The Experts below are selected from a list of 10305 Experts worldwide ranked by ideXlab platform
Haifeng Qian - One of the best experts on this subject based on the ideXlab platform.
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Metabolomic modulations in a freshwater microbial community exposed to the fungicide azoxystrobin
Journal of environmental sciences (China), 2020Co-Authors: Mengwei Zhang, Wanyue Liu, Zhenyan Zhang, Zhigao Zhou, Haifeng QianAbstract:Abstract An effective broad-spectrum fungicide, azoxystrobin (AZ), has been widely detected in Aquatic ecosystems, potentially affecting the growth of Aquatic Microorganisms. In the present study, the eukaryotic alga Monoraphidium sp. and the cyanobacterium Pseudanabaena sp. were exposed to AZ for 7 days. Our results showed that 0.2–0.5 mg/L concentrations of AZ slightly inhibited the growth of Monoraphidium sp. but stimulated Pseudanabaena sp. growth. Meanwhile, AZ treatment effectively increased the secretion of total organic carbon (TOC) in the culture media of the two species, and this phenomenon was also found in a freshwater microcosm experiment (containing the natural microbial community). We attempted to assess the effect of AZ on the function of Aquatic microbial communities through metabolomic analysis and further explore the potential risks of this compound. The metabonomic profiles of the microcosm indicated that the most varied metabolites after AZ treatment were related to the citrate cycle (TCA), fatty acid biosynthesis and purine metabolism. We thereby inferred that the microbial community increased extracellular secretions by adjusting metabolic pathways, which might be a stress response to reduce AZ toxicity. Our results provide an important theoretical basis for further study of fungicide stress responses in Aquatic microcosm microbial communities, as well as a good start for further explorations of AZ detoxification mechanisms, which will be valuable for the evaluation of AZ environmental risk.
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insights into the transcriptional responses of a microbial community to silver nanoparticles in a freshwater microcosm
Environmental Pollution, 2020Co-Authors: Michel Lavoie, Zhigao Zhou, Haifeng Qian, Xiangjie Pan, Willie J G M Peijnenburg, Xiangliang Pan, Zhiqiang CaiAbstract:Silver nanoparticles (AgNPs) are widely used because of their excellent antibacterial properties. They are, however, easily discharged into the water environment, causing potential adverse environmental effects. Meta-transcriptomic analyses are helpful to study the transcriptional response of prokaryotic and eukaryotic Aquatic Microorganisms to AgNPs. In the present study, microcosms were used to investigate the toxicity of AgNPs to a natural Aquatic microbial community. It was found that a 7-day exposure to 10 μg L-1 silver nanoparticles (AgNPs) dramatically affected the structure of the microbial community. Aquatic micro eukaryota (including eukaryotic algae, fungi, and zooplankton) and bacteria (i.e., heterotrophic bacteria and cyanobacteria) responded differently to the AgNPs stress. Meta-transcriptomic analyses demonstrated that eukaryota could use multiple cellular strategies to cope with AgNPs stress, such as enhancing nitrogen and sulfur metabolism, over-expressing genes related to translation, amino acids biosynthesis, and promoting bacterial-eukaryotic algae interactions. By contrast, bacteria were negatively affected by AgNPs with less signs of detoxification than in case of eukaryota; various pathways related to energy metabolism, DNA replication and genetic repair were seriously inhibited by AgNPs. As a result, eukaryotic algae (mainly Chlorophyta) dominated over cyanobacteria in the AgNPs treated microcosms over the 7-d exposure. The present study helps to understand the effects of AgNPs on Aquatic Microorganisms and provides insights into the contrasting AgNPs toxicity in eukaryota and bacteria.
