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Acta Agronomica Sinica ›› 2024, Vol. 50 ›› Issue (10): 2538-2549.doi: 10.3724/SP.J.1006.2024.44046

• TILLAGE & CULTIVATION·PHYSIOLOGY & BIOCHEMISTRY • Previous Articles     Next Articles

Photosynthetic repair of Glycine max (Linn.) Merr. by compound fungus agents and immobilization effect under cadmium stress

LIU Hong-Yuan(), CEN Kai, LIU Yi-Lin, LOU Xue-Yi, ZHANG Ya-Ting, WU Jia-Rui, TAN Yu-Yu, ZHU Jia-Cheng, FANG Fang, LIU Peng*()   

  1. College of Life Science, Zhejiang Normal University / Botany Laboratory, Jinhua 321004, Zhejiang, China
  • Received:2024-03-13 Accepted:2024-06-20 Online:2024-10-12 Published:2024-07-08
  • Contact: *E-mail: sky79@zjnu.cn
  • Supported by:
    National Natural Science Foundation of China(32001224);National Natural Science Foundation of China(41702181);Project of Jinhua Science and Technology Program(2022-4-049)

Abstract:

Cadmium, a highly toxic heavy metal affecting food crops like soybean, not only inhibits plant growth and development but also damages the photosynthetic system, leading to reduced photosynthesis rates. Current cadmium remediation technologies primarily focus on the application of plant hormones and alteration of planting patterns, while the interaction between microorganisms and plants remains underexplored. This study aims to explore the remediation potential of compound white rot fungi in addressing cadmium pollution and the practical application value of immobilization technology. Four types of white rot fungi and Glycine max (Linn.) Merr. were used to prepare solid bacterial agents and set up a soil cultivation method for soybeans. We simulated cadmium-contaminated soil concentrations of 0, 50, and 100 mg L-1. Three treatments were conducted for each concentration: a control group (CK) with no treatment, an experimental group with free strains (EG1), and an experimental group with solid agents (EG2). We examined the effects of mixed fermentation and immobilization technology on the strains’ adsorption efficiency and established the correlation between cadmium toxicity, immobilized microspheres, and soybean plants. The results indicate that, except for Phanerochaete chrysosporium, the other three strains demonstrated good compatibility. A mixed group of bacterial strains containing Pleurotus sajor-caju and Coriolus versicolor in a 1:1 ratio achieved an adsorption rate of 87.33% in cadmium-contaminated solutions at a concentration of 50 mg L-1. To prolong the duration and improve the adsorption effect of the mixed strain, PVA mixed pellets with a sodium alginate (SA) concentration of 10 g L-1, biochar mass concentration of 15 g L-1, and bacterial content of 2% achieved a degradation rate of (95.12 ± 1.68)% within 96 hours after adding appropriate additives. Introducing immobilized mixed bacteria into simulated cadmium-contaminated soil inhibited the growth and photosynthetic indices of soybeans. The maximum decrease in Fo was 42.5%, and the maximum increase in Fv/Fm was 17.2%. After 14 days, the soybean antioxidant system was enhanced, with the highest activities of SOD, POD, and CAT being 27.34%, 12.41%, and 13.58%, respectively, in the CK group. Additionally, there was an increase in proline content and a decrease in malondialdehyde content, indicating enhanced plant resistance. In conclusion, cadmium stress suppresses the photochemical reaction center II in plants’ photosystems. The immobilization of mixed strains results in higher adsorption efficiency compared to single or free states. Applying a reliable bacterial agent enables soybeans to effectively trigger their light protection mechanism, produce osmoregulatory substances, and activate the antioxidant system, thus maintaining a stable redox environment and coping with cadmium stress.

Key words: white rot fungi, mixed fermentation, immobilization technology, cadmium-contaminated soil

Fig. 1

Degradation rate of four white rot fungi at different concentrations of Cd2+ The error bars indicate the standard deviation. Different lowercase letters indicate significant differences between treatments of the same variety (P <0.05)."

