Adsorption capacities of poly-γ-glutamic acid and its sodium salt for cesium removal from radioactive wastewaters

Sakamoto, S.; Kawase, Y.

doi:10.1016/j.jenvrad.2016.10.004

Cited by 46 publications

(21 citation statements)

References 40 publications

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“…The molecular structure of γ-PGA contains amide linkages between the γ-amino and γ-carboxylic acid functional groups, leaving the γ-carboxylate group available for cation binding. The γ-PGA is of a particular research interest because of its potential implication in the removal of heavy metals in water treatment [16, 17]. The γ-PGA showed a great affinity to Cu(II), Al(III), Cr(III), Fe(III) and Pb(II), which induce flocculation [18–20].…”

Section: Introductionmentioning

confidence: 99%

Complexation and conformation of lead ion with poly-γ-glutamic acid in soluble state

et al. 2019

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Complexation of microbial polymer in soluble state could impact the solubility, mobility, and bioavailability of heavy metals in the environment. The complexation of a bacterial exopolymer, poly-γ-glutamic acid (γ-PGA), with Pb2+ was studied using the polarographic method and circular dichroism measurement in soluble state. The number of available binding sites was determined based on the Chau’s method and was found to be 0.04, 1.12, 3.56 and 4.51 mmol/(g dry weight of γ-PGA) at pH 3.4, 4.2, 5.0 and 6.2, respectively. Further, the number of binding sites was determined based on the Ruzic’s method and was found to be 3.60 and 4.41 mmol/(g dry weight of γ-PGA) for pH 5.0 and 6.2, respectively. The constant (expressed as log K) values were 5.8 and 6.0 at pH 5.0 and 6.2. Compared to biopolymers secreted by other microorganisms, such as extracellular polymeric substances extraction from activated sludge, γ-PGA was a more efficient Pb2+ carrier from pH 5.0 to 6.2. The secondary structure of γ-PGA varied significantly when Pb2+ added. Ca2+ or Mg2+ replace a portion of the adsorbed Pb2+. However, the portion of Pb2+ involved in changing the γ-PGA conformation was not easily replaced by Ca2+ and Mg2+.

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Section: Introductionmentioning

confidence: 99%

Complexation and conformation of lead ion with poly-γ-glutamic acid in soluble state

et al. 2019

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“…This condition may be attributed to the fact that the WHC of protein was related to the distribution of its hydrophilic and hydrophobic groups. By contrast, γ‐PGA was an anionic polymer that contains a large amount of free carboxyl groups that can form hydrogen bonds with water (Sakamoto & Kawase, 2016), resulting in γ‐PGA absorbing a larger amount of water. On the other hand, interaction between WG and γ‐PGA may occur, forming a polypeptide‐WG complex network structure, binding more water molecules, and promoting increased water retention of the WG system, which is similar to the results previously reported by Li et al.…”

Section: Resultsmentioning

confidence: 99%

Effect of poly‐γ‐glutamic acid on hydration and structure of wheat gluten

Xie

Xiu-yuan

Shen

et al. 2020

Journal of Food Science

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In recent years, hydrocolloids have been used extensively as enhancers in dough products. However, studies on the effect of hydrophilic polymers on wheat gluten (WG) within the dough are scarce. In the present study, polyγ-glutamic acid (γ-PGA), a new and healthy food additive, was added to the WG to investigate its effect on hydration, rheological properties, and structures of WG. Results showed that with the addition of γ-PGA, the water-holding capacity (WHC) of WG and the content of bound water increased, whereas the content of immobilized water decreased. In addition, γ-PGA changed the rheological properties of WG. The elastic properties of WG gradually weakened and the viscous properties gradually increased. Furthermore, scanning electron microscopy (SEM) results showed that with the addition of γ-PGA, the structure of the WG network became more uniform and the pore size was smaller. A change also occurred in the secondary structure of WG, in which the α-helix content was significantly reduced while the contents of β-turn angles were significantly increased, thereby suggesting that γ-PGA not only functions as a filler in the WG system, but also interacts with WG. From the present study, we conclude that γ-PGA can interact with WG and water to change the WG secondary structure. γ-PGA can also restrict moisture migration and enhance the WHC of WG, thereby changing the WG microstructure and improving its functional properties. This condition provides the basis for γ-PGA to be recommended as WG enhancer for addition in WG-containing products such as bread, seitan (meat replacement), and others.

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“…Poly(γ-glutamic acid) (γ-PGA) is a microbial biopolymer, composed of d - and l -glutamic acid monomers connected by γ-amide linkage . Because of the presence of several carboxylic groups on its side chain, γ-PGA is water-soluble, biodegradable, and nontoxic, and has broad applications in fields of daily chemicals, food, medicine, environmental protection, and agriculture. − The γ-PGA producing strains can be divided into two types: glutamic acid-dependent strains and non-glutamic acid-dependent strains. Most of the reported production strains, such as Bacillus subtilis NX-2 and Bacillus licheniformis NCIM2324, are glutamic acid-dependent.…”

Section: Introductionmentioning

confidence: 99%

Development of a Robust Bacillus amyloliquefaciens Cell Factory for Efficient Poly(γ-glutamic acid) Production from Jerusalem Artichoke

Qiu

Zhu

Sha

et al. 2020

ACS Sustainable Chem. Eng.

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Bacillus amyloliquefaciens NB, a glutamate-independent poly-γ-glutamic acid (γ-PGA)-producing strain, can directly utilize inulin-containing sustainable materials. However, low γ-PGA yield and lack of efficient genetic engineering approaches have hindered the industrial use of this strain. Here, we used the CRISPR-Cas9n technique to engineer B. amyloliquefaciens to enhance γ-PGA production. We engineered three modules involved in inulin hydrolysis, reducing sugars metabolism, and γ-PGA synthesis in B. amyloliquefaciens. Specifically, overexpresed the native inulin hydrolase CscA and two expressionoptimized levanase and endoinulinase, overexpressed of key genes related to reducing sugar metabolism to increased ATP production, and removed polysaccharide operon epsA-O and γ-PGA hydrolase cwlO. Finally, the highest production of γ-PGA (32.14 ± 0.38 g/L) was obtained in a 7.5 L fed-batch fermenter. Thus, we successfully constructed an ideal candidate strain for efficient γ-PGA production from inulin, which provides an important research basis for the development of more biobased products.

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Adsorption capacities of poly-γ-glutamic acid and its sodium salt for cesium removal from radioactive wastewaters

Cited by 46 publications

References 40 publications

Complexation and conformation of lead ion with poly-γ-glutamic acid in soluble state

Complexation and conformation of lead ion with poly-γ-glutamic acid in soluble state

Effect of poly‐γ‐glutamic acid on hydration and structure of wheat gluten

Development of a Robust Bacillus amyloliquefaciens Cell Factory for Efficient Poly(γ-glutamic acid) Production from Jerusalem Artichoke

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