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feedback regulation between Aquatic Microorganisms and the bloom forming cyanobacterium microcystis aeruginosa
Applied and Environmental Microbiology, 2019Co-Authors: Meng Zhang, Zhenyan Zhang, Zhigao Zhou, Hans W Paerl, Yiling Chen, Haifeng QianAbstract:The frequency and intensity of cyanobacterial blooms are increasing worldwide. Interactions between toxic cyanobacteria and Aquatic Microorganisms need to be critically evaluated to understand microbial drivers and modulators of the blooms. In this study, we applied 16S/18S rRNA gene sequencing and metabolomics analyses to measure the microbial community composition and metabolic responses of the cyanobacterium Microcystis aeruginosa in a coculture system receiving dissolved inorganic nitrogen and phosphorus (DIP) close to representative concentrations in Lake Taihu, China. M. aeruginosa secreted alkaline phosphatase using a DIP source produced by moribund and decaying Microorganisms when the P source was insufficient. During this process, M. aeruginosa accumulated several intermediates in energy metabolism pathways to provide energy for sustained high growth rates and increased intracellular sugars to enhance its competitive capacity and ability to defend itself against microbial attack. It also produced a variety of toxic substances, including microcystins, to inhibit metabolite formation via energy metabolism pathways of Aquatic Microorganisms, leading to a negative effect on bacterial and eukaryotic microbial richness and diversity. Overall, compared with the monoculture system, the growth of M. aeruginosa was accelerated in coculture, while the growth of some cooccurring Microorganisms was inhibited, with the diversity and richness of eukaryotic Microorganisms being more negatively impacted than those of prokaryotic Microorganisms. These findings provide valuable information for clarifying how M. aeruginosa can potentially modulate its associations with other Microorganisms, with ramifications for its dominance in Aquatic ecosystems.IMPORTANCE We measured the microbial community composition and metabolic responses of Microcystis aeruginosa in a microcosm coculture system receiving dissolved inorganic nitrogen and phosphorus (DIP) close to the average concentrations in Lake Taihu. In the coculture system, DIP is depleted and the growth and production of Aquatic Microorganisms can be stressed by a lack of DIP availability. M. aeruginosa could accelerate its growth via interactions with specific cooccurring Microorganisms and the accumulation of several intermediates in energy metabolism-related pathways. Furthermore, M. aeruginosa can decrease the carbohydrate metabolism of cooccurring Aquatic Microorganisms and thus disrupt microbial activities in the coculture. This also had a negative effect on bacterial and eukaryotic microbial richness and diversity. Microcystin was capable of decreasing the biomass of total phytoplankton in Aquatic microcosms. Overall, compared to the monoculture, the growth of total Aquatic Microorganisms is inhibited, with the diversity and richness of eukaryotic Microorganisms being more negatively impacted than those of prokaryotic Microorganisms. The only exception is M. aeruginosa in the coculture system, whose growth was accelerated.
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Aquatic ecotoxicity of an antidepressant sertraline hydrochloride on microbial communities
Science of The Total Environment, 2019Co-Authors: Zhaopeng Yang, Zhigao Zhou, Xiangliang Pan, Youchao Zhu, Qi Zhang, Haifeng QianAbstract:Abstract Sertraline hydrochloride (Ser-HCl), a widely used antidepressant, becomes an Aquatic contaminant via metabolic excretion and improper disposal; however, it is unknown how Ser-HCl affects Aquatic microbial communities. The present study investigated the effects of Ser on the structures of Aquatic microbial communities via high-throughput sequencing analyses. Ser-HCl treatment inhibited the growth of two model algae (the green alga, Chlorella vulgaris, and the cyanobacterium, Microcystis aeruginosa) and decreased the chlorophyll a (Chl-a) concentration in the microcosm to reduce the photosynthetic efficiency. High-throughput sequencing analyses showed that exposure to Ser-HCl disturbed the balance of cyanobacteria species by stimulating the growth of specific cyanobacteria. Among eukaryotes, the richness as well as the diversity indices were significantly enhanced after 5 days of Ser-HCl treatment but sharply decreased with exposure time. Nucleariida occupied an absolute majority (97.83%) within the eukaryotes, implicating that Ser-HCl disturbed the ecological equilibrium in microcosms. Ser-HCl will continue to be an environmental contaminant due to its wide usage and production. Our current study clarified the potential ecological risk of Ser-HCl to Aquatic Microorganisms. These findings suggest that more attention should be given to the negative effects of these bioactive pollutants on Aquatic environments.
Arash Komeili - One of the best experts on this subject based on the ideXlab platform.
