The enrichment of an alkaliphilic biofilm consortia capable of the anaerobic degradation of isosaccharinic acid from cellulosic materials incubated within an anthropogenic, hyperalkaline

12 Anthropogenic hyper-alkaline sites provide an environment that is analogous to 13 proposed cementitious geological disposal facilities (GDF) for radioactive waste. Under 14 anoxic, alkaline conditions cellulosic wastes will hydrolyse to a range of cellulose 15 degradation products (CDP) dominated by isosaccharinic acids (ISA). In order to investigate 16 the potential for microbial activity in a cementitious GDF, cellulose samples were incubated 17 in the alkaline (~pH 12), anaerobic zone of a lime kiln waste site. Following retrieval, these 18 samples had undergone partial alkaline hydrolysis and were colonised by a Clostridia 19 dominated biofilm community, where hydrogenotrophic, alkaliphilic methanogens were also 20 present. When these samples were used to establish an alkaline CDP fed microcosm, the 21 community shifted away from Clostridia, methanogens became undetectable and a flocculate 22 FEMS Microbiology Ecology Advance Access published July 20, 2015