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Liu A, Wang W, Zheng X, Chen X, Fu W, Wang G, Ji J, Jin C, Guan C. Improvement of the Cd and Zn phytoremediation efficiency of rice (Oryza sativa) through the inoculation of a metal-resistant PGPR strain. CHEMOSPHERE 2022; 302:134900. [PMID: 35568210 DOI: 10.1016/j.chemosphere.2022.134900] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 05/04/2022] [Accepted: 05/06/2022] [Indexed: 06/15/2023]
Abstract
Cadmium (Cd) and zinc (Zn) in contaminated soil inhibit rice yield and produce toxic effects on human body through rice accumulation. Plant growth promoting rhizobacteria (PGPR) assisted phytoremediation is an effective ecological measure to improve the remediation efficiency of heavy metal contaminated soil. The purpose of this study was to investigate the efficiency of the combination of rice and Cd/Zn-tolerant PGPR strain Bacillus sp. ZC3-2-1 for the remediation of Cd-Zn contaminated soil. Moreover, the effects of inoculations on rhizosphere bacterial communities and ion homeostasis of rice under Cd-Zn exposure will also be explored. The results showed that compared with the treatment without inoculation, ZC3-2-1 decreased the bioavailable Cd and Zn concentrations in soil by 39.3% and 32.0%, respectively, and increase the phytoextraction of Cd2+ and Zn2+ by rice to 48.2% and 8.0%, respectively. This inoculation process significantly increased the rice biomass, resulting that the contents of Cd2+ and Zn2+ per biomass unit of rice didn't change significantly. This fact meant that ZC3-2-1 could improve the phytoremediation efficiency of Cd-Zn contaminated soil by promoting the phytoextraction and immobilization of the metal, while might not affect the crop food safety. Besides, through regulation of the Na+ and Mg2+ concentration in rice, ZC3-2-1 played a positive role in maintaining ion homeostasis which was disrupted by Zn or Cd. Moreover, ZC3-2-1 could modulate the beneficial bacterial communities in rice rhizosphere soil, and then enhanced Cd-Zn immobilization and enzyme activities in soil, leading to the enhancement of rice growth and phytoremediation efficiency. Above all, this study provided novel insights into developing an efficient phytoremediation system and safe production of rice in Cd-Zn contaminated soil with the application of Bacillus sp. ZC3-2-1, as well as advance our understanding of the principles of rhizosphere bacterial community assemble and maintaining ion homeostasis in rice during this phytoremediation process.
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Affiliation(s)
- Anran Liu
- School of Environmental Science and Engineering, Tianjin University, 92 Weijin Road, Tianjin, 300072, China
| | - Wenjing Wang
- School of Environmental Science and Engineering, Tianjin University, 92 Weijin Road, Tianjin, 300072, China
| | - Xiaoyan Zheng
- School of Environmental Science and Engineering, Tianjin University, 92 Weijin Road, Tianjin, 300072, China
| | - Xiancao Chen
- School of Environmental Science and Engineering, Tianjin University, 92 Weijin Road, Tianjin, 300072, China
| | - Wenting Fu
- School of Environmental Science and Engineering, Tianjin University, 92 Weijin Road, Tianjin, 300072, China
| | - Gang Wang
- School of Environmental Science and Engineering, Tianjin University, 92 Weijin Road, Tianjin, 300072, China
| | - Jing Ji
- School of Environmental Science and Engineering, Tianjin University, 92 Weijin Road, Tianjin, 300072, China
| | - Chao Jin
- School of Environmental Science and Engineering, Tianjin University, 92 Weijin Road, Tianjin, 300072, China
| | - Chunfeng Guan
- School of Environmental Science and Engineering, Tianjin University, 92 Weijin Road, Tianjin, 300072, China.
