1
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Liu M, Mahata C, Wang Z, Kumar S, Zheng Y. Comparative exploration of biological treatment of hydrothermal liquefaction wastewater from sewage sludge: Effects of culture, fermentation conditions, and ammonia stripping. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2024; 349:119527. [PMID: 37951111 DOI: 10.1016/j.jenvman.2023.119527] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2023] [Revised: 10/31/2023] [Accepted: 11/01/2023] [Indexed: 11/13/2023]
Abstract
Hydrothermal liquefaction wastewater from sewage sludge (sludge HTLWW) is an emerging waste stream that requires treatment before being discharged into the environment. Biological treatment of sludge HTLWW is an attractive option due to the low cost and operational flexibility. In this study, we investigated and compared the performance of three bacterial strains and four fungal strains for biodegradation of sludge HTLWW. Our screening experiments established pH and mineral supplementation (iron, magnesium, calcium, and phosphorus) conditions that greatly improved COD removal and chemical compound degradation by the microbes. An ammonia stripping pretreatment improved COD removal efficiency of Rhodococci jostii RHA1 by 44%. All tested bacterial strains can tolerate 10× dilution of HTLWW and remove 35-44% of COD in 2-15 days, while all tested fungal strains were able to tolerate 20× dilution and were better at degrading phenolic compounds than bacteria. HTLWW treatment with biomass pellets of fungus Aspergillus niger NRRL 2001 achieved the best COD removal efficiency of 47% in 12 days without the need of nutrient supplementation. Comparisons on chemical compound degradation by the tested microbes suggested that organic acids in HTLWW were highly degradable, followed by phenolic compounds. N-heterocyclic compounds were resistant to biodegradation and were removed by 38%. This study demonstrated pure culture biological treatment of sludge HTLWW with diverse types of microorganisms, which would guide the culture development and bioprocess parameter optimization for treating HTLWW of different compositions.
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Affiliation(s)
- Meicen Liu
- Department of Grain Science and Industry, Kansas State University, 1980 Kimball Avenue, Manhattan, KS, 66506, USA.
| | - Chandan Mahata
- Department of Biological Systems Engineering, Virginia Tech, 1230 Washington St. SW, Blacksburg, VA, 24061, USA
| | - Zhiwu Wang
- Department of Biological Systems Engineering, Virginia Tech, 1230 Washington St. SW, Blacksburg, VA, 24061, USA
| | - Sandeep Kumar
- Department of Civil and Environmental Engineering, Old Dominion University, Norfolk, VA, 23529, USA
| | - Yi Zheng
- Department of Grain Science and Industry, Kansas State University, 1980 Kimball Avenue, Manhattan, KS, 66506, USA.
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2
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Müller H, Deffur C, Schmideder S, Barthel L, Friedrich T, Mirlach L, Hammel JU, Meyer V, Briesen H. Synchrotron radiation-based microcomputed tomography for three-dimensional growth analysis of Aspergillus niger pellets. Biotechnol Bioeng 2023; 120:3244-3260. [PMID: 37475650 DOI: 10.1002/bit.28506] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Revised: 05/05/2023] [Accepted: 07/11/2023] [Indexed: 07/22/2023]
Abstract
Filamentous fungi produce a wide range of relevant biotechnological compounds. The close relationship between fungal morphology and productivity has led to a variety of analytical methods to quantify their macromorphology. Nevertheless, only a µ-computed tomography (µ-CT) based method allows a detailed analysis of the 3D micromorphology of fungal pellets. However, the low sample throughput of a laboratory µ-CT limits the tracking of the micromorphological evolution of a statistically representative number of submerged cultivated fungal pellets over time. To meet this challenge, we applied synchrotron radiation-based X-ray microtomography at the Deutsches Elektronen-Synchrotron [German Electron Synchrotron Research Center], resulting in 19,940 3D analyzed individual fungal pellets that were obtained from 26 sampling points during a 48 h Aspergillus niger submerged batch cultivation. For each of the pellets, we were able to determine micromorphological properties such as number and density of spores, tips, branching points, and hyphae. The computed data allowed us to monitor the growth of submerged cultivated fungal pellets in highly resolved 3D for the first time. The generated morphological database from synchrotron measurements can be used to understand, describe, and model the growth of filamentous fungal cultivations.
