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Huang W, Chen H, Jia M, Li Q, Chen M, Guo X. Genomic and proteomic analyses reveal the reduction mechanism of hexavalent chromium by the culturing supernatant of strain Pediococcus acidilactici 13-7. JOURNAL OF HAZARDOUS MATERIALS 2024; 477:135161. [PMID: 39038378 DOI: 10.1016/j.jhazmat.2024.135161] [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: 12/25/2023] [Revised: 05/30/2024] [Accepted: 07/08/2024] [Indexed: 07/24/2024]
Abstract
This study used lactic acid bacteria with high antioxidative properties to screen for strains capable of reducing hexavalent chromium [Cr (VI)] in their culturing supernatants. The strain Pediococcus acidilactici 13-7 exhibited potent Cr (VI)-reducing capability and remarkable resistance to Cr (VI) even at concentration as high as 24 mM. Comparative genomics analysis revealed a unique gene, ChrR, associated with Cr (VI) reduction in this strain, distinguishing it from four reference strains of P. acidilactici. The proteomic investigation identified proteins linked to the ChrR gene, such as nqo1, frdA, and gshR, indicating significant enrichment in redox-related functions and oxidative phosphorylation pathways. These findings suggest that P. acidilactici 13-7 possesses superior electron transfer capacity compared to other strains, making it more adaptable under highly oxidative conditions by modulating the external environment to mitigate oxidative stress. Collectively, the results demonstrated the potential application of this lactic acid bacterial strain for bioremediation of heavy metals by its ability to reduce Cr (VI), and shed light on the molecular mechanisms underlying Cr (VI) reduction of the strain P. acidilactici 13-7.
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Affiliation(s)
- Wenkang Huang
- School of Life Sciences, Lanzhou University, Lanzhou, Gansu Province 730000, China; Probiotics and Life Health Institute, Lanzhou University, Lanzhou 730000, China
| | - Hu Chen
- School of Life Sciences, Lanzhou University, Lanzhou, Gansu Province 730000, China
| | - Mengya Jia
- School of Life Sciences, Lanzhou University, Lanzhou, Gansu Province 730000, China; Probiotics and Life Health Institute, Lanzhou University, Lanzhou 730000, China
| | - Qiang Li
- School of Life Sciences, Lanzhou University, Lanzhou, Gansu Province 730000, China; Probiotics and Life Health Institute, Lanzhou University, Lanzhou 730000, China
| | - Mengyan Chen
- School of Life Sciences, Lanzhou University, Lanzhou, Gansu Province 730000, China; Probiotics and Life Health Institute, Lanzhou University, Lanzhou 730000, China
| | - Xusheng Guo
- School of Life Sciences, Lanzhou University, Lanzhou, Gansu Province 730000, China; Probiotics and Life Health Institute, Lanzhou University, Lanzhou 730000, China.
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Jia B, Wan J, Liu H, Yan B, Zhang L, Su X. DIET-like and MIET-like mutualism of S. oneidensis MR-1 and metal-reducing function microflora boosts Cr(VI) reduction. JOURNAL OF HAZARDOUS MATERIALS 2024; 465:133401. [PMID: 38171202 DOI: 10.1016/j.jhazmat.2023.133401] [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: 11/15/2023] [Revised: 12/18/2023] [Accepted: 12/27/2023] [Indexed: 01/05/2024]
Abstract
Microbial treatment of Cr(VI) is an environmentally friendly and low-cost approach. However, the mechanism of mutualism and the role of interspecies electron transfer in Cr(VI) reducing microflora are unclear. Herein, we constructed an intersymbiotic microbial association flora to augment interspecies electron transfer via functionalizing electroactive Shewanella oneidensis MR-1 with metal-reducing microflora, and thus the efficiency of Cr(VI) reduction. The findings suggest that the metal-reducing active microflora could converts glucose into lactic acid and riboflavin for S. oneidensis MR-1 to act as a carbon source and electron mediator. Thus, when adding initial 25 mg/L Cr (VI), this microflora exhibited an outstanding Cr (VI) removal efficiency (100%) at 12 h and elevated Cr (III) immobilization efficiency (80%) at 60 h with the assistance of 25 mg/L Cu(II). A series of electrochemical experiments proved this remarkable removal efficiency were ascribed to the improved interspecies electron transfer efficiency through direct interspecies electron transfer and riboflavin through mediated interspecies electron transfer. Furthermore, the metagenomic analysis revealed the expression level of the electron transport pathway was promoted. Intriguing high abundance of genes participating in the bio-reduction and biotransformation of Cr(VI) was also observed in functional microflora. These outcomes give a novel strategy for enhancing the reduction and fixation of harmful heavy metals by coculturing function microflora with electrogenic microorganisms.