Table 1

Cd2+ adsorption by each group of mixed white rot fungi strains at different times"

分组Group 24 h 48 h 72 h 96 h
1/2 黄孢+1/2 云芝
1/2 P. chrysosporium + 1/2 C. versicolor
69.60±0.12 d 71.20±0.76 e 72.63±0.22 d 73.54±0.33 f
1/2 黃孢+1/2 平菇
1/2 P. chrysosporium + 1/2 P. ostreatus
65.03±0.44 e 65.62±0.57 f 72.88±0.11 d 73.36±0.45 f
1/2 黃孢+1/2 凤尾
1/2 P. chrysosporium + 1/2 P. sajor-caju
75.29±0.86 c 77.91±0.54 c 78.48±0.95 c 79.75±0.18 d
1/2 云芝+1/2 黃孢
1/2 C. versicolor + 1/2 P. chrysosporium
70.02±0.58 d 70.19±0.87 e 74.34±0.32 c 74.37±0.15 e
1/2 云芝+1/2 平菇
1/2 C. versicolor + 1/2 P. ostreatus
84.31±0.71 a 84.20±0.94 a 84.91±0.87 a 85.13±0.67 b
1/2 云芝+1/2 凤尾
1/2 C. versicolor + 1/2 P. sajor-caju
85.15±0.24 a 85.94±0.91 a 86.63±0.93 a 86.79±0.54 a
1/2 平菇+1/2 黃孢
1/2 P. ostreatus + 1/2 P. chrysosporium
68.92±0.91 d 73.00±0.12 d 74.08±0.12 c 73.92±0.27 ef
1/2 平菇+1/2 云芝
1/2 P. ostreatus + 1/2 C. versicolor
65.11±0.23 e 70.48±0.65 e 74.66±0.78 c 74.79±0.78 e
1/2 平菇+1/2 凤尾
1/2 P. ostreatus + 1/2 P. sajor-caju
58.73±0.78 g 67.25±0.76 f 68.18±0.87 e 69.10±0.45 g
1/2 凤尾+1/2 黃孢
1/2 P. sajor-caju + 1/2 P. chrysosporium
59.13±0.21 g 66.06±0.69 f 67.23±0.78 e 67.81±0.54 h
1/2 凤尾+1/2 云芝
1/2 P. sajor-caju + 1/2 C. versicolor
75.88±0.87 c 76.00±0.86 c 80.23±0.21 b 81.27±0.67 c
1/2 凤尾+1/2 平菇
1/2 P. sajor-caju + 1/2 P. ostreatus
78.51±0.97 b 82.39±0.24 b 84.28±0.67 a 84.58±0.45 b
1/3 黃孢+1/3 云芝+1/3 平菇
1/3 P. chrysosporium + 1/3 C. versicolor + 1/3 P. ostreatus
73.51±0.95 c 75.29±0.81 c 80.17±0.43 b 81.91±0.78 c
1/3 黃孢+1/3 平菇+1/3 凤尾
1/3 P. chrysosporium + 1/3 P. ostreatus + 1/3 P. sajor-caju
62.54±0.57 f 64.72±0.88 f 65.46±0.12 f 66.31±0.34 i
1/3 云芝+1/3 平菇+1/3 凤尾
1/3 C. versicolor + 1/3 P. ostreatus + 1/3 P. sajor-caju
79.21±0.41 b 76.50±0.61 c 84.24±0.57 a 85.14±0.78 b

Table 2

Factor levels of orthogonal experiments (33) of immobilized white rot bacteria"

试验号
Test number
A B C 96 h Cd吸附率
96 h Cd adsorption rate (%)
SA质量浓度
SA mass concentration
(g L-1)
BC质量浓度
BC mass concentration
(g L-1)
加菌量
Amount of mixed fungi
(%)
1 1(5) 1(15) 1(1) 86.65±0.16 b
2 1 2(20) 2(2) 91.62±1.85 a
3 1 3(25) 3(3) 83.07±0.01 c
4 2(10) 1 2 93.88±0.74 a
5 2 2 3 92.56±2.07 c
6 2 3 1 90.59±0.21 b
7 3(15) 1 3 84.99±0.83 b
8 3 2 1 86.99±0.83 b
9 3 3 2 87.29±0.82 a

Table 3

Selection of other production formulations and production conditions"

