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Wu M, Xu Y, Zhao C, Huang H, Liu C, Duan X, Zhang X, Zhao G, Chen Y. Efficient nitrate and Cr(VI) removal by denitrifier: The mechanism of S. oneidensis MR-1 promoting electron production, transportation and consumption. JOURNAL OF HAZARDOUS MATERIALS 2024; 469:133675. [PMID: 38508109 DOI: 10.1016/j.jhazmat.2024.133675] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Revised: 01/21/2024] [Accepted: 01/29/2024] [Indexed: 03/22/2024]
Abstract
When Cr(VI) and nitrate coexist, the efficiency of both bio-denitrification and Cr(VI) bio-reduction is poor because chromate hinders bacterial normal functions (i.e., electron production, transportation and consumption). Moreover, under anaerobic condition, the method about efficient nitrate and Cr(VI) removal remained unclear. In this paper, the addition of Shewanella oneidensis MR-1 to promote the electron production, transportation and consumption of denitrifier and cause an increase in the removal of nitrate and Cr(VI). The efficiency of nitrate and Cr(VI) removal accomplished by P. denitrificans as a used model denitrifier increased respectively from 51.3% to 96.1% and 34.3% to 99.8% after S. oneidensis MR-1 addition. The mechanism investigations revealed that P. denitrificans provided S. oneidensis MR-1 with lactate, which was utilized to secreted riboflavin and phenazine by S. oneidensis MR-1. The riboflavin served as coenzymes of cellular reductants (i.e., thioredoxin and glutathione) in P. denitrificans, which created favorable intracellular microenvironment conditions for electron generation. Meanwhile, phenazine promoted biofilm formation, which increased the adsorption of Cr(VI) on the cell surface and accelerated the Cr(VI) reduction by membrane bound chromate reductases thereby reducing damage to other enzymes respectively. Overall, this strategy reduced the negative effect of chromate, thus improved the generation, transportation, and consumption of electrons. SYNOPSIS: The presence of S. oneidensis MR-1 facilitated nitrate and Cr(VI) removal by P. denitrificans through decreasing the negative effect of chromate due to the metabolites' secretion.
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Affiliation(s)
- Meirou Wu
- State Key Laboratory of Pollution Control and Resources Reuse, School of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, China
| | - Yanan Xu
- State Key Laboratory of Pollution Control and Resources Reuse, School of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, China
| | - Chunxia Zhao
- State Key Laboratory of Pollution Control and Resources Reuse, School of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, China
| | - Haining Huang
- State Key Laboratory of Pollution Control and Resources Reuse, School of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, China
| | - Chao Liu
- State Key Laboratory of Pollution Control and Resources Reuse, School of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, China
| | - Xu Duan
- State Key Laboratory of Pollution Control and Resources Reuse, School of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, China
| | - Xuemeng Zhang
- State Key Laboratory of Pollution Control and Resources Reuse, School of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, China
| | - Guohua Zhao
- School of Chemical Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, China
| | - Yinguang Chen
- State Key Laboratory of Pollution Control and Resources Reuse, School of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, China.
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2
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Cao L, Lu M, Zhao M, Zhang Y, Nong Y, Hu M, Wang Y, Li T, Chen F, Wang M, Liu J, Li E, Sun H. Physiological and transcriptional studies reveal Cr(VI) reduction mechanisms in the exoelectrogen Cellulomonas fimi Clb-11. Front Microbiol 2023; 14:1161303. [PMID: 37303804 PMCID: PMC10251745 DOI: 10.3389/fmicb.2023.1161303] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2023] [Accepted: 04/24/2023] [Indexed: 06/13/2023] Open
Abstract
A facultative exoelectrogen, Cellulomonas fimi strain Clb-11, was isolated from polluted river water. This strain could generate electricity in microbial fuel cells (MFCs) with carboxymethyl cellulose (CMC) as the carbon source, and the maximum output power density was 12.17 ± 2.74 mW·m-2. In addition, Clb-11 could secrete extracellular chromate reductase or extracellular electron mediator to reduce Cr(VI) to Cr(III). When the Cr(VI) concentration was less than 0.5 mM in Luria-Bertani (LB) medium, Cr(VI) could be completely reduced by Clb-11. However, the Clb-11 cells swelled significantly in the presence of Cr(VI). We employed transcriptome sequencing analysis to identify genes involved in different Cr(VI) stress responses in Clb-11. The results indicate that 99 genes were continuously upregulated while 78 genes were continuously downregulated as the Cr(VI) concentration increased in the growth medium. These genes were mostly associated with DNA replication and repair, biosynthesis of secondary metabolites, ABC transporters, amino sugar and nucleotide sugar metabolism, and carbon metabolism. The swelling of Clb-11 cells might have been related to the upregulation of the genes atoB, INO1, dhaM, dhal, dhak, and bccA, which encode acetyl-CoA C-acetyltransferase, myo-inositol-1-phosphate synthase, phosphoenolpyruvate-glycerone phosphotransferase, and acetyl-CoA/propionyl-CoA carboxylase, respectively. Interestingly, the genes cydA and cydB related to electron transport were continuously downregulated as the Cr(VI) concentration increased. Our results provide clues to the molecular mechanism of Cr(VI) reduction by microorganisms in MFCs systems.
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Aththanayake AMKCB, Rathnayake IVN, Deeyamulla MP, Megharaj M. Staphylococcus edaphicus KCB02A11 incorporated with natural adsorbents: first report on its tolerance and removal of hexavalent chromium [Cr(VI)]. World J Microbiol Biotechnol 2023; 39:173. [PMID: 37115249 DOI: 10.1007/s11274-023-03614-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Accepted: 04/10/2023] [Indexed: 04/29/2023]
Abstract
Deteriorating the quality of different parts of the ecosystem due to toxic metals is a serious global issue. Hexavalent chromium is a metal that can cause adverse effects on all living beings, including plants, animals, and microorganisms, on exposure to high concentrations for prolonged periods. Removing hexavalent chromium from various types of wastes is challenging; hence the present study investigated the use of bacteria incorporated with selected natural substrates in removing hexavalent chromium from water. Isolated Staphylococcus edaphicus KCB02A11 has shown higher removal efficiency with a wide hexavalent chromium range (0.025-8.5 mg/L) within 96 h. Incorporating the isolated strain with natural substrates commonly found in the environment (hay and wood husk) showed high removal potential [100% removal with 8.5 mg/L of Cr(VI)], even within less than 72 h, with the formation of biofilms on the used substrates applied for metal removal on a large scale for prolonged periods. This study is the first report investigating hexavalent chromium tolerance and removal by Staphylococcus edaphicus KCB02A11.