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Affiliation(s)
- Henri Müller
- School of Life Sciences Weihenstephan, Chair of Process Systems Engineering, Technical University of Munich, Freising, Germany
| | - Charlotte Deffur
- School of Life Sciences Weihenstephan, Chair of Process Systems Engineering, Technical University of Munich, Freising, Germany
| | - Stefan Schmideder
- School of Life Sciences Weihenstephan, Chair of Process Systems Engineering, Technical University of Munich, Freising, Germany
| | - Lars Barthel
- Chair of Applied and Molecular Microbiology, Institute of Biotechnology, Technische Universität Berlin, Berlin, Germany
| | - Tiaan Friedrich
- School of Life Sciences Weihenstephan, Chair of Process Systems Engineering, Technical University of Munich, Freising, Germany
| | - Lukas Mirlach
- School of Life Sciences Weihenstephan, Chair of Process Systems Engineering, Technical University of Munich, Freising, Germany
| | - Jörg U Hammel
- Helmholtz-Zentrum hereon, Institute of Materials Physics, Geesthacht, Germany
| | - Vera Meyer
- Chair of Applied and Molecular Microbiology, Institute of Biotechnology, Technische Universität Berlin, Berlin, Germany
| | - Heiko Briesen
- School of Life Sciences Weihenstephan, Chair of Process Systems Engineering, Technical University of Munich, Freising, Germany
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3
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Lyu J, Torchia C, Post H, Moran Torres JP, Altelaar AFM, de Cock H, Wösten HAB. The α-(1,3)-glucan synthase gene agsE impacts the secretome of Aspergillus niger. Antonie Van Leeuwenhoek 2023:10.1007/s10482-023-01853-w. [PMID: 37316742 PMCID: PMC10371888 DOI: 10.1007/s10482-023-01853-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2023] [Accepted: 06/05/2023] [Indexed: 06/16/2023]
Abstract
Aspergillus niger is widely used as a cell factory for the industrial production of enzymes. Previously, it was shown that deletion of α-1-3 glucan synthase genes results in smaller micro-colonies in liquid cultures of Aspergillus nidulans. Also, it has been shown that small wild-type Aspergillus niger micro-colonies secrete more protein than large mirco-colonies. We here assessed whether deletion of the agsC or agsE α-1-3 glucan synthase genes results in smaller A. niger micro-colonies and whether this is accompanied by a change in protein secretion. Biomass formation was not affected in the deletion strains but pH of the culture medium had changed from 5.2 in the case of the wild-type to 4.6 and 6.4 for ΔagsC and ΔagsE, respectively. The diameter of the ΔagsC micro-colonies was not affected in liquid cultures. In contrast, diameter of the ΔagsE micro-colonies was reduced from 3304 ± 338 µm to 1229 ± 113 µm. Moreover, the ΔagsE secretome was affected with 54 and 36 unique proteins with a predicted signal peptide in the culture medium of MA234.1 and the ΔagsE, respectively. Results show that these strains have complementary cellulase activity and thus may have complementary activity on plant biomass degradation. Together, α-1-3 glucan synthesis (in)directly impacts protein secretion in A. niger.
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Affiliation(s)
- Jun Lyu
- Microbiology, Utrecht University, Padualaan 8, 3584, CH, Utrecht, The Netherlands
| | - Costanza Torchia
- Microbiology, Utrecht University, Padualaan 8, 3584, CH, Utrecht, The Netherlands
| | | | - Juan P Moran Torres
- Microbiology, Utrecht University, Padualaan 8, 3584, CH, Utrecht, The Netherlands
| | - A F Maarten Altelaar
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Padualaan 8, 3584, CH, Utrecht, The Netherlands
| | - Hans de Cock
- Microbiology, Utrecht University, Padualaan 8, 3584, CH, Utrecht, The Netherlands
| | - Han A B Wösten
- Microbiology, Utrecht University, Padualaan 8, 3584, CH, Utrecht, The Netherlands.
