Biology subjects

Fuentes-Schweizer, P.

Publications and source records attributed to Fuentes-Schweizer, P..

3 recordsLinked to original sources

bioRxiv2020

Temperature and elemental sulfur shape microbial communities in two extremely acidic aquatic volcanic environments

Aquatic environments of volcanic origin provide an exceptional opportunity to study the adaptations of microbial communities to early planet life conditions such as high temperatures, high metal concentrations, and low pH. Here, we characterized the prokaryotic communities and physicochemical properties of seepage sites at the bottom of the Poas Volcano crater and the Agrio River, two geologically related extremely acidic environments located in the Central Volcanic mountain range of Costa Rica. Both locations hold a very low pH (pH 1.79-2.20) and have high sulfate and iron concentrations (Fe = 47-206 mg/L, SO42- = 1170-2460 mg/L measured as S), but significant differences in their temperature (90.0-95.0{degrees}C in the seepages at Poas Volcano versus 19.1-26.6 {degrees}C in Agrio River) and in the abundance of elemental sulfur. Based on the analysis of 16S rRNA gene sequences, we determined that Sulfobacillus spp., sulfur-oxidizing bacteria, represented more than half (58.4-78.4%) of the sequences in Poas Volcano seepage sites, while Agrio River was dominated by the iron- and sulfur-oxidizing Leptospirillum (7.4-55.5%) and members of the archeal order Thermoplasmatales (16.0-58.2%). Both environments share some chemical characteristics and part of their microbiota, however the temperature and the presence of reduced sulfur are likely the main distinguishing feature ultimately shaping their microbial communities. Our data suggest that in the Poas Volcano-Agrio River system there is a common metabolism but with specialization of species that adapt to the physicochemical conditions of each environment.

microbiology↗

bioRxiv2020

C1 compounds shape the microbial community of an abandoned century-old oil exploration well.

The search for microorganisms that degrade hydrocarbons is highly relevant because it enables the bioremediation of these substances cheaply and without dangerous by-products. In this work, we studied the microbial communities of an exploratory oil well, abandoned a century ago, located in the Cahuita National Park of Costa Rica. Cahuita well is characterized by a continuous efflux of methane and the presence of a mixture of hydrocarbons including C2-dibenzothiophene, phenanthrene or anthracene, fluoranthene pyrene, dibenzothiophene, tricyclic terpanes, pyrene, sesquiterpenes, sterane and n-alkanes. Based on the analysis of 16S rRNA gene amplicons, we detected a significant abundance of methylotrophic bacteria (Methylobacillus (6.3-26.0 % of total reads) and Methylococcus (4.1-30.6 %)) and the presence of common genera associated with hydrocarbon degradation, such as Comamonas (0.8-4.6 %), Hydrogenophaga (1.5-3.3 %) Rhodobacter (1.0-4.9 %) and Flavobacterium (1.1-6.5 %). We evidenced the presence of methane monooxygenase (MMO) activities, responsible for the first step in methane metabolism, by amplifying the pmo gene from environmental DNA. We also isolated a strain of Methylorubrum rhodesianum, which was capable of using methanol as its sole carbon source. This work represents a contribution to the understanding of the ecology of communities of microorganisms in environments with permanently high concentrations of methane and hydrocarbons, which also has biotechnological implications for the bioremediation of highly polluting petroleum components.

microbiology↗

bioRxiv2020

The putative phosphate transporter PitB (PP1373) is involved in tellurite uptake in Pseudomonas putida KT2440

Tellurium oxyanions are chemical species with great toxicity; their presence in the environment has increased because of mining industries and photovoltaic and electronic waste. Recovery strategies based on microorganisms for this metalloid are of interest, but further studies of the transport systems and enzymes responsible for implementing tellurium transformations are required because many mechanisms remain unknown. Here, we investigated the involvement in tellurite uptake of the putative phosphate transporter PitB (PP1373) in soil bacterium Pseudomonas putida KT2440. For this purpose, through a method based on the CRISPR/Cas9 system, we generated a strain deficient in pitB gene and characterized its phenotype on exposing it to varied concentrations of tellurite. Growth curves and Transmission Electronic Microscopy experiments of wild type and {Delta}pitB showed that both strains were able to internalize tellurite into the cytoplasm and reduce the oxyanion to black nano-sized and rod-shaped tellurium particles, however, {Delta}pitB strain showed an increased resistance to the tellurite toxic effects. At a concentration of 100 uM tellurite, where the biomass formation of wild type strain decreased by half, we observed a greater ability of {Delta}pitB to reduce this oxyanion with respect to wild type strain (~38% vs ~16%), which is related by the greater biomass production of {Delta}pitB and not by a greater consumption of tellurite per cell. The phenotype of the mutant was restored on over-expressing pitB in trans. In summary, our results indicate that PitB is one of several transporters responsible for tellurite uptake in P. putida KT2440.

microbiology↗