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Affiliation(s)
- A M K C B Aththanayake
- Department of Microbiology, Faculty of Science, University of Kelaniya, Kelaniya, 11600, Sri Lanka
| | - I V N Rathnayake
- Department of Microbiology, Faculty of Science, University of Kelaniya, Kelaniya, 11600, Sri Lanka.
| | - M P Deeyamulla
- Department of Chemistry, Faculty of Science, University of Kelaniya, Kelaniya, 11600, Sri Lanka
| | - Mallavarapu Megharaj
- Global Centre for Environmental Remediation (GCER), College of Engineering, Science and Environment, The University of Newcastle, University Drive, ATC Building, Callaghan, NSW, 2308, Australia
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4
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Pinel-Cabello M, Jauregui R, Jroundi F, Geffers R, Jarek M, Link A, Vilchez-Vargas R, Merroun ML. Genetic mechanisms for Se(VI) reduction and synthesis of trigonal 1-D nanostructures in Stenotrophomonas bentonitica: Perspectives in eco-friendly nanomaterial production and bioremediation. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 862:160635. [PMID: 36476772 DOI: 10.1016/j.scitotenv.2022.160635] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Revised: 11/15/2022] [Accepted: 11/28/2022] [Indexed: 06/17/2023]
Abstract
Selenate (Se(VI)) is one of the most soluble and toxic species of Se. Microbial Se(VI) reduction is an efficient tool for bioremediation strategies. However, this process is limited to a few microorganisms, and its molecular basis remains unknown. We present detailed Se(VI)-resistance mechanisms under 50 and 200 mM, in Stenotrophomonas bentonitica BII-R7, coupling enzymatic reduction of Se(VI) to formation of less toxic trigonal Se (t-Se). The results reveal a concentration-dependent response. Despite the lack of evidence of Se(VI)-reduction to Se(0) under 50 mM Se(VI), many genes were highly induced, indicating that Se(VI)-resistance could be based on intracellular reduction to Se(IV), mainly through molybdenum-dependent enzymes (e.g. respiratory nitrate reductase), and antioxidant activity by enzymes like glutathione peroxidase. Although exposure to 200 mM provoked a sharp drop in gene expression, a time-dependent process of reduction and formation of amorphous (a), monoclinic (m) and t-Se nanostructures was unravelled: a-Se nanospheres were initially synthesized intracellularly, which would transform into m-Se and finally into t-Se nanostructures during the following phases. This is the first work describing an intracellular Se(VI) reduction and biotransformation process to long-term stable and insoluble t-Se nanomaterials. These results expand the fundamental understanding of Se biogeochemical cycling, and the effectiveness of BII-R7 for bioremediation purposes.
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Affiliation(s)
| | - Ruy Jauregui
- AgResearch Grasslands Research Centre, Tennent Drive, Palmerston North, New Zealand
| | - Fadwa Jroundi
- Department of Microbiology, University of Granada, Granada, Spain
| | - Robert Geffers
- Genome Analytics, Helmholtz Centre for Infection Research (HZI), 38124 Braunschweig, Germany
| | - Michael Jarek
- Genome Analytics, Helmholtz Centre for Infection Research (HZI), 38124 Braunschweig, Germany
| | - Alexander Link
- Department of Gastroenterology, Hepatology and Infectious Diseases, University of Magdeburg, Leipziger Str. 44, 39120 Magdeburg, Germany
| | - Ramiro Vilchez-Vargas
- Department of Gastroenterology, Hepatology and Infectious Diseases, University of Magdeburg, Leipziger Str. 44, 39120 Magdeburg, Germany
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Shi Y, Wang Z, Li H, Yan Z, Meng Z, Liu C, Chen J, Duan C. Resistance mechanisms and remediation potential of hexavalent chromium in Pseudomonas sp. strain AN-B15. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2023; 250:114498. [PMID: 36608568 DOI: 10.1016/j.ecoenv.2023.114498] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Revised: 12/12/2022] [Accepted: 01/01/2023] [Indexed: 06/17/2023]
Abstract
The understanding of bacterial resistance to hexavalent chromium [Cr(VI)] are crucial for the enhancement of Cr(VI)-polluted soil bioremediation. However, the mechanisms related to plant-associated bacteria remain largely unclear. In this study, we investigate the resistance mechanisms and remediation potential of Cr(VI) in a plant-associated strain, AN-B15. The results manifested that AN-B15 efficiently reduced Cr(VI) to soluble organo-Cr(III). Specifically, 84.3 % and 56.5 % of Cr(VI) was removed after 48 h in strain-inoculated solutions supplemented with 10 and 20 mg/L Cr(VI) concentrations, respectively. Transcriptome analyses revealed that multiple metabolic systems are responsible for Cr(VI) resistance at the transcriptional level. In response to Cr(VI) exposure, strain AN-B15 up-regulated the genes involved in central metabolism, providing the reducing power by which enzymes (ChrR and azoR) transformed Cr(VI) to Cr(III) in the cytoplasm. Genes involved in the alleviation of oxidative stress and DNA repair were significantly up-regulated to neutralize Cr(VI)-induced toxicity. Additionally, genes involved in organosulfur metabolism and certain ion transporters were up-regulated to counteract the starvation of sulfur, molybdate, iron, and manganese induced by Cr(VI) stress. Furthermore, a hydroponic culture experiment showed that toxicity and uptake of Cr(VI) by plants under Cr(VI) stress were reduced by strain AN-B15. Specifically, strain AN-B15 inoculation increased the fresh weights of the wheat root and shoot by 55.5 % and 18.8 %, respectively, under Cr(VI) stress (5 mg/L). The elucidation of bacterial resistance to Cr(VI) has an important implication for exploiting microorganism for the effective remediation of Cr(VI)-polluted soils.
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Affiliation(s)
- Yu Shi
- Yunnan Key Laboratory for Plateau Mountain Ecology and Restoration of Degraded Environments, School of Ecology and Environmental Science, Yunnan University, Kunming 650091, China; Yunnan International Cooperative Center of Plateau Lake Ecological Restoration and Watershed Management & Yunnan Think Tank of Ecological Civilization, Kunming, Yunnan 650091, China
| | - Zitong Wang
- Yunnan Key Laboratory for Plateau Mountain Ecology and Restoration of Degraded Environments, School of Ecology and Environmental Science, Yunnan University, Kunming 650091, China
| | - Huifen Li
- Qingdao Shangde Biotech Co Ltd,Qingdao 266111, China
| | - Zhengjian Yan
- Yunnan Key Laboratory for Plateau Mountain Ecology and Restoration of Degraded Environments, School of Ecology and Environmental Science, Yunnan University, Kunming 650091, China
| | - Zhuang Meng
- Qingdao Shangde Biotech Co Ltd,Qingdao 266111, China
| | - Chang'e Liu
- Yunnan Key Laboratory for Plateau Mountain Ecology and Restoration of Degraded Environments, School of Ecology and Environmental Science, Yunnan University, Kunming 650091, China
| | - Jinquan Chen
- Yunnan Key Laboratory for Plateau Mountain Ecology and Restoration of Degraded Environments, School of Ecology and Environmental Science, Yunnan University, Kunming 650091, China.
| | - Changqun Duan
- Yunnan Key Laboratory for Plateau Mountain Ecology and Restoration of Degraded Environments, School of Ecology and Environmental Science, Yunnan University, Kunming 650091, China; Yunnan International Cooperative Center of Plateau Lake Ecological Restoration and Watershed Management & Yunnan Think Tank of Ecological Civilization, Kunming, Yunnan 650091, China.
