Bacteria Metabolically Engineered for Enhanced Phytochelatin Production and Cadmium Accumulation

ABSTRACT Phytochelatins (PCs) with good binding affinities for a wide range of heavy metals were exploited to develop microbial sorbents for cadmium removal. PC synthase from Schizosaccharomyces pombe (SpPCS) was overexpressed in Escherichia coli, resulting in PC synthesis and 7.5-times-higher Cd accumulation. The coexpression of a variant γ-glutamylcysteine synthetase desensitized to feedback inhibition (GshI*) increased the supply of the PC precursor glutathione, resulting in further increases of 10- and 2-fold in PC production and Cd accumulation, respectively. A Cd transporter, MntA, was expressed with SpPCS and GshI* to improve Cd uptake, resulting in a further 1.5-fold increase in Cd accumulation. The level of Cd accumulation in this recombinant E. coli strain (31.6 μmol/g [dry weight] of cells) was more than 25-fold higher than that in the control strain.

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Selenium Enhances Cadmium Accumulation Capability in Two Mustard Family Species—Brassica napus and B. juncea

Plants ◽

10.3390/plants9070904 ◽

2020 ◽

Vol 9 (7) ◽

pp. 904 ◽

Cited By ~ 1

Author(s):

Zhong-Wei Zhang ◽

Yi-Ying Dong ◽

Ling-Yang Feng ◽

Zong-Lin Deng ◽

Qiang Xu ◽

...

Keyword(s):

Brassica Napus ◽

Brassica Juncea ◽

Brassica Species ◽

Dry Weight ◽

Cadmium Accumulation ◽

Cd Accumulation ◽

Cd Toxicity ◽

Valence States ◽

Early Seedling ◽

High Level

Oilseed rape (Brassica napus) is a Cadmium (Cd) hyperaccumulator. However, high-level Cd at the early seedling stage seriously arrests the growth of rape, which limits its applications. Brassica juncea had higher Cd accumulation capacity, but its biomass was lower, also limiting its applications. Previous studies have confirmed that Selenium (Se) can alleviate Cd toxicity. However, the regulatory mechanism of Se in different valence states of Cd accumulation was unclear. In this study, we investigated the ameliorating effects of three Se valence states, Na2SeO4 [Se(VI)], Na2SeO3 [Se(IV)] and Se-Met [Se(II)], to Cd toxicity by physiological and biochemical approaches in hydroponically-cultured Brassica juncea and Brassica napus seedlings. Although Se treatments slightly inhibited seedling Cd concentration, it tripled or quadrupled the Cd accumulation level per plant, because dry weight increased about four times more with Se and Cd application than with Cd treatment alone. Among the different valence states of Se, Se(II) had the most marked effect on reducing Cd toxicity as evidenced by decreased growth inhibition and Cd content. The application of Se(II) was effective in reducing Cd-induced reactive oxygen species accumulation, and promoted the antioxidant enzyme activity and photosynthesis of both Brassica species. In addition, Se(II) treatment increased the concentrations of Cd in the cell wall and soluble fractions, but the Cd concentration in the organelle part was reduced.

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Reducing Cadmium Accumulation in Plants: Structure–Function Relations and Tissue-Specific Operation of Transporters in the Spotlight

Plants ◽

10.3390/plants9020223 ◽

2020 ◽

Vol 9 (2) ◽

pp. 223 ◽

Cited By ~ 5

Author(s):

Xin Huang ◽

Songpo Duan ◽

Qi Wu ◽

Min Yu ◽

Sergey Shabala

Keyword(s):

