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Phyllosphere yeasts rapidly break down biodegradable plastics.

Kitamoto HK, Shinozaki Y, Cao XH, Morita T, Konishi M, Tago K, Kajiwara H, Koitabashi M, Yoshida S, Watanabe T, Sameshima-Yamashita Y, Nakajima-Kambe T, Tsushima S - AMB Express (2011)

Bottom Line: The use of biodegradable plastics can reduce the accumulation of environmentally persistent plastic wastes.Strains of P. antarctica isolated from leaves and husks of paddy rice displayed strong degradation activity on these films at 30°C.Reliable source of biodegradable plastic-degrading microorganisms are now in our hands.

View Article: PubMed Central - HTML - PubMed

Affiliation: National Institute for Agro-Environmental Sciences (NIAES), 3-1-3 Kannondai, Tsukuba, Ibaraki 305-8604 Japan. kitamoto@affrc.go.jp.

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.

No MeSH data available.


Related in: MedlinePlus

Screening and evaluation of biodegradable plastic degrading yeast from phyllosphere. (A) Screening method and degradation of 2 × 2-cm squares of PBSA and PBS mulch film at 30°C by yeasts (NRL-A and NRL-B) isolated from two rice leaves. (B) Quantification of film degradation rates of PBSA film by strain NRL-A (open circle), NRL-B (open triangle), and degradation rates of PBS film by NRL-A (closed circle), NRL-B (closed triangle).
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Figure 2: Screening and evaluation of biodegradable plastic degrading yeast from phyllosphere. (A) Screening method and degradation of 2 × 2-cm squares of PBSA and PBS mulch film at 30°C by yeasts (NRL-A and NRL-B) isolated from two rice leaves. (B) Quantification of film degradation rates of PBSA film by strain NRL-A (open circle), NRL-B (open triangle), and degradation rates of PBS film by NRL-A (closed circle), NRL-B (closed triangle).

Mentions: 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. Several strains of phyllosphere yeasts are reported to produce lipases (Ruinen 1963, Fonseca and Inácio 2006, Seo et al. 2007). Therefore, we speculated that the lipases from phyllosphere microorganisms might effectively degrade biodegradable plastics. For isolation of such yeasts, we used FMM agar plates containing oil and an emulsified biodegradable plastic (i.e. PBSA) in the upper layer, along with nutrients suited to the isolation of yeast. Yeast colonies that could assimilate PBSA emulsion or oil by producing lipase or esterase were expected to grow on this medium and to become surrounded by a clear zone if the enzyme degraded the PBSA emulsion (Figure 2A). Such yeasts were isolated from two leaves of paddy rice (Figure 2A, B). The colony surfaces of yeast on each selection agar plate are uniform. Both strains were identified as P. antarctica, and they were named NRL-A and NRL-B. At the second screening, squares of the target biodegradable plastic film (2 × 2 cm) were mounted on the surface of the yeast lawn of the plate, and observed the degradation rate as described in material and methods. Both strains degraded PBS and PBSA films on the same agar plate. As previously reported (Uchida et al. 2000, Maeda et al. 2005, Masaki et al. 2005), PBSA film was easier to biodegrade than PBS film.


Phyllosphere yeasts rapidly break down biodegradable plastics.

Kitamoto HK, Shinozaki Y, Cao XH, Morita T, Konishi M, Tago K, Kajiwara H, Koitabashi M, Yoshida S, Watanabe T, Sameshima-Yamashita Y, Nakajima-Kambe T, Tsushima S - AMB Express (2011)

Screening and evaluation of biodegradable plastic degrading yeast from phyllosphere. (A) Screening method and degradation of 2 × 2-cm squares of PBSA and PBS mulch film at 30°C by yeasts (NRL-A and NRL-B) isolated from two rice leaves. (B) Quantification of film degradation rates of PBSA film by strain NRL-A (open circle), NRL-B (open triangle), and degradation rates of PBS film by NRL-A (closed circle), NRL-B (closed triangle).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3293741&req=5

Figure 2: Screening and evaluation of biodegradable plastic degrading yeast from phyllosphere. (A) Screening method and degradation of 2 × 2-cm squares of PBSA and PBS mulch film at 30°C by yeasts (NRL-A and NRL-B) isolated from two rice leaves. (B) Quantification of film degradation rates of PBSA film by strain NRL-A (open circle), NRL-B (open triangle), and degradation rates of PBS film by NRL-A (closed circle), NRL-B (closed triangle).
Mentions: 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. Several strains of phyllosphere yeasts are reported to produce lipases (Ruinen 1963, Fonseca and Inácio 2006, Seo et al. 2007). Therefore, we speculated that the lipases from phyllosphere microorganisms might effectively degrade biodegradable plastics. For isolation of such yeasts, we used FMM agar plates containing oil and an emulsified biodegradable plastic (i.e. PBSA) in the upper layer, along with nutrients suited to the isolation of yeast. Yeast colonies that could assimilate PBSA emulsion or oil by producing lipase or esterase were expected to grow on this medium and to become surrounded by a clear zone if the enzyme degraded the PBSA emulsion (Figure 2A). Such yeasts were isolated from two leaves of paddy rice (Figure 2A, B). The colony surfaces of yeast on each selection agar plate are uniform. Both strains were identified as P. antarctica, and they were named NRL-A and NRL-B. At the second screening, squares of the target biodegradable plastic film (2 × 2 cm) were mounted on the surface of the yeast lawn of the plate, and observed the degradation rate as described in material and methods. Both strains degraded PBS and PBSA films on the same agar plate. As previously reported (Uchida et al. 2000, Maeda et al. 2005, Masaki et al. 2005), PBSA film was easier to biodegrade than PBS film.

Bottom Line: The use of biodegradable plastics can reduce the accumulation of environmentally persistent plastic wastes.Strains of P. antarctica isolated from leaves and husks of paddy rice displayed strong degradation activity on these films at 30°C.Reliable source of biodegradable plastic-degrading microorganisms are now in our hands.

View Article: PubMed Central - HTML - PubMed

Affiliation: National Institute for Agro-Environmental Sciences (NIAES), 3-1-3 Kannondai, Tsukuba, Ibaraki 305-8604 Japan. kitamoto@affrc.go.jp.

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.

No MeSH data available.


Related in: MedlinePlus