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Affiliation(s)
- Boyu Jia
- School of Environment and Energy, Guangdong Provincial Key Laboratory of Solid Wastes Pollution Control and Recycling, South China University of Technology, Guangzhou, Guangdong 510006, China
| | - Juanjuan Wan
- School of Environment and Energy, Guangdong Provincial Key Laboratory of Solid Wastes Pollution Control and Recycling, South China University of Technology, Guangzhou, Guangdong 510006, China
| | - Hui Liu
- Huadian Coal Industry Group Co., Ltd, Beijing 100035, China
| | - Bo Yan
- SCNU Environmental Research Institute, Guangdong Provincial Key Laboratory of Chemical Pollution and Environmental Safety & MOE Key Laboratory of Theoretical Chemistry of Environment, South China Normal University, Guangzhou 510006, China; School of Environment, South China Normal University, University Town, Guangzhou 510006, China
| | - Lijuan Zhang
- SCNU Environmental Research Institute, Guangdong Provincial Key Laboratory of Chemical Pollution and Environmental Safety & MOE Key Laboratory of Theoretical Chemistry of Environment, South China Normal University, Guangzhou 510006, China; School of Environment, South China Normal University, University Town, Guangzhou 510006, China.
| | - Xintai Su
- School of Environment and Energy, Guangdong Provincial Key Laboratory of Solid Wastes Pollution Control and Recycling, South China University of Technology, Guangzhou, Guangdong 510006, China.
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Xia G, Zhu S, Zhao W, Yang X, Sheng L, Mao H. Arbuscular mycorrhizal fungi alter rhizosphere fungal community characteristics of Acorus calamus to improve Cr resistance. PeerJ 2023; 11:e15681. [PMID: 37953782 PMCID: PMC10638908 DOI: 10.7717/peerj.15681] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Accepted: 06/13/2023] [Indexed: 11/14/2023] Open
Abstract
To investigate changes in fungal community characteristics under different Cr(VI) concentration stresses and the advantages of adding arbuscular mycorrhizal fungi (AMF), we used high throughput sequencing to characterize the fungal communities. Cr(VI) stress reduced rhizosphere soil SOM (soil organic matter) content and AMF addition improved this stress phenomenon. There were significant differences in fungal community changes under different Cr(VI) concentrations. The fungal community characteristics changed through inhibition of fungal metabolic ability, as fungal abundance increased after AMF addition, and the fungal diversity increased under high Cr(VI) concentration. The dominant phyla were members of the Ascomycota, Basidiomycota, Mortierellomycota, and Rozellomycota. Dominant groups relevant to Cr resistance were Ascomycota and Basidiomycota fungi. Moreover, Fungal community characteristics were analyzed using high-throughput sequencing of the cytochrome c metabolic pathway, NADH dehydrogenase, and NADH: ubiquinone reductase and all these functions were enhanced after AMF addition. Therefore, Cr(VI) stress significantly affects fungal community structure, while AMF addition could increase its SOM content, and metabolic capacity, and improve fungal community tolerance to Cr stress. This study contributed to the understanding response of rhizosphere fungal community in AMF-assisted wetland phytoremediation under Cr stress.
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Affiliation(s)
- Guodong Xia
- Guizhou Minzu University, The Karst Environmental Geological Hazard Prevention of Key Laboratory of State Ethnic Affairs Commission, Guiyang, Guizhou, China
| | - Sixi Zhu
- Guizhou Minzu University, The Karst Environmental Geological Hazard Prevention of Key Laboratory of State Ethnic Affairs Commission, Guiyang, Guizhou, China
| | - Wei Zhao
- Guizhou Minzu University, The Karst Environmental Geological Hazard Prevention of Key Laboratory of State Ethnic Affairs Commission, Guiyang, Guizhou, China
| | - Xiuqing Yang
- Guizhou Minzu University, Guiyang, Guizhou, China
| | - Luying Sheng
- Guizhou Minzu University, The Karst Environmental Geological Hazard Prevention of Key Laboratory of State Ethnic Affairs Commission, Guiyang, Guizhou, China
| | - Huan Mao
- Guizhou Minzu University, The Karst Environmental Geological Hazard Prevention of Key Laboratory of State Ethnic Affairs Commission, Guiyang, Guizhou, China
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Sun X, Feng H, Luo J, Lin L, Zhang H, Duan Y, Liu F, Zhang K, Wang B, Li D, Hu Y, Zhu Z. A novel N-arachidonoyl-l-alanine-catabolizing strain of Serratia marcescens for the bioremediation of Cd and Cr co-contamination. ENVIRONMENTAL RESEARCH 2023; 222:115376. [PMID: 36736755 DOI: 10.1016/j.envres.2023.115376] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Revised: 01/03/2023] [Accepted: 01/25/2023] [Indexed: 06/18/2023]
Abstract
Cadmium (Cd) and chromium (Cr) are widespread contaminants with a high risk to the environment and humans. Herein we isolated a novel strain of Serratia marcescens, namely strain S27, from soil co-contaminated with Cd and Cr. This strain showed strong resistance to Cd as well as Cr. S27 cells demonstrated Cd adsorption rate of 45.8% and Cr reduction capacity of 84.4% under optimal growth conditions (i.e., 30 °C, 200 rpm, and pH 7.5). Microscopic characterization of S27 cells revealed the importance of the functional groups C-O-C, C-H-O, C-C, C-H, and -OH, and also indicated that Cr reduction occurred on bacterial cell membrane. Cd(II) and Cr(VI) bioaccumulation on S27 cell surface was mainly in the form of Cd(OH)2 and Cr2O3, respectively. Further, metabolomic analyses revealed that N-arachidonoyl-l-alanine was the key metabolite that promoted Cd and Cr complexation by S27; it primarily promotes γ-linolenic acid (GLA) metabolism, producing siderophores and coordinating with organic acids to enhance metal bioavailability. To summarize, our results suggest that S27 is promising for the bioremediation of environments contaminated with Cd and Cr in tropical regions.