Structure Function ◽

Current Knowledge ◽

Cadmium Accumulation ◽

Major Focus ◽

Phloem Tissue ◽

Cd Uptake ◽

Major Health ◽

Cd Accumulation ◽

Tissue Specific

Cadmium (Cd) is present in many soils and, when entering the food chain, represents a major health threat to humans. Reducing Cd accumulation in plants is complicated by the fact that most known Cd transporters also operate in the transport of essential nutrients such as Zn, Fe, Mn, or Cu. This work summarizes the current knowledge of mechanisms mediating Cd uptake, radial transport, and translocation within the plant. It is concluded that real progress in the field may be only achieved if the transport of Cd and the above beneficial micronutrients is uncoupled, and we discuss the possible ways of achieving this goal. Accordingly, we suggest that the major focus of research in the field should be on the structure–function relations of various transporter isoforms and the functional assessment of their tissue-specific operation. Of specific importance are two tissues. The first one is a xylem parenchyma in plant roots; a major “controller” of Cd loading into the xylem and its transport to the shoot. The second one is a phloem tissue that operates in the last step of a metal transport. Another promising and currently underexplored avenue is to understand the role of non-selective cation channels in Cd uptake and reveal mechanisms of their regulation.

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Effects of exogenous indole-3-acetic acid on the growth and cadmium accumulation of lettuce under cadmium stress

E3S Web of Conferences ◽

10.1051/e3sconf/201913607002 ◽

2019 ◽

Vol 136 ◽

pp. 07002

Author(s):

Le Liang ◽

Wanjia Tang ◽

Xuemei Peng ◽

Jing Lu ◽

Han Liu ◽

...

Keyword(s):

Acetic Acid ◽

Dry Weight ◽

Cadmium Stress ◽

Optimal Dose ◽

Cadmium Accumulation ◽

Cd Uptake ◽

Cd Toxicity ◽

Substantial Decline ◽

Indole 3 Acetic Acid ◽

Exogenous Iaa

Indole-3-acetic acid (IAA) plays crucial roles in plant growth and stress tolerance. In present study, the effects of spraying different concentrations (0, 25, 50, 100 and 200 μmol/L) of IAA on the growth and cadmium (Cd) accumulation in lettuce (Lactuca sativa) were investigated. The lettuce exposed to Cd exhibited a substantial decline in growth, and the Cd content of them significantly increased. Spraying exogenous IAA resulted in alleviating the inhibitory of Cd toxicity to lettuce. The dry weight in shoots of lettuce increased by spraying with IAA compared with the Cd treatment alone, but the dry weight of roots had no significantly differences. Although exogenous IAA increased the root Cd content, it significantly reduced shoot Cd content, indicating its role in Cd transport. Therefore, spraying IAA effectively alleviated Cd toxicity and reduced Cd uptake in the edible parts of lettuce, and the 100 μmol/L IAA was the optimal dose.

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Secretory expression of cyclohexanone monooxygenase by methylotrophic yeast for efficient omeprazole sulfide bio-oxidation

Bioresources and Bioprocessing ◽

10.1186/s40643-021-00430-1 ◽

2021 ◽

Vol 8 (1) ◽

Author(s):

Ya-Jing Li ◽

Yu-Cong Zheng ◽

Qiang Geng ◽

Feng Liu ◽

Zhi-Jun Zhang ◽

...

Keyword(s):