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single cell determination of iron content in magnetotactic bacteria implications for the iron biogeochemical cycle
Environmental Microbiology, 2020Co-Authors: Matthieu Amor, Mickael Tharaud, Alexandre Gelabert, Arash KomeiliAbstract:Magnetotactic bacteria (MTB) are ubiquitous Aquatic Microorganisms that mineralize dissolved iron into intracellular magnetic crystals. After cell death, these crystals are trapped into sediments that remove iron from the soluble pool. MTB may significantly impact the iron biogeochemical cycle, especially in the ocean where dissolved iron limits nitrogen fixation and primary productivity. A thorough assessment of their impact has been hampered by a lack of methodology to measure the amount of, and variability in, their intracellular iron content. We quantified the iron mass contained in single MTB cells of Magnetospirillum magneticum strain AMB-1 using a time-resolved inductively coupled plasma-mass spectrometry methodology. Bacterial iron content depends on the external iron concentration, and reaches a maximum value of ~10-6 ng of iron per cell. From these results, we calculated the flux of dissolved iron incorporation into environmental MTB populations and conclude that MTB may mineralize a significant fraction of dissolved iron into crystals.
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single cell determination of iron content in magnetotactic bacteria implications for the iron biogeochemical cycle
bioRxiv, 2019Co-Authors: Matthieu Amor, Mickael Tharaud, Alexandre Gelabert, Arash KomeiliAbstract:Magnetotactic bacteria (MTB) are ubiquitous Aquatic Microorganisms that biomineralize dissolved iron from the environment into intracellular nanoparticles of magnetite [Fe(II)Fe(III)2O4] or greigite [Fe(II)Fe(III)2S4] in a genetically controlled manner. After cell death, these magnetite and greigite crystals are trapped into sediments which effectively removes iron from the soluble pool. MTB may significantly impact the iron biogeochemical cycle, especially in the ocean where dissolved iron limits nitrogen fixation and primary productivity. Although MTB are ubiquitous in the environment, their impact on the biogeochemical cycling of metallic elements is still poorly constrained. A thorough assessment of the mass of iron incorporated by MTB has been hampered by a lack of methodology to accurately measure the amount of, and variability in, their intracellular iron content. Here, we quantify the mass of iron contained in single MTB cells of the model organism, Magnetospirillum magneticum sp. AMB-1, using a time-resolved mass spectrometry methodology. Bacterial iron content depends on the external iron concentration, and reaches a maximum value of 10-6 ng of iron per cell when bacteria are cultivated with initial iron concentrations of 100 μM or higher. From our experimental results, we calculated the flux of dissolved iron incorporation into natural MTB populations and conclude that MTB may mineralize a significant fraction of environmental dissolved iron into crystals.
Atsushi Miyawaki - One of the best experts on this subject based on the ideXlab platform.
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on chip microrobot for investigation of stimulant property of Aquatic Microorganisms
International Symposium on Micro-NanoMechatronics and Human Science, 2013Co-Authors: Tomohiro Kawahara, Fumihito Arai, Hiroyuki Kawano, Ikuko Shihiraishikawa, Atsushi MiyawakiAbstract:In this paper, we discuss a novel, magnetically driven microrobot equipped with a frame structure to measure the stimulant property of Aquatic Microorganisms. The fabricated microfluidic chip and microrobots are shown. The untethered microrobot is composed of a Si-Ni hybrid structure constructed by MEMS techniques. The microrobots with 5 μm width force sensors are actuated in a microfluidic chip by permanent magnets so that they can stimulate Microorganisms with the desired force within the stable environment of the closed microchip. The unique properties of Pleurosira laevis (P. laevis) are also evaluated by using the developed on-chip microrobots.
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on chip microrobot for investigating the response of Aquatic Microorganisms to mechanical stimulation
Lab on a Chip, 2013Co-Authors: Tomohiro Kawahara, Fumihito Arai, Hiroyuki Kawano, Ikuko Shihiraishikawa, Masakuni Sugita, Masaya Hagiwara, Atsushi MiyawakiAbstract:In this paper, we propose a novel, magnetically driven microrobot equipped with a frame structure to measure the effects of stimulating Aquatic Microorganisms. The design and fabrication of the force-sensing structure with a displacement magnification mechanism based on beam deformation are described. The microrobot is composed of a Si–Ni hybrid structure constructed using micro-electro-mechanical system (MEMS) technologies. The microrobots with 5 μm-wide force sensors are actuated in a microfluidic chip by permanent magnets so that they can locally stimulate the Microorganisms with the desired force within the stable environment of the closed microchip. They afford centimetre-order mobility (untethered drive) and millinewton-order forces (high power) as well as force-sensing. Finally, we apply the developed microrobots for the quantitative evaluation of the stimuation of Pleurosira laevis (P. laevis) and determine the relationship between the applied force and the response of a single cell.