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Gong B, Tan Z, Yang X, Liang L, Wu P, Li Y. Induction of zincophore pseudopaline secretion by Cr(VI) and intracellular formation of granules from nanocrystal aggregation by Cr(III) in Pseudomonas aeruginosa. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2022; 323:116201. [PMID: 36099868 DOI: 10.1016/j.jenvman.2022.116201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2022] [Revised: 08/26/2022] [Accepted: 09/05/2022] [Indexed: 06/15/2023]
Abstract
When microorganisms are challenged with toxic metals, intracellular granules are commonly observed, however, the exact nature of these granules is poorly understood. Here we show that when Pseudomonas aeruginosa CCTCC AB93066 were exposed to Cr(VI), Cr can enter the cell in the form of both Cr(VI) and Cr(III), and intracellular granules of several hundred nanometers were formed in the nucleoid region and were built up by aggregation of nanocrystals. We suggested that these nanocrystals are organic crystals. Transcriptomic profiles and liquid chromatography tandem mass spectrometry (LC-MS/MS) analysis indicated that pseudopaline (a metallophore that can complex with Zn2+) production and pseudopaline-Zn2+ import into bacterial cells were enhanced upon Cr(VI) exposure. It was proposed that pseudopaline can scavenge Zn2+ which is essential for transcription alteration and DNA repair. Excessive pseudopaline might precipitate as nanospheres in the nuclear region that are further agglomerated by Cr(III) to form larger granules. During this process, Cr(III) is sequestered and immobilized. Hence we revealed pseudopaline production and zinc acquisition is crucial for alleviation of Cr(VI) toxicity and intracellular granules are composed of organic nanospheres which are aggregated by Cr(III).
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Affiliation(s)
- Beini Gong
- College of Natural Resources and Environment, South China Agricultural University, Guangzhou, 510642, PR China
| | - Zewen Tan
- College of Natural Resources and Environment, South China Agricultural University, Guangzhou, 510642, PR China
| | - Xiuyue Yang
- College of Natural Resources and Environment, South China Agricultural University, Guangzhou, 510642, PR China
| | - Lingling Liang
- College of Natural Resources and Environment, South China Agricultural University, Guangzhou, 510642, PR China
| | - Pingxiao Wu
- School of Environment and Energy, South China University of Technology, Guangzhou, 510006, China; The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, Guangzhou, 510006, China; Guangdong Provincial Key Laboratory of Solid Wastes Pollution Control and Recycling, Guangzhou, 510006, China.
| | - Yongtao Li
- College of Natural Resources and Environment, South China Agricultural University, Guangzhou, 510642, PR China.
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7
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Pang B, Yu H, Zhang J, Ye F, Wu H, Shang C. Identification of differentially expressed genes for Pseudomonas sp. Cr13 stimulated by hexavalent chromium. PLoS One 2022; 17:e0272528. [PMID: 35930609 PMCID: PMC9355187 DOI: 10.1371/journal.pone.0272528] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2021] [Accepted: 07/20/2022] [Indexed: 12/02/2022] Open
Abstract
Over exploitation of mineral resources has increasingly caused serious heavy metal contamination such as chromium (Cr). Cr(VI), the pathogenicity factor, is one of common environmental contaminants and widely known health hazards to living organisms. Therefore, it is urgent to control the polluted soil. Up to now, little is known about the regulatory mechanisms of Cr response in Pseudomonas sp. Cr13. In this study, transcriptome and differentially expressed genes in Pseudomonas sp. Cr13 strain was characterized by a comparison between Cr(VI)-treated sample and control sample using transcriptome sequencing approach. In total, 2974 genes were annotated, including 1245 (1154 down-regulated genes and 91 up-regulated genes) differentially expressed genes (DEGs). All DEGs could be assigned to 29 pathways, of which pathways related to amino acid metabolism, carbohydrate metabolism, energy metabolism and signal transduction mechanism were significantly enriched in Pseudomonas sp. Cr13. A possible mechanism for Cr toxicity response might be an active efflux which utilized a heavy metal translocating P-type ATPase to lower the intracellular Cr concentration. The down-regulated genes related to the antioxidant defense system had a key role in Cr reduction, such as SodA, Gst, osmC, BtuE, KatE, csdA and AhpC. The proteins that were visibly up-regulated, were likely to involve in alleviating Cr(VI) stress, and the significantly down-regulated genes such as MarR, Lrp, FhlA, GntR, HrcA, LysR family genes, were likely to reduce Cr(VI) induced oxidative stress. In addition, real-time quantitative PCR was used to analyze the expression patterns of some Cr responsive genes. This study reported the first identification of Cr responsive genes, and inferred the underlying regulatory mechanisms of response to Cr(VI) stress in Pseudomonas sp. Cr13.
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Affiliation(s)
- Bingbing Pang
- College of Life Science, Guangxi Normal University, Guilin, China
- Key Laboratory of Ecology of Rare and Endangered Species and Environmental Protection (Guangxi Normal University), Ministry of Education, Guilin, China
- Guangxi Key Laboratory of Landscape Resources Conservation and Sustainable Utilization in Lijiang River Basin, Guangxi Normal University, Guilin, China
| | - Hongling Yu
- College of Life Science, Guangxi Normal University, Guilin, China
- Key Laboratory of Ecology of Rare and Endangered Species and Environmental Protection (Guangxi Normal University), Ministry of Education, Guilin, China
- Guangxi Key Laboratory of Landscape Resources Conservation and Sustainable Utilization in Lijiang River Basin, Guangxi Normal University, Guilin, China
| | - Jin Zhang
- College of Life Science, Guangxi Normal University, Guilin, China
- Key Laboratory of Ecology of Rare and Endangered Species and Environmental Protection (Guangxi Normal University), Ministry of Education, Guilin, China
- Guangxi Key Laboratory of Landscape Resources Conservation and Sustainable Utilization in Lijiang River Basin, Guangxi Normal University, Guilin, China
| | - Fengcai Ye
- College of Life Science, Guangxi Normal University, Guilin, China
- Key Laboratory of Ecology of Rare and Endangered Species and Environmental Protection (Guangxi Normal University), Ministry of Education, Guilin, China
- Guangxi Key Laboratory of Landscape Resources Conservation and Sustainable Utilization in Lijiang River Basin, Guangxi Normal University, Guilin, China
| | - Haifeng Wu
- College of Life Science, Guangxi Normal University, Guilin, China
- Key Laboratory of Ecology of Rare and Endangered Species and Environmental Protection (Guangxi Normal University), Ministry of Education, Guilin, China
- Guangxi Key Laboratory of Landscape Resources Conservation and Sustainable Utilization in Lijiang River Basin, Guangxi Normal University, Guilin, China
| | - Changhua Shang
- College of Life Science, Guangxi Normal University, Guilin, China
- Key Laboratory of Ecology of Rare and Endangered Species and Environmental Protection (Guangxi Normal University), Ministry of Education, Guilin, China
- Guangxi Key Laboratory of Landscape Resources Conservation and Sustainable Utilization in Lijiang River Basin, Guangxi Normal University, Guilin, China
- * E-mail:
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Gong Y, Wu Y, Khan A, Song P, Wang Z, Ni H, Ji J, Salama ES, Liu P, Li X. Improving selenium accumulation in broilers using Escherichia coli Nissle 1917 with surface-displayed selenite reductase SerV01. Food Funct 2022; 13:4537-4550. [PMID: 35348561 DOI: 10.1039/d2fo00206j] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Selenium levels have a critical impact on livestock and poultry, and selenium nanoparticles (SeNPs) have shown significant efficiency in supplementation. This study identified a high-efficiency selenite reductase, SerV01, in Staphylococcus aureus LZ-01, which can convert Se2O32- to SeNPs. Subsequently, SerV01 was introduced into the intestines of the broilers using the surface display-engineered E. coli Nissle 1917 (EcN). The results showed that the engineered bacteria (EcN-IS) significantly increased the selenium content by 0.87 mg kg-1, 0.52 mg kg-1, and 6.10 mg L-1 in the liver, breast muscle, and serum, respectively. With SeNPs + EcN-IS treatment, glutathione peroxidase and thioredoxin reductase levels reached 0.7536 ± 0.03176 U μL-1 protein and 2.463 ± 0.1685 U μL-1 protein, respectively. With the modified probiotics, the proportion of beneficial intestinal flora increased, with Lactobacillus and Propionibacterium accounting for 75.85% and 0.19%. This technology provides a novel idea to facilitate the exploitation of selenium in broiler diets and improve antioxidant capability.