项目
Item
处理组
Processing group
机械强度
Mechanical strength
(mN)
Cd吸附率
Cd adsorption rate (%)
交联时间
Cross-linking time
1 h 1531±47.49 e 86.45±1.59 c
4 h 1944±64.40 d 90.42±0.55 b
8 h 2024±44.92 cd 82.91±1.47 d
12 h 2103±85.02 c 75.55±1.62 f
24 h 2388±41.54 b 73.33±2.15 f
36 h 2767±63.98 a 69.56±0.99 g
保存方法
Method of saving
冷冻保存
Cryopreservation
2054±64.23 d 80.67±0.51 e
0.2 mol L-1 NaH2PO4的饱和硼酸溶液
0.2 mol L-1 NaH2PO4 of a saturated boric acid solution
2411±45.41 b 83.54±1.03 d
湿体冷藏环境
Moisture cold storage environment
2326±06.43 c 84.34±1.27 cd
5 mg L-1 Cd模拟废水中冷藏
5 mg L-1 Cd simulated wastewater
2453±56.65 a 91.44±1.35 b
二氧化硅和
沸石添加情况
SiO2 and zeolite addition condition
加入10 g二氧化硅, 未加入沸石
10 g of silica was added, and no modified zeolite was added
2508±42.68 b 91.65±0.47 b
加入5 g沸石, 未加入二氧化硅
5 g of modified zeolite was added, without silica being added
2487±26.32 bc 92.39±0.79 b
加入10 g二氧化硅, 5 g沸石
10 g of silica was added and 5 g of modified zeolite
2523±12.54 b 95.12±1.68 a

Fig. 2

Visual view sphere EM scan figure of immobilized mixed pellets"

Table 4

Apparent determination of immobilized PVA"

小球各指标
Small ball indicators
载菌量
Loage
(cfu mL-1)
真密度
True density
(g L-1)
堆积密度
Accumulacking density (g L-1)
含水倍率
Water content (%)
含水率
Rate of water content (%)
比表面积
Specific surface area (m2 g-1)
测定结果
Determination results
(4.13±0.01)×106 1.231±0.014 0.734±0.001 55.20±2.21 1.147±0.04 318.69±4.27

Fig. 3

Effect of cadmium on soybean plant height and leaf area under different treatments The error bars represent the standard deviation. Different lowercase letters represent significant differences among treatments during the same reproductive period at the P < 0.05. CK: no treatment; EG1: free strain; EG2: solid bacteria agent; Cd0: 0 mg L-1 Cd; Cd50: 50 mg L-1 Cd Cd100: 100 mg L-1 Cd."

Fig. 4

Effect of cadmium on various fluorescence parameters of soybean under different treatments The error bars indicate the standard deviation. Different lowercase letters indicate significant differences between treatments during the same stress period (P <0.05). Treatments are the same as those given in Fig. 3."

Fig. 5

Effect of cadmium on SOD, POD, and CAT activity of soybean under different treatments The error bars indicate the standard deviation. Different lowercase letters indicate significant differences between treatments during the same stress period (P < 0.05). Treatments are the same as those given in Fig. 3."

Fig. 6

Changes of Pro content and MDA content in soybean under different cadmium treatments The error bars indicate the standard deviation. Different lowercase letters indicate significant differences between treatments during the same stress period (P < 0.05). Treatments are the same as those given in Fig. 3."

