Presence, distribution, and diversity of iron-oxidizing bacteria at a landfill leachate-impacted groundwater surface water interface

Abstract

We examined the presence of iron-oxidizing bacteria (IOB) at a groundwater surface water interface (GSI) impacted by reduced groundwater originating as leachate from an upgradient landfill. IOB enrichments and quantifications were obtained, at high vertical resolution, by an iron/oxygen opposing gradient cultivation method. The depth-resolved soil distribution profiles of water content, Fe(2+), and total Fe indicated sharp gradients within the top 10 cm sediments of the GSI, where the IOB density was the highest. In addition, the vertical distribution of iron-reducing bacteria at the same sampling site mirrored the IOB distribution. Clone libraries from two separate IOB enrichments indicated a stratified IOB community with clear differences at short vertical distances. Alpha- and Betaproteobacteria were the dominant phylotypes. Clones from the near-surface sediment (1-2 cm below ground surface) were dominated by members of the Bradyrhizobiaceae and Comamonadaceae; clones from the deeper sediments were phylogenetically more diverse, dominated by members of the Rhodocyclaceae. The iron deposition profiles indicated that active iron oxidation occurred only within the near-to-surface GSI sediments. The match between the iron deposition profiles and the IOB abundance profiles strongly hints at the contribution of the IOB community to Fe oxidation in this Fe-rich GSI ecosystem.

Changes in bacterial community of anthracene bioremediation in municipal solid waste composting soil

“…Some other profiling techniques, such as community-level physiological profiling, restriction fragment length polymorphism, denaturing gradient gel electrophoresis, and phospholipid fatty acid profiling, have been applied to investigate the composition of bacterial community in contaminated aquifers near MSW composting sites (Röling et al, 2000;Tian et al, 2005;Yu et al, 2010). Among available DNA profiling techniques, TRFLP has been used to monitor structural changes of various soil microbial communities (Dunbar et al, 2000;Singh et al, 2006;Grant et al, 2007).…”

“…The knowledge about the microbial community structure in MSW composting soil is very important for development of bioremediation technology. Numerous studies have investigated the bacterial community structure in contaminated aquifers near MSW composting sites (Röling et al, 2000;Tian et al, 2005;Yu et al, 2010). However, these previous works have not investigated the links of PAHs to the bacterial communities.…”

Distribution and Diversity of Gallionella -Like Neutrophilic Iron Oxidizers in a Tidal Freshwater Marsh

“…Yu and colleagues also found large changes in the phylogenetic diversity of iron-oxidizing bacteria across short vertical distances at a contaminated aquifer site (47). When the vegetation type and the distribution of the Gallionella-related communities are integrated over all sampling times and depths, however, no statistically significant relationship emerges between them, except for the near-absence of detectable FeOB in sediments from the Salix-vegetated marsh.…”

Molecular characterization of phenanthrene-degrading methanogenic communities in leachate-contaminated aquifer sediment

“…Leachate from municipal solid waste (MSW) composting site may lead to serious PAH contamination in aquifers (Jiries et al 2005). Numerous studies have investigated the structures of bacterial communities in leachate-contaminated aquifers (Gros et al 2003;Tian et al 2005;Yu et al 2010). However, all these previous works have not investigated the links of the microbial communities to PAH biodegradation.…”