Figure 1.
The red stars indicate the two major sampling areas in Northern Ireland and Chernobyl (Ukraine). The map on the right shows the location of the sampling sites in the Chernobyl area according to the background level of radiation (µSv/h) (adapted from [47]). The photographs at the bottom show some examples of biofilms growing on concrete walls or pillars that were sampled.
Table 1.
Location, measured ambient radioactivity at sampling sites, number of sequences analyzed per gene library and Operational Taxonomic Units (OTUs) detected for samples analyzed in this study.
Figure 2.
Relative distribution of major bacterial and eukaryotic taxa in SSU rRNA gene libraries from concrete-associated biofilm microbial communities.
Figure 3.
Phylogenetic tree of SSU rDNA sequences from Chernobyl concrete biofilms belonging to the Proteobacteria.
The tree was reconstructed by maximum likelihood using 767 non-ambiguously aligned positions. Bootstrap values higher than 50% are given at nodes. Colored circles show the presence of the OTU in the different samples, and the internal number corresponds to the number of occurrences of sequences in the corresponding gene libraries. Unc., uncultured.
Figure 4.
Phylogenetic tree of bacterial SSU rDNA sequences to the exclusion of Proteobacteria retrieved from sunlight-exposed biofilms in Chernobyl.
The tree was reconstructed by maximum likelihood using 634 non-ambiguously aligned positions. Bootstrap values higher than 50% are given at nodes. Colored circles show the presence of the OTU in the different samples, and the internal number corresponds to the number of occurrences of sequences in the corresponding gene libraries. Unc., uncultured.
Figure 5.
Phylogenetic tree of eukaryote SSU rDNA sequences from Chernobyl sunlight-exposed biofilms.
The tree was reconstructed by maximum likelihood using 1,199 non-ambiguously aligned positions. Bootstrap values higher than 50% are given at nodes. Colored circles show the presence of the OTU in the different samples, and the internal number corresponds to the number of occurrences of sequences in the corresponding gene libraries. Unc., uncultured.
Figure 6.
Cluster analysis of DGGE fingerprints for bacteria (A) and eukaryotes (B) in Chernobyl concrete biofilms.
The histogram shows the relative levels of radioactivity measured in situ in Chernobyl samples (µSv/h).
Table 2.
Taxonomic affiliation of relatively abundant and distinctive bacterial and eukaryotic SSU rDNA fragments from DGGE gels (Figure 6) and correspondence with sequences from SSU rRNA gene libraries.
Figure 7.
Percentage of sequence identity at SSU rRNA genes and adjacent ITS regions in the same Rubrobacter OTU from different populations.
Note that the scale at the ordinates begins at 92% to maximize potential differences between samples and markers. The bars correspond to the standard deviation.
Figure 8.
Relationship between SSU rRNA and the corresponding ITS variability (number of differing nucleotides) by comparison with Northern Ireland control sequences.
Each graph corresponds to a sampled location in the Chernobyl area. Each color represents a particular reference sequence: red (Ref-127), green (Ref-128), blue (Ref-2).
Table 3.
Summary of the tests of the different effects using a deviance analysis using Type III decomposition.
Figure 9.
Adjusted means by population of the number of differing nucleotides as compared to the control Northern Ireland sequences (Ref-127, Ref-128, Ref-2 from left to right).
The Y-axis represents the number of expected differences when assuming a similar level of SSU rRNA variation set to the general mean (i.e. ca. 13 differing nucleotides).