[1] Shi W G, Zhang Y H, Chen S L, Polle A, Rennenberg H, Luo Z B. Physiological and molecular mechanisms of heavy metal accumulation in nonmycorrhizal versus mycorrhizal plants. Plant Cell Environ, 2019, 42: 1087-1103.
[2] 尚晓静, 张富美, 程伟, 苏莉, 侯瑞. 裂褶菌菌株G18对孔雀石绿染料的脱色优化. 菌物学报, 2020, 39: 1580-1592.
doi: 10.13346/j.mycosystema.200055
Shang X J, Zhang F M, Cheng W, Su L, Hou R. Decolorization optimization of malachite green dye by Schizomycete strain G18. J Microbiol, 2020, 39: 1580-1592 (in Chinese with English abstract).
[3] Sharma S, Pandey L M. Hydrophobic surface induced biosorption and microbial ex situ remediation of oil-contaminated sites. Ind Eng Chem Res, 2021, 60: 9378-9388.
[4] Takahashi M, Nakamura H. Toothpick method to evaluate soil antagonism against the white root rot fungus, Rosellinia necatrix. J Gen Plant Pathol, 2020, 86: 55-59.
doi: 10.1007/s10327-019-00887-1
[5] 杨珍, 戴传超, 王兴祥, 李孝刚. 作物土传真菌病害发生的根际微生物机制研究进展. 土壤学报, 2019, 56: 12-22.
Yang Z, Dai C C, Wang X X, Li X G. Advance in research on rhizosphere microbial mechanisms of crop soil-borne fungal diseases. Acta Pedol Sin, 2019, 56: 12-22 (in Chinese with English abstract).
[6] Ben Ayed A, Akrout I, Albert Q, Greff S, Simmler C, Armengaud J, Kielbasa M, Turbé-Doan A, Chaduli D, Navarro D, Bertrand E, Faulds C B, Chamkha M, Maalej A, Zouari-Mechichi H, Sciara G, Mechichi T, Record E. Biotransformation of the fluoroquinolone, levofloxacin, by the white-rot fungus Coriolopsis gallica. J Fungi, 2022, 8: 965.
[7] 许飘. 白腐真菌对重金属的吸附富集特性及其重金属耐受性和抗性机制研究. 湖南大学博士学位论文, 湖南长沙, 2016.
Xu P. Mechanism of Heavy Metal Tolerance and Resistance of White Rot Fungi. PhD Dissertation of Hunan University, Changsha, Hunan, China, 2016 (in Chinese with English abstract).
[8] Liang J, Gong S X, Sun Y H, Zhang J J, Zhang J F. Enhanced degradation of phenol by a novel biomaterial through the immobilization of bacteria on cationic straw. Water Sci Technol, 2021, 84: 3791-3798.
doi: 10.2166/wst.2021.498 pmid: 34928844
[9] 朱晓丽, 张婵娟, 张星, 寇志健, 王军强, 尚小清. 生物炭固定化硫酸盐还原菌对镉污染土壤的钝化修复. 环境科学学报, 2023, 43: 421-429.
Zhu X L, Zhang C J, Zhang X, Kou Z J, Wang J Q, Shang X Q. Passivation and remediation of cadmium-contaminated soil by biochar-immobilized sulfate-reducing bacteria. J Environ Sci, 2023, 43: 421-429 (in Chinese with English abstract).
[10] 吴正可, 刘国华, 李阳, 郑爱娟, 常文环, 陈志敏, 蔡辉益. 混菌固态发酵菜籽粕工艺优化. 中国农业科学, 2019, 52: 4603-4612.
doi: 10.3864/j.issn.0578-1752.2019.24.014
Wu Z K, Liu G H, Li Y, Zheng A J, Chang W Q, Chen Z M, Cai H Y. Optimization of solid fermentation of rapeseed meal with mixed bacteria. Sci Agric Sin, 2019, 52: 4603-4612 (in Chinese with English abstract).
[11] Duan-Mu H Z, Wang Y, Bai X, Cheng S F, Deyholos M K, Wong G K S, Li D, Zhu D, Li R, Yu Y, Cao L, Chen C, Zhu Y M. Wild soybean roots depend on specific transcription factors and oxidation reduction related genesin response to alkaline stress. Funct Integr Genomics, 2015, 15: 651-660.
[12] Ji H S, Bang S G, Ahn M-A, Kim G, Kim E, Eom S H, Hyun T K. Molecular cloning and functional characterization of heat stress-responsive superoxide dismutases in garlic (Allium sativum L.). Antioxidants (Bsael), 2021, 10: 815.
[13] Tulsiyan K D, Mahalik A, Dandekar B R, Mondal J, Biswal H S. Enhancement of peroxidase activity in magnetic ionic liquids. ACS Sustainable Chem Eng, 2023, 23: 8487-8494.
