查看更多>>摘要：? 2022 Elsevier LtdEstuarine mangrove wetlands are generally considered a major source of methane (CH4) emissions. Anaerobic methane oxidation (AMO) is an important pathway for reducing CH4 emissions and is known to be tightly linked to carbon, nitrogen, sulfur and metal cycling processes largely driven by microorganisms. However, these coupled processes and their contributions to mitigating global warming remain unclear in mangrove wetlands. In this study, the depth-specific potential methane oxidation rates of nitrate-, nitrite- and nitrous oxide-dependent anaerobic methane oxidation (nitrate-, nitrite- and N2O-AMO) and sulfate-dependent anaerobic methane oxidation (sulfate-AMO) processes were investigated using stable isotope tracing along with an assessment of the vertical nutrient and CH4 content profiles in mangrove sediments. The results indicated that nitrite-AMO, nitrate-AMO, N2O-AMO and sulfate-AMO were active and exhibited methane oxidation rates varying from 24.1 to 1077.4, 14.1 to 66.1, 14.3 to 40.9 and 4.2–36.7 nmol CO2 g?1 dry soil d?1, respectively. Furthermore, nitrite-AMO and N2O-AMO tended to be more active in the upper sediment layers, while nitrate-AMO and sulfate-AMO displayed higher rates in the deeper layers. The contribution rate of nitrite-AMO to the total of the 4 AMO processes examined in the mangrove sediments reached 28.90–95.80%, followed by nitrate-AMO (2.73–46.46%), sulfate-AMO (1.46–24.65%) and N2O-AMO (1.70–4.47%), suggesting that the nitrite-AMO process is a significant methane sink in mangrove wetland ecosystems. The temporal and spatial variations in the nitrite-AMO bacterial depth and genus-specific distribution, abundance, activity and sensitivity to environmental factors were then investigated. The absolute abundances of the nitrite-AMO bacterial 16S rRNA and pmoA genes were 0.51–6.55 × 107 and 0.79–8.43 × 106 copies g?1 ds, respectively, and these values decreased with sediment depth; most of the samples were characterized as belonging to Group B of NC10. In addition, NO2? is the limiting factor for nitrite-AMO bacteria in mangrove wetlands.
查看更多>>摘要：? 2022 The Author(s)Three cleaning methods, namely i) a commercial biocide applied by brush with the subsequent extraction of organic remains by a rod, ii) a scalpel or iii) a Nd:YVO4 laser at 355 nm, single application as well as paired combinations, were tested for removing from a granite two different crustose lichens: Diploschistes scruposus (lighter with a clearly distinguished thallus) and Polysporina simplex (darker with a poorly developed thallus). In addition to the removal rate, side effects such as melting of biotite and feldspar grains and chromatic changes were assessed. The multianalytical approach was based on stereomicroscopy, light microscopy, Fourier Transform Infrared spectroscopy, Scanning Electron Microscopy and color spectrophotometry. Combining cleaning methods enhanced the removal efficacy. Biocide followed by laser was the most effective method for removing both lichens colonizing this granite. Mineral melting was more intense for the samples covered by Polysporina simplex due to its lower coverage degree and darker color.
查看更多>>摘要：? 2021 Elsevier LtdSerious concerns have been raised regarding resistomes caused by corpse decomposition in the aquatic environment, which has posed threats to the water environment and human health. However, antibiotic resistance genes (ARGs) in large-volume tap water and their temporal stability during corpse decay are poorly explored. Here, high-throughput quantitative polymerase chain reaction (HT-qPCR) and amplicon sequencing were applied to profile ARGs and bacterial communities in experimental and control groups containing 50 L of tap water at 7th, 15th and 100th day during corpse decomposition. Our results suggested that most of the ARGs in experimental group had higher abundance compared with the control group independent of time. Some ARGs’ absolute abundance like tetracycline and beta-lactamase was even enriched by 259 – 413,640-folds during corpse decay. Twelve opportunistic pathogens, especially Burkholderia, Legionella and Halomonas, remarkably increased as decomposition proceeded. Furthermore, network analysis showed that opportunistic pathogens were significantly associated with ARGs. Our results emphasize that corpse decay increases the abundance and diversity of ARGs in large-volume drinking water independent of time while exhibiting temporal persistence of ARGs, thereby uncovering the harmful effects of animal cadavers. Our study also provides valuable suggestions for the risk assessment and management of source water caused by corpse decay. It also provides valuable suggestions for the risk assessment and management of source water caused by corpse decay.
查看更多>>摘要：? 2021 Elsevier LtdThe Antarctic continent is not exempted from anthropogenic contamination. Diesel spills on Antarctic soils occur frequently. There, extreme climate conditions and the scarce infrastructure, cause that few remediation strategies become feasible. Bioremediation has proven to be an effective approach for hydrocarbon-contaminated soils in Antarctica, allowing the removal of up to 80% of the contaminant by biostimulating soil microbial communities in biopiles. However, little is known on the changes that this treatment cause in the microbial communities, and how may this knowledge be used for future bioremediation schemes. In this work, we analyzed the changes in the bacterial community composition of biostimulated (BS) and control (CC) biopiles at Carlini Station (Arg.), Antarctica, from our previously reported “on-site” bioremediation scheme. The results showed that hydrocarbon biodegradation in Antarctic soils was accompanied by a significant change in bacterial community composition, with a progressive differentiation between the treated (BS) and non-treated (CC) systems as a function of time. Microbial diversity decreased in the BS system due to the enrichment in genera Pseudomonas, Rhodococcus, and Rhodanobacter, that seemed to follow an r/K (or copiotrophic/oligotrophic) strategist dynamic, in which Pseudomonas increased significantly at the early stages of the treatment (from initial 23.8% up to 33.2% at day 20, r strategist), while Rhodococcus and Rhodanobacter (K strategists) became dominant since day 20 and until the end of the experiment (from 5.4% to 2.4% at T = 0 days, up to 17.4% and 14.0% at the end of the experiment, respectively). In the control system, Sphingomonas (14.0% at T = 30 days), Pseudomonas (10.5% at T = 30 days), and Rhizorhapis (9.9% at T = 30 days) were the genera with higher relative abundance during the entire treatment period, with no short-term shifts in dominances and a more diverse and even bacterial community.
查看更多>>摘要：? 2021 Elsevier LtdAntibiotic pollution and antibiotic-induced antimicrobial resistance (AMR) are identified as one of the global threats to human and environmental health. Among various antibiotic remediation options, biological methods are considered sustainable and efficient. However, there are limited reports on remediation of high antibiotic loads using biological methods. High antibiotic loads are prevalent in pharmaceutical, aquaculture, and hospital wastewaters. Considering this, herein we explored for the first time the ?-lactamase preparation of Bacillus cereus EMB20 for in-vitro remediation of Ampicillin (Amp) and other ?-lactam antibiotics. Amp concentrations of 50, 100, and 200 mg L?1 were observed to be completely remediated within an hour of treatment, while almost 90% reduction was detected in the case of 300 mg L?1 Amp at the same time period. The enzyme was observed to be active at a broad pH range and showed complete removal of 100 mg L?1 Amp at pH 5, 7, 9. Moreover, the Amp hydrolyzed products were identified using mass spectrometry and the products exhibited no antibiotic and toxic activities. Interestingly, the enzymatic preparation was also active in removing high levels of amoxicillin, meropenem (carbapenem), and the mixture of these two with Amp, within an hour of treatment. In conclusion, the study provides a novel strategy that could be used efficiently for the abatement of ?-lactam-based antibiotic pollution and the consequent spread of AMR in the environment.
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