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Affiliation(s)
- Yuxin Gong
- Gansu Key Laboratory of Biomonitoring and Bioremediation for Environmental Pollution, School of Life Sciences, Lanzhou University, Tianshuinanlu #222, Lanzhou 730000, Gansu, China.
| | - Ying Wu
- Gansu Key Laboratory of Biomonitoring and Bioremediation for Environmental Pollution, School of Life Sciences, Lanzhou University, Tianshuinanlu #222, Lanzhou 730000, Gansu, China.
| | - Aman Khan
- Gansu Key Laboratory of Biomonitoring and Bioremediation for Environmental Pollution, School of Life Sciences, Lanzhou University, Tianshuinanlu #222, Lanzhou 730000, Gansu, China.
| | - Peizhi Song
- Gansu Key Laboratory of Biomonitoring and Bioremediation for Environmental Pollution, School of Life Sciences, Lanzhou University, Tianshuinanlu #222, Lanzhou 730000, Gansu, China.
| | - Zhenfei Wang
- Gansu Key Laboratory of Biomonitoring and Bioremediation for Environmental Pollution, School of Life Sciences, Lanzhou University, Tianshuinanlu #222, Lanzhou 730000, Gansu, China.
| | - Hongyuhang Ni
- Department of Infectious Diseases and Public Health, Jockey Club College of Veterinary Medicine and Life Sciences, City University of Hong Kong, Kowloon, Hong Kong
| | - Jing Ji
- Gansu Key Laboratory of Biomonitoring and Bioremediation for Environmental Pollution, School of Life Sciences, Lanzhou University, Tianshuinanlu #222, Lanzhou 730000, Gansu, China.
| | - El-Sayed Salama
- Department of Occupational and Environmental Health, School of Public Health, Lanzhou University, Lanzhou, 730000, Gansu, PR China
| | - Pu Liu
- Gansu Key Laboratory of Biomonitoring and Bioremediation for Environmental Pollution, School of Life Sciences, Lanzhou University, Tianshuinanlu #222, Lanzhou 730000, Gansu, China.
| | - Xiangkai Li
- Gansu Key Laboratory of Biomonitoring and Bioremediation for Environmental Pollution, School of Life Sciences, Lanzhou University, Tianshuinanlu #222, Lanzhou 730000, Gansu, China.
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Li SW, Wen Y, Leng Y. Transcriptome analysis provides new insights into the tolerance and reduction of Lysinibacillus fusiformis 15-4 to hexavalent chromium. Appl Microbiol Biotechnol 2021; 105:7841-7855. [PMID: 34546405 DOI: 10.1007/s00253-021-11586-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2021] [Revised: 08/22/2021] [Accepted: 08/26/2021] [Indexed: 12/13/2022]
Abstract
Microbial bioremediation of Cr(VI)-contaminated environments has drawn extensive concern. However, the molecular processes underlying the microbial Cr(VI) tolerance and reduction remain unclear. We isolated a Cr(VI)-reducing Lysinibacillus fusiformis strain 15-4 from soil on the Qinghai-Tibet Plateau. When grown in 1 mM and 2 mM Cr(VI)-containing medium, strain 15-4 could reduce 100% and 93.7% of Cr(VI) to Cr(III) after 36 h and 60 h of incubation, respectively. To know the molecular processes in response to Cr(VI), transcriptome sequencing was carried out using RNA-Seq technology. The results annotated a total of 3913 expressed genes in the strain. One thousand ninety-eight genes (28.1%) were significantly (fold change ≥ 2, false discovery rate ≤ 0.05) expressed in response to Cr(VI), of which 605 (55.1%) were upregulated and 493 (44.9%) were downregulated. The enrichment analysis showed that a total of 630 differentially expressed genes (DEGs) were enriched to 122 KEGG pathways, of which 8 pathways were significantly (p < 0.05) enriched in Cr(VI)-treated sample, including ATP-binding cassette (ABC) transporters (97 DEGs), ribosome (40), sulfur metabolism (16), aminoacyl-tRNA biosynthesis (19), porphyrin metabolism (20), quorum sensing (44), oxidative phosphorylation (17), and histidine metabolism (10), suggesting that these pathways play key roles to cope with Cr(VI) in the strain. The highly upregulated DEGs consisted of 29 oxidoreductase, 18 dehydrogenase, 14 cell redox homeostasis and stress response protein, and 10 DNA damage and repair protein genes. However, seven Na+:H+ antiporter complex-coding DEGs and most of transcriptional regulator-coding DEGs were significantly downregulated in the Cr-treated sample. Many of FMN/NAD(P)H-dependent reductase-encoding genes were greatly induced by Cr, suggesting the involvement of these genes in Cr(VI) reduction in strain 15-4. Sulfur and iron ions as well as the thiol-disulfide exchange reactions might play synergistic roles in Cr reduction.Key points• Lysinibacillus fusiformis 15-4 was able to tolerate and reduce Cr(VI) to Cr(III).• Transcriptome analysis revealed that 1098 DEGs and 8 key KEGG pathways significantly responded to Cr(VI).• Sulfur metabolism, protein biosynthesis, and porphyrin metabolism were the key pathways associated with the survival of strain 15-4 in response to Cr(VI).
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Affiliation(s)
- Shi-Weng Li
- School of Environmental and Municipal Engineering, Lanzhou Jiaotong University, Lanzhou, People's Republic of China. .,School of Chemical and Biological Engineering, Lanzhou Jiaotong University, Lanzhou, 730070, People's Republic of China. .,Key Laboratory of Extreme Environmental Microbial Resources and Engineering in Gansu Province, Lanzhou, 730000, People's Republic of China.
