Biodegradation of the alkaline cellulose degradation products generated during radioactive waste disposal

• Published in: PloS one 2014-09, Vol.9 (9), p.e107433
• Main Authors: Rout, Simon P, Radford, Jessica, Laws, Andrew P, Sweeney, Francis, Elmekawy, Ahmed, Gillie, Lisa J, Humphreys, Paul N
• Format: Article
• Language: English
• Subjects: Acids; Bacteria; Bacteria - genetics; Bacteria - metabolism; Biodegradation; Biodegradation, Environmental; Biology and Life Sciences; Cellulose; Cellulose - chemistry; Coal mining; Degradation products; Disposal sites; Earth Sciences; Ecology and Environmental Sciences; Ferric Compounds - chemistry; Geologic Sediments - chemistry; Geologic Sediments - microbiology; Hydrogen-Ion Concentration; Iron; Laboratories; Liquor; Methanogenesis; Microbial activity; Microbiology; Microorganisms; Migration; Molecular Typing; Museums; Nitrogen; Pressure vessels; Radioactive Waste; Radioactive waste disposal; Radioactive wastes; Reduction; RNA, Ribosomal, 16S - genetics; Sediments; Studies; Substrates; Sugar Acids - chemistry; Sulfate reduction; Sulfates; Waste disposal; Waste disposal sites; Waste management
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0107433

The anoxic, alkaline hydrolysis of cellulosic materials generates a range of cellulose degradation products (CDP) including α and β forms of isosaccharinic acid (ISA) and is expected to occur in radioactive waste disposal sites receiving intermediate level radioactive wastes. The generation of ISA's is of particular relevance to the disposal of these wastes since they are able to form complexes with radioelements such as Pu enhancing their migration. This study demonstrates that microbial communities present in near-surface anoxic sediments are able to degrade CDP including both forms of ISA via iron reduction, sulphate reduction and methanogenesis, without any prior exposure to these substrates. No significant difference (n = 6, p = 0.118) in α and β ISA degradation rates were seen under either iron reducing, sulphate reducing or methanogenic conditions, giving an overall mean degradation rate of 4.7 × 10(-2) hr(-1) (SE ± 2.9 × 10(-3)). These results suggest that a radioactive waste disposal site is likely to be colonised by organisms able to degrade CDP and associated ISA's during the construction and operational phase of the facility.