[14] Ren H, Li J, Liu P, Ren X Y, Song T, Gao G S, Li D W, Liu S T. Cloning of catalase gene and antioxidant genes in Scophthalmus maximus response to metalloprotease of Vibrio anguillarum stress. J Oceanol Limnol, 2022, 40: 322-335.
[15] Gao Q, Xu L, Li X, Yang W W, Mi Q L, Lu L M, Liu X, Wang K, Lu Y F, Chen Z Y, Li X M, Li L Q. Proteome and physiological analyses reveal tobacco (Nicotiana tabacum) peroxidase 7 (POD 7) functions in responses to copper stress. Transgenic Res, 2022, 31: 431-444.
doi: 10.1007/s11248-022-00310-0 pmid: 35793054
[16] Lee M R, Kim C S, Park T, Choi Y S, Lee K H. Optimization of the ninhydrin reaction and development of a multiwell plate- based high-throughput proline detection assay. Anal Biochem, 2018, 556: 57-62.
[17] Stenholm A, Hedeland M, Pettersson C E. Neomycin removal using the white rot fungus Trametes versicolor. J Environ Sci Health A Tox Hazard Subst Environ Eng, 2022, 57: 436-447.
[18] 黄仕元, 李胜, 王振宇, 林森焕, 邓简. 固定化白腐真菌对复合污染废水的处理. 应用化工, 2022, 51: 103-106.
Huang S Y, Li S, Wang Z Y, Lin S H, Deng J. Treatment of compound-contaminated wastewater by immobilized white-rot fungi. Appl Chem Ind, 2022, 51: 103-106 (in Chinese with English abstract).
[19] Liu W T, Li J T, Zheng Z Q, Li F Y. Microbial immobilization technology for remediation of petroleum hydrocarbon contaminated soil. J Eng Technol, 2021, 21: 339-347.
[20] 渠心静, 陈铭, 廖皎, 张宸辉, 陈隆升, 袁军. 磷缓解油茶铝胁迫的叶片生理响应. 中南林业科技大学学报, 2021, 41(7): 62-71.
Qu X J, Chen M, Liao J, Zhang C H, Chen L S, Yuan J. Phosphorus alleviates leaf physiological responses of Camellia oleifera aluminum stress. J Central South Univ For Technol, 2021, 41(7): 62-71 (in Chinese with English abstract).
[21] 张星雨, 叶志彪, 张余洋. 植物响应镉胁迫的生理与分子机制研究进展. 植物生理学报, 2021, 57: 1437-1450.
Zhang X Y, Ye Z B, Zhang Y Y. Progress on the physiological and molecular mechanisms of plant response to cadmium stress. Plant Physiol J, 2021, 57: 1437-1450 (in Chinese with English abstract).
[22] 谢德志, 魏子璐, 朱峻熠, 杜莹, 金水虎, 岳春雷. 水禾对镉胁迫的生理响应. 浙江农林大学学报, 2020, 37: 683-692.
Xie D Z, Wei Z L, Zhu J Y, Du Y, Jin S H, Yue C L. Physiological response of water weed to cadmium stress. J Zhejiang A&F Univ, 2020, 37: 683-692 (in Chinese with English abstract).
[23] Cao D Q, Wang X, Wang Q H, Fang X M, Jin J Y, Hao X D, Iritani E, Katagiri N. Removal of heavy metal ions by ultrafiltration with recovery of extracellular polymer substances from excess sludge. J Membr Sci, 2020, 606: 118103.
[24] Zuchowski J, Pecio L, Jaszek M, Stochmal A. Solid-state fermentation of rapeseed meal with the white-rot fungi Trametes versicolor and Pleurotus ostreatus. Appl Biochem Biotechnol, 2013, 171: 2075-2081.
[25] Tomm H A, Ucciferri L, Ross A C. Advances in microbial culturing conditions to activate silent biosynthetic gene clusters for novel metabolite production. J Ind Microbiol Biotechnol, 2019, 46: 1381-1400.
[26] Opong-Danouanh E, Blime M Srapato S, Mangoni A, Tasdemir D. Induction of isochromanones by co-cultivation of the marine fungus Cosmospora sp. and the phytopathogen Magnaporthe oryzae. Int J Mol Sci, 2022, 23: 782.
[27] Birhanli E, Erdogan S, Yesilada O, Onal Y. Laccase production by newly isolated white rot fungus Funalia trogii: effect of immobilization matrix on laccase production. Biochem Eng J, 2013, 71: 134-139.