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4
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Li K, Zheng J, Yu L, Wang B, Pan L. Exploration of the Strategy for Improving the Expression of Heterologous Sweet Protein Monellin in Aspergillus niger. J Fungi (Basel) 2023; 9:jof9050528. [PMID: 37233239 DOI: 10.3390/jof9050528] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Revised: 04/23/2023] [Accepted: 04/27/2023] [Indexed: 05/27/2023] Open
Abstract
Aspergillus niger is a primary cell factory for food-grade protein (enzyme) production due to its strong protein secretion capacity and unique safety characteristics. The bottleneck issue for the current A. niger expression system is the difference in expression yield of heterologous proteins of non-fungal origin compared to those of fungal origin, which is about three orders of magnitude. The sweet protein monellin, derived from West African plants, has the potential to become a food-grade sweetener due to its high sweetness and the benefit of not containing sugar itself, but it is extremely difficult to establish a research model for heterologous expression in A. niger, owing to extremely low expression, a small molecular weight, and being undetectable with conventional protein electrophoresis. HiBiT-Tag was fused with low-expressing monellin in this work to create a research model for heterologous protein expression in A. niger at ultra-low levels. We increased monellin expression by increasing the monellin copy number, fusing monellin with the endogenous highly expressed glycosylase glaA, and eliminating extracellular protease degradation, among other strategies. In addition, we investigated the effects of overexpression of molecular chaperones, inhibiting the ERAD pathway, and enhancing the synthesis of phosphatidylinositol, phosphatidylcholine, and diglycerides in the biomembrane system. Using medium optimization, we finally obtained 0.284 mg/L of monellin in the supernatant of the shake flask. This is the first time recombinant monellin has been expressed in A. niger, with the goal of investigating ways to improve the secretory expression of heterologous proteins at ultra-low levels, which can serve as a model for the expression of other heterologous proteins in A. niger.
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Affiliation(s)
- Ke Li
- School of Biology and Biological Engineering, South China University of Technology, Guangzhou Higher Education Mega Center, Guangzhou 510006, China
| | - Junwei Zheng
- School of Biology and Biological Engineering, South China University of Technology, Guangzhou Higher Education Mega Center, Guangzhou 510006, China
| | - Leyi Yu
- School of Biology and Biological Engineering, South China University of Technology, Guangzhou Higher Education Mega Center, Guangzhou 510006, China
| | - Bin Wang
- School of Biology and Biological Engineering, South China University of Technology, Guangzhou Higher Education Mega Center, Guangzhou 510006, China
| | - Li Pan
- School of Biology and Biological Engineering, South China University of Technology, Guangzhou Higher Education Mega Center, Guangzhou 510006, China
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5
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Heterogeneity in Spore Aggregation and Germination Results in Different Sized, Cooperative Microcolonies in an Aspergillus niger Culture. mBio 2023; 14:e0087022. [PMID: 36629410 PMCID: PMC9973262 DOI: 10.1128/mbio.00870-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The fungus Aspergillus niger is among the most abundant fungi in the world and is widely used as a cell factory for protein and metabolite production. This fungus forms asexual spores called conidia that are used for dispersal. Notably, part of the spores and germlings aggregate in an aqueous environment. The aggregated conidia/germlings give rise to large microcolonies, while the nonaggregated spores/germlings result in small microcolonies. Here, it is shown that small microcolonies release a larger variety and quantity of secreted proteins compared to large microcolonies. Yet, the secretome of large microcolonies has complementary cellulase activity with that of the small microcolonies. Also, large microcolonies are more resistant to heat and oxidative stress compared to small microcolonies, which is partly explained by the presence of nongerminated spores in the core of the large microcolonies. Together, it is proposed that heterogeneity in germination and aggregation has evolved to form a population of different sized A. niger microcolonies, thereby increasing stress survival and producing a meta-secretome more optimally suited to degrade complex substrates. IMPORTANCE Aspergillus niger can form microcolonies of different size due to partial aggregation of spores and germlings. So far, this heterogeneity was considered a negative trait by the industry. We here, however, show that heterogeneity in size within a population of microcolonies is beneficial for food degradation and stress survival. This functional heterogeneity is not only of interest for the industry to make blends of enzymes (e.g., for biofuel or bioplastic production) but could also play a role in nature for effective nutrient cycling and survival of the fungus.
