Organic Acid Production by Filamentous Fungi

Magnuson, Jon; Lasure, Linda L.

doi:10.1007/978-1-4419-8859-1_12

Cited by 228 publications

(176 citation statements)

References 165 publications

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“…T. emersonii also has GRAS status making it an excellent model species to investigate hydrolytic enzymes that have orthologs in plant and human pathogens. Growth of T. emersonii in complex media causes a rapid reduction in extracellular pH most likely because of the conversion of sugars into organic acids (35). In this study, we have shown that spent media contain abundant acid-acting proteolytic activity against macromolecular substrates such as BSA, particularly when T. emersonii is grown in media with reduced nitrogen content.…”

Section: Discussionmentioning

confidence: 74%

Inhibition of a Secreted Glutamic Peptidase Prevents Growth of the Fungus Talaromyces emersonii

O’Donoghue

Mahon

Goetz

et al. 2008

Journal of Biological Chemistry

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The thermophilic filamentous fungus Talaromyces emersonii secretes a variety of hydrolytic enzymes that are of interest for processing of biomass into fuel. Many carbohydrases have been isolated and characterized from this fungus, but no studies had been performed on peptidases. In this study, two acid-acting endopeptidases were isolated and characterized from the culture filtrate of T. emersonii. One of these enzymes was identified as a member of the recently classified glutamic peptidase family and was subsequently named T. emersonii glutamic peptidase 1 (TGP1). The second enzyme was identified as an aspartyl peptidase (PEP1). TGP1 was cloned and sequenced and shown to exhibit 64 and 47% protein identity to peptidases from Aspergillus niger and Scytalidium lignocolum, respectively. Substrate profiling of 16 peptides determined that TGP1 has broad specificity with a preference for large residues in the P1 site, particularly Met, Gln, Phe, Lys, Glu, and small amino acids at P1 such as Ala, Gly, Ser, or Thr. This enzyme efficiently cleaves an internally quenched fluorescent substrate containing the zymogen activation sequence (k cat /K m ‫؍‬ 2 ؋ 10 5 M ؊1 s ؊1 ). Maximum hydrolysis occurs at pH 3.4 and 50°C. The reaction is strongly inhibited by a transition state peptide analog, TA1 (K i ‫؍‬ 1.5 nM), as well as a portion of the propeptide sequence, PT1 (K i ‫؍‬ 32 nM). Ex vivo studies show that hyphal extension of T. emersonii in complex media is unaffected by the aspartyl peptidase inhibitor pepstatin but is inhibited by TA1 and PT1. This study provides insight into the functional role of the glutamic peptidase TGP1 for growth of T. emersonii.As chemoheterotrophs, filamentous fungi secrete a variety of polymer-degrading hydrolases such as peptidases and carbohydrases that degrade organic material in the local environment to provide essential nutrients for the growing hyphae. Many fungi release organic acids to acidify the environment while secreting enzymes that are optimally active under these conditions. Traditionally, acid-acting fungal peptidases were assigned to the aspartic protease family and include aspergillopepsin from various Aspergillus species (1) and penicillopepsin from Penicillium species (2). These enzymes have two active-site aspartic acid residues and are strongly inhibited by pepstatin. Recently, two distinct groups of acid peptidases were identified that are insensitive to pepstatin and lack the catalytic motif observed in pepsintype peptidases. One group, "sedolisins" possess a fold similar to members of the subtilisin family but contain an active site triad of serine (S), glutamic acid (E), and aspartic acid (D) (3). They are sensitive to leupeptin and have homologs in bacteria (4), fungi (5), slime mold (6), and mammals (7). The second group of pepstatin-insensitive acid peptidases share a distinct set of structural, enzymatic, and physicochemical properties, and to date have only been identified in a select group of fungi (8). Members of this novel family possess a catalytic dyad consis...

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Section: Discussionmentioning

confidence: 74%

Inhibition of a Secreted Glutamic Peptidase Prevents Growth of the Fungus Talaromyces emersonii

O’Donoghue

Mahon

Goetz

et al. 2008

Journal of Biological Chemistry

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“…[14][15][16][17][18] Examples include the citric acid production process using A. niger and penicillin production using P. chrysogenum, in which incremental improvements and new insights have been documented over many decades. 15,[19][20][21][22][23][24] The characterization of filamentous fungal hosts for expression of proteins also dominates the literature, and this field has been thoroughly reviewed in recent years. 18,25 …”

Section: Cellular Performance Of Established Fungal Cell Factoriesmentioning

confidence: 99%

Integrated Approaches for Assessment of Cellular Performance in Industrially Relevant Filamentous Fungi

WorkmanMhairi

Andersen

ThykaerJette

2013

Industrial Biotechnology

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The performance of filamentous fungi in submerged cultivation determines their suitability for large-scale industrial biotechnology processes and is the result of complex interplay between the physical and chemical parameters of the process and the cellular biology of the fungi. Filamentous fungi have a natural ability to degrade complex substrates through secretion of a large number of diverse enzymes and to produce a number of metabolites that inhibit or prevent the growth of other species in the surroundings. These features have been exploited by industry, resulting in multi-billion dollar processes for producing enzymes and metabolites of value. However, the wealth of diversity of these species is still not fully represented in large-scale bioprocesses, and thus advancement from discovery to application is one of the challenges for modern biotechnology. Acceleration of the process can be achieved through integrated approaches for assessing cellular performance (quantitative physiology), genetic modification of strains (metabolic engineering), and omics analyses and modeling (systems biology). In this review, we evaluate stateof-the-art of filamentous fungal applications in industrial biotechnology , focusing on physiological aspects of the fungi that provide the basis of their cellular performance. We also discuss the advancement of systems biology approaches and how the establishment of these tools for fungal research has begun to reveal the possibilities for further exploitation of these organisms. Increased future focus on multicellular physiology and relevant assays will lead to fungal cells and processes that are customizable to a greater degree, finally allowing the full potential of these complex organisms and their product diversity to unfold.

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“…The common chemical forms of manganese dioxide found naturally are +2 and +4 [1]. The oxides and peroxides of manganese are used for manufacturing metal alloys to increase hardness and for enhancement of alloy to be corrosion resistance and as a desulfurizing, deoxidizing element in various industrial processes [2,3]. Manganese plays an important role in steel production, preparation of dietary additives, chemical production, in battery cells industry [4,5].…”

Section: Introductionmentioning

confidence: 99%

Reductive Acid Leaching of Low Grade Manganese Ores

Das¹,

Swain²,

Panda³

et al. 2012

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Manganese recoveries from low-grade ores using organic acids as reducing agents were investigated in the present work. The acid leaching potential of both oxalic acid and citric acid were estimated. Manganese leaching amount were measured by using standard manganese curve and estimated by titration method. Effects of various acid concentrations on leaching efficiency were studied. The observed result suggested prominent manganese recovery of 66% by oxalic acid at 2 M concentration whereas citric acid had less effect on leaching showing leaching percentage upto 40% in 6 days. Acid leaching of manganese ore with both the acids gave a comparative data stating that oxalic acid leached better than citric acid.

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Organic Acid Production by Filamentous Fungi

Cited by 228 publications

References 165 publications

Inhibition of a Secreted Glutamic Peptidase Prevents Growth of the Fungus Talaromyces emersonii

Inhibition of a Secreted Glutamic Peptidase Prevents Growth of the Fungus Talaromyces emersonii

Integrated Approaches for Assessment of Cellular Performance in Industrially Relevant Filamentous Fungi

Reductive Acid Leaching of Low Grade Manganese Ores

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