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Affiliation(s)
- Xiaoyan Sun
- College of Tropical Crops, Hainan University, Haikou, 570228, China
| | - Huiping Feng
- College of Tropical Crops, Hainan University, Haikou, 570228, China
| | - Jialiang Luo
- College of Tropical Crops, Hainan University, Haikou, 570228, China
| | - Li Lin
- Sugarcane Research Institute, Guangxi Academy of Agricultural Sciences, Nanning, 53007, China
| | - Haixiang Zhang
- College of Tropical Crops, Hainan University, Haikou, 570228, China
| | - Yali Duan
- College of Tropical Crops, Hainan University, Haikou, 570228, China
| | - Fan Liu
- College of Tropical Crops, Hainan University, Haikou, 570228, China
| | - Kailu Zhang
- College of Tropical Crops, Hainan University, Haikou, 570228, China
| | - Baijie Wang
- College of Tropical Crops, Hainan University, Haikou, 570228, China
| | - Dong Li
- Key Laboratory of Agro-Forestry Environmental Processes and Ecological, Regulation of Hainan Province/Center for Eco-Environmental Restoration, Engineering of Hainan Province/School of Ecology & Environment/State Key, Laboratory of Marine Resource Utilization in South China Sea/Key Laboratory for Environmental Toxicology of Haikou, Hainan University, Haikou, Hainan, 570228, China.
| | - Yueming Hu
- College of Tropical Crops, Hainan University, Haikou, 570228, China
| | - Zhiqiang Zhu
- College of Tropical Crops, Hainan University, Haikou, 570228, China.
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Yang W, Hong W, Huang Y, Li S, Li M, Zhong H, He Z. Exploration on the Cr(VI) resistance mechanism of a novel thermophilic Cr(VI)-reducing bacteria Anoxybacillus flavithermus ABF1 isolated from Tengchong geothermal region, China. ENVIRONMENTAL MICROBIOLOGY REPORTS 2022; 14:795-803. [PMID: 35701897 DOI: 10.1111/1758-2229.13070] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Accepted: 04/02/2022] [Indexed: 06/15/2023]
Abstract
Hexavalent chromium resistance and reduction mechanisms of microorganism provide a critical guidance for Cr(VI) bioremediation. However, related researches are limited in mesophiles and deficient for thermophiles. In this work, a novel alkaline Cr(VI)-reducing thermophile Anoxybacillus flavithermus ABF1 was isolated from geothermal region. The mechanisms of Cr(VI) resistance and reduction were investigated. The results demonstrated that A. flavithermus ABF1 could survive in a wide temperature range from 50°C to 70°C and in pH range of 7.0-9.0. Strain ABF1 showed excellent growth activity and Cr(VI) removal performance when initial Cr(VI) concentration was lower than 200 mg L-1 . 93.71% of Cr(VI) was removed at initial concentration of 20 mg L-1 after 72 h. The majority of Cr(VI) was found to be reduced extracellularly by enzymes secreted by cells. XPS and Raman analysis further manifested that Cr2 O3 was the product of Cr(VI) reduction. Moreover, the Cr(VI) transportation-related gene cysP and Cr(VI) reduction-related gene azoR of A. flavithermus ABF1 played key roles in inhibiting Cr(VI) entering cells and promoting extracellular Cr(VI) reduction respectively. This work provides novel insight into the mechanisms of Cr(VI) resistance and detoxication of thermophiles, which leads to a promising alternative strategy for heavy metal bioremediation in areas with elevated temperature.
