Anaerobic Biodegradation of Aliphatic Polyesters:  Poly(3-hydroxybutyrate-c o-3-hydroxyoctanoate) and Poly(ε-caprolactone)

• Published in: Biomacromolecules Vol. 3; no. 4; pp. 813 - 822
• Main Authors: Federle, Thomas W, Barlaz, Morton A, Pettigrew, Charles A, Kerr, Kathy M, Kemper, Joseph. J, Nuck, Barbara A, Schechtman, Lee A
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 01.07.2002
• Subjects: Anaerobiosis; Biodegradation, Environmental; Bioreactors - microbiology; Carbon Dioxide - metabolism; Geologic Sediments - microbiology; Methane - metabolism; Polyesters - metabolism; Radioactive Tracers; Refuse Disposal - methods; Sewage - microbiology; Time Factors
• ISSN: 1525-7797; 1526-4602
• DOI: 10.1021/bm025520w

Poly(3-hydroxybutyrate-co-3-hydroxyoctanoate), PHBO, represents a class of PHA copolymers that contain both short-chain-length and medium-chain-length repeat units. Radiolabeled and cold PHBO, containing 90 mol % 3-hydroxybutyrate and 10 mol % 3-hydroxyoctanoate were chemically synthesized using a new difunctional alkoxyzinc initiator. 14C-PHBO was incubated with samples of anaerobic digester sludge, septage, freshwater sediment, and marine sediment under conditions resembling those in situ. In addition, it was incubated in laboratory-scale landfill reactors. 14C-PCL (poly-ε-caprolactone) was incubated with anaerobic digester sludge and in landfill reactors. Biodegradation was determined by measuring generation of 14CO2 and 14CH4 resulting from mineralization of the radiolabeled polymers. PHBO was extensively mineralized in digester sludge, septage sediments, and the landfill reactors, with half-lives less than 30 days. PCL was not significantly mineralized in digester sludge over 122 days. In the landfill reactors, PCL mineralization was slow and was preceded by a long lag period (>200 days), suggesting that PCL mineralization is limited by its rate of hydrolysis. The results indicate that PHBO is practically biodegradable in the major anaerobic habitats that it may enter. In contrast, anaerobic biodegradation of PCL is less ubiquitous and much slower.