Fermentation Broth ◽

Enantiomeric Excess ◽

Catalytic Efficiency ◽

Methylotrophic Yeast ◽

Fold Increase ◽

Dry Weight ◽

Cyclohexanone Monooxygenase ◽

E Coli ◽

A Cell ◽

Omeprazole Sulfide

AbstractProchiral pyrmetazole can be asymmetrically oxidized into (S)-omeprazole, a proton pump inhibitor that is used to treat gastroesophageal reflux, by an engineered cyclohexanone monooxygenase (CHMOAcineto-Mut) that has high stereoselectivity. CHMOAcineto-Mut is produced by heterologous expression in Escherichia coli, where it is expressed intracellularly. Thus, isolating this useful biocatalyst requires tedious cell disruption and subsequent purification, which hinders its use for industrial purposes. Here, we report the extracellular production of CHMOAcineto-Mut by a methylotrophic yeast, Pichia pastoris, for the first time. The recombinant CHMOAcineto-Mut expressed by P. pastoris showed a higher flavin occupation rate than that produced by E. coli, and this was accompanied by a 3.2-fold increase in catalytic efficiency. At a cell density of 150 g/L cell dry weight, we achieved a recombinant CHMOAcineto-Mut production rate of 1,700 U/L, representing approximately 85% of the total protein secreted into the fermentation broth. By directly employing the pH adjusted supernatant as a biocatalyst, we were able to almost completely transform 10 g/L of pyrmetazole into the corresponding (S)-sulfoxide, with > 99% enantiomeric excess.

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Effects of Silcon on Growth and Cadmium Accumulation by Flue-Cured Tobacco

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1092-1093.608 ◽

2015 ◽

Vol 1092-1093 ◽

pp. 608-612

Author(s):

Yan Fang Ren ◽

Jun Yu He ◽

Dong Liu ◽

Yan Chao Zhang ◽

Hui Qing Chang

Keyword(s):

Nicotiana Tabacum ◽

Leaf Area ◽

Contaminated Soils ◽

Growth Yield ◽

Dry Weight ◽

Cadmium Accumulation ◽

Cadmium Content ◽

Tobacco Plants ◽

Cd Accumulation ◽

Cd Translocation

Tobacco (Nicotiana tabacumL.) is able to accumulate cadmium in leaves and reduction of cadmium content can reduce health hazards to smokers. In the present study, the influence of silicon on the growth, yield and the content and distribution of cadmium (Cd) in flue-cured tobacco plants in the presence of cadmium was investigated by pot experiment. The results showed that Cd reduced the growth of both shoots and roots. Application of Si significantly increased the dry weight of roots and shoots in flue-cured tobacco grown in Cd contaminated soils, but not the largest leaf area. Si reduced the Cd concentration and accumulation in the root, stem and leaf of flue-cured tobacco compared with Cd alone. Si restricted the transport of Cd from roots to shoots. These results demonstrate that 1 and 2 g/kg Si could enhance Cd tolerance in flue-cured tobacco and decrease of Cd accumulation in plant and Cd translocation to shoots.

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Effect of Cadmium on Growth, Photosynthetic Pigments, Iron and Cadmium Accumulation of Faba Bean (Vicia faba cv. Aštar)

Agriculture (Pol nohospodárstvo) ◽

10.1515/agri-2016-0008 ◽

2016 ◽

Vol 62 (2) ◽

pp. 72-79 ◽

Cited By ~ 3

Author(s):

Beáta Piršelová ◽

Roman Kuna ◽

Peter Lukáč ◽

Michaela Havrlentová

Keyword(s):

Vicia Faba ◽

Faba Bean ◽

Contaminated Soils ◽

Growth Parameters ◽

Photosynthetic Pigment ◽

Dry Weight ◽

Cadmium Accumulation ◽

Fresh Weight ◽

Cd Accumulation ◽

Photosynthetic Pigment Content

Abstract The influence of different concentrations of cadmium (Cd) ions (50 and 100 mg/kg soil) on growth, photosynthetic pigment content, Cd, and iron accumulation in faba bean (Vicia faba L. cv. Aštar) was studied under laboratory conditions. No significant changes were observed in the growth parameters of shoots (length, fresh, and dry weight). Both tested Cd doses resulted in decrease in root fresh weight by 31.7% and 28.68% and in dry weight by 32.2% and 33.33%, respectively. Increased accumulation of Cd was observed in roots (125- and 173-fold higher than in control) and shoots (125- and 150-fold higher than in control) as a result of applied doses of Cd. Increased accumulation of iron was detected in roots (1.45- and 1.69-fold higher than in control). Decrease in the content of chlorophyll a (by 25.52 and 24.83%, respectively) and chlorophyll b (by 6.90%) after application of Cd 100 as well as decrease in carotenoids (by 40.39 and 38.36%, respectively) was detected. Weak translocation of Cd from roots to shoots pointed to low phytoremediation potential of the tested bean variety in contaminated soil. However, the high tolerance of this cultivar, its relative fast growth, as well as priority of Cd accumulation in roots presume this plant species for phytostabilisation and revegetation of the Cd-contaminated soils.

