal growth indicated that it secreted a BP-degrading enzyme, and has directly contributing to accelerating the degradation of film. Treatment with the culture filtrate decomposed 91.2 wt%, 23.7 wt%, and 14.6 wt% of PBSA, PBS, and commercially available BP polymer blended mulch film, respectively, on unsterlized soil within 6 days. The PCR-DGGE analysis of the transition of soil microbial community during film degradation revealed that the process was accompanied with drastic changes in the population of soil fungi and Acantamoeba spp., as well as the growth of inoculated strain B47-9. It has a potential for application in the development of an effective method for accelerating degradation of used plastics under actual field conditions.

Estudio comparativo de la compostabilidad de fundas plásticas de PEBD, oxo-biodegradables y de papel distribuidas en el Distrito Metropolitano de Quito

“…Una combinación entre estas moléculas forma la estructura básica de los plásticos biodegradables. En las Tabla 2 y Tabla 3 se presentan las estructuras y las aplicaciones de los dos tipos de plásticos biodegradables [1,18].…”

“…Por su alta biodegradabilidad y biocompatibilidad, y dado que su materia prima consta de recursos renovables, son aplicados constantemente en los materiales de empaque, dispositivos médicos y productos de higiene personal [18].…”

Phylloplane Fungal Enzyme Accelerate Decomposition of Biodegradable Plastic Film in Agricultural Settings

“…We prepared a culture broth of fungal strain B47-9 with enzymatic activity to degrade emulsified PBSA at 0.28 U/mL as described by Koitabashi et al (2012). To prepare the enzyme solution, we removed mycelia from the broth by using a membrane filter with a pore size of 0.45 um (Advantec C045A090C; Toyo Roshi Kaisha, Ltd., Tokyo, Japan).…”

“…When the fungus was applied to a commercially available mulch film (composed of a mixture of PBS, PBSA, and PBAT) that was placed on the surface of sterilized soil in a Petri dish, the film lost up to 99.8% of its weight after six days of incubation at 28°C, whereas the same film treated with water did not degrade (Koitabashi et al 2012). Moreover, when the fungal strain was cultivated in a liquid medium containing emulsified PBSA as the only carbon source, it secreted a BP-degrading enzyme that was isolated and identified as a Paraphoma-related cutinase-like enzyme (PCLE).…”

“…We previously selected the Paraphoma-related fungal strain B47-9, isolated from leaves, as a strain that strongly degrades PBS and PBSA films (Koitabashi et al 2012). When the fungus was applied to a commercially available mulch film (composed of a mixture of PBS, PBSA, and PBAT) that was placed on the surface of sterilized soil in a Petri dish, the film lost up to 99.8% of its weight after six days of incubation at 28°C, whereas the same film treated with water did not degrade (Koitabashi et al 2012).…”