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Affiliation(s)
- Wenjing Yang
- School of Minerals Processing and Bioengineering, Central South University, Changsha, China
| | - Wanqi Hong
- School of Minerals Processing and Bioengineering, Central South University, Changsha, China
| | - Yongji Huang
- School of Minerals Processing and Bioengineering, Central South University, Changsha, China
| | - Shuzhen Li
- School of Minerals Processing and Bioengineering, Central South University, Changsha, China
| | - Mengke Li
- School of Minerals Processing and Bioengineering, Central South University, Changsha, China
| | - Hui Zhong
- School of Life Sciences, Central South University, Changsha, China
| | - Zhiguo He
- School of Minerals Processing and Bioengineering, Central South University, Changsha, China
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Yu Z, Pei Y, Zhao S, Kakade A, Khan A, Sharma M, Zain H, Feng P, Ji J, Zhou T, Wang H, Wu J, Li X. Metatranscriptomic analysis reveals active microbes and genes responded to short-term Cr(VI) stress. ECOTOXICOLOGY (LONDON, ENGLAND) 2021; 30:1527-1537. [PMID: 33123966 DOI: 10.1007/s10646-020-02290-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 10/10/2020] [Indexed: 06/11/2023]
Abstract
Heavy metals have been severely polluting the environment. However, the response mechanism of microbial communities to short-term heavy metals stress remains unclear. In this study, metagenomics (MG) and metatranscriptomics (MT) was performed to observe the microbial response to short-term Cr(VI) stress. MG data showed that 99.1% of species were similar in the control and Cr(VI) treated groups. However, MT data demonstrated that 83% of the microbes were active in which 58.7% increased, while the relative abundance of 41.3% decreased after short-term Cr(VI) incubation. The MT results also revealed 9% of microbes were dormant in samples. Genes associated with oxidative stress, Cr(VI) transport, resistance, and reduction, as well as genes with unknown functions were 2-10 times upregulated after Cr(VI) treatment. To further confirm the function of unknown genes, two genes (314 and 494) were selected to detect the Cr(VI) resistance and reduction ability. The results showed that these genes significantly increased the Cr(VI) remediation ability of Escherichia coli. MT results also revealed an increase in the expression of some rare genera (at least two times) after Cr(VI) treatment, indicating these rare species played a crucial role in microbial response to short-term Cr(VI) stress. In summary, MT is an efficient way to understand the role of active and dormant microbes in specific environmental conditions.
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Affiliation(s)
- Zhengsheng Yu
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Tianshuinanlu #222, Lanzhou, 730000, Gansu, PR China
- Gansu Key Laboratory of Biomonitoring and Bioremediation for Environment Pollution, School of Life Science, Lanzhou University, Tianshuinanlu #222, Lanzhou, 730000, Gansu, PR China
| | - Yaxin Pei
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Tianshuinanlu #222, Lanzhou, 730000, Gansu, PR China
- Gansu Key Laboratory of Biomonitoring and Bioremediation for Environment Pollution, School of Life Science, Lanzhou University, Tianshuinanlu #222, Lanzhou, 730000, Gansu, PR China
| | - Shuai Zhao
- Gansu Key Laboratory of Biomonitoring and Bioremediation for Environment Pollution, School of Life Science, Lanzhou University, Tianshuinanlu #222, Lanzhou, 730000, Gansu, PR China
| | - Apurva Kakade
- Gansu Key Laboratory of Biomonitoring and Bioremediation for Environment Pollution, School of Life Science, Lanzhou University, Tianshuinanlu #222, Lanzhou, 730000, Gansu, PR China
| | - Aman Khan
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Tianshuinanlu #222, Lanzhou, 730000, Gansu, PR China
| | - Monika Sharma
- Gansu Key Laboratory of Biomonitoring and Bioremediation for Environment Pollution, School of Life Science, Lanzhou University, Tianshuinanlu #222, Lanzhou, 730000, Gansu, PR China
| | - Hajira Zain
- Gansu Key Laboratory of Biomonitoring and Bioremediation for Environment Pollution, School of Life Science, Lanzhou University, Tianshuinanlu #222, Lanzhou, 730000, Gansu, PR China
| | - Pengya Feng
- Gansu Key Laboratory of Biomonitoring and Bioremediation for Environment Pollution, School of Life Science, Lanzhou University, Tianshuinanlu #222, Lanzhou, 730000, Gansu, PR China
| | - Jing Ji
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Tianshuinanlu #222, Lanzhou, 730000, Gansu, PR China
- Gansu Key Laboratory of Biomonitoring and Bioremediation for Environment Pollution, School of Life Science, Lanzhou University, Tianshuinanlu #222, Lanzhou, 730000, Gansu, PR China
| | - Tuoyu Zhou
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Tianshuinanlu #222, Lanzhou, 730000, Gansu, PR China
| | - Haoyang Wang
- McMaster University, 1280 Main Street West, Hamilton, ON, Canada
| | - Jingyuan Wu
- The First Clinical Medical College, Lanzhou University, Tianshuinanlu #222, Lanzhou, 730000, Gansu, PR 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, PR China.
- Gansu Key Laboratory of Biomonitoring and Bioremediation for Environment Pollution, School of Life Science, Lanzhou University, Tianshuinanlu #222, Lanzhou, 730000, Gansu, PR China.