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6
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Jiang C, Wang H, Liu M, Wang L, Yang R, Wang P, Lu Z, Zhou Y, Zheng Z, Zhao G. Identification of chitin synthase activator in Aspergillus niger and its application in citric acid fermentation. Appl Microbiol Biotechnol 2022; 106:6993-7011. [PMID: 36149454 DOI: 10.1007/s00253-022-12174-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Revised: 08/30/2022] [Accepted: 09/01/2022] [Indexed: 11/02/2022]
Abstract
The biosynthesis of citric acid (CA) using Aspergillus niger as a carrier is influenced by mycelium morphology, which is determined by the expression level of morphology-related genes. As a key component of the fungal cell wall, chitin content has an important effect on morphogenesis, and to investigate the effects of this on fermentation performance, we used RNA interference to knockdown chitin synthase C (CHSC) and chitin synthase activator (CHS3) to obtain the single-gene mutant strains A. niger chs3 and chsC and the double mutant A. niger chs3C. We found that the CA fermentation performance of the two single mutants was significantly better than that of the double mutant. The mutant A. niger chs3-4 exhibited CA production potential compared to that of the parent strain in scale-up fermentation; we determined certain characteristics of CA high-yielding strain fermentation pellets. In addition, when chsC alone was silenced, there was very little change in chs3 mRNA levels, whereas those of chsC were significantly reduced when only chs3 was silenced. As this may be because of a synergistic effect between chsC and chs3, and we speculated that the latent activation target of CHS3 is CHSC, our results confirmed this hypothesis. This study is the first application of a separation and combination silence strategy of chitin synthase and chitin synthase activator in the morphology of A. niger CA fermentation. Furthermore, it provides new insights into the method for the morphological study of A. niger fermentation and the interaction of homologous genes. KEY POINTS: • The function of chitin synthase C (chsC) and chitin synthase activator (chs3) is tightly interrelated. • Mycelial morphology was optimized by knockdown of CHS3, resulting in the overproduction of citric acid. • The separation and combination silence strategies are promising tools for the interaction of homologous housekeeping genes.
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Affiliation(s)
- Chunxu Jiang
- Hefei Institutes of Physical Science, Comprehensive Laboratory Building, Chinese Academy of Sciences, 350 Shushanhu Road, P.O. Box 1138, Hefei Anhui, 230031, People's Republic of China.,University of Science and Technology of China, Hefei, Anhui, People's Republic of China
| | - Han Wang
- Hefei Institutes of Physical Science, Comprehensive Laboratory Building, Chinese Academy of Sciences, 350 Shushanhu Road, P.O. Box 1138, Hefei Anhui, 230031, People's Republic of China.
| | - Menghan Liu
- COFCO Biotechnology Co, Ltd. No. 1, Zhongliang Avenue, Bengbu Anhui, 233010, People's Republic of China
| | - Li Wang
- Hefei Institutes of Physical Science, Comprehensive Laboratory Building, Chinese Academy of Sciences, 350 Shushanhu Road, P.O. Box 1138, Hefei Anhui, 230031, People's Republic of China
| | - Ruwen Yang
- COFCO Biotechnology Co, Ltd. No. 1, Zhongliang Avenue, Bengbu Anhui, 233010, People's Republic of China
| | - Peng Wang
- Hefei Institutes of Physical Science, Comprehensive Laboratory Building, Chinese Academy of Sciences, 350 Shushanhu Road, P.O. Box 1138, Hefei Anhui, 230031, People's Republic of China
| | - Zongmei Lu
- COFCO Biotechnology Co, Ltd. No. 1, Zhongliang Avenue, Bengbu Anhui, 233010, People's Republic of China
| | - Yong Zhou
- COFCO Biotechnology Co, Ltd. No. 1, Zhongliang Avenue, Bengbu Anhui, 233010, People's Republic of China.
