Biodegradability of plastics

International Journal of Molecular Sciences

Volumn 10, Issue 9, 2009, Pages 3722-3742

  Tokiwa, Yutaka ^a   Calabia, Buenaventurada P ^b   Ugwu, Charles U ^a   Aiba, Seiichi ^b  

^a Okinawa Industrial Technology Center   (Japan)

^b NATIONAL INSTITUTE OF ADVANCED INDUSTRIAL SCIENCE AND TECHNOLOGY AIST   (Japan)

Author keywords

Aliphatic polyesters; Bio based plastics; Biodegradability; Enzymatic degradation; Microbial degradation

Indexed keywords

ALIPHATIC COMPOUND; AROMATIC COMPOUND; COPOLYMER; ESTERASE; NYLON; PLASTIC; POLY(3 HYDROXYBUTYRIC ACID); POLY(BETA PROPIOLACTONE); POLY(BUTYLENE SUCCINATE); POLY(ETHYLENE SUCCINATE); POLYAMIDE; POLYCAPROLACTONE; POLYCARBONATE; POLYESTER; POLYETHYLENE; POLYETHYLENE ADIPATE; POLYLACTIC ACID; POLYMER; POLYURETHAN; STARCH; TRIACYLGLYCEROL LIPASE; UNCLASSIFIED DRUG;

BIODEGRADABILITY; BIODEGRADATION; BIODIVERSITY; CHEMICAL STRUCTURE; ENVIRONMENTAL IMPACT; ENZYMATIC DEGRADATION; ENZYME ACTIVITY; FOSSIL; FUNGUS; GLASS TRANSITION TEMPERATURE; GRAM NEGATIVE BACTERIUM; GRAM POSITIVE BACTERIUM; LIPOLYSIS; MATERIALS; MELTING POINT; MICROBIAL DEGRADATION; MOLECULAR WEIGHT; NOMENCLATURE; NONHUMAN; REVIEW; RHIZOPUS;

ALIPHATIC POLYESTERS; BIO-BASED PLASTICS; BIODEGRADABILITY; ENZYMATIC DEGRADATION; MICROBIAL DEGRADATION;

ANIMALS; BACTERIA; BIOCATALYSIS; BIODEGRADABLE PLASTICS; BIODEGRADATION, ENVIRONMENTAL; ENZYMES; HUMANS; TRANSITION TEMPERATURE;

EID: 70350041101     PISSN: None     EISSN: 14220067     Source Type: Journal    
DOI: 10.3390/ijms10093722     Document Type: Review

References (99)