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Gong WJ, Wang XR, Zhao HP. Microbial reduction of Cr(VI) in the presence of Ni, Cu and Zn by bacterial consortium enriched from an electroplating contaminated site. Biodegradation 2021; 32:711-722. [PMID: 34528116 DOI: 10.1007/s10532-021-09962-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Accepted: 09/09/2021] [Indexed: 11/30/2022]
Abstract
The bioremediation of Cr(VI) has been intensively reported in recent years, while little information about Cr(VI)-reducing consortium enriched from in-situ contaminated soil has been revealed, specifically the functional genes involved. In this study, we verified a Cr(VI) reduction process by a consortium enriched from in-situ contaminated soil through enzymatic analysis. The chromate reductase gene ChrR has been successfully amplified and further analyzed, provided solid evidence to prove the Cr(VI) bio-reduction was an enzyme-mediated process. Meanwhile, the analysis of metabolic pathways demonstrates that the consortium could detoxicate and resist Cr(VI) and co-existing metals (Ni2+, Zn2+ and Cu2+) through membrane transport and DNA repair process. The co-existing heavy metals Zn and Cu had a relatively significant negative and positive effects on Cr(VI) reduction respectively, which may play important roles in the Cr(VI) contaminated soil bioremediation.
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Affiliation(s)
- Wen-Jing Gong
- MOE Key Lab of Environmental Remediation and Ecosystem Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Xing-Run Wang
- Chinese Research Academy of Environmental Sciences, Beijing, 100012, China
| | - He-Ping Zhao
- MOE Key Lab of Environmental Remediation and Ecosystem Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, Zhejiang, China.
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Yang X, Zhao Z, Nguyen BV, Hirayama S, Tian C, Lei Z, Shimizu K, Zhang Z. Cr(VI) bioremediation by active algal-bacterial aerobic granular sludge: Importance of microbial viability, contribution of microalgae and fractionation of loaded Cr. JOURNAL OF HAZARDOUS MATERIALS 2021; 418:126342. [PMID: 34329001 DOI: 10.1016/j.jhazmat.2021.126342] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Revised: 06/03/2021] [Accepted: 06/03/2021] [Indexed: 06/13/2023]
Abstract
In this study, chromium (Cr) was used as an example of the most toxic heavy metals that threaten human health, and Cr(VI) bioremediation was implemented by using a new type of aerobic granular sludge (AGS), i.e., algal-bacterial AGS. Results showed that the total Cr removal efficiency by active algal-bacterial AGS was 85.1 ± 0.6% after 6 h biosorption at pH 6 and room temperature, which could be further improved to 93.8 ± 0.4% with external electron donor (glucose) supply. However, inactivation dramatically decreased the total Cr removal efficiency to 29.6 ± 3.5%, and no effect was noticed when external electron donor was provided. With an antibiotic (levofloxacin) or metabolic inhibitor (NaN3) addition, the total Cr removal efficiency of bacterial AGS was inhibited by 16.0% or 10.1%, but this efficiency was maintained in the case of algal-bacterial AGS. Analysis of extracellular polymeric substances (EPS) composition revealed that under Cr(VI) exposure, more loosely bound EPS were secreted by algal-bacterial AGS, favoring Cr(VI) reduction. Results from chemical fractionation indicated that 90.5 ± 4.2% of the loaded Cr on algal-bacterial AGS was in an immobile form, reflecting the low environmental risk of Cr-loaded algal-bacterial AGS after biosorption of hazardous heavy metals from wastewater.
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Affiliation(s)
- Xiaojing Yang
- Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8572, Japan
| | - Ziwen Zhao
- Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8572, Japan
| | - Bach Van Nguyen
- Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8572, Japan
| | - Shota Hirayama
- Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8572, Japan
| | - Caixing Tian
- Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8572, Japan
| | - Zhongfang Lei
- Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8572, Japan.
| | - Kazuya Shimizu
- Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8572, Japan
| | - Zhenya Zhang
- Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8572, Japan
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9
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Yang X, Zhao Z, Zhang G, Hirayama S, Nguyen BV, Lei Z, Shimizu K, Zhang Z. Insight into Cr(VI) biosorption onto algal-bacterial granular sludge: Cr(VI) bioreduction and its intracellular accumulation in addition to the effects of environmental factors. JOURNAL OF HAZARDOUS MATERIALS 2021; 414:125479. [PMID: 33677316 DOI: 10.1016/j.jhazmat.2021.125479] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Revised: 02/18/2021] [Accepted: 02/18/2021] [Indexed: 06/12/2023]
Abstract
Hexavalent chromium (Cr(VI)) is one of the typical heavy metals that pose a great threat to the environment. As a novel biotechnology, algal-bacterial aerobic granular sludge (AGS) possesses the merits of both bacterial AGS and algae. This study firstly evaluated Cr(VI) removal via biosorption by algal-bacterial AGS under different operation conditions and then some environmental factors. Results show that the highest Cr(VI) reduction (99.3%) and total Cr removal (89.1%) were achieved within 6 h at pH 2 and 6, respectively. The coexisting oxyanions exhibited slight effects, while both tested natural organic matters (humic acid and tannic acid) and carbon sources promoted Cr(VI) reduction at some appropriate concentrations. The coexistence of metal cations favored Cr(VI) reduction, achieving the highest enhancement of 8.1% by Cu2+ at 5 mg/L, while the total Cr removal was suppressed to some extent. Salinity > 5 g/L severely inhibited both Cr(VI) reduction and total Cr removal. Moreover, the loaded Cr in algal-bacterial AGS was found to be almost in the form of Cr(III), with 66.8% being contributed by intracellular accumulation. This work suggests that Cr(VI) reduction and intracellular accumulation are the main mechanisms involved in Cr(IV) biosorption onto algal-bacterial AGS.