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Effect of passivator DHJ-C on the growth and cadmium accumulation of Brassica napus in Cd-contaminated soil

Applied Biological Chemistry ◽

10.1186/s13765-021-00601-w ◽

2021 ◽

Vol 64 (1) ◽

Author(s):

Xin Wang ◽

Qian Liu ◽

Yunbao Wan ◽

Chenxi Cao ◽

Jiuyuan Bai ◽

...

Keyword(s):

Brassica Napus ◽

Contaminated Soil ◽

Dry Weight ◽

Cadmium Accumulation ◽

Inhibitory Effect ◽

Cd Accumulation ◽

Physiology And Biochemistry ◽

Soil Urease ◽

Mature Period ◽

Mda Content

AbstractThe farmland polluted by cadmium is increasing drastically, which seriously threatened agricultural production and food safety. Nowadays, efficient and convenient way to solve the problem is urgently needed. In this experiment, a particular compound passivator DHJ-C was applied for soil remediation by pot experiment and the effect on both soil and plant was evaluated. The DHJ-C reduced the toxicity of Cd on soil enzyme activity and growth inhibition on Brassica napus. The soil urease and sucrase activity were significantly increased. The dry weight of mature oilseed rape increased by 14.6–36.0% and the yield of seeds increased by 14.1–52% per plant, which suggested that the passivator effectively reduced the detrimental effects on rape. Similarly, the results of physiology and biochemistry also indicated that DHJ-C can distinctly alleviate the inhibitory effect of Cd on plant growth. Such as the MDA content in plant was reduced by 52.1% in 10 mg/kg Cd treatment. Compared with control, Cd accumulation in seedling stage and mature period was significantly reduced as the concentration of Cd in aboveground part even decreased by 18.4 and 32.0% respectively. Overall, DHJ-C hold sufficient ability to be applied as an excellent passivator to reduce Cd toxicity in contaminated soil and significantly increase the yield of rapeseed.

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Variation in Cadmium Accumulation among Potato Cultivars Grown on Different Agricultural Sites: A Potential Tool for Reducing Cadmium in Tubers

Horticulturae ◽

10.3390/horticulturae7100377 ◽

2021 ◽

Vol 7 (10) ◽

pp. 377

Author(s):

Sary H. Brengi ◽

Abdel-Ghany M. El-Gindy ◽

Islam El-Sharkawy ◽

Ibrahim A. Abouelsaad

Keyword(s):

Soil Properties ◽

Solanum Tuberosum L ◽

Clay Content ◽

Cadmium Accumulation ◽

Potato Cultivars ◽

Export Market ◽

Cd Uptake ◽

Cd Accumulation ◽

Growing Seasons

Potato (Solanum tuberosum L.) is an important crop in Egypt with great trade value for the export market. The addition of agrochemicals with possibly containing heavy metals, such as cadmium (Cd), decreases the quality of the final product. Generally, little is known about the factors that influence Cd content in this crop. The current study estimated the Cd levels in different organs of three potato cultivars grown in four commercial regions across Egypt. Further, we investigated the soil properties that affected Cd uptake during two growing seasons. With the exception of the Cd content of the soils, no relationships were detected between the tested soil properties (i.e., pH, conductivity, organic matter, and clay content) and Cd content in potato organs, because the soil from different regions showed comparable levels for these parameters. The average Cd content in the peeled tubers among different cultivars (0.145 mg Kg−1 DW) was below the maximum limit (0.5 mg Kg−1 DW). The patterns of Cd accumulation in potato organs were constant among cultivars, with the highest levels detected in leaves (~82%), followed by stems (~16.5%), and the lowest content observed in tubers (~1.5%). The study showed that the tested potato cultivars exhibited diversity in the accumulation levels of Cd in the tubers (~2.6-fold). The cultivar Suntana displayed the lowest Cd levels among different field sites for the two growing seasons, suggesting the potential involvement of genetic factors.

