Application of Molecular Techniques To Elucidate the Influence of Cellulosic Waste on the Bacterial Community Structure at a Simulated Low-Level-Radioactive-Waste Site

Abstract

Low-level-radioactive-waste (low-level-waste) sites, including those at various U.S. Department of Energy sites, frequently contain cellulosic waste in the form of paper towels, cardboard boxes, or wood contaminated with heavy metals and radionuclides such as chromium and uranium. To understand how the soil microbial community is influenced by the presence of cellulosic waste products, multiple soil samples were obtained from a nonradioactive model low-level-waste test pit at the Idaho National Laboratory. Samples were analyzed using 16S rRNA gene clone libraries and 16S rRNA gene microarray (PhyloChip) analyses. Both methods revealed changes in the bacterial community structure with depth. In all samples, the PhyloChip detected significantly more operational taxonomic units, and therefore relative diversity, than the clone libraries. Diversity indices suggest that diversity is lowest in the fill and fill-waste interface (FW) layers and greater in the wood waste and waste-clay interface layers. Principal-coordinate analysis and lineage-specific analysis determined that the Bacteroidetes and Actinobacteria phyla account for most of the significant differences observed between the layers. The decreased diversity in the FW layer and increased members of families containing known cellulosedegrading microorganisms suggest that the FW layer is an enrichment environment for these organisms. These results suggest that the presence of the cellulosic material significantly influences the bacterial community structure in a stratified soil system.The processing of nuclear materials, operation of nuclear reactors, and research and development activities at government sites, hospitals, universities, and radiochemical and radiopharmaceutical manufacturers have led to the generation of a substantial amount of low-level mixed radioactive and heavy metal wastes that have been disposed of in pits, trenches, and other waste sites (2). Codisposed of with metals and radionuclides were large quantities of cellulose-containing materials such as wood, paper towels, cardboard, cheesecloth, and other materials (53). These wastes result from glove box operations, decontamination, housekeeping, maintenance, and construction activities and can constitute up to 90% of the volume of typical low-level radioactive waste (low-level waste [LLW]) (60). While there are over 20,000 commercial users of radioactive materials (2), the Department of Energy (DOE) complex houses the majority of disposed LLW waste at sites including Savannah River, Hanford, Idaho National Laboratory (INL), and Nevada test sites (3). Prior to 2000, the DOE disposed of approximately 2 million cubic meters of LLW and has projected the disposal of an additional 10

Actinobacteria occurrence and their metabolic characteristics in the nickel-contaminated soil sample

“…and Streptomyces spp. is not surprising in heavymetal contaminated soil and their occurrence in this polluted environment was confirmed by several authors (Joynt et al 2006;Schmidt et al 2009;Field et al 2010;El-Meleigy et al 2011;Karelová et al 2011;Lin et al 2011;Al-Kadeeb et al 2012). Similarly, the occurrence of the bacterial subclass Rubrobacteridae clones is not surprising as well, because 70% of the actinobacterial clones belonged to the genus Rubrobacter, a widespread taxa that has yet few cultured representatives in soils (Holmes et al 2000).…”

Resuscitation of viable but non‐culturable bacteria to enhance the cellulose‐degrading capability of bacterial community in composting

“…Moreover, Field et al . () observed that members of Actinobacteria containing known cellulose‐degrading bacteria increased in the fill‐waste interface layer, which suggested the potential capabilities of the Actinobacteria phylum to degrade cellulose. Additionally, our previous studies found that extracellular organic matter (EOM) from M .…”

“…Strains in group 1 belonged to Gram‐negative bacteria, which were well supported by the studies that Rpf also resuscitated and stimulated the growth of some Gram‐negative bacteria (Su et al ., ,b, ,b,c,d). In particular, ZS2R8 was closely related to uncultured bacterium clone FW2_72B () which was detected at low‐level waste site with cellulosic contaminants (Field et al ., ). Strains in group 2 were closely related to Bacillus sp., which were low G+C Gram‐positive bacteria.…”

Sulfurirhabdus autotrophica gen. nov., sp. nov., isolated from a freshwater lake

“…The type strain of Sulfuricella denitrificans was isolated from a cold anoxic hypolimnion of a freshwater lake, and was characterized as a psychrotolerant sulfur oxidizer (Watanabe et al, 2012). Based on nucleotide sequences, its close relatives have been found in freshwater lake sediments (Nelson et al, 2007;Song et al, 2012;Watanabe et al, 2013), Thioploca samples from two freshwater lakes (Nemoto et al, 2011), drinking water distribution systems (Li et al, 2010;Sun et al, 2014a, b), the sediment of a drinking water reservoir (Cheng et al, 2014), soil (Field et al, 2010), a bioreactor (Wang et al, 2015), subglacial sediment (Boyd et al, 2014), wetland sediment (Liu et al, 2014), a limestone aquifer (Herrmann et al, 2015), groundwater (Hong et al, 2013), black shale (Li et al, 2014), a horizontal subsurface flow system constructed in wetlands (Zhong et al, 2015) and the freshwater layer of a meromictic lake (Kubo et al, 2014). Members of the genus Sulfuricella are likely to contribute to sulfur cycling in a wide range of freshwater ecosystems, but only two cultured strains of the genus Sulfuricella have, so far, been described (Watanabe et al, 2015b).…”