Continuous citric acid production in repeated-fed batch fermentation by Aspergillus niger immobilized on a new porous foam

Yu, Bo; Zhang, Xin; Sun, Wenjun; Xi, Xun; Zhao, Nan; Huang, Zijian; Ying, Zhuojun; Liu, Li; Liu, Dong; Niu, Huanqing; Wu, Jinglan; Zhuang, Wei; Zhu, Chenjie; Chen, Yong

doi:10.1016/j.jbiotec.2018.03.015

Cited by 43 publications

(31 citation statements)

References 37 publications

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“…The adhesion of spores to surrounding substances, the cross-linking and attachment between hyphae, and the production of biofilms are the three basic elements of the formation of filamentous fungal biofilms [11,12]. In fungi, the ability of conidia to adsorb on carriers is critical to immobilization (biofilm formation) [4,8]. This adsorption mainly depends on the hydrophobic and electrostatic forces of the spores.…”

Section: Discussionmentioning

confidence: 99%

“…Aspergillus niger 831 [8] parental strain used in this study was a newly established strain which was mutagenized by the ATCC 12846 strain and maintained on conventional potato dextrose agar (PDA) plates. Its genomic sequence is not clear at present, but the base sequences of genes MidA, CchA, CrzA and CnaA were found to be the same to those from A. niger CBS 513.88.…”

Section: Strains and Mediamentioning

confidence: 99%

“…The fermentation medium was synthetic medium composed as follows: glucose (100 g/L), (NH 4 ) 2 SO 4 (2 g/L), NaNO 3 (1 g/L), KH 2 PO 4 (0.5 g/L), and MgSO 4 ·7H 2 O (0.3 g/L), dissolved in 1 L of wheat bran extract. The preparation method of wheat bran extract was carried out according to a method as described previously [8]. Required amounts of wheat bran were immersed in water to obtain a suspension of 15 g/L wheat bran, which was used for subsequent hydrolysis by autoclaving at 121 °C for 60 min.…”

Section: Strains and Mediamentioning

confidence: 99%

“…Biofilms growing on the elastomeric carbon black polyurethane [8] were obtained after 48 h immobilized fermentation in the fermentation medium. Samples were washed 3 times with PBS buffer, and stored at − 80 °C.…”

Section: Scanning Electron Microscopy (Sem)mentioning

confidence: 99%

“…production, although we have developed a relatively optimal immobilization carrier, the mechanism of biofilm formation in the fermentation process has not been well studied [8].…”

mentioning

confidence: 99%

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Calcineurin signaling pathway influences Aspergillus niger biofilm formation by affecting hydrophobicity and cell wall integrity

Liu

Sun

et al. 2020

Biotechnol Biofuels

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Background: Biofilms, as a kind of fixed-cell community, can greatly improve industrial fermentation efficiency in immobilized fermentation, but the regulation process is still unclear, which restricts their application. Ca 2+ was reported to be a key factor affecting biofilm formation. However, the effect of Ca 2+ on biofilm structure and microbiology was yet only studied in bacteria. How Ca 2+ -mediated calcineurin signaling pathway (CSP) alters biofilm formation in bacteria and fungi has rarely been reported. On this basis, we investigated the regulation of CSP on the formation of biofilm in Aspergillus niger.Results: Deletion of the key genes MidA, CchA, CrzA or CnaA in the CSP lowered the Ca 2+ concentration in the mycelium to a different extent, inhibited the formation of A. niger biofilm, reduced the hydrophobicity and adhesion of spores, destroyed the cell wall integrity of hyphae, and reduced the flocculation ability of hyphae. qRT-PCR results showed that the expression of spore hydrophobic protein RodA, galactosaminogalactan (GAG) biosynthesis genes (uge3, uge5, agd3, gtb3), and α-1,3-glucan biosynthesis genes (ags1, ags3) in the ∆MidA, ∆CchA, ∆CrzA, ∆CnaA strains were significantly down-regulated compared with those of the wild type (WT). In addition, the transcription levels of the chitin synthesis gene (chsB, chsD) and β-1,3-glucan synthesis gene (FksA) were consistent with the change in chitin and β-1,3-glucan contents in mutant strains. Conclusion:These results indicated that CSP affected the hydrophobicity and adhesion of spores, the integrity of mycelial cell walls and flocculation by affecting Ca 2+ levels in mycelium, which in turn affected biofilm formation. This work provides a possible explanation for how CSP changes the formation of A. niger biofilm, and reveals a pathway for controlling biofilm formation in industrial immobilized fermentation.