[28] 陈金媛, 沈洋洋, 李烜桢. 白腐真菌Ganoderma sinense对镉和蒽的去除能力. 环境工程学报, 2016, 10: 787-791.
Chen J Y, Shen Y Y, Li X Z. Removal capacity of cadmium and anthracene by the white rot fungus Ganoderma sinense. Chin J Environ Eng, 2016, 10: 787-791 (in Chinese with English abstract).
[29] 余泽海, 胡云霜, 张晏菘, 邱慧敏, 李志霞, 林宏飞. 聚乙烯醇/海藻酸钠/水性聚氨酯复合载体制备及固定化硝化菌降解氨氮废水的研究. 水处理技术, 2022, 48(11): 94-97.
Yu Z H, Hu Y S, Zhang Y S, Qiu H M, Li Z X, Lin H F. Study on preparation of polyvinyl alcohol / sodium alginate / waterborne polyurethane composite carrier and degradation of ammonia nitrogen wastewater by immobilized nitrifiers. Technol Water Treatment, 2022, 48(11): 94-97 (in Chinese with English abstract).
[30] 毛轩雯, 李逸雯, 姜小羽, 王颜和, 吴楠, 蒋云杰, 刘粤, 游薇, 王婷舒, 肖茵翠, 方芳, 刘鹏. 混合白腐真菌的固定化及其在治理铅污染废水中的应用. 微生物学报, 2024, 64: 283-302.
Mao X W, Li Y W, Jiang X Y, Wang Y H, Wu N, Jiang Y J, Liu Y, You W, Wang T S, Xiao Y C, Fang F, Liu P. Immobilization of mixed white-rot fungi and its application in the treatment of lead-contaminated wastewater. Acta Microbiol Sin, 2024, 64: 283-302 (in Chinese with English abstract).
[31] 张靖雯, 肖盈, 陈佳志. 复合固定化菌株L5降解高效氯氰菊酯的特性研究. 广东化工, 2021, 48(22): 116-118.
Zhang J W, Xiao Y, Chen J Z. Characterization of efficient cypermethrin degradation in compound immobilized strain L5. Guangdong Chem Ind, 2021, 48(22): 116-118 (in Chinese with English abstract).
[32] Jiang Y, Yu G B, Zhou Y, Liu Y Y, Feng Y H, Li J C. Effects of sodium alginate on microstructural and properties of bacterial cellulose nanocrystal stabilized emulsions. Colloid Surf A Physicochem Eng Aspects, 2020, 607: 125474.
[33] 戴海根, 吴宏伟, 吴尚卫, 崔莹, 杨冰, 第乙林, 赵春旭. 干旱胁迫对鹰嘴紫云英种子萌发及幼苗叶绿素荧光特性的影响. 草原与草坪, 2022, 42(5): 95-105.
Dai H G, Wu H W, Wu S W, Cui Y, Yang B, Di Y L, Zhao C X. Effect of drought stress on seed germination and chlorophyll fluorescence characteristics of young seedlings. Grassl & Turf, 2022, 42(5): 95-105 (in Chinese with English abstract).
[34] Cao Y N, Tan Q, Zhang F, Ma C X, Xiao J, Chen G C. Phytoremediation potential evaluation of multiple Salix clones for heavy metals (Cd, Zn and Pb) in flooded soils. Sci Total Environ, 2022, 813: 152482.
[35] Cui Y Y, Zhang Q Y, Liu P, Zhang Y C. Effects of polyethylene and heavy metal cadmium on the growth and development of Brassica chinensis var. chinensis. Water Air Soil Pollut, 2022, 233: 426.
[36] Pan T W, Dong Q Y, Cai Y X, Cai K Z. Silicon-mediated regulation of cadmium transport and activation of antioxidant defense system enhances Pennisetum glaucum resistance to cadmium stress. Plant Physiol Biochem, 2023, 195: 206-213.
[37] 张琼, 陆銮眉, 戴清霞, 朱丽霞, 郑海燕. 镉胁迫对水仙根系抗氧化系统的影响. 福建农业学报, 2016, 31: 591-595.
Zhang Q, Lu L M, Dai Q X, Zhu L X, Zheng H Y. Effect of cadmium stress on the antioxidant system of Narcissus roots. Fujian J Agric Sci, 2016, 31: 591-595 (in Chinese with English abstract).
[38] Georgieva K, Mihailova G, Fernández-Marín B, Bertazza G, Govoni A, Arzac M I, Laza J M, Vilas J L, García-Plazaola J I, Rapparini F. Protective strategies of Haberlea rhodopensis for acquisition of freezing tolerance: interaction between dehydration and low temperature. Int J Mol Sci, 2022, 23: 15050.
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