1. Wang, F.; Lee, S.J. Poly(3-hydroxybutyrate) production with high productivity and high polymer content by a fed-batch culture of Alcaligenes latus under nitrogen limitation. Appl. Environ. Microbiol. 1997, 63, 3703-3706. (Pubitemid 27383175)
2. Tokiwa, Y.; Ugwu, C.U. Biotechnological production of (R)-3-hydroxybutyric acid monomer. J. Biotechnol. 2007, 132, 264-272. (Pubitemid 47632864)
3. Tokiwa, Y.; Calabia, B.P. Biological production of functional chemicals from renewable resources. Can. J. Chem. 2008, 86, 548-555.
4. Tokiwa, Y.; Ando, T.; Suzuki T. Degradation of polycaprolactone by a fungus. J. Ferm. Technol. 1976, 54, 603-608.
5. Tokiwa, Y.; Suzuki, T. Purification of polyethylene adipate-degrading enzyme produced by Penicillium sp. strain 14-3. Agric. Biol. Chem. 1977a, 41, 265-274. (Pubitemid 8115060)
6. Tokiwa, Y.; Suzuki, T. Hydrolysis of polyesters by lipases. Nature 1977b, 270, 76-78.
7. Tokiwa, Y. Biodegradation of polycarbonates. In Miscellaneous Biopolymers and Biodegradation of Polymers; Matsumura, S., Steinbuchel, A., Eds.; WILEH-VCH Verlag GmbH: Weinheim, Germany, 2002; Volume 9, pp. 417-422.
8. Nishida, H.; Tokiwa, Y. Distribution of poly(β-hydroxybutyrate) and poly(ε-caprolactone) aerobic degrading microorganisms in different environments. J. Environ. Polym. Degrad. 1993a, 1, 227-233.
9. Mergaert, J.; Swings, J. Biodiversity of microorganisms that degrade bacterial and synthetic polyesters. J. Ind. Microbiol. 1996, 17, 463-469. (Pubitemid 27064591)
10. Suyama, T.; Tokiwa, Y.; Oichanpagdee, P.; Kanagawa, T.; Kamagata, Y. Phylogenetic affiliation of soil bacteria that degrade aliphatic polyesters available commercially as biodegradable plastics. Appl. Environ. Microbiol. 1998a, 64, 5008-5011. (Pubitemid 28557874)
11. Pranamuda, H.; Tokiwa, Y.; Tanaka, H. Polylactide degradation by an Amycolatopsis sp. Appl. Environ. Microbiol. 1997, 63, 1637-1640. (Pubitemid 27174883)
12. Tokiwa, Y.; Suzuki, T. Hydrolysis of polyesters by Rhizopus delemar lipase. Agric.Biol. Chem. 1978, 42, 1071-1072. (Pubitemid 8366001)
13. Iwata, T.; Doi, Y. Morphology and enzymatic degradation of poly(L-lactic acid) single crystals. Macromolecules 1998, 31, 2461-2467.
14. Tsuji, H.; Miyauchi, S. Poly(L-lactide) 6. Effects of crystallinity on enzymatic hydrolysis of poly(l-lactide) without free amorphous region. Polym. Degrad. Stab. 2001, 71, 415-424.
15. Tokiwa, Y.; Suzuki, T. Hydrolysis of copolyesters containing aromatic and aliphatic ester blocks by lipase. J. Appl. Polym. Sci. 1981, 26, 441-448. (Pubitemid 12445644)
16. Tokiwa, Y.; Suzuki, T.; Ando, T. Synthesis of copolyamide-esters and some aspects involved in their hydrolysis by lipase. J. Appl. Polym. Sci. 1979, 24, 1701-1711. (Pubitemid 10412317)
17. Tokiwa, Y.; Suzuki, T. Degradation of poly(ethylene glycol) adipate by a fungus. J. Ferm. Technol. 1974, 52, 393-398.
18. Sanchez, J.G.; Tsuchii, A.; Tokiwa, Y. Degradation of polycaprolactone at 50°C by a thermotolerant Aspergillus sp. Biotechnol. Lett. 2000, 22, 849-853. (Pubitemid 30399250)
19. Abou-Zeid, D.M.; Muller, R.J.; Deckwer, W.D. Degradation of natural and synthetic polyesters under anaerobic conditions. J. Biotechnol. 2001, 86, 113-126.
20. Cook, W.J.; Cameron, J.A.; Bell, J.P.; Huang, S.J. Scanning electron microscopic visualization of biodegradation of polycaprolactones by fungi. J. Polym. Sci., Polym. Lett. Ed. 1981, 19, 159-165.