| | - Ya Wen
- School of Chemical and Biological Engineering, Lanzhou Jiaotong University, Lanzhou, 730070, People's Republic of China
| | - Yan Leng
- School of Chemical and Biological Engineering, Lanzhou Jiaotong University, Lanzhou, 730070, People's Republic of China
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Lara P, Vega-Alvarado L, Sahonero-Canavesi DX, Koenen M, Villanueva L, Riveros-Mckay F, Morett E, Juárez K. Transcriptome Analysis Reveals Cr(VI) Adaptation Mechanisms in Klebsiella sp. Strain AqSCr. Front Microbiol 2021; 12:656589. [PMID: 34122372 PMCID: PMC8195247 DOI: 10.3389/fmicb.2021.656589] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Accepted: 04/13/2021] [Indexed: 11/19/2022] Open
Abstract
Klebsiella sp. strain AqSCr, isolated from Cr(VI)-polluted groundwater, reduces Cr(VI) both aerobically and anaerobically and resists up 34 mM Cr(VI); this resistance is independent of the ChrA efflux transporter. In this study, we report the whole genome sequence and the transcriptional profile by RNA-Seq of strain AqSCr under Cr(VI)-adapted conditions and found 255 upregulated and 240 downregulated genes compared to controls without Cr(VI) supplementation. Genes differentially transcribed were mostly associated with oxidative stress response, DNA repair and replication, sulfur starvation response, envelope-osmotic stress response, fatty acid (FA) metabolism, ribosomal subunits, and energy metabolism. Among them, genes not previously associated with chromium resistance, for example, cybB, encoding a putative superoxide oxidase (SOO), gltA2, encoding an alternative citrate synthase, and des, encoding a FA desaturase, were upregulated. The sodA gene encoding a manganese superoxide dismutase was upregulated in the presence of Cr(VI), whereas sodB encoding an iron superoxide dismutase was downregulated. Cr(VI) resistance mechanisms in strain AqSCr seem to be orchestrated by the alternative sigma factors fecl, rpoE, and rpoS (all of them upregulated). Membrane lipid analysis of the Cr(IV)-adapted strain showed a lower proportion of unsaturated lipids with respect to the control, which we hypothesized could result from unsaturated lipid peroxidation followed by degradation, together with de novo synthesis mediated by the upregulated FA desaturase-encoding gene, des. This report helps to elucidate both Cr(VI) toxicity targets and global bacterial response to Cr(VI).
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Affiliation(s)
- Paloma Lara
- Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
| | - Leticia Vega-Alvarado
- Instituto de Ciencias Aplicadas y Tecnología, Universidad Nacional Autónoma de México, Ciudad de México, Mexico
| | - Diana X Sahonero-Canavesi
- Department of Marine Microbiology and Biogeochemistry (MMB), NIOZ Royal Netherlands Institute for Sea Research, Texel, Netherlands
| | - Michel Koenen
- Department of Marine Microbiology and Biogeochemistry (MMB), NIOZ Royal Netherlands Institute for Sea Research, Texel, Netherlands
| | - Laura Villanueva
- Department of Marine Microbiology and Biogeochemistry (MMB), NIOZ Royal Netherlands Institute for Sea Research, Texel, Netherlands.,Faculty of Geosciences, Department of Earth Sciences, Utrecht University, Utrecht, Netherlands
| | - Fernando Riveros-Mckay
- Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
| | - Enrique Morett
- Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
| | - Katy Juárez
- Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
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11
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Pei Y, Tao C, Ling Z, Yu Z, Ji J, Khan A, Mamtimin T, Liu P, Li X. Exploring novel Cr(VI) remediation genes for Cr(VI)-contaminated industrial wastewater treatment by comparative metatranscriptomics and metagenomics. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 742:140435. [PMID: 32623159 DOI: 10.1016/j.scitotenv.2020.140435] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Revised: 06/17/2020] [Accepted: 06/20/2020] [Indexed: 06/11/2023]
Abstract
Microbial remediation is a promising method to treat Cr(VI) in industrial wastewater. The remediation efficiency and stress-resistance ability of Cr(VI) remediation genes in microbes are the limiting factors for their application in industrial wastewater treatment. To screen novel highly efficient Cr(VI) remediation genes, comparative metatranscriptomic and metagenomic analyses were performed on long-term Cr(VI)-contaminated riparian soil with/without additional Cr(VI) treatment. The most suitable Cr(VI) treatment time was determined to be 30 min according to the high quality RNA yield and fold changes in gene expression. Six novel genes, which had complete open reading frames (ORFs) in metagenomic libraries, were identified from unculturable microbes. In the phenotypic functional assay, all novel genes enhanced the Cr(VI) resistance/reduction ability of E. coli. In the industrial wastewater treatment, E-mcr and E-gsr presented at least 50% Cr(VI) removal efficiencies in the presence of 200-600 μM of Cr(VI), without a decrease in efficiency over 17 days. The stress resistance assay showed that gsr increased the growth rate of E. coli by at least 30% under different extreme conditions, and thus, gsr was identified as a general stress-response gene. In the Cr valence distribution assay, E-mcr presented ~40 μM higher extracellular Cr (III) compared to E-yieF. Additionally, transmission electron microscopy (TEM) of E-mcr showed bulk black agglomerates on the cell surface. Thus, mcr was identified as a membrane chromate reductase gene. This research provides a new idea for studying novel highly efficient contaminant remediation genes from unculturable microbes.
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Affiliation(s)
- Yaxin Pei
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Tianshuinanlu #222, Lanzhou 730000, Gansu, China; Key Laboratory for Resources Utilization Technology of Unconventional Water of Gansu province, Gansu Academy of Membrane Science and Technology, Duanjiatanlu #1272, Lanzhou 730000, Gansu, China
| | - Chen Tao
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Shuangqinglu #18, Beijing 100085, China
| | - Zhenmin Ling
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Tianshuinanlu #222, Lanzhou 730000, Gansu, China; Key Laboratory for Resources Utilization Technology of Unconventional Water of Gansu province, Gansu Academy of Membrane Science and Technology, Duanjiatanlu #1272, Lanzhou 730000, Gansu, China
| | - Zhengsheng Yu
- Key Laboratory for Resources Utilization Technology of Unconventional Water of Gansu province, Gansu Academy of Membrane Science and Technology, Duanjiatanlu #1272, Lanzhou 730000, Gansu, China
| | - Jing Ji
- Key Laboratory for Resources Utilization Technology of Unconventional Water of Gansu province, Gansu Academy of Membrane Science and Technology, Duanjiatanlu #1272, Lanzhou 730000, Gansu, China; Gansu Key Laboratory of Biomonitoring and Bioremediation for Environment Pollution, School of Life Science, Lanzhou University, Tianshuinanlu #222, Lanzhou 730000, Gansu, China
| | - Aman Khan
- Key Laboratory for Resources Utilization Technology of Unconventional Water of Gansu province, Gansu Academy of Membrane Science and Technology, Duanjiatanlu #1272, Lanzhou 730000, Gansu, China; Gansu Key Laboratory of Biomonitoring and Bioremediation for Environment Pollution, School of Life Science, Lanzhou University, Tianshuinanlu #222, Lanzhou 730000, Gansu, China
| | - Tursunay Mamtimin
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Tianshuinanlu #222, Lanzhou 730000, Gansu, China; Gansu Key Laboratory of Biomonitoring and Bioremediation for Environment Pollution, School of Life Science, Lanzhou University, Tianshuinanlu #222, Lanzhou 730000, Gansu, China
| | - Pu Liu
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Tianshuinanlu #222, Lanzhou 730000, Gansu, China
| | - Xiangkai Li
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Tianshuinanlu #222, Lanzhou 730000, Gansu, China; Key Laboratory for Resources Utilization Technology of Unconventional Water of Gansu province, Gansu Academy of Membrane Science and Technology, Duanjiatanlu #1272, Lanzhou 730000, Gansu, China.