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Section: Discussionmentioning

confidence: 99%

Section: Strains and Mediamentioning

confidence: 99%

Section: Strains and Mediamentioning

confidence: 99%

Section: Scanning Electron Microscopy (Sem)mentioning

confidence: 99%

“…production, although we have developed a relatively optimal immobilization carrier, the mechanism of biofilm formation in the fermentation process has not been well studied [8].…”

mentioning

confidence: 99%

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Calcineurin signaling pathway influences Aspergillus niger biofilm formation by affecting hydrophobicity and cell wall integrity

Liu

Sun

et al. 2020

Biotechnol Biofuels

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Assessing the predictive capabilities of design heuristics and coarse‐grain simulation toward understanding and optimizing site‐specific covalent immobilization of β‐lactamase

Soltani

Hunt

Smith

et al. 2022

Biotechnology Journal

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For industrial applications, covalent immobilization of enzymes provides minimum leakage, recoverability, reusability, and high stability. Yet, the suitability of a given site on the enzyme for immobilization remains a trial‐and‐error procedure. Here, we investigate the reliability of design heuristics and a coarse‐grain molecular simulation in predicting the optimum sites for covalent immobilization of TEM‐1 β‐lactamase. We utilized Escherichia coli‐lysate‐based cell‐free protein synthesis (CFPS) to produce variants containing a site‐specific incorporated unnatural amino acid with a unique moiety to facilitate site directed covalent immobilization. To constrain the number of potential immobilization sites, we investigated the predictive capability of several design heuristics. The suitability of immobilization sites was determined by analyzing expression yields, specific activity, immobilization efficiency, and stability of variants. These experimental findings are compared with coarse‐grain simulation of TEM‐1 domain stability and thermal stability and analyzed for a priori predictive capabilities. This work demonstrates that the design heuristics successfully identify a subset of locations for experimental validation. Specifically, the nucleotide following amber stop codon and domain stability correlate well with the expression yield and specific activity of the variants, respectively. Our approach highlights the advantages of combining coarse‐grain simulation and high‐throughput experimentation using CFPS to identify optimal enzyme immobilization sites.

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Fungal‐Based Biorefinery: From Renewable Resources to Organic Acids

Varriale

Ulber

2023

ChemBioEng Reviews

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Biorefineries are facilities in which lignocellulosic biomasses are converted in a wide range of bioproducts facilitating the transition from the use of petrochemical resources to renewable ones. Organic acids are considered very attractive for their utilization in different industrial areas as building blocks or as final bioproducts leading to a considerable market growth. They are metabolites which are naturally produced by microbials. The production of these molecules by filamentous fungi are attracting more attention due to their ability to hydrolyze lignocellulosic biomasses and to contextually produce different organic acids. Contrarily to a lot of other microorganisms, fungi have the ability to ferment pentoses, broadening the substrate utilization. The integrated use of lignocellulosic biomasses as material input and fungi as biocatalyst can contribute to make biorefineries more successful. This review gives an overview about the lignocellulosic biomass structure and hydrolysis, fungal morphology, and how they are connected. Further, it describes some relevant organic acids with regard to their processes, biocatalysts, industrial applications, and market considerations.

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Continuous citric acid production in repeated-fed batch fermentation by Aspergillus niger immobilized on a new porous foam

Cited by 43 publications

References 37 publications

Calcineurin signaling pathway influences Aspergillus niger biofilm formation by affecting hydrophobicity and cell wall integrity

Calcineurin signaling pathway influences Aspergillus niger biofilm formation by affecting hydrophobicity and cell wall integrity

Assessing the predictive capabilities of design heuristics and coarse‐grain simulation toward understanding and optimizing site‐specific covalent immobilization of β‐lactamase

Fungal‐Based Biorefinery: From Renewable Resources to Organic Acids

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