Evidence of the Generation of Isosaccharinic Acids and Their Subsequent Degradation by Local Microbial Consortia within Hyper-Alkaline Contaminated Soils, with Relevance to Intermediate Level Radioactive Waste Disposal

The contamination of surface environments with hydroxide rich wastes leads to the formation of high pH (>11.0) soil profiles. One such site is a legacy lime works at Harpur Hill, Derbyshire where soil profile indicated in-situ pH values up to pH 12. Soil and porewater profiles around the site indicated clear evidence of the presence of the α and β stereoisomers of isosaccharinic acid (ISA) resulting from the anoxic, alkaline degradation of cellulosic material. ISAs are of particular interest with regards to the disposal of cellulosic materials contained within the intermediate level waste (ILW) inventory of the United Kingdom, where they may influence radionuclide mobility via complexation events occurring within a geological disposal facility (GDF) concept. The mixing of uncontaminated soils with the alkaline leachate of the site resulted in ISA generation, where the rate of generation in-situ is likely to be dependent upon the prevailing temperature of the soil. Microbial consortia present in the uncontaminated soil were capable of surviving conditions imposed by the alkaline leachate and demonstrated the ability to utilise ISAs as a carbon source. Leachate-contaminated soil was sub-cultured in a cellulose degradation product driven microcosm operating at pH 11, the consortia present were capable of the degradation of ISAs and the generation of methane from the resultant H2/CO2 produced from fermentation processes. Following microbial community analysis, fermentation processes appear to be predominated by Clostridia from the genus Alkaliphilus sp, with methanogenesis being attributed to Methanobacterium and Methanomassiliicoccus sp. The study is the first to identify the generation of ISA within an anthropogenic environment and advocates the notion that microbial activity within an ILW-GDF is likely to influence the impact of ISAs upon radionuclide migration

Desulfuribacillus alkaliarsenatis gen. nov. sp. nov., a deep-lineage, obligately anaerobic, dissimilatory sulfur and arsenate-reducing, haloalkaliphilic representative of the order Bacillales from soda lakes

An anaerobic enrichment culture inoculated with a sample of sediments from soda lakes of the Kulunda Steppe with elemental sulfur as electron acceptor and formate as electron donor at pH 10 and moderate salinity inoculated with sediments from soda lakes in Kulunda Steppe (Altai, Russia) resulted in the domination of a Gram-positive, spore-forming bacterium strain AHT28. The isolate is an obligate anaerobe capable of respiratory growth using elemental sulfur, thiosulfate (incomplete reduction) and arsenate as electron acceptor with H2, formate, pyruvate and lactate as electron donor. Growth was possible within a pH range from 9 to 10.5 (optimum at pH 10) and a salt concentration at pH 10 from 0.2 to 2 M total Na+ (optimum at 0.6 M). According to the phylogenetic analysis, strain AHT28 represents a deep independent lineage within the order Bacillales with a maximum of 90 % 16S rRNA gene similarity to its closest cultured representatives. On the basis of its distinct phenotype and phylogeny, the novel haloalkaliphilic anaerobe is suggested as a new genus and species, Desulfuribacillus alkaliarsenatis (type strain AHT28T = DSM24608T = UNIQEM U855T)

Viroplasm and large virus-like particles in the dinoflagellate Gymnodinium uberrimum

Virus-like particles (VLPs) measuring 385±5 nm in diameter are described in the freshwater dinoflagellate Gymnodinium uberrimum . The VLPs are found in association with, and “budding” from a vesicular viroplasmic area. A similar viroplasm was also found in a chrysophycean alga, Mallomonas sp. collected from the same general area in Saginaw Bay of Lake Huron. The nature of these VLPs and their virogenic stroma, in these algae from the Laurentian Great Lakes are discussed in the present report.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/41733/1/709_2005_Article_BF01275735.pd

Microbial diversity and biogeochemical cycling in soda lakes

Soda lakes contain high concentrations of sodium carbonates resulting in a stable elevated pH, which provide a unique habitat to a rich diversity of haloalkaliphilic bacteria and archaea. Both cultivation-dependent and -independent methods have aided the identification of key processes and genes in the microbially mediated carbon, nitrogen, and sulfur biogeochemical cycles in soda lakes. In order to survive in this extreme environment, haloalkaliphiles have developed various bioenergetic and structural adaptations to maintain pH homeostasis and intracellular osmotic pressure. The cultivation of a handful of strains has led to the isolation of a number of extremozymes, which allow the cell to perform enzymatic reactions at these extreme conditions. These enzymes potentially contribute to biotechnological applications. In addition, microbial species active in the sulfur cycle can be used for sulfur remediation purposes. Future research should combine both innovative culture methods and state-of-the-art ‘meta-omic’ techniques to gain a comprehensive understanding of the microbes that flourish in these extreme environments and the processes they mediate. Coupling the biogeochemical C, N, and S cycles and identifying where each process takes place on a spatial and temporal scale could unravel the interspecies relationships and thereby reveal more about the ecosystem dynamics of these enigmatic extreme environments