21. Tokiwa, Y.; Suzuki, T.; Takeda, K. Two types of lipases in hydrolysis of polyester. Agric. Biol. Chem. 1988, 52, 1937-1943.
22. Seretoudi, G.; Bikiaris, D.; Panayiotou, C. Synthesis, characterization and biodegradability of poly(ethylene succinate)/poly(ε-caprolactone) block copolymers. Polymer 2002, 43, 5405-5415. (Pubitemid 34887107)
23. Tokiwa, Y.; Calabia, B.P. Biodegradability and biodegradation of polyesters. J. Polym. Environ. 2007, 15, 259-267.
24. Tanio, T.; Fukui, T.; Shirakura, Y.; Saito, T.; Tomita, K.; Kaiho, T.; Masamune, S. An extracellular poly(3-hydroxybutyrate) depolymerase from Alcaligenes faecalis. Eur. J. Biochem. 1982, 124, 71-77.
25. Mukai, K.; Doi, Y.; Sema, Y.; Tomita, K. Substrate specificities in hydrolysis of polyhydroxyalkanoates by microbial esterases. Biotechnol. Lett. 1993, 15, 601-604. (Pubitemid 23204469)
26. Nishida, H.; Suzuki, S.; Tokiwa, Y. Distribution of poly(-propiolactone) aerobic degrading microorganisms in different environments. J. Environ. Polym. Degrad. 1998, 6, 43-57. (Pubitemid 28279122)
27. Kobayashi, T.; Sugiyama, A.; Kawase, Y.; Saito, T.; Mergaert, J.; Swings, J. Biochemical and genetic characterization of an extracellular poly (3-hydroxybutyrate) depolymerase from Acidovorax sp. strain TP4. J. Polym. Environ. 1999, 7, 9-18.
28. Calabia, B.P.; Tokiwa, Y. A novel PHB depolymerase from a thermophilic Streptomyces sp. Biotechnol. Lett. 2006, 28, 383-388.
29. Takiyama, E.; Fujimaki, T. Bionolle biodegradable plastic through chemical synthesis. In Biodegradable Plastics and Polymers; Doi, Y., Fukuda, K., Eds.; Elsevier Science: Amsterdam, The Netherlands, 1994; pp. 150-174.
30. Pranamuda, H.; Tokiwa, Y.; Tanaka, H. Microbial degradation of an aliphatic polyester with a high melting point, poly(tetramethylene succinate). Appl. Environ. Microbiol. 1995, 61, 1828-1832.
31. Jarerat, A.; Tokiwa, Y. Degradation of poly(tetramethylene succinate) by thermophilic actinomycetes. Biotechnol. Lett. 2001a, 23, 647-651. (Pubitemid 32385670)
32. Maeda, Y.; Nakayama, A.; Iyoda, J.; Hayashi, K.; Yamamoto, N. Synthesis and biodegradation of the copolymers of succinic anhydride with various oxiranes. Kobunshi Ronbunshu. 1993, 50, 723-729.
33. Kasuya, K.; Takagi, K.; Ishiwatari, S.; Yoshida, Y.; Doi, Y. Biodegradabilities of various aliphatic polyesters in natural waters. Polym. Degrad. Stab. 1997, 59, 327-332. (Pubitemid 128389730)
34. Tansengco, M.L.; Tokiwa, Y. Thermophilic microbial degradation of polyethylene succinate. World J. Microbiol. Biotechnol. 1998a, 14, 133-138. (Pubitemid 28139578)
35. Tezuka, Y.; Ishii, N.; Kasuya, K.; Mitomo, H. Degradation of poly(ethylene succinate) by mesophilic bacteria. Polym. Degrad. Stab. 2004, 84, 115-121.
36. Ishii, N.; Inoue, Y.; Shimada, K.; Tesuka, Y.; Mitomo, H.; Kasuya, K. Fungal degradation of poly(ethylene succinate). Polym. Degrad. Stab. 2007, 92, 44-52.
37. Bikiaris, D.N.; Papageorgiou, G.Z.; Achilias, D.S. Synthesis and comparative biodegradability studies of three poly(alkylene succinate)s. Polym. Degrad. Stab. 2006, 91, 31-43. (Pubitemid 41455139)
38. Witt, U.; Muller, R.-J.; Deckwer, W.-D. Biodegradation of polyester copolymers containing aromatic compounds. J. Macromol. Sci. Pure Appl. Chem. 1995, 4, 851-856.
39. Kleeberg, I.; Hetz, C.; Kroppenstedt, R.-M.; Muller, R.-J.; Deckwer, W.-D. Biodegradation of aliphatic-aromatic copolyesters by Thermomonospora fusca and other thermophilic compost isolates. Appl. Environ. Microbiol. 1998, 64, 1731-1735.