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Nano-aquarium for dynamic observation of Aquatic Microorganisms fabricated by femtosecond laser direct writing of photostructurable glass
Laser-based Micro- and Nanopackaging and Assembly II, 2008Co-Authors: Yasutaka Hanada, Hiroyuki Kawano, Atsushi Miyawaki, Koji Sugioka, I Ishikawa, K MidorikawaAbstract:We demonstrate the fabrication of three-dimensional (3-D) hollow microstructures embedded in photostructurable glass by a femtosecond (fs) laser direct writing. Fs laser direct writing followed by annealing and successive wet etching in dilute hydrofluoric (HF) acid solution resulted in the rapid manufacturing of microchips with 3-D hollow microstructures for the dynamic observation of living Microorganisms in fresh water. The embedded microchannel structure enables us to analyze the continuous motion of Euglena gracilis . A microchamber with a movable microneedle demonstrates its ability for the elucidation of the information transmission process in Pleurosira laevis . Such microchips, referred to as nano-aquariums realize the efficient and highly functional observation of Microorganisms.
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nano aquarium fabrication by femtosecond laser direct writing for microscopic observation of Aquatic Microorganisms
The Review of Laser Engineering, 2008Co-Authors: Yasutaka Hanada, Hiroyuki Kawano, Atsushi Miyawaki, Koji Sugioka, I Ishikawa, K MidorikawaAbstract:We demonstrate the fabrication of three-dimensional (3-D) hollow microstructures embedded in photostructurable glass by a femtosecond (fs) laser direct writing. Fs laser direct writing followed by annealing and successive wet etching in dilute hydrofluoric (HF) acid solution resulted in the rapid manufacturing of microchips with 3-D hollow microstructures for the dynamic observation of living Microorganisms in fresh water. The embedded microchannel structure enables us to analyze the continuous motion of flagellum movement of Euglena gracilis. Such microchips, referred to as nano-aquariums realize the efficient and highly functional observation of Microorganisms.
Józef Szarek - One of the best experts on this subject based on the ideXlab platform.
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Impact of Pesticide Contamination on Aquatic Microorganism Populations in the Littoral Zone
2016Co-Authors: S. Lew, Anna Biedunkiewicz, M. Lew, Józef SzarekAbstract:Abstract The effect of pesticide contamination of the littoral zone on the population of bacteria and fungi was analyzed using the example of a eutrophic water reservoir exposed for [30 years to the influence of expired crop-protection chemicals, mainly DDT. For three consecutive years, quantity analyses of bacteria and fungi were conducted and the composition of the microorganism population analyzed against seasonal dynamics. Mold and yeast-like fungi were also isolated and identified. Within the Bacteria domain, in addition to the large groups of Microorganisms (Alphaprotobacteria, Betaprobacteria, and Gammaproteobacteria, Actinobacteria, and Cytophaga-Flavobacterium), the analysis also involved the presence of bacteria predisposed to degraded pesticides in natural environments: Pseudomonas spp. and Alcaligenes spp. The quantity dynamics of Aquatic Microorganisms indicated that bacteria and fungi under the influence of long-term exposure to DDT can adapt to the presence of this pesticide in water. No modifying effect of DDT was observed on the quantity of Microorganisms or the pattern of seasonal relationships in the eutrophic lake. Changes were shown in the percentage share of large groups of bacteria in the community of Microorganisms as was an effect of con-tamination on the species diversity of fungi. The data show the effectiveness of Aquatic microorganism–community analyses as a tool for indicating changes in the water environment caused by pesticide contamination. Pesticide presence in natural ecosystems results from wide application in contemporary agriculture systems, application over many years, and the storage of pesti-cides past their expiration date in disposal sites unsuit-able for this purpose (Carabias-Martinez et al. 2003
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Impact of Pesticide Contamination on Aquatic Microorganism Populations in the Littoral Zone
