Degradation of benzene, toluene, and xylene isomers by a bacterial consortium obtained from rhizosphere soil of Cyperus sp. grown in a petroleum-contaminated area

Cost and pollution by the use of xylene in cervical cytology in four Peruvian hospitals

Background: Cytological samples are cleared with xylene in two or three baths during a Pap test, however, this solvent has a high degree of toxicity, and being a controlled reagent infers high costs for its purchase and implications for environmental pollution. We estimated the impact of xylene during the Pap test in terms of the number of liters and cost of two baths of xylene, and also estimated the impact with three baths  Methods: This cross-sectional study was carried out in four hospitals of EsSalud in Peru in two stages. First, the analysis of the impact due to the use of two baths of xylene was conducted during the period 2015-2019, and second, the estimates were calculated based on the assumption of three baths of xylene for the years 2020-2025. The assumption was based on the recommendations of the 2018 EsSalud cytology guideline. The monthly amount of xylene was ~10 liters per bath/month and the cost per liter was estimated at 8.13 USD (27 soles).  Results: For the staining of 594,898 cytology tests, 7,848 liters of xylene were necessary, resulting in a cost of 60,861 USD (202,068 soles) during the period 2015-2019. The estimates showed a maximum assumption of 9,483 liters and 77,110 USD (256,040 soles) for the use of three baths of xylene in the four EsSalud hospitals (p = 0.0025) during the period 2020-2025.   Conclusions: We determined that there was a high economic impact of using xylene with two baths from 2015 to 2019 and a dramatic increase in costs with the possible use of three baths of xylene in the Pap test for the following five years.

Cost and pollution by the use of xylene in cervical cytology in four Peruvian hospitals

Background: Cytological samples are cleared with xylene in two or three baths during a Pap test, however, this solvent has a high degree of toxicity, and being a controlled reagent infers high costs for its purchase and implications for environmental pollution. We estimated the impact of xylene during the Pap test in terms of the number of liters and cost of two baths of xylene, and also estimated the impact with three baths  Methods: This cross-sectional study was carried out in four hospitals of EsSalud in Peru in two stages. First, the analysis of the impact due to the use of two baths of xylene was conducted during the period 2015-2019, and second, the estimates were calculated based on the assumption of three baths of xylene for the years 2020-2025. The assumption was based on the recommendations of the 2018 EsSalud cytology guideline. The monthly amount of xylene was ~10 liters per bath/month and the cost per liter was estimated at 8.13 USD (27 soles).  Results: For the staining of 594,898 cytology tests, 7,848 liters of xylene were necessary, resulting in a cost of 60,861 USD (202,068 soles) during the period 2015-2019. The estimates showed a maximum assumption of 9,483 liters and 77,110 USD (256,040 soles) for the use of three baths of xylene in the four EsSalud hospitals (p = 0.0025) during the period 2020-2025.   Conclusions: We determined that there was a high economic impact of using xylene with two baths from 2015 to 2019 and a dramatic increase in costs with the possible use of three baths of xylene in the Pap test for the following five years.

Cost and pollution by the use of xylene in cervical cytology in four Peruvian hospitals

Background: Cytological samples are cleared with xylene in two or three baths during a Pap test, however, this solvent has a high degree of toxicity, and being a controlled reagent infers high costs for its purchase and implications for environmental pollution. We estimated the impact of xylene during the Pap test in terms of the number of liters and cost of two baths of xylene, and also estimated the impact with three baths  Methods: This cross-sectional study was carried out in four hospitals of EsSalud in Peru in two stages. First, the analysis of the impact due to the use of two baths of xylene was conducted during the period 2015-2019, and second, the estimates were calculated based on the assumption of three baths of xylene for the years 2020-2025. The assumption was based on the recommendations of the 2018 EsSalud cytology guideline. The monthly amount of xylene was ~10 liters per bath/month and the cost per liter was estimated at 8.13 USD (27 soles).  Results: For the staining of 594,898 cytology tests, 7,848 liters of xylene were necessary, resulting in a cost of 60,861 USD (202,068 soles) during the period 2015-2019. The estimates showed a maximum assumption of 9,483 liters and 77,110 USD (256,040 soles) for the use of three baths of xylene in the four EsSalud hospitals (p = 0.0025) during the period 2020-2025.   Conclusions: We determined that there was a high economic impact of using xylene with two baths from 2015 to 2019 and a dramatic increase in costs with the possible use of three baths of xylene in the Pap test for the following five years.

Identification of degrader bacteria and fungi enriched in rhizosphere soil from a toluene phytoremediation site using DNA stable isotope probing

Improved knowledge of the ecology of contaminant-degrading organisms is paramount for effective assessment and remediation of aromatic hydrocarbon-impacted sites. DNA stable isotope probing was used herein to identify autochthonous degraders in rhizosphere soil from a hybrid poplar phytoremediation system incubated under semi-field-simulated conditions. High-throughput sequencing of bacterial 16S rRNA and fungal internal transcribed spacer (ITS) rRNA genes in metagenomic samples separated according to nucleic acid buoyant density was used to identify putative toluene degraders. Degrader bacteria were found mainly within the Actinobacteria and Proteobacteria phyla and classified predominantly as Cupriavidus, Rhodococcus, Luteimonas, Burkholderiaceae, Azoarcus, Cellulomonadaceae, and Pseudomonas organisms. Purpureocillium lilacinum and Mortierella alpina fungi were also found to assimilate toluene, while several strains of the fungal poplar endophyte Mortierella elongatus were indirectly implicated as potential degraders. Finally, PICRUSt2 predictive taxonomic functional modeling of 16S rRNA genes was performed to validate successful isolation of stable isotope-labeled DNA in density-resolved samples. Four unique sequences, classified within the Bdellovibrionaceae, Intrasporangiaceae, or Chitinophagaceae families, or within the Sphingobacteriales order were absent from PICRUSt2-generated models and represent potentially novel putative toluene-degrading species. This study illustrates the power of combining stable isotope amendment with advanced metagenomic and bioinformatic techniques to link biodegradation activity with unisolated microorganisms. Novelty statement: This study used emerging molecular biological techniques to identify known and new organisms implicated in aromatic hydrocarbon biodegradation from a field-scale phytoremediation system, including organisms with phyto-specific relevance and having potential for downstream applications (amendment or monitoring) in future and existing systems. Additional novelty in this study comes from the use of taxonomic functional modeling approaches for validation of stable isotope probing techniques. This study provides a basis for expanding existing reference databases of known aromatic hydrocarbon degraders from field-applicable sources and offers technological improvements for future site assessment and management purposes.