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12
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Zhu Y, Yan J, Xia L, Zhang X, Luo L. Mechanisms of Cr(VI) reduction by Bacillus sp. CRB-1, a novel Cr(VI)-reducing bacterium isolated from tannery activated sludge. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2019; 186:109792. [PMID: 31629191 DOI: 10.1016/j.ecoenv.2019.109792] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2019] [Revised: 10/07/2019] [Accepted: 10/10/2019] [Indexed: 06/10/2023]
Abstract
Cr(VI) reduction by microorganisms has been extensively reported, however, the mechanism of Cr(VI) reduction varies among different microorganisms. In this study, a Cr(VI)-reducing bacterium identified as Bacillus sp. was isolated from tannery activated sludge, strain CRB-1 was able to completely reduce 50 mg/L of Cr(VI) within 24 h under aerobic conditions and exhibited considerable Cr(VI) removal efficiency in the pH range from 7.0 to 9.0, temperature 24-42 °C. Cr(VI) reduction assays with resting cells, permeabilized cells, and subcellular fractions suggested that Cr(VI) reduction mainly occurred in the cytoplasm. According to qRT-PCR analysis, a chrA gene and a nitR2 gene were up-regulated under Cr(VI) stress. Heterologous expression of the chrA gene and the nitR2 gene indicated that ChrA was associated with Cr(VI) resistance, while NitR2 was responsible for Cr(VI) reduction. Furthermore, soluble end products were detected. On the basis of FTIR, it was speculated that the formation of soluble end products may be due to the complexation of EPS with Cr(III). Consequently, the Cr(VI)-reducing ability of strain CRB-1 and its chromate reductases enables CRB-1 a potential candidate for Cr(VI) bioremediation.
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Affiliation(s)
- Yunfei Zhu
- School of Biology and Biological Engineering, South China University of Technology, Guangzhou, 510006, China
| | - Junwei Yan
- School of Biology and Biological Engineering, South China University of Technology, Guangzhou, 510006, China
| | - Li Xia
- School of Biology and Biological Engineering, South China University of Technology, Guangzhou, 510006, China
| | - Xiang Zhang
- School of Biology and Biological Engineering, South China University of Technology, Guangzhou, 510006, China
| | - Lixin Luo
- School of Biology and Biological Engineering, South China University of Technology, Guangzhou, 510006, China.
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13
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Chromium(VI) reduction in Streptomyces sp. M7 mediated by a novel Old Yellow Enzyme. Appl Microbiol Biotechnol 2019; 103:5015-5022. [DOI: 10.1007/s00253-019-09841-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2019] [Revised: 04/08/2019] [Accepted: 04/09/2019] [Indexed: 11/25/2022]
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14
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Roles of Bacillus subtilis RecA, Nucleotide Excision Repair, and Translesion Synthesis Polymerases in Counteracting Cr(VI)-Promoted DNA Damage. J Bacteriol 2019; 201:JB.00073-19. [PMID: 30745368 DOI: 10.1128/jb.00073-19] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Accepted: 01/29/2019] [Indexed: 11/20/2022] Open
Abstract
Bacteria deploy global programs of gene expression, including components of the SOS response, to counteract the cytotoxic and genotoxic effects of environmental DNA-damaging factors. Here we report that genetic damage promoted by hexavalent chromium elicited the SOS response in Bacillus subtilis, as evidenced by the induction of transcriptional uvrA-lacZ, recA-lacZ, and P recA-gfp fusions. Accordingly, B. subtilis strains deficient in homologous recombination (RecA) and nucleotide excision repair (NER) (UvrA), components of the SOS response, were significantly more sensitive to Cr(VI) treatment than were cells of the wild-type strain. These results strongly suggest that Cr(VI) induces the formation in growing B. subtilis cells of cytotoxic and genotoxic bulky DNA lesions that are processed by RecA and/or the NER pathways. In agreement with this notion, Cr(VI) significantly increased the formation of DNA-protein cross-links (DPCs) and induced mutagenesis in recA- and uvrA-deficient B. subtilis strains, through a pathway that required YqjH/YqjW-mediated translesion synthesis. We conclude that Cr(VI) promotes mutagenesis and cell death in B. subtilis by a mechanism that involves the formation of DPCs and that such deleterious effects are counteracted by both the NER and homologous recombination pathways, belonging to the RecA-dependent SOS system.IMPORTANCE It has been shown that, following permeation of cell barriers, Cr(VI) kills B. subtilis cells following a mechanism of reactive oxygen species-promoted DNA damage, which is counteracted by the guanine oxidized repair system. Here we report a distinct mechanism of Cr(VI)-promoted DNA damage that involves production of DPCs capable of eliciting the bacterial SOS response. We also report that the NER and homologous recombination (RecA) repair pathways, as well as low-fidelity DNA polymerases, counteract this metal-induced mechanism of killing in B. subtilis Hence, our results contribute to an understanding of how environmental pollutants activate global programs of gene expression that allow bacteria to contend with the cytotoxic and genotoxic effects of heavy metals.
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15
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McClary JS, Boehm AB. Transcriptional Response of Staphylococcus aureus to Sunlight in Oxic and Anoxic Conditions. Front Microbiol 2018; 9:249. [PMID: 29599752 PMCID: PMC5863498 DOI: 10.3389/fmicb.2018.00249] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2017] [Accepted: 01/31/2018] [Indexed: 12/20/2022] Open
Abstract
The transcriptional response of Staphylococcus aureus strain Newman to sunlight exposure was investigated under both oxic and anoxic conditions using RNA sequencing to gain insight into potential mechanisms of inactivation. S. aureus is a pathogenic bacterium detected at recreational beaches which can cause gastrointestinal illness and skin infections, and is of increasing public health concern. To investigate the S. aureus photostress response in oligotrophic seawater, S. aureus cultures were suspended in seawater and exposed to full spectrum simulated sunlight. Experiments were performed under oxic or anoxic conditions to gain insight into the effects of oxygen-mediated and non-oxygen-mediated inactivation mechanisms. Transcript abundance was measured after 6 h of sunlight exposure using RNA sequencing and was compared to transcript abundance in paired dark control experiments. Culturable S. aureus decayed following biphasic inactivation kinetics with initial decay rate constants of 0.1 and 0.03 m2 kJ−1 in oxic and anoxic conditions, respectively. RNA sequencing revealed that 71 genes had different transcript abundance in the oxic sunlit experiments compared to dark controls, and 18 genes had different transcript abundance in the anoxic sunlit experiments compared to dark controls. The majority of genes showed reduced transcript abundance in the sunlit experiments under both conditions. Three genes (ebpS, NWMN_0867, and NWMN_1608) were found to have the same transcriptional response to sunlight between both oxic and anoxic conditions. In the oxic condition, transcripts associated with porphyrin metabolism, nitrate metabolism, and membrane transport functions were increased in abundance during sunlight exposure. Results suggest that S. aureus responds differently to oxygen-dependent and oxygen-independent photostress, and that endogenous photosensitizers play an important role during oxygen-dependent indirect photoinactivation.
