Limits...
Distribution of microbial arsenic reduction, oxidation and extrusion genes along a wide range of environmental arsenic concentrations.

Escudero LV, Casamayor EO, Chong G, Pedrós-Alió C, Demergasso C - PLoS ONE (2013)

Bottom Line: A combination of primers from the literature and newly designed primers were used to explore the presence of the arsC gene, coding for the reduction of As (V) to As (III) in one of the most common detoxification mechanisms.The arrA gene, involved in anaerobic respiration using As (V) as electron acceptor, was found in all the systems studied.The As (III) oxidation gene aioA and the As (III) transport gene acr3 were tracked with two primer sets each and they were also found to be spread through the As concentration gradient.

View Article: PubMed Central - PubMed

Affiliation: Centro de Investigación Científico Tecnológico para la Minería-CICITEM, Universidad Católica del Norte, Antofagasta, Chile ; Centro de Biotecnología, Universidad Católica del Norte, Antofagasta, Chile.

ABSTRACT
The presence of the arsenic oxidation, reduction, and extrusion genes arsC, arrA, aioA, and acr3 was explored in a range of natural environments in northern Chile, with arsenic concentrations spanning six orders of magnitude. A combination of primers from the literature and newly designed primers were used to explore the presence of the arsC gene, coding for the reduction of As (V) to As (III) in one of the most common detoxification mechanisms. Enterobacterial related arsC genes appeared only in the environments with the lowest As concentration, while Firmicutes-like genes were present throughout the range of As concentrations. The arrA gene, involved in anaerobic respiration using As (V) as electron acceptor, was found in all the systems studied. The As (III) oxidation gene aioA and the As (III) transport gene acr3 were tracked with two primer sets each and they were also found to be spread through the As concentration gradient. Sediment samples had a higher number of arsenic related genes than water samples. Considering the results of the bacterial community composition available for these samples, the higher microbial phylogenetic diversity of microbes inhabiting the sediments may explain the increased number of genetic resources found to cope with arsenic. Overall, the environmental distribution of arsenic related genes suggests that the occurrence of different ArsC families provides different degrees of protection against arsenic as previously described in laboratory strains, and that the glutaredoxin (Grx)-linked arsenate reductases related to Enterobacteria do not confer enough arsenic resistance to live above certain levels of As concentrations.

Show MeSH
Relative abundance of different phylogenetic groups of bacteria in 16 (indicated by an asterisk in Table 1) of the samples analyzed by DGGE.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC3815024&req=5

pone-0078890-g003: Relative abundance of different phylogenetic groups of bacteria in 16 (indicated by an asterisk in Table 1) of the samples analyzed by DGGE.

Mentions: The relative abundance of the major bacterial groups was analyzed by DGGE (Fig.3, Table S1). There was considerable variation among the 16 samples (indicated by asterisks in Table 1). For example, one sample was dominated by Bacteroidetes and another by Deinococcus-Thermus, even though neither one of this groups was abundant in general. Overall, however, Proteobacteria and Firmicutes were the dominant groups (Fig. 3, Table S1). Two samples, one water with low As and one sediment with high As, were selected to build clone libraries as examples (Fig. 4). Firmicutes were clearly dominant in both, followed by Proteobacteria. The particular Proteobacterial classes in each one, however, were different: gamma and epsilon in the water sample and alpha, gamma and delta in the sediment.


Distribution of microbial arsenic reduction, oxidation and extrusion genes along a wide range of environmental arsenic concentrations.

Escudero LV, Casamayor EO, Chong G, Pedrós-Alió C, Demergasso C - PLoS ONE (2013)

Relative abundance of different phylogenetic groups of bacteria in 16 (indicated by an asterisk in Table 1) of the samples analyzed by DGGE.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3815024&req=5

pone-0078890-g003: Relative abundance of different phylogenetic groups of bacteria in 16 (indicated by an asterisk in Table 1) of the samples analyzed by DGGE.
Mentions: The relative abundance of the major bacterial groups was analyzed by DGGE (Fig.3, Table S1). There was considerable variation among the 16 samples (indicated by asterisks in Table 1). For example, one sample was dominated by Bacteroidetes and another by Deinococcus-Thermus, even though neither one of this groups was abundant in general. Overall, however, Proteobacteria and Firmicutes were the dominant groups (Fig. 3, Table S1). Two samples, one water with low As and one sediment with high As, were selected to build clone libraries as examples (Fig. 4). Firmicutes were clearly dominant in both, followed by Proteobacteria. The particular Proteobacterial classes in each one, however, were different: gamma and epsilon in the water sample and alpha, gamma and delta in the sediment.

Bottom Line: A combination of primers from the literature and newly designed primers were used to explore the presence of the arsC gene, coding for the reduction of As (V) to As (III) in one of the most common detoxification mechanisms.The arrA gene, involved in anaerobic respiration using As (V) as electron acceptor, was found in all the systems studied.The As (III) oxidation gene aioA and the As (III) transport gene acr3 were tracked with two primer sets each and they were also found to be spread through the As concentration gradient.

View Article: PubMed Central - PubMed

Affiliation: Centro de Investigación Científico Tecnológico para la Minería-CICITEM, Universidad Católica del Norte, Antofagasta, Chile ; Centro de Biotecnología, Universidad Católica del Norte, Antofagasta, Chile.

ABSTRACT
The presence of the arsenic oxidation, reduction, and extrusion genes arsC, arrA, aioA, and acr3 was explored in a range of natural environments in northern Chile, with arsenic concentrations spanning six orders of magnitude. A combination of primers from the literature and newly designed primers were used to explore the presence of the arsC gene, coding for the reduction of As (V) to As (III) in one of the most common detoxification mechanisms. Enterobacterial related arsC genes appeared only in the environments with the lowest As concentration, while Firmicutes-like genes were present throughout the range of As concentrations. The arrA gene, involved in anaerobic respiration using As (V) as electron acceptor, was found in all the systems studied. The As (III) oxidation gene aioA and the As (III) transport gene acr3 were tracked with two primer sets each and they were also found to be spread through the As concentration gradient. Sediment samples had a higher number of arsenic related genes than water samples. Considering the results of the bacterial community composition available for these samples, the higher microbial phylogenetic diversity of microbes inhabiting the sediments may explain the increased number of genetic resources found to cope with arsenic. Overall, the environmental distribution of arsenic related genes suggests that the occurrence of different ArsC families provides different degrees of protection against arsenic as previously described in laboratory strains, and that the glutaredoxin (Grx)-linked arsenate reductases related to Enterobacteria do not confer enough arsenic resistance to live above certain levels of As concentrations.

Show MeSH