40. Kleeberg, I.; Welzel, K.; Vanden Heuvel, J.; Muller, R.-J.; Deckwer, W.-D. Characterization of a new extracellular hydrolase from Thermobifida fusca degrading aliphatic-aromatic copolyesaters. Biomacromolecules 2005, 6, 262-270.
41. Chowdhury, A.A. Poly-β-hydroxybuttersaure abbauende Bakterien und exo-enzyme. Arch. Microbiol. 1963, 47, 167-200.
42. Lee, S.Y. Bacterial polyhydroxyalkanoates. Biotechnol. Bioeng. 1996, 49, 1-14.
43. Tokiwa, Y.; Iwamoto, A.; Koyama, M.; Kataoka, N.; Nishida, H. Biological recycling of plastics containing ester bonds. Makromol. Chem., Makromol. Symp. 1992, 57, 273-279.
44. Calabia, B.P.; Tokiwa, Y. Microbial degradation of poly(D-3- hydroxybutyrate) by a new thermophilic streptomyces isolate. Biotechnol. Lett. 2004, 26, 15-19. (Pubitemid 38161951)
45. Tseng, M.; Hoang, K.C.; Yang, M.K.; Yang, S.F.; Chu, W.S. Polyester-degrading thermophilic actinomycetes isolated from different environment in Taiwan. Biodegradation 2007, 18, 579-583. (Pubitemid 47305473)
46. Carothers, W.H.; Hill, J.W. Studies of polymerization and ring formation. XV. Artificial fibers from synthetic linear condensation superpolymers. J. Am. Chem. Soc. 1932, 54, 1579-1596.
47. Uruyama, H.; Kanamori, T.; Kimura, Y. Properties and biodegradability of polymer blends of poly(L-lactide)s with different optical purity of the lactate units. Macromol. Mater. Eng. 2002, 287, 116-121.
48. Ohkita, T.; Lee, S.H. Thermal degradation and biodegradability of poly(lactic acid)/corn starch biocomposites. J. App. Polym. Sci. 2006, 100, 3009-3017.
49. Tokiwa, Y.; Calabia, B.P. Biodegradability and biodegradation of poly(lactide). Appl. Microbiol. 2006, 72, 244-251.
50. Pranamuda, H.; Tsuchii, A.; Tokiwa, Y. Poly(L-lactide degrading enzyme produced by Amycolatopsis sp. Macromol. Biosci. 2001, 1, 25-29.
51. Jarerat, A.; Tokiwa, Y. Degradation of poly(L-lactide) by fungus. Macromol. Biosci. 2001b, 1, 136-140.
52. Jarerat, A.; Tokiwa, Y. Poly(L-lactide) degradation by Saccharotrix waywayandensis. Biotechnol. Lett. 2003a, 25, 401-404.
53. Jarerat, A.; Tokiwa, Y. Poly(L-lactide) degradation by Kibdelosporangium aridum. Biotechnol. Lett. 2003b, 25, 2035-2038.
54. Jarerat, A.; Tokiwa, Y.; Tanaka, H. Microbial poly(L-lactide) degrading enzyme induced by amino acids, peptides and poly(L-amino acids). J. Polym. Environ. 2004, 12, 139-146. (Pubitemid 39159951)
55. Williams, D.F. Enzymatic hydrolysis of polylactic acid. Eng. Med. 1981, 10, 5-7.
56. Reeve, M.S.; McCarthy, S.P.; Downey, M.J.; Gross, R.A. Polylactide stereochemistry: Effect on enzymatic degradability. Macromolecules 1994, 27, 825-831.
57. McDonald, R.T.; McCarthy, S.; Gross, R.A. Enzymatic degradability of poly(lactide): Effects of chain stereochemistry and material crystallinity. Macromolecules 1996, 29, 7356-7361. (Pubitemid 126525583)
58. Fukuzaki, H.; Yoshida, M.; Asano, M.; Kumakura, M. Synthesis of copoly(D,L-lactic acid) with relative low molecular weight and in vitro degradation. Eur. Polym. J. 1989, 25, 1019-1026. (Pubitemid 20731896)
59. Lim, H.A.; Raku, T.; Tokiwa, Y. Hydrolysis of polyesters by serine proteases. Biotechnol. Lett. 2005, 27, 459-464.
60. Iwamoto, A.; Tokiwa, Y. Enzymatic degradation of plastics containing polycaprolactone. Polym. Degrad. Stab. 1994, 45, 205-213.
61. Tokiwa, Y.; Iwamoto, A.; Koyama, M. Development of biodegradable plastics containing polycaprolactone and/or starch. Polym. Mats. Sci. Eng. 1990, 63, 742-746.