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Affiliation(s)
- Jill S McClary
- Civil and Environmental Engineering, Stanford University, Stanford, CA, United States
| | - Alexandria B Boehm
- Civil and Environmental Engineering, Stanford University, Stanford, CA, United States
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16
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Copper (II) binding of NAD(P)H- flavin oxidoreductase (NfoR) enhances its Cr (VI)-reducing ability. Sci Rep 2017; 7:15481. [PMID: 29133854 PMCID: PMC5684319 DOI: 10.1038/s41598-017-15588-y] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Accepted: 10/23/2017] [Indexed: 12/16/2022] Open
Abstract
Microbes can reduce hexavalent chromium Cr (VI) to the less toxic and soluble trivalent Cr (III). Copper stimulates microbial reduction of Cr (VI) by the Bacillus, Ochrobactrum, and Gluconobacter species; however, the mechanism remains unclear. In our study, the rate of Cr (VI) reduction by Staphylococcus aureus LZ-01 was increased by 210 % when supplemented with 60 μM Cu (II). A putative NAD(P)H-flavin oxidoreductase gene (nfoR) was upregulated under Cr (VI) stress. NfoR-knockout mutant displayed impaired reduction of Cr (VI) and Cu (II)-enhanced Cr (VI) reduction by nfoR isogenic mutant was attenuated in the presence of Cu (II). In vitro tests showed an increased Vmax value of 25.22 μM min−1 mg−1 NfoR in the presence of Cu (II). Together, these results indicate that NfoR is responsible for Cu (II) enhancement. Isothermal titration calorimetry (ITC) assays confirmed the interaction of NfoR with Cu (II) at the dissociation constant of 85.5 μM. Site-directed mutagenesis indicates that His100, His128, and Met165 residues may be important for Cu (II) binding, while Cys163 is necessary for the FMN binding of NfoR. These findings show that Cu (II)-enhanced NfoR belongs to a new branch of Cr (VI) reductases and profoundly influences Cr (VI) reduction.
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17
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Xu L, Huo M, Sun C, Cui X, Zhou D, Crittenden JC, Yang W. Bioresources inner-recycling between bioflocculation of Microcystis aeruginosa and its reutilization as a substrate for bioflocculant production. Sci Rep 2017; 7:43784. [PMID: 28252111 PMCID: PMC5333146 DOI: 10.1038/srep43784] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Accepted: 01/30/2017] [Indexed: 11/09/2022] Open
Abstract
Bioflocculation, being environmental-friendly and highly efficient, is considered to be a promising method to harvest microalgae. However, one limitation of this technology is high expense on substrates for bioflocculant bacteria cultivation. In this regard, we developed an innovative method for the inner-recycling of biomass that could harvest the typical microalgae, Microcystis aeruginosa, using a bioflocculant produced by Citrobacter sp. AzoR-1. In turn, the flocculated algal biomass could be reutilized as a substrate for Citrobacter sp. AzoR-1 cultivation and bioflocculant production. The experimental results showed that 3.4 ± 0.1 g of bioflocculant (hereafter called MBF-12) was produced by 10 g/L of wet biomass of M. aeruginosa (high-pressure steam sterilized) with an additional 10 g/L of glucose as an extra carbon source. The efficiency of MBF-12 for M. aeruginosa harvesting could reach ~95% under the optimized condition. Further analysis showed that MBF-12, dominated by ~270 kDa biopolymers, contributed the bioflocculation mechanisms of interparticle bridging and biosorption process. Bioflocculant synthesis by Citrobacter sp. AzoR-1 using microalga as a substrate, including the polyketide sugar unit, lipopolysaccharide, peptidoglycan and terpenoid backbone pathways. Our research provides the first evidence that harvested algae can be reutilized as a substrate to grow a bioflocculant using Citrobacter sp. AzoR-1.
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Affiliation(s)
- Liang Xu
- School of Environment, Northeast Normal University, Changchun 130117, China
- Jilin Institute of Chemical Technology, Jilin, 132022, China
| | - Mingxin Huo
- School of Environment, Northeast Normal University, Changchun 130117, China
| | - Caiyun Sun
- School of Environment, Northeast Normal University, Changchun 130117, China
| | - Xiaochun Cui
- School of Environment, Northeast Normal University, Changchun 130117, China
| | - Dandan Zhou
- School of Environment, Northeast Normal University, Changchun 130117, China
| | - John C. Crittenden
- Brook Byers Institute for Sustainable Systems, and School of Civil & Environmental Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Wu Yang
- School of Environment, Northeast Normal University, Changchun 130117, China
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18
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Yu Z, He Z, Tao X, Zhou J, Yang Y, Zhao M, Zhang X, Zheng Z, Yuan T, Liu P, Chen Y, Nolan V, Li X. The shifts of sediment microbial community phylogenetic and functional structures during chromium (VI) reduction. ECOTOXICOLOGY (LONDON, ENGLAND) 2016; 25:1759-1770. [PMID: 27637513 DOI: 10.1007/s10646-016-1719-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 08/29/2016] [Indexed: 05/13/2023]
Abstract
The Lanzhou reach of the Yellow River, located at the upstream of Lanzhou, has been contaminated by heavy metals and polycyclic aromatic hydrocarbons over a long-time. We hypothesized that indigenous microbial communities would remediate those contaminants and some unique populations could play an important role in this process. In this study, we investigated the sediment microbial community structure and function from the Lanzhou reach. Sediment samples were collected from two nearby sites (site A and site B) in the Lanzhou reach along the Yellow River. Sediment geochemical property data showed that site A sediment samples contained significantly (p < 0.05) higher heavy metals than site B, such as chromium (Cr), manganese (Mn), and copper (Cu). Both site A and B samples were incubated with or without hexavalent chromium (Cr (VI)) for 30 days in the laboratory, and Cr (VI) reduction was only observed in site A sediment samples. After incubation, MiSeq sequencing of 16S rRNA gene amplicons revealed that the phylogenetic composition and structure of microbial communities changed in both samples, and especially Proteobacteria, as the most abundant phylum increased from 45.1 % to 68.2 % in site A, and 50.1 % to 71.3 % in site B, respectively. Some unique OTUs and populations affiliated with Geobacter, Clostridium, Desulfosporosinus and Desulfosporosinus might be involved in Cr (VI) reduction in site A. Furthermore, GeoChip 4.0 (a comprehensive functional gene array) data showed that genes involved in carbon and nitrogen cycling and metal resistance significantly (p < 0.05) increased in site A sediment samples. All the results indicated that indigenous sediment microbial communities might be able to remediate contaminants like Cr (VI), and this information provides possible strategies for future bioremediation of the Lanzhou reach.
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Affiliation(s)
- Zhengsheng Yu
- Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, Gansu, 730000, China
| | - Zhili He
- Department of Microbiology and Plant Biology and Institute for Environmental Genomics, University of Oklahoma, Norman, OK, 73019, USA
| | - Xuanyu Tao
- Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, Gansu, 730000, China
| | - Jizhong Zhou
- Department of Microbiology and Plant Biology and Institute for Environmental Genomics, University of Oklahoma, Norman, OK, 73019, USA
| | - Yunfeng Yang
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing, 100084, China
| | - Mengxin Zhao
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing, 100084, China
| | - Xiaowei Zhang
- Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, Gansu, 730000, China
| | - Zhe Zheng
- Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, Gansu, 730000, China
| | - Tong Yuan
- Department of Microbiology and Plant Biology and Institute for Environmental Genomics, University of Oklahoma, Norman, OK, 73019, USA
| | - Pu Liu
- Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, Gansu, 730000, China
| | - Yong Chen
- Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, Gansu, 730000, China
| | - Virgo Nolan
- Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, Gansu, 730000, China
| | - Xiangkai Li
- Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, Gansu, 730000, China.