Archives of Environmental Contamination and Toxicology, 2013Co-Authors: Anna Biedunkiewicz, Józef SzarekAbstract:The effect of pesticide contamination of the littoral zone on the population of bacteria and fungi was analyzed using the example of a eutrophic water reservoir exposed for >30 years to the influence of expired crop-protection chemicals, mainly DDT. For three consecutive years, quantity analyses of bacteria and fungi were conducted and the composition of the microorganism population analyzed against seasonal dynamics. Mold and yeast-like fungi were also isolated and identified. Within the Bacteria domain, in addition to the large groups of Microorganisms (Alphaprotobacteria, Betaprobacteria, and Gammaproteobacteria, Actinobacteria, and Cytophaga-Flavobacterium), the analysis also involved the presence of bacteria predisposed to degraded pesticides in natural environments: Pseudomonas spp. and Alcaligenes spp. The quantity dynamics of Aquatic Microorganisms indicated that bacteria and fungi under the influence of long-term exposure to DDT can adapt to the presence of this pesticide in water. No modifying effect of DDT was observed on the quantity of Microorganisms or the pattern of seasonal relationships in the eutrophic lake. Changes were shown in the percentage share of large groups of bacteria in the community of Microorganisms as was an effect of contamination on the species diversity of fungi. The data show the effectiveness of Aquatic microorganism–community analyses as a tool for indicating changes in the water environment caused by pesticide contamination.
Matthieu Amor - One of the best experts on this subject based on the ideXlab platform.
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single cell determination of iron content in magnetotactic bacteria implications for the iron biogeochemical cycle
Environmental Microbiology, 2020Co-Authors: Matthieu Amor, Mickael Tharaud, Alexandre Gelabert, Arash KomeiliAbstract:Magnetotactic bacteria (MTB) are ubiquitous Aquatic Microorganisms that mineralize dissolved iron into intracellular magnetic crystals. After cell death, these crystals are trapped into sediments that remove iron from the soluble pool. MTB may significantly impact the iron biogeochemical cycle, especially in the ocean where dissolved iron limits nitrogen fixation and primary productivity. A thorough assessment of their impact has been hampered by a lack of methodology to measure the amount of, and variability in, their intracellular iron content. We quantified the iron mass contained in single MTB cells of Magnetospirillum magneticum strain AMB-1 using a time-resolved inductively coupled plasma-mass spectrometry methodology. Bacterial iron content depends on the external iron concentration, and reaches a maximum value of ~10-6 ng of iron per cell. From these results, we calculated the flux of dissolved iron incorporation into environmental MTB populations and conclude that MTB may mineralize a significant fraction of dissolved iron into crystals.
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single cell determination of iron content in magnetotactic bacteria implications for the iron biogeochemical cycle
bioRxiv, 2019Co-Authors: Matthieu Amor, Mickael Tharaud, Alexandre Gelabert, Arash KomeiliAbstract:Magnetotactic bacteria (MTB) are ubiquitous Aquatic Microorganisms that biomineralize dissolved iron from the environment into intracellular nanoparticles of magnetite [Fe(II)Fe(III)2O4] or greigite [Fe(II)Fe(III)2S4] in a genetically controlled manner. After cell death, these magnetite and greigite crystals are trapped into sediments which effectively removes iron from the soluble pool. MTB may significantly impact the iron biogeochemical cycle, especially in the ocean where dissolved iron limits nitrogen fixation and primary productivity. Although MTB are ubiquitous in the environment, their impact on the biogeochemical cycling of metallic elements is still poorly constrained. A thorough assessment of the mass of iron incorporated by MTB has been hampered by a lack of methodology to accurately measure the amount of, and variability in, their intracellular iron content. Here, we quantify the mass of iron contained in single MTB cells of the model organism, Magnetospirillum magneticum sp. AMB-1, using a time-resolved mass spectrometry methodology. Bacterial iron content depends on the external iron concentration, and reaches a maximum value of 10-6 ng of iron per cell when bacteria are cultivated with initial iron concentrations of 100 μM or higher. From our experimental results, we calculated the flux of dissolved iron incorporation into natural MTB populations and conclude that MTB may mineralize a significant fraction of environmental dissolved iron into crystals.