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Affiliation(s)
- Xiaojing Yang
- Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8572, Japan
| | - Ziwen Zhao
- Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8572, Japan
| | - Guanghao Zhang
- Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8572, Japan
| | - Shota Hirayama
- Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8572, Japan
| | - Bach Van Nguyen
- Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8572, Japan
| | - Zhongfang Lei
- Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8572, Japan.
| | - Kazuya Shimizu
- Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8572, Japan
| | - Zhenya Zhang
- Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8572, Japan
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Rahman Z, Thomas L. Chemical-Assisted Microbially Mediated Chromium (Cr) (VI) Reduction Under the Influence of Various Electron Donors, Redox Mediators, and Other Additives: An Outlook on Enhanced Cr(VI) Removal. Front Microbiol 2021; 11:619766. [PMID: 33584585 PMCID: PMC7875889 DOI: 10.3389/fmicb.2020.619766] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Accepted: 12/16/2020] [Indexed: 12/13/2022] Open
Abstract
Chromium (Cr) (VI) is a well-known toxin to all types of biological organisms. Over the past few decades, many investigators have employed numerous bioprocesses to neutralize the toxic effects of Cr(VI). One of the main process for its treatment is bioreduction into Cr(III). Key to this process is the ability of microbial enzymes, which facilitate the transfer of electrons into the high valence state of the metal that acts as an electron acceptor. Many underlying previous efforts have stressed on the use of different external organic and inorganic substances as electron donors to promote Cr(VI) reduction process by different microorganisms. The use of various redox mediators enabled electron transport facility for extracellular Cr(VI) reduction and accelerated the reaction. Also, many chemicals have employed diverse roles to improve the Cr(VI) reduction process in different microorganisms. The application of aforementioned materials at the contaminated systems has offered a variety of influence on Cr(VI) bioremediation by altering microbial community structures and functions and redox environment. The collective insights suggest that the knowledge of appropriate implementation of suitable nutrients can strongly inspire the Cr(VI) reduction rate and efficiency. However, a comprehensive information on such substances and their roles and biochemical pathways in different microorganisms remains elusive. In this regard, our review sheds light on the contributions of various chemicals as electron donors, redox mediators, cofactors, etc., on microbial Cr(VI) reduction for enhanced treatment practices.
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Affiliation(s)
- Zeeshanur Rahman
- Department of Botany, Zakir Husain Delhi College, University of Delhi, Delhi, India
| | - Lebin Thomas
- Department of Botany, Hansraj College, University of Delhi, Delhi, India
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Xia X, Wu S, Zhou Z, Wang G. Microbial Cd(II) and Cr(VI) resistance mechanisms and application in bioremediation. JOURNAL OF HAZARDOUS MATERIALS 2021; 401:123685. [PMID: 33113721 DOI: 10.1016/j.jhazmat.2020.123685] [Citation(s) in RCA: 83] [Impact Index Per Article: 27.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2020] [Revised: 07/16/2020] [Accepted: 08/05/2020] [Indexed: 05/21/2023]
Abstract
The heavy metals cadmium (Cd) and chromium (Cr) are extensively used in industry and result in water and soil contamination. The highly toxic Cd(II) and Cr(VI) are the most common soluble forms of Cd and Cr, respectively. They enter the human body through the food chain and drinking water and then cause serious illnesses. Microorganisms can adsorb metals or transform Cd(II) and Cr(VI) into insoluble or less bioavailable forms, and such strategies are applicable in Cd and Cr bioremediation. This review focuses on the highlighting of novel achievements on microbial Cd(II) and Cr(VI) resistance mechanisms and their bioremediation applications. In addition, the knowledge gaps and research perspectives are also discussed in order to build a bridge between the theoretical breakthrough and the resolution of Cd(II) and Cr(VI) contamination problems.
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Affiliation(s)
- Xian Xia
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei 430070, PR China; Hubei Key Laboratory of Edible Wild Plants Conservation & Utilization, Hubei Engineering Research Center of Special Wild Vegetables Breeding and Comprehensive Utilization Technology, National Experimental Teaching Demonstrating Center, College of Life Sciences, Hubei Normal University, Huangshi, 435002, PR China
| | - Shijuan Wu
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei 430070, PR China
| | - Zijie Zhou
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei 430070, PR China
| | - Gejiao Wang
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei 430070, PR China.