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Zhou J, Song Z, Zhang R, Liu R, Wu Q, Li J, Tang X, Xu B, Ding J, Han N, Huang Z. Distinctive molecular and biochemical characteristics of a glycoside hydrolase family 20 β-N-acetylglucosaminidase and salt tolerance. BMC Biotechnol 2017; 17:37. [PMID: 28399848 PMCID: PMC5387316 DOI: 10.1186/s12896-017-0358-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Accepted: 04/04/2017] [Indexed: 12/05/2022] Open
Abstract
Background Enzymatic degradation of chitin has attracted substantial attention because chitin is an abundant renewable natural resource, second only to lignocellulose, and because of the promising applications of N-acetylglucosamine in the bioethanol, food and pharmaceutical industries. However, the low activity and poor tolerance to salts and N-acetylglucosamine of most reported β-N-acetylglucosaminidases limit their applications. Mining for novel enzymes from new microorganisms is one way to address this problem. Results A glycoside hydrolase family 20 (GH 20) β-N-acetylglucosaminidase (GlcNAcase) was identified from Microbacterium sp. HJ5 harboured in the saline soil of an abandoned salt mine and was expressed in Escherichia coli. The purified recombinant enzyme showed specific activities of 1773.1 ± 1.1 and 481.4 ± 2.3 μmol min−1 mg−1 towards p-nitrophenyl β-N-acetylglucosaminide and N,N'-diacetyl chitobiose, respectively, a Vmax of 3097 ± 124 μmol min−1 mg−1 towards p-nitrophenyl β-N-acetylglucosaminide and a Ki of 14.59 mM for N-acetylglucosamine inhibition. Most metal ions and chemical reagents at final concentrations of 1.0 and 10.0 mM or 0.5 and 1.0% (v/v) had little or no effect (retaining 84.5 − 131.5% activity) on the enzyme activity. The enzyme can retain more than 53.6% activity and good stability in 3.0–20.0% (w/v) NaCl. Compared with most GlcNAcases, the activity of the enzyme is considerably higher and the tolerance to salts and N-acetylglucosamine is much better. Furthermore, the enzyme had higher proportions of aspartic acid, glutamic acid, alanine, glycine, random coils and negatively charged surfaces but lower proportions of cysteine, lysine, α-helices and positively charged surfaces than its homologs. These molecular characteristics were hypothesised as potential factors in the adaptation for salt tolerance and high activity of the GH 20 GlcNAcase. Conclusions Biochemical characterization revealed that the GlcNAcase had novel salt–GlcNAc tolerance and high activity. These characteristics suggest that the enzyme has versatile potential in biotechnological applications, such as bioconversion of chitin waste and the processing of marine materials and saline foods. Molecular characterization provided an understanding of the molecular–function relationships for the salt tolerance and high activity of the GH 20 GlcNAcase. Electronic supplementary material The online version of this article (doi:10.1186/s12896-017-0358-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Junpei Zhou
- Engineering Research Center of Sustainable Development and Utilization of Biomass Energy, Ministry of Education, Yunnan Normal University, Kunming, 650500, People's Republic of China.,College of Life Sciences, Yunnan Normal University, No. 768 Juxian Street, Chenggong, Kunming, Yunnan, 650500, People's Republic of China.,Key Laboratory of Yunnan for Biomass Energy and Biotechnology of Environment, Yunnan, Kunming, 650500, People's Republic of China.,Key Laboratory of Enzyme Engineering, Yunnan Normal University, Kunming, 650500, People's Republic of China
| | - Zhifeng Song
- College of Life Sciences, Yunnan Normal University, No. 768 Juxian Street, Chenggong, Kunming, Yunnan, 650500, People's Republic of China
| | - Rui Zhang
- Engineering Research Center of Sustainable Development and Utilization of Biomass Energy, Ministry of Education, Yunnan Normal University, Kunming, 650500, People's Republic of China.,College of Life Sciences, Yunnan Normal University, No. 768 Juxian Street, Chenggong, Kunming, Yunnan, 650500, People's Republic of China.,Key Laboratory of Yunnan for Biomass Energy and Biotechnology of Environment, Yunnan, Kunming, 650500, People's Republic of China.,Key Laboratory of Enzyme Engineering, Yunnan Normal University, Kunming, 650500, People's Republic of China