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19
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Zhang H, Ma Y, Liu P, Li X. Multidrug resistance operon emrAB contributes for chromate and ampicillin co-resistance in a Staphylococcus strain isolated from refinery polluted river bank. SPRINGERPLUS 2016; 5:1648. [PMID: 27722066 PMCID: PMC5033799 DOI: 10.1186/s40064-016-3253-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Accepted: 09/08/2016] [Indexed: 01/18/2023]
Abstract
EmrAB operon is known for multidrug resistance in bacteria and yet has not been reported related to heavy metal resistance or antibiotics/heavy metal co-resistance. Strain Staphylococcus aureus LZ-01 which was isolated from industrial wastewater discharging site can co-resist to 6 mM Cr(VI) and 0.75 mg/ml ampicillin. Transcriptome data showed that an emrAB operon was upregulated (1.29-folds for emrA, 2.14-folds for emrB) under 0.4 mM Cr(VI) treatment. Quantitative PCR results revealed that this operon was upregulated (1.60-folds for emrA, 2.34-folds for emrB) after 0.20 mg/ml ampicillin treatment. Mutant strain with emrA gene knockout resulted in a 0.83-folds decrease in chromate resistance, and a 0.80-folds decrease in ampicillin resistance; while emrB knockout strain resulted in a 0.33-folds decrease in chromate resistance, and a 0.60-folds decrease in ampicillin resistance. The complemented strains of both deletion mutants basically restored their resistant performance. The presence of 0.50 mM Cr(VI) induced an elevation in ampicillin resistance from 0.50 to 2.50 mg/ml in the strain LZ-01, similarly, its Cr(VI) resistance was also found to be elevated from 6 to 10 mM by 0.15 mg/ml ampicillin induction. The induction effect could be eliminated by deletion of emrA or emrB. Our results demonstrated that the chromosomal emrAB operon in Staphylococcus aureus LZ-01 was a new type of multidrug resistance system, which conferred both ampicillin and chromate resistance to host cells inhabiting polluted environments.
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Affiliation(s)
- He Zhang
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Tianshuinanlu #222, Lanzhou, 730000 Gansu People's Republic of China
| | - Yantian Ma
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Tianshuinanlu #222, Lanzhou, 730000 Gansu People's Republic of China ; School of Life Sciences, Nanchang University, Nanchang, 300031 Jiangxi People's Republic of China
| | - Pu Liu
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Tianshuinanlu #222, Lanzhou, 730000 Gansu People's Republic of China
| | - Xiangkai Li
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Tianshuinanlu #222, Lanzhou, 730000 Gansu People's Republic of China
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20
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Huang J, Li J, Wang G. Production of a microcapsule agent of chromate-reducing Lysinibacillus fusiformis ZC1 and its application in remediation of chromate-spiked soil. SPRINGERPLUS 2016; 5:561. [PMID: 27218011 PMCID: PMC4856709 DOI: 10.1186/s40064-016-2177-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Accepted: 04/18/2016] [Indexed: 11/10/2022]
Abstract
Lysinibacillus fusiformis ZC1 is an efficient Cr(VI)-reducing bacterium that can transform the toxic and soluble chromate [Cr(VI)] form to the less toxic and precipitated chromite form [Cr(III)]. As such, this strain might be applicable for bioremediation of Cr(VI) in soil by reducing its bioavailability. The study objective was to prepare a microcapsule agent of strain ZC1 for bioremediation of Cr(VI)-contaminated soil. Using a single-factor orthogonal array design, the optimal fermentation medium was obtained and consisted of 6 g/L corn flour, 12 g/L soybean flour, 8 g/L NH4Cl and 6 g/L CaCl2. After enlarged fermentation, the cell and spore densities were 5.9 × 109 and 1.7 × 108 cfu/mL, respectively. The fermentation products were collected and embedded with 1 % gum arabic and 1 % sorbitol as the microcapsule carriers and were subsequently spray-dried. Strain ZC1 exhibited viable cell counts of (3.6 ± 0.44) × 1010 cfu/g dw after 50-day storage at room temperature. In simulated soil bioremediation experiments, 67 % of Cr(VI) was reduced in 5 days with the inoculation of this microcapsule agent, and the Cr(VI) concentration was below the soil Cr(VI) standard level. The results demonstrated that the microcapsule agent of strain ZC1 is efficient for bioremediation of Cr(VI)-contaminated soil.
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Affiliation(s)
- Jun Huang
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070 People's Republic of China
| | - Jingxin Li
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070 People's Republic of China
| | - Gejiao Wang
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070 People's Republic of China
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Gillan DC. Metal resistance systems in cultivated bacteria: are they found in complex communities? Curr Opin Biotechnol 2016; 38:123-30. [DOI: 10.1016/j.copbio.2016.01.012] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2015] [Revised: 01/27/2016] [Accepted: 01/28/2016] [Indexed: 12/11/2022]
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Wu W, Huang H, Ling Z, Yu Z, Jiang Y, Liu P, Li X. Genome sequencing reveals mechanisms for heavy metal resistance and polycyclic aromatic hydrocarbon degradation in Delftia lacustris strain LZ-C. ECOTOXICOLOGY (LONDON, ENGLAND) 2016; 25:234-247. [PMID: 26589947 DOI: 10.1007/s10646-015-1583-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 10/30/2015] [Indexed: 06/05/2023]
Abstract
Strain LZ-C, isolated from a petrochemical wastewater discharge site, was found to be resistant to heavy metals and to degrade various aromatic compounds, including naphenol, naphthalene, 2-methylnaphthalene and toluene. Data obtained from 16S rRNA gene sequencing showed that this strain was closely related to Delftia lacustris. The 5,889,360 bp genome of strain LZ-C was assembled into 239 contigs and 197 scaffolds containing 5855 predicted open reading frames (ORFs). Among these predicted ORFs, 464 were different from the type strain of Delftia. The minimal inhibitory concentrations were 4 mM, 30 µM, 2 mM and 1 mM for Cr(VI), Hg(II), Cd(II) and Pb(II), respectively. Both genome sequencing and quantitative real-time PCR data revealed that genes related to Chr, Czc and Mer family genes play important roles in heavy metal resistance in strain LZ-C. In addition, the Na(+)/H(+) antiporter NhaA is important for adaptation to high salinity resistance (2.5 M NaCl). The complete pathways of benzene and benzoate degradation were identified through KEGG analysis. Interestingly, strain LZ-C also degrades naphthalene but lacks the key naphthalene degradation gene NahA. Thus, we propose that strain LZ-C exhibits a novel protein with a function similar to NahA. This study is the first to reveal the mechanisms of heavy metal resistance and salinity tolerance in D. lacustris and to identify a potential 2-methylnaphthalene degradation protein in this strain. Through whole-genome sequencing analysis, strain LZ-C might be a good candidate for the bioremediation of heavy metals and polycyclic aromatic hydrocarbons.
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Affiliation(s)
- Wenyang Wu
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, Gansu, People's Republic of China
| | - Haiying Huang
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, Gansu, People's Republic of China
| | - Zhenmin Ling
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, Gansu, People's Republic of China
| | - Zhengsheng Yu
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, Gansu, People's Republic of China
| | - Yiming Jiang
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, Gansu, People's Republic of China
| | - Pu Liu
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, Gansu, People's Republic of China
| | - Xiangkai Li
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, Gansu, People's Republic of China.
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