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12
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Han H, Zheng Y, Zhou T, Liu P, Li X. Cu(II) nonspecifically binding chromate reductase NfoR promotes Cr(VI) reduction. Environ Microbiol 2020; 23:415-430. [PMID: 33201569 DOI: 10.1111/1462-2920.15329] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 10/30/2020] [Accepted: 11/15/2020] [Indexed: 11/26/2022]
Abstract
Cu(II)-enhanced microbial Cr(VI) reduction is common in the environment, yet its mechanism is unknown. The specific activity of chromate reductase, NfoR, from Staphylococcus aureus sp. LZ-01 was augmented 1.5-fold by Cu(II). Isothermal titration calorimetry and spectral data show that Cu(II) binds to NfoR nonspecifically. Further, Cu(II) stimulates the nitrobenzene reduction of NfoR, indicating that Cu(II) promotes electron transfer. The crystal structure of NfoR in complex with CuSO4 (1.46 Å) was determined. The overall structure of NfoR-Cu(II) complex is a dimer that covalently binds with FMN and Cu(II)-binding pocket is located at the interface of the NfoR dimer. Structural superposition revealed that NfoR resembles the structure of class II chromate reductase. Site-directed mutagenesis revealed that Leu46 and Phe123 were involved in NADH binding, whereas Trp70 and Ser45 were the key residues for nitrobenzene binding. Furthermore, His100 and Asp171 were preferential affinity sites for Cu(II) and that Cys163 is an active site for FMN binding. Attenuation reductase activity in C163S can be partially restored to 54% wild type by increasing Cu(II) concentration. Partial restoration indicates dual-channel electron transfer of NfoR via Cu(II) and FMN. We propose a catalytic mechanism for Cu(II)-enhanced NfoR activity in which Cu(I) is formed transiently. Together, the current results provide an insight on Cu (II)-induced enhancement and benefit of Cr(VI) bioremediation.
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Affiliation(s)
- Huawen Han
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Science, Lanzhou University, Lanzhou, China
| | - Yuanzhang Zheng
- Department of Chemistry and Biochemistry, Loyola University Chicago, Chicago, IL, USA
| | - Tuoyu Zhou
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Science, Lanzhou University, Lanzhou, China
| | - Pu Liu
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Science, Lanzhou University, Lanzhou, China
| | - Xiangkai Li
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Science, Lanzhou University, Lanzhou, China
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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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NfoR: Chromate Reductase or Flavin Mononucleotide Reductase? Appl Environ Microbiol 2020; 86:AEM.01758-20. [PMID: 32887719 PMCID: PMC7642083 DOI: 10.1128/aem.01758-20] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Accepted: 09/01/2020] [Indexed: 01/07/2023] Open
Abstract
Soil bacteria can detoxify Cr(VI) ions by reduction. Within the last 2 decades, numerous reports of chromate reductase enzymes have been published. These reports describe catalytic reduction of chromate ions by specific enzymes. These enzymes each have sequence similarity to known redox-active flavoproteins. We investigated the enzyme NfoR from Staphylococcus aureus, which was reported to be upregulated in chromate-rich soils and to have chromate reductase activity (H. Han, Z. Ling, T. Zhou, R. Xu, et al., Sci Rep 7:15481, 2017, https://doi.org/10.1038/s41598-017-15588-y). We show that NfoR has structural similarity to known flavin mononucleotide (FMN) reductases and reduces FMN as a substrate. NfoR binds FMN with a dissociation constant of 0.4 μM. The enzyme then binds NADPH with a dissociation constant of 140 μM and reduces the flavin at a rate of 1,350 s-1 Turnover of the enzyme is apparently limited by the rate of product release that occurs, with a net rate constant of 0.45 s-1 The rate of product release limits the rate of observed chromate reduction, so the net rate of chromate reduction by NfoR is orders of magnitude lower than when this process occurs in solution. We propose that NfoR is an FMN reductase and that the criterion required to define chromate reduction as enzymatic has not been met. That NfoR expression is increased in the presence of chromate suggests that the survival adaption was to increase the net rate of chromate reduction by facile, adventitious redox processes.IMPORTANCE Chromate is a toxic by-product of multiple industrial processes. Chromate reduction is an important biological activity that ameliorates Cr(VI) toxicity. Numerous researchers have identified chromate reductase activity by observing chromate reduction. However, all identified chromate reductase enzymes have flavin as a cofactor or use a flavin as a substrate. We show here that NfoR, an enzyme claimed to be a chromate reductase, is in fact an FMN reductase. In addition, we show that reduction of a flavin is a viable way to transfer electrons to chromate but that it is unlikely to be the native function of enzymes. We propose that upregulation of a redox-active flavoprotein is a viable means to detoxify chromate that relies on adventitious reduction that is not catalyzed.