Bacterial Bioreporter-Based Mercury and Phenanthrene Assessment in Yangtze River Delta Soils of China

Genetically engineered bacterial whole-cell bioreporters were deployed to investigate bioavailable mercury (b-Hg) and phenanthrene (b-PHE). Characterized by high sensitivity and specificity in aqueous solutions, the bioreporter system could detect in amended soils the concentrations of b-Hg and b-PHE in the ranges of 19.6 to 111.6 and 21.5 to 110.9 μg kg, respectively. The sensitivity of the system allowed for the combined analysis of b-Hg and b-PHE from real environmental samples. Therefore, soil samples from three large refinery facilities were tested, and the results from the instrumental analysis strongly correlated with the ones obtained with the bioreporter method. Large-scale and fast screening of soil contamination across the Yangtze River Delta in Eastern China was conducted. More than 36% of the samples contained b-Hg, whereas the fractions of b-PHE were below the detection limit for all the samples. These results indicated a higher toxicity and more hazardous condition for Hg contamination than for PHE. Population densities and airborne 10-μm particulate matter (PM10) concentrations were used as parameters for comparison with the spatial distribution of the b-Hg and b-PHE fractions. The results revealed that the bioreporters could offer a rapid and cost-efficient method to test soil samples from contaminated areas and provide a screening tool for environmental risk assessment.

Benzene and Naphthalene Degrading Bacterial Communities in an Oil Sands Tailings Pond

Oil sands process-affected water (OSPW), produced by surface-mining of oil sands in Canada, is alkaline and contains high concentrations of salts, metals, naphthenic acids, and polycyclic aromatic compounds (PAHs). Residual hydrocarbon biodegradation occurs naturally, but little is known about the hydrocarbon-degrading microbial communities present in OSPW. In this study, aerobic oxidation of benzene and naphthalene in the surface layer of an oil sands tailings pond were measured. The potential oxidation rates were 4.3 μmol L^-1 OSPW d^-1 for benzene and 21.4 μmol L^-1 OSPW d^-1 for naphthalene. To identify benzene and naphthalene-degrading microbial communities, metagenomics was combined with stable isotope probing (SIP), high-throughput sequencing of 16S rRNA gene amplicons, and isolation of microbial strains. SIP using ¹³C-benzene and ¹³C-naphthalene detected strains of the genera Methyloversatilis and Zavarzinia as the main benzene degraders, while strains belonging to the family Chromatiaceae and the genus Thauera were the main naphthalene degraders. Metagenomic analysis revealed a diversity of genes encoding oxygenases active against aromatic compounds. Although these genes apparently belonged to many phylogenetically diverse taxa, only a few of these taxa were predominant in the SIP experiments. This suggested that many members of the community are adapted to consuming other aromatic compounds, or are active only under specific conditions. 16S rRNA gene sequence datasets have been submitted to the Sequence Read Archive (SRA) under accession number SRP109130. The Gold Study and Project submission ID number in Joint Genome Institute IMG/M for the metagenome is Gs0047444 and Gp0055765.

Synthesis and characterization of BiPO4/g-C3N4 nanocomposites with significantly enhanced visible-light photocatalytic activity for benzene degradation

BiPO₄/g-C₃N₄ nanocomposites were fabricated by a hydrothermal method including calcination and showed high photocatalytic activity under visible light.

High sulfate reduction efficiency in a UASB using an alternative source of sulfidogenic sludge derived from hydrothermal vent sediments

Sulfidogenesis in reactors is mostly achieved through adaptation of predominantly methanogenic granular sludge to sulfidogenesis. In this work, an upflow anaerobic sludge blanket (UASB) reactor operated under sulfate-reducing conditions was inoculated with hydrothermal vent sediments to carry out sulfate reduction using volatile fatty acids (VFAs) as substrate and chemical oxygen demand (COD)/SO4 (-2) ratios between 0.49 and 0.64. After a short period of adaptation, a robust non-granular sludge was capable of achieving high sulfate reduction efficiencies while avoiding competence with methanogens and toxicity to the microorganisms due to high sulfide concentration. The highest sulfide concentration (2,552 mg/L) was obtained with acetate/butyrate, and sulfate reduction efficiencies were up to 98 %. A mixture of acetate/butyrate, which produced a higher yielding of HS(-), was preferred over acetate/propionate/butyrate since the consumption of COD was minimized during the process. Sludge was analyzed, and some of the microorganisms identified in the sludge belong to the genera Desulfobacterium, Marinobacter, and Clostridium. The tolerance of the sludge to sulfide may be attributed to the syntrophy among these microorganisms, some of which have been reported to tolerate high concentrations of sulfide. To the best of our knowledge, this is the first report on the analysis of the direct utilization of hydrothermal vent sediments as an alternate source of sludge for sulfate reduction under high sulfide concentrations.