62. Iwamoto, A.; Tokiwa, Y. Effect of the phase structure on biodegradability of polypropylene/poly(ε-caprolactone) blends. J. Appl. Polym. Sci. 1994, 52, 1357-1360.
63. Kumagai, Y.; Doi, Y. Enzymatic degradation and morphologies of binary blends of microbial poly(3-hydroxybutyrate) with poly(ε-caprolactone), poly(1,4-butylene adipate and poly(vinyl acetate). Polym. Degrad. Stab. 1992, 36, 241-248.
64. Koyama, N.; Doi, Y. Miscibility of binary blends of poly[(R)-3- hydroxybutyric and poly[(S)-lactic acid]. Polymer 1997, 38, 1589-1593. (Pubitemid 27205627)
65. Liu, L.; Li, S.; Garreau, H.; Vert, M. Selective enzymatic degradations of poly(L-lactide) and poly(ε-caprolactone) blend films. Biomacromolecules 2000, 3, 350-359.
66. Takagi, S.; Koyama, M.; Kameyama, H.; Tokiwa, Y. Development of polycaprolactone/ gelatinized starch blends and their enzymatic degradation. In Biodegradable Plastics and Polymers; Doi, Y., Fukuda, K., Eds.; Elsevier Science: Amsterdam, The Netherlands, 1994; pp. 437-442. (Pubitemid 24810050)
67. Pranamuda, H.; Tokiwa, Y.; Tanaka, H. Physical properties and biodegradability of blends containing poly(ε-caprolactone) and tropical starches. J. Environ. Polym. Degrad. 1996, 4, 1-7.
68. Noomhorm, C.; Tokiwa, Y. Effect of poly(dioxalane) as compatibilizer in poly(ε-caprolactone)/tapioca starch blends. J. Polym. Environ. 2006, 14, 149-156. (Pubitemid 44088861)
69. Ramkumar, D.H.S.; Bhattacharya, M. Effect of crystallinity on the mechanical properties of starch/synthetic polymer blends. J. Mat. Sci. 1997, 32, 2565-2572. (Pubitemid 127503407)
70. Chandra, R.; Rustgi, R. Biodegradable polymers. Prog. Polym. Sci. 1998, 23, 1273-1335.
71. Dubois, P.; Narayan, R. Biodegradable compositions by reactive processing of aliphatic polyester/polysaccharide blends. Macromol. Symp. 2003, 198, 233-243.
72. Jang, W.J.; Shin, B.Y.; Lee, T.J.; Narayan, R. Thermal properties and morphology of biodegradable PLA/starch compatibilized blends. J. Ind. Eng. Chem. 2007, 13, 457-464.
73. Ratto, J.A.; Stenhouse, P.J.; Auerbach, M.; Mitchell, J.; Farrel, R. Processing, performance and biodegradability of a thermoplastic aliphatic polyester/starch system. Polymer 1999, 40, 6777-6788. (Pubitemid 29404816)
74. Imai, Y.; Kojima, K.; Masuhara, E. Tissue response by polymeric materials after long-term implantation in dog. Jpn. J. Artif. Organs. 1979, 8, 246-249.
75. Kawaguchi, T.; Nakano, M.; Juni, K.; Inoue, S.; Yoshida, Y. Examination of biodegradability of poly(ethylene carbonate) and poly poly(propylene carbonate) in the peritoneal cavity in rats. Chem. Pharm. Bull. 1983, 31, 1400-1403.
76. Nishida, H.; Tokiwa, Y. Confirmation of poly(1,3-dioxolan-2-one)- degrading microorganisms in the environment. Chem. Lett. 1994, 3, 421-422.
77. Suyama, T.; Hosoya, H.; Tokiwa, Y. Bacterial isolates degrading aliphatic polycarbonates. FEMS Microbiol. Lett. 1998b, 161, 255-261. (Pubitemid 28179430)
78. Pranamuda, H.; Chollakup, R.; Tokiwa, Y. Degradation of polycarbonate by a polyester-degrading strain, Amycolatopsis sp. strain HT-6. Appl. Environ. Microbiol. 1999, 65, 4220-4222. (Pubitemid 129519888)
79. Suyama, T.; Tokiwa, Y. Enzymatic degradation of aliphatic polycarbonate, poly(tetramethylene carbonate). Enz. Microb. Technol. 1997, 20, 122-126. (Pubitemid 27065124)
80. Darby, R.T.; Kaplan, A.M. Fungal susceptibility of polyurethanes. Appl. Microbiol. 1968, 16, 900-905.