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Liao Q, Tang J, Wang H, Yang W, He L, Wang Y, Yang Z. Dynamic proteome responses to sequential reduction of Cr(VI) and adsorption of Pb(II) by Pannonibacter phragmitetus BB. JOURNAL OF HAZARDOUS MATERIALS 2020; 386:121988. [PMID: 31901545 DOI: 10.1016/j.jhazmat.2019.121988] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Revised: 11/30/2019] [Accepted: 12/26/2019] [Indexed: 06/10/2023]
Abstract
Here, the microbial responses to Cr(VI) and Pb(II) with bio-removal of the metals in water by Pannonibacter phragmitetus BB were explored. The comparative bacterial proteomics showed that the intracellular and extracellular Cr(VI) reduction proteins, Pb(II) adsorption by the lipoprotein and sugar-related bacterial proteins, as well as Pb(II) precipitation by phosphate and OH- were vital to the bio-removal of Cr(VI) and Pb(II). Moreover, the influx and efflux channels of Cr(VI) and Cr(III), Pb(II) transporters, extracellular siderophores for Pb(II) complexation and antioxidant proteins enabled the strain BB to resist the toxicity of Cr(VI) and Pb(II). In addition, the dynamic expression levels of the proteins related to reduction and transportation of Cr(VI), and adsorption, transportation and complexation of Pb(II) were dependent on the corresponding metal, respectively. The anti-oxidative stress system, such as superoxide dismutase, and Na+/H+ antiporters played central roles in the protein-protein interaction network to resist and detoxify Cr(VI) and Pb(II). The results of our study provide a novel insight for the physiological responses of the strain BB to the combined stresses of Pb(II) and Cr(VI).
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Affiliation(s)
- Qi Liao
- Institute of Environmental Science and Engineering, School of Metallurgy and Environment, Central South University, 410083, Changsha, China; National Engineering Research Center for Heavy Metals Pollution Control and Treatment, 410083, Changsha, China
| | - Jiaqi Tang
- Institute of Environmental Science and Engineering, School of Metallurgy and Environment, Central South University, 410083, Changsha, China
| | - Haiying Wang
- Institute of Environmental Science and Engineering, School of Metallurgy and Environment, Central South University, 410083, Changsha, China; National Engineering Research Center for Heavy Metals Pollution Control and Treatment, 410083, Changsha, China; Water Pollution Control Technology Key Lab of Hunan Province, 410083, Changsha, China
| | - Weichun Yang
- Institute of Environmental Science and Engineering, School of Metallurgy and Environment, Central South University, 410083, Changsha, China; National Engineering Research Center for Heavy Metals Pollution Control and Treatment, 410083, Changsha, China; Water Pollution Control Technology Key Lab of Hunan Province, 410083, Changsha, China
| | - Lixu He
- Institute of Environmental Science and Engineering, School of Metallurgy and Environment, Central South University, 410083, Changsha, China
| | - Yangyang Wang
- Institute of Environmental Science and Engineering, School of Metallurgy and Environment, Central South University, 410083, Changsha, China; College of Environment and Planning, Henan University, 475004, Kaifeng, China
| | - Zhihui Yang
- Institute of Environmental Science and Engineering, School of Metallurgy and Environment, Central South University, 410083, Changsha, China; National Engineering Research Center for Heavy Metals Pollution Control and Treatment, 410083, Changsha, China.
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16
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An Q, Deng S, Xu J, Nan H, Li Z, Song JL. Simultaneous reduction of nitrate and Cr(VI) by Pseudomonas aeruginosa strain G12 in wastewater. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2020; 191:110001. [PMID: 31812281 DOI: 10.1016/j.ecoenv.2019.110001] [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: 08/23/2019] [Revised: 11/20/2019] [Accepted: 11/23/2019] [Indexed: 06/10/2023]
Abstract
The interference of toxic heavy metals in the process of microbial aerobic denitrification is a hot issue in industry wastewater treatment in recent years. In this study, a multifunctional aerobic denitrifying bacterium - Pseudomonas aeruginosa G12 isolated from sewage sludge was used to explore the simultaneous removal ability to NO3--N and Cr(VI) in wastewater by a series of batch experiments. The results showed that G12 could effectively remove NO3--N (500 mg L-1) and Cr(VI) (10 mg L-1) by 98% and 93%, respectively. Meanwhile, the study found that the strain G12 had the potential to adapt to the complex external environment, including different carbon resources, nitrogen sources, and the coexisting heavy metals (Mn2+ and Cu2+). The strain G12 also had the considerable tolerance to initial NO3--N (100-700 mg L-1) and Cr(VI) (1-20 mg L-1) concentrations. The instrument analysis methods-Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD), from the molecular level, further confirmed that the strain G12 could remove NO3--N by aerobic denitrification, and the reduced functional groups (amino group, amide group, hydroxyl group and carboxyl group) on the surface of bacteria could transform Cr(VI) to Cr(III) (mainly CrCl3). This study will offer a promising new microbial resource for nitrogen and Cr(VI) removal in industry wastewater treatment.
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Affiliation(s)
- Qiang An
- College of Environment and Ecology, Chongqing University, Chongqing, 400045, PR China; The Key Laboratory of Eco-environments in Three Gorges Reservoir Region, Chongqing University, Chongqing, 400045, PR China.
| | - Shuman Deng
- College of Environment and Ecology, Chongqing University, Chongqing, 400045, PR China
| | - Jia Xu
- College of Environment and Ecology, Chongqing University, Chongqing, 400045, PR China
| | - Hongyan Nan
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai, 2002405, PR China
| | - Zheng Li
- College of Environment and Ecology, Chongqing University, Chongqing, 400045, PR China
| | - Jia-Li Song
- College of Environment and Ecology, Chongqing University, Chongqing, 400045, PR China
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