| | - Zhiming Zheng
- Hefei Institutes of Physical Science, Comprehensive Laboratory Building, Chinese Academy of Sciences, 350 Shushanhu Road, P.O. Box 1138, Hefei Anhui, 230031, People's Republic of China.
| | - Genhai Zhao
- Hefei Institutes of Physical Science, Comprehensive Laboratory Building, Chinese Academy of Sciences, 350 Shushanhu Road, P.O. Box 1138, Hefei Anhui, 230031, People's Republic of China.
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7
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Ijadpanahsaravi M, Teertstra WR, Wösten HAB. Inter- and intra-species heterogeneity in germination of Aspergillus conidia. Antonie Van Leeuwenhoek 2022; 115:1151-1164. [PMID: 35857156 PMCID: PMC9363317 DOI: 10.1007/s10482-022-01762-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Accepted: 07/05/2022] [Indexed: 11/26/2022]
Abstract
Aspergilli are among the most abundant fungi worldwide. They degrade organic material and can be pathogens of plants and animals. Aspergilli spread by forming high numbers of conidia. Germination of these stress resistant asexual spores is characterized by a swelling and a germ tube stage. Here, we show that conidia of Aspergillusniger,Aspergillusoryzae,Aspergillusclavatus, Aspergillusnidulans and Aspergillusterreus show different swelling and germ tube formation dynamics in pure water or in water supplemented with (in)organic nutrients. Apart from inter-species heterogeneity, intra-species heterogeneity was observed within spore populations of the aspergilli except for A.terreus. Sub-populations of conidia differing in size and/or contrast showed different swelling and germ tube formation dynamics. Together, data imply that aspergilli differ in their competitive potential depending on the substrate. Moreover, results suggest that intra-species heterogeneity provides a bet hedging mechanism to optimize survival of aspergilli.
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Affiliation(s)
- Maryam Ijadpanahsaravi
- Microbiology, Department of Biology, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - Wieke R. Teertstra
- Microbiology, Department of Biology, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - Han A. B. Wösten
- Microbiology, Department of Biology, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
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8
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Müller H, Barthel L, Schmideder S, Schütze T, Meyer V, Briesen H. From spores to fungal pellets: a new high throughput image analysis highlights the structural development of Aspergillus niger. Biotechnol Bioeng 2022; 119:2182-2195. [PMID: 35477834 DOI: 10.1002/bit.28124] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Revised: 03/21/2022] [Accepted: 04/22/2022] [Indexed: 11/10/2022]
Abstract
Many filamentous fungi are exploited as cell factories in biotechnology. Cultivated under industrially relevant submerged conditions, filamentous fungi can adopt different macromorphologies ranging from dispersed mycelia over loose clumps to pellets. Central to the development of a pellet morphology is the agglomeration of spores after inoculation followed by spore germination and outgrowth into a pellet population which is usually very heterogeneous. As the dynamics underlying population heterogeneity are not yet fully understood, we present here a new high-throughput image analysis pipeline based on stereomicroscopy to comprehensively assess the developmental program starting from germination up to pellet formation. To demonstrate the potential of this pipeline, we used data from 44 sampling times harvested during a 48 h submerged batch cultivation of the fungal cell factory Aspergillus niger. The analysis of up to 1700 spore agglomerates and 1500 pellets per sampling time allowed the precise tracking of the morphological development of the overall culture. The data gained were used to calculate size distributions and area fractions of spores, spore agglomerates, spore agglomerates within pellets, pellets, and dispersed mycelia. This approach eventually enables the quantification of culture heterogeneities and pellet breakage. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Henri Müller
- Technical University of Munich, School of Life Sciences Weihenstephan, Chair of Process Systems Engineering, Freising, Germany
| | - Lars Barthel
- Chair of Applied and Molecular Microbiology, Institute of Biotechnology, Technische Universität Berlin, Straße des 17. Juni 135, 10623, Berlin, Germany