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Secretory Expression of Cyclohexanone Monooxygenase by Methylotrophic Yeast for Efficient Omeprazole Sulfide Bio-oxidation

10.21203/rs.3.rs-600789/v1 ◽

2021 ◽

Author(s):

Ya-Jing Li ◽

Yu-Cong Zheng ◽

Qiang Geng ◽

Feng Liu ◽

Zhi-Jun Zhang ◽

...

Keyword(s):

Fermentation Broth ◽

Enantiomeric Excess ◽

Catalytic Efficiency ◽

Methylotrophic Yeast ◽

Fold Increase ◽

Dry Weight ◽

Cyclohexanone Monooxygenase ◽

E Coli ◽

A Cell ◽

Omeprazole Sulfide

Abstract Prochiral pyrmetazole can be asymmetrically oxidized into (S)-omeprazole, a proton pump inhibitor that is used to treat gastroesophageal reflux, by an engineered cyclohexanone monooxygenase (CHMOAcineto-Mut) that has high stereoselectivity. CHMOAcineto-Mut is produced by heterologous expression in Escherichia coli, where it is expressed intracellularly. Thus, isolating this useful biocatalyst requires tedious cell disruption and subsequent purification, which hinders its use for industrial purposes. Here, we report the extracellular production of CHMOAcineto-Mut by a methylotrophic yeast, Pichia pastoris, for the first time. The recombinant CHMOAcineto-Mut expressed by P. pastoris showed a higher flavin occupation rate than that produced by E. coli, and this was accompanied by a 3.2-fold increase in catalytic efficiency. At a cell density of 150 g/L cell dry weight, we achieved a recombinant CHMOAcineto-Mut production rate of 1,700 U/L, representing approximately 85% of the total protein secreted into the fermentation broth. By directly employing the pH adjusted supernatant as a biocatalyst, we were able to almost completely transform 10 g/L of pyrmetazole into the corresponding (S)-sulfoxide, with >99% enantiomeric excess.

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Effects of hyperaccumulator plant straw on biomass and cadmium accumulation of lettuce

E3S Web of Conferences ◽

10.1051/e3sconf/201913607005 ◽

2019 ◽

Vol 136 ◽

pp. 07005

Author(s):

Le Liang ◽

Ran Zhang ◽

Yan Zhao ◽

Ying Zhu ◽

Qiaoman Ao ◽

...

Keyword(s):

Cadmium Accumulation ◽

Solanum Nigrum ◽

Cd Stress ◽

Bidens Pilosa ◽

Cd Uptake ◽

Cd Accumulation ◽

Accumulator Plant ◽

Hyperaccumulator Plant ◽

Straw Application ◽

Ground Part

To study the effects of hyper-accumulator plant straw on the biomass and cadmium (Cd) accumulation of lettuce (Lactuca sativa), the pot experiments were conducted to study the effects of straw application of three hyper-accumulator plants (Solanum nigrum, Bidens pilosa and Galinsoga parviflora) on the biomass and Cd accumulation of lettuce under Cd stress. The results show that: compared with no straw application, the biomass of lettuce was increased after applying three kinds of hyper-accumulator plant straw: S. nigrum, B. pilosa and G. parviflora, Cd content in the above ground part of lettuce was increased by 4.46%, 1.20% and 0.63% respectively, compared with that of non-application, and Cd content in the root of lettuce was decreased. The application of three kinds of hyperaccumulator plant straw promoted the growth of lettuce and increased Cd uptake by lettuce of aerial part.

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