Occurrence of Resistance to Antibiotics, UV-B, and Arsenic in Bacteria Isolated from Extreme Environments in High-Altitude (Above 4400 m) Andean Wetlands

Abstract

High-altitude Andean wetlands are pristine environments with extreme conditions such as high UV radiation, high heavy metal content (mainly arsenic), high salinity, and oligotrophy. In this paper, the UV-B resistance and tolerance to arsenic of phylogenetically characterized bacteria (Actinobacteria [six isolates], Firmicutes [four isolates], and gamma-Proteobacteria [three isolates]) isolated from Laguna Vilama (4400-m altitude) and Laguna Azul (4560 m) were determined. In addition, given that multiple antibiotic resistances were also determined, a relationship between antibiotic resistances as a consequence of mutagenic ability or in relation to metal resistance is proposed. High UV-B resistances were found, since after 30 min (0.7 KJ m(-2)) and 60 min (1.4 KJ m(-2)) of irradiation, most of the studied bacteria did not show a decreased survival; what is more, many of them had an improved survival with the increased doses. Augmentations in mutagenesis rates were observed after UV-B irradiation in only 4 of the 13 tested isolates. Arsenite tolerance was also established in 8 of the 13 tested strains: Staphylococcus saprophyticus A3 and Micrococcus sp. A7, which were able to grow in media containing up to 10 mM As(III). Finally, predominance of antibiotic resistances (azithromycin, erythromycin, clarithromycin, roxithromycin, streptomycin, chloramphenicol, gentamycin, kanamycin, tetracycline, and ampicillin) was found, in all the isolated strains from both wetlands, with unexpectedly high minimal inhibitory concentrations (MICs; >2 mg mL(-1)) for macrolides. These results demonstrate that in extreme environments like high-altitude wetlands there is a correlation of multiresistances to UV-B radiation and arsenic, and that antibiotic resistances are also widespread in these pristine environments, where antibiotic selective pressure is supposed to be absent.

Natural Hot Spots for Gain of Multiple Resistances: Arsenic and Antibiotic Resistances in Heterotrophic, Aerobic Bacteria from Marine Hydrothermal Vent Fields

“…Some studies demonstrated that microorganisms from extreme environments with multiple heavy metal resistances, namely, arsenate and antimonite, are also resistant to antibiotics that, surprisingly, are not found in the environment from which the organisms originated (15,16). Resistances are commonly coupled in genetic elements that, despite being common on plasmids, can occur also in the chromosomes (17,18).…”

“…In order to create a collection of aerobic heterotrophic bacterial strains from the Lucky Strike vent site, aliquots from sediment samples were inoculated in Reasoner's 2A (R2A) agar (Oxoid, Thermo Scientific, United Kingdom) containing (amounts in grams/liter are given in parentheses) yeast extract (0.5), proteose peptone (0.5), casein hydrolysate (0.5), glucose (0.5), starch (0.5), sodium pyruvate (0.3), di-potassium hydrogen phosphate (0.3), magnesium sulfate anhydrous (0.024), and agar-agar (15), and prepared with seawater filtrate (SWF) collected from coastal seawater. Each dilution was incubated at 15°C for up to 1 month.…”

Distribution of microbial communities in Guiyu soils and sediments investigated by 16S rRNA gene library and denaturing gradient gel electrophoresis (DGGE) fingerprinting

“…The 16S rRNA gene library revealed that the Acidobacteria which could cumulate heavy metals occupied 60% of bacteria in the plant rhizosphere microbial communities and the other bacteria were Firmicutes, CFB (Gremion et al, 2003). A lot of Firmicutes bacteria could produce endospores, which could resist dehydration and survive in extreme conditions (Dib et al, 2008). In this paper, the CB01, CB02 and CB03 in the DGGE were detected to be Bacilli of Firmicutes.…”

Gamma irradiation in modulating cadmium bioremediation potential of Aspergillus sp.

“…Mutation of fungi for making them metal resistant are usually done by chemical applications [23][24]. Some groups have worked on use of UV radiation to induce metal resistance in bacteria [25][26].It is already reported that exposure to gamma showed maximum potential to induce mutation in fungi (Metarhizium anisopliae) than that of UV or other chemical mutagens [14].Gamma exposed fungal strain improvement for different industrial as well as ecological purposes are also reported earliar [27][28]. Thus our study showed that possibility of utilising gamma irradiation for increasing Cd removal efficiency of fungi.…”