| | - Stefan Schmideder
- Technical University of Munich, School of Life Sciences Weihenstephan, Chair of Process Systems Engineering, Freising, Germany
| | - Tabea Schütze
- Chair of Applied and Molecular Microbiology, Institute of Biotechnology, Technische Universität Berlin, Straße des 17. Juni 135, 10623, Berlin, Germany
| | - Vera Meyer
- Chair of Applied and Molecular Microbiology, Institute of Biotechnology, Technische Universität Berlin, Straße des 17. Juni 135, 10623, Berlin, Germany
| | - Heiko Briesen
- Technical University of Munich, School of Life Sciences Weihenstephan, Chair of Process Systems Engineering, Freising, Germany
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9
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Morita Y, Katakura Y, Takegawa K, Higuchi Y. Correlative Localization Analysis Between mRNA and Enhanced Green Fluorescence Protein-Fused Protein by a Single-Molecule Fluorescence in situ Hybridization Using an egfp Probe in Aspergillus oryzae. FRONTIERS IN FUNGAL BIOLOGY 2021; 2:721398. [PMID: 37744096 PMCID: PMC10512357 DOI: 10.3389/ffunb.2021.721398] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Accepted: 09/09/2021] [Indexed: 09/26/2023]
Abstract
Although subcellular localization analysis of proteins fused with enhanced green fluorescence protein (EGFP) has been widely conducted in filamentous fungi, little is known about the localization of messenger RNAs (mRNAs) encoding the EGFP-fused proteins. In this study, we performed single-molecule fluorescence in situ hybridization (smFISH) using an egfp probe to simultaneously visualize EGFP-fused proteins and their mRNAs in the hyphal cells of the filamentous fungus Aspergillus oryzae. We investigated the subcellular localization of mRNAs encoding cytoplasmic EGFP, an actin marker protein Lifeact tagged with EGFP, and several EGFP-fused proteins AoSec22, AoSnc1, AoVam3, and AoUapC that localize to the endoplasmic reticulum (ER), the apical vesicle cluster Spitzenkörper, vacuolar membrane, and plasma membrane, respectively. Visualization of these mRNAs by smFISH demonstrated that each mRNA exhibited distinct localization patterns likely depending on the mRNA sequence. In particular, we revealed that mRNAs encoding Lifeact-EGFP, EGFP-AoSec22, EGFP-AoVam3, and AoUapC-EGFP, but not cytoplasmic EGFP and EGFP-AoSnc1, were preferentially localized at the apical cell, suggesting certain mechanisms to regulate the existence of these transcripts among hyphal regions. Our findings provide the distinct localization information of each mRNA in the hyphal cells of A. oryzae.
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Affiliation(s)
| | | | | | - Yujiro Higuchi
- Department of Bioscience and Biotechnology, Faculty of Agriculture, Kyushu University, Fukuoka, Japan
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10
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Schmideder S, Müller H, Barthel L, Friedrich T, Niessen L, Meyer V, Briesen H. Universal law for diffusive mass transport through mycelial networks. Biotechnol Bioeng 2020; 118:930-943. [PMID: 33169831 DOI: 10.1002/bit.27622] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Revised: 10/13/2020] [Accepted: 10/31/2020] [Indexed: 01/01/2023]
Abstract
Filamentous fungal cell factories play a pivotal role in biotechnology and circular economy. Hyphal growth and macroscopic morphology are critical for product titers; however, these are difficult to control and predict. Usually pellets, which are dense networks of branched hyphae, are formed during industrial cultivations. They are nutrient- and oxygen-depleted in their core due to limited diffusive mass transport, which compromises productivity of bioprocesses. Here, we demonstrate that a generalized law for diffusive mass transport exists for filamentous fungal pellets. Diffusion computations were conducted based on three-dimensional X-ray microtomography measurements of 66 pellets originating from four industrially exploited filamentous fungi and based on 3125 Monte Carlo simulated pellets. Our data show that the diffusion hindrance factor follows a scaling law with respect to the solid hyphal fraction. This law can be harnessed to predict diffusion of nutrients, oxygen, and secreted metabolites in any filamentous pellets and will thus advance the rational design of pellet morphologies on genetic and process levels.
