Anoxic Biodegradation of Isosaccharinic Acids at Alkaline pH by Natural Microbial Communities.
Anoxic Biodegradation of Isosaccharinic Acids at Alkaline pH by Natural Microbial Communities.
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DOI：
10.1371/journal.pone.0137682
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发表时间：
2015
期刊：
影响因子：
3.7
通讯作者：
Humphreys PN
中科院分区：
文献类型：
--
作者：
Rout SP;Charles CJ;Doulgeris C;McCarthy AJ;Rooks DJ;Loughnane JP;Laws AP;Humphreys PN
英国中级放射性废物(ILW)长期管理的一个设计概念是将其处置到胶结性地质处置设施(GDF)。在GDF内预期的碱性(10.0<；pH>；13.0)缺氧条件下，纤维素废物将发生化学水解。产生的纤维素降解产物主要是α-和β-异糖酸(ISA)，它们是一种有机碳源，可能使GDF随后的微生物定居成为可能。从中性、近地表沉积物建立的微宇宙显示，在pH 10.0以下的产甲烷条件下，ISA完全降解。降解率随着pH的升高而降低，β-ISA发酵受到的影响比α-ISA大。伴随着降解率的下降，微生物种群从与梭状芽胞杆菌相关的生物体转移到更多样化的梭状芽胞杆菌群落。当pH值增加到10.0时，水产碱菌的检出率增加，古细菌种群中的产氢产甲烷菌占主导地位。在pH 10.0以下产生甲烷，在较高的pH值下乙酸盐积累，反映了乙酰碎屑产甲烷菌的减少。PH升高到11.0时，会导致ISA的积累，不会产生甲烷，系统中的生物量会减少。这项研究首次证明了从ISA产生甲烷的近表面微生物群落以前没有接触过这些化合物，直到(包括)pH 10.0。
One design concept for the long-term management of the UK’s intermediate level radioactive wastes (ILW) is disposal to a cementitious geological disposal facility (GDF). Under the alkaline (10.0<pH>13.0) anoxic conditions expected within a GDF, cellulosic wastes will undergo chemical hydrolysis. The resulting cellulose degradation products (CDP) are dominated by α- and β-isosaccharinic acids (ISA), which present an organic carbon source that may enable subsequent microbial colonisation of a GDF. Microcosms established from neutral, near-surface sediments demonstrated complete ISA degradation under methanogenic conditions up to pH 10.0. Degradation decreased as pH increased, with β-ISA fermentation more heavily influenced than α-ISA. This reduction in degradation rate was accompanied by a shift in microbial population away from organisms related to Clostridium sporosphaeroides to a more diverse Clostridial community. The increase in pH to 10.0 saw an increase in detection of Alcaligenes aquatilis and a dominance of hydrogenotrophic methanogens within the Archaeal population. Methane was generated up to pH 10.0 with acetate accumulation at higher pH values reflecting a reduced detection of acetoclastic methanogens. An increase in pH to 11.0 resulted in the accumulation of ISA, the absence of methanogenesis and the loss of biomass from the system. This study is the first to demonstrate methanogenesis from ISA by near surface microbial communities not previously exposed to these compounds up to and including pH 10.0.