Phyllosphere yeasts rapidly break down biodegradable plastics

Hiroko K Kitamoto,Tomotake Morita,Toshiaki Nakajima-Kambe,Yukiko Shinozaki,Yuka Sameshima-Yamashita,Hideyuki Kajiwara,Takashi Watanabe,Shigenobu Yoshida,Motoo Koitabashi,Xiao-Hong Cao,Seiya Tsushima,Kanako Tago,Masaaki Konishi

doi:10.1186/2191-0855-1-44

Abstract

The use of biodegradable plastics can reduce the accumulation of environmentally persistent plastic wastes. The rate of degradation of biodegradable plastics depends on environmental conditions and is highly variable. Techniques for achieving more consistent degradation are needed. However, only a few microorganisms involved in the degradation process have been isolated so far from the environment. Here, we show that Pseudozyma spp. yeasts, which are common in the phyllosphere and are easily isolated from plant surfaces, displayed strong degradation activity on films made from poly-butylene succinate or poly-butylene succinate-co-adipate. Strains of P. antarctica isolated from leaves and husks of paddy rice displayed strong degradation activity on these films at 30°C. The type strain, P. antarctica JCM 10317, and Pseudozyma spp. strains from phyllosphere secreted a biodegradable plastic-degrading enzyme with a molecular mass of about 22 kDa. Reliable source of biodegradable plastic-degrading microorganisms are now in our hands.

Highlights

For the last 60 years, the use of synthetic polymers has grown progressively because of their low cost, reproducibility, and resistance to physical aging and biological attack
Typical rates of degradation of biodegradable plastic in soil To determine the typical rate of biodegradation of biodegradable plastic, we incubated mulch film made from poly-butylene succinate-co-adipate (PBSA) (2 × 2 cm squares) in soil obtained from fields
Isolation of phyllosphere yeast strains capable of degrading biodegradable plastic film We observed that the chemical structures of plant surfaces are similar to those of biodegradable plastics, which led us to determine whether the microflora of plant surfaces might produce enzymes with activity against biodegradable plastics

Summary

Introduction

For the last 60 years, the use of synthetic polymers has grown progressively because of their low cost, reproducibility, and resistance to physical aging and biological attack. Devices and materials made of synthetic polymers are sometimes used for short-term applications and are subsequently disposed at high rates to the natural environment; ideally such items should be biodegradable so that they do not accumulate in the environment. The environmentally beneficial perception of these materials, and their range of potential applications is expandin: it already extends to composting bags, mulch films, packaging of agricultural supplies, silage wrap, landfill covers, planter boxes, fishing nets, bundling string, seed coatings, and pellet coatings for the delayed release of pesticides, herbicides, and. The main component of biodegradable mulch films is poly-butylene succinate (PBS). Several biodegradable polymers, such as poly-butylene succinate-co-adipate (PBSA), are added to control mechanical strength (Xu and Guo 2010). Three microorganisms that produce enzymes that degrade solid PBS and PBSA film are the bacterium Acidovorax delafieldii strain BS-3, which has been isolated from soil (Uchida et al 2000), the yeast

Methods

Results

Conclusion