| | - Rui Liu
- College of Life Sciences, Yunnan Normal University, No. 768 Juxian Street, Chenggong, Kunming, Yunnan, 650500, People's Republic of China
| | - Qian Wu
- Engineering Research Center of Sustainable Development and Utilization of Biomass Energy, Ministry of Education, Yunnan Normal University, Kunming, 650500, People's Republic of China.,College of Life Sciences, Yunnan Normal University, No. 768 Juxian Street, Chenggong, Kunming, Yunnan, 650500, People's Republic of China.,Key Laboratory of Yunnan for Biomass Energy and Biotechnology of Environment, Yunnan, Kunming, 650500, People's Republic of China.,Key Laboratory of Enzyme Engineering, Yunnan Normal University, Kunming, 650500, People's Republic of China
| | - Junjun Li
- Engineering Research Center of Sustainable Development and Utilization of Biomass Energy, Ministry of Education, Yunnan Normal University, Kunming, 650500, People's Republic of China.,College of Life Sciences, Yunnan Normal University, No. 768 Juxian Street, Chenggong, Kunming, Yunnan, 650500, People's Republic of China.,Key Laboratory of Yunnan for Biomass Energy and Biotechnology of Environment, Yunnan, Kunming, 650500, People's Republic of China.,Key Laboratory of Enzyme Engineering, Yunnan Normal University, Kunming, 650500, People's Republic of China
| | - Xianghua Tang
- Engineering Research Center of Sustainable Development and Utilization of Biomass Energy, Ministry of Education, Yunnan Normal University, Kunming, 650500, People's Republic of China.,College of Life Sciences, Yunnan Normal University, No. 768 Juxian Street, Chenggong, Kunming, Yunnan, 650500, People's Republic of China.,Key Laboratory of Yunnan for Biomass Energy and Biotechnology of Environment, Yunnan, Kunming, 650500, People's Republic of China.,Key Laboratory of Enzyme Engineering, Yunnan Normal University, Kunming, 650500, People's Republic of China
| | - Bo Xu
- Engineering Research Center of Sustainable Development and Utilization of Biomass Energy, Ministry of Education, Yunnan Normal University, Kunming, 650500, People's Republic of China.,College of Life Sciences, Yunnan Normal University, No. 768 Juxian Street, Chenggong, Kunming, Yunnan, 650500, People's Republic of China.,Key Laboratory of Yunnan for Biomass Energy and Biotechnology of Environment, Yunnan, Kunming, 650500, People's Republic of China.,Key Laboratory of Enzyme Engineering, Yunnan Normal University, Kunming, 650500, People's Republic of China
| | - Junmei Ding
- Engineering Research Center of Sustainable Development and Utilization of Biomass Energy, Ministry of Education, Yunnan Normal University, Kunming, 650500, People's Republic of China.,College of Life Sciences, Yunnan Normal University, No. 768 Juxian Street, Chenggong, Kunming, Yunnan, 650500, People's Republic of China.,Key Laboratory of Yunnan for Biomass Energy and Biotechnology of Environment, Yunnan, Kunming, 650500, People's Republic of China.,Key Laboratory of Enzyme Engineering, Yunnan Normal University, Kunming, 650500, People's Republic of China
| | - Nanyu Han
- Engineering Research Center of Sustainable Development and Utilization of Biomass Energy, Ministry of Education, Yunnan Normal University, Kunming, 650500, People's Republic of China.,College of Life Sciences, Yunnan Normal University, No. 768 Juxian Street, Chenggong, Kunming, Yunnan, 650500, People's Republic of China.,Key Laboratory of Yunnan for Biomass Energy and Biotechnology of Environment, Yunnan, Kunming, 650500, People's Republic of China.,Key Laboratory of Enzyme Engineering, Yunnan Normal University, Kunming, 650500, People's Republic of China
| | - Zunxi Huang
- Engineering Research Center of Sustainable Development and Utilization of Biomass Energy, Ministry of Education, Yunnan Normal University, Kunming, 650500, People's Republic of China. .,College of Life Sciences, Yunnan Normal University, No. 768 Juxian Street, Chenggong, Kunming, Yunnan, 650500, People's Republic of China. .,Key Laboratory of Yunnan for Biomass Energy and Biotechnology of Environment, Yunnan, Kunming, 650500, People's Republic of China. .,Key Laboratory of Enzyme Engineering, Yunnan Normal University, Kunming, 650500, People's Republic of China.
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