81. Crabbe, J.R.; Campbell, J.R.; Thompson, L.; Walz, S.L.; Schultz, W.W. Biodegradation of a colloidal ester-based polyurethane by soil fungi. Int. Biodeterior. Biodegrad. 1994, 33, 103-113.
82. Nakajima-Kambe, T.; Onuma, F.; Kimpara, N.; Nakahara, T. Isolation and characterization of a bacterium which utilizes polyester polyurethane as a sole carbon and nitrogen source. FEMS Microbiol. Lett. 1995, 129, 39-42.
83. Santerre, J.P.; Labow, R.S.; Duguay, D.G.; Erfle, D.; Adams, G.A. Biodegradation evaluation of polyether and polyester-urethanes with oxidative and hydrolytic enzymes. J. Biomed. Mater. Res. 1994, 28, 1187-1199.
84. Wang, G.B.; Santerre, J.P.; Labow, R.S. High-performance liquid chromatographic separation and tandem mass spectrometric identification of breakdown products associated with the biological hydrolysis of a biomedical polyurethane. J. Chromatogr. B Biomed. Sci. Appl. 1997, 698, 69-80.
85. Kinoshita, S.; Kageyama, S.; Iba, K.; Yamada, Y.; Okada, H. Utilization of a cyclic dimmer and linear oligomers of ε-amino caproic acid by Achromobacter guttatus K172. Agric. Boil. Chem. 1975, 39, 1219-1223.
86. Kanagawa, K.; Negoro, S.; Takada, N.; Okada, H. Plasmid dependence of Pseudomonas sp. strain NK87 enzymes that degrade 6-aminohexanoaate-cyclic dimer. J. Bacteriol. 1989, 171, 3181-3186. (Pubitemid 19145671)
87. Deguchi, T.; Kitaoka, Y.; Kakzawa, M.; Nishida, T. Purification and characterization of a nylon-degrading enzyme. Appl. Environ. Microbiol. 1998, 64, 1366-1371.
88. Hashimoto, K.; Hamano, T.; Okada, M. Degradation of several polyamides in soil. J. Appl. Polymer. Sci. 1994, 54, 1579-1583.
89. Kawasaki, N.; Atsuyoshi, N.; Naoko, Y.; Takeda, S.; Kawata, Y.; Yamamoto, N.; Aiba, S. Synthesis, thermal and mechanical properties and biodegradation of branched polyamide 4. Polymer 2005, 46, 9987-9993. (Pubitemid 41455229)
90. Hashimoto, K.; Sudo, M.; Ohta, K.; Sugimura, T.; Yamada, H. Biodegradation of nylon 4 and its blend with nylon 6. J. Appl. Polym. Sci. 2002, 86, 2307-2311.
91. Yamano, N.; Nakayama, A.; Kawasaki, N.; Yamamoto, N.; Aiba, S. Mechanism and characterization of polyamide 4 degradation by Pseudomonas sp. J. Polym. Environ. 2008, 16, 141-146.
92. Tokiwa, Y.; Suzuki, T.; Ando, T. Synthesis of copolyamide-esters and some aspects involved in their hydrolysis of lipase. J. Appl. Polym. Sci. 1979, 24, 1701-1711. (Pubitemid 10412317)
93. Komatsu, S.; Tokiwa, Y. Synthesis of coplyamide-esters and their enzymatic hydrolysis. Japanese J. Polym. Sci. Tech. (Koubunshi Ronbunshu) 1993, 50, 785-788.
94. Tsuchii, A.; Suzuki, T.; Fukuoka, S. Microbial degradation of polyethylene oligomers. Rep. Ferment. Res. Inst. 1980, 55, 35-40.
95. Bikiaris, D.; Panayiotou, C. LDPE/starch blends compatibilized with PE-g-MA copolymers. J. Appl. Polym. Sci. 1998, 70, 1503-1521. (Pubitemid 128567120)
96. Griffin, G.J.L. Degradation of polyethylene in compost burial. J. Polym. Sci. Polym. Symp. 2007, 57, 281-286.
97. Hakkarainen, M.; Albertsson, A.C. Environmental degradation of polyethylene. Adv. Polym. Sci. 2004, 169, 177-199.
98. Cacciari, I.; Quatrini, P.; Zirletta, G.; Mincione, E.; Vinciguerra, V.; Lupatelli, P.; Sermanni, G.G. Isotactic polypropylene biodegradation by a microbial community: Physico-chemical characterization of metabolites produced. Appl. Environ. Microbiol. 1993, 59, 3695-3700.
99. Mor, R.; Silvan, A. Biofilm formation and partial biodegradation of polystyrene by the actinomycete Rhodococcus ruber: Biodegradation of polystyrene. Biodegradation 2008, 19, 851-858.