ANAEROBIC MICROBIAL-DEGRADATION OF POLY(3-HYDROXYALKANOATES) WITH VARIOUS TERMINAL ELECTRON ACCEPTORS

The microbial degradation of poly (3-hydroxyalkanoates) (PHAs) under a naerobic conditions with various terminal electron accepters was exami ned. Nitrate-reducing consortia were established using activated sludg e, and PHAs were shown to be biodegradable under these conditions. A p ositive correlation between carbon dioxide production and nitrate redu ction was demonstrated. Nitrous oxide accumulated as the main N-contai ning product of nitrate reduction. The amount of PHAs in activated slu dge cultures decreased approximately 20% within 40 days of incubation. Attempts were made to establish iron- and sulfate-reducing consortia from spring water, yet it could not be demonstrated that the mixed cul tures were capable of degrading PHAs. Pure cultures of iron- and sulfa te-reducing bacteria could not utilize PHAs as sole carbon sources. Me thanogenic environments sampled included pond sediment and rumen fluid . PHAs were fermented to methane and carbon dioxide after 10 weeks by a sediment consortium, with 43 to 57% of the substrate carbon transfor med to methane. Although it could not be demonstrated that PHAs were b iodegraded by a rumen fluid consortium, a facultative anaerobic bacter ium, identified as a Staphylococcus sp., that could grow on PHAs was i solated from rumen fluid.