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Affiliation(s)
- Stefan Schmideder
- School of Life Sciences Weihenstephan, Chair of Process Systems Engineering, Technical University of Munich, Freising, Germany
| | - Henri Müller
- School of Life Sciences Weihenstephan, Chair of Process Systems Engineering, Technical University of Munich, Freising, Germany
| | - Lars Barthel
- Institute of Biotechnology, Faculty III Process Sciences, Chair of Applied and Molecular Microbiology, Technische Universität Berlin, Berlin, Germany
| | - Tiaan Friedrich
- School of Life Sciences Weihenstephan, Chair of Process Systems Engineering, Technical University of Munich, Freising, Germany
| | - Ludwig Niessen
- School of Life Sciences Weihenstephan, Chair of Technical Microbiology, Technical University of Munich, Freising, Germany
| | - Vera Meyer
- Institute of Biotechnology, Faculty III Process Sciences, Chair of Applied and Molecular Microbiology, Technische Universität Berlin, Berlin, Germany
| | - Heiko Briesen
- School of Life Sciences Weihenstephan, Chair of Process Systems Engineering, Technical University of Munich, Freising, Germany
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11
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Higuchi Y, Takegawa K. Single-Molecule FISH Reveals Subcellular Localization of α-Amylase and Actin mRNAs in the Filamentous Fungus Aspergillus oryzae. Front Microbiol 2020; 11:578862. [PMID: 33072046 PMCID: PMC7536267 DOI: 10.3389/fmicb.2020.578862] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Accepted: 09/01/2020] [Indexed: 11/13/2022] Open
Abstract
The machinery for mRNA localization is one of crucial molecular structures allowing cellular spatiotemporal organization of protein synthesis. Although the molecular mechanisms underlying mRNA localization have been thoroughly investigated in unicellular organisms, little is known about multicellular and multinuclear filamentous fungi. Here, we conducted single-molecule fluorescence in situ hybridization (smFISH) to first visualize the mRNA molecules of α-amylase, which are encoded by amyB, and which are thought to be abundantly secreted from the hyphal tips of the industrially important fungus Aspergillus oryzae. Consistent with previous biochemical studies, fluorescein amidite (FAM) fluorescence derived from amyB expression was observed in A. oryzae hyphae cultured in a minimal medium containing maltose instead of glucose as the sole carbon source. Moreover, after more than 1 h incubation with fresh maltose-containing medium, the fluorescence of amyB mRNAs was observed throughout the cells, suggesting α-amylase secretion potentially from each cell, instead of the hyphal tip only. Furthermore, in cultures with complete medium containing maltose, amyB mRNAs were excluded from the tip regions, where no nuclei exist. In contrast, mRNAs of actin, encoded by actA, were localized mainly to the tip, where actin proteins also preferentially reside. Collectively, our smFISH analyses revealed distinct localization patterns of α-amylase and actin mRNAs in A. oryzae hyphal cells.
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Affiliation(s)
- Yujiro Higuchi
- Department of Bioscience and Biotechnology, Faculty of Agriculture, Kyushu University, Fukuoka, Japan
| | - Kaoru Takegawa
- Department of Bioscience and Biotechnology, Faculty of Agriculture, Kyushu University, Fukuoka, Japan
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12
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Li C, Zhou J, Du G, Chen J, Takahashi S, Liu S. Developing Aspergillus niger as a cell factory for food enzyme production. Biotechnol Adv 2020; 44:107630. [PMID: 32919011 DOI: 10.1016/j.biotechadv.2020.107630] [Citation(s) in RCA: 57] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Revised: 09/05/2020] [Accepted: 09/05/2020] [Indexed: 02/06/2023]
Abstract
Aspergillus niger has become one of the most important hosts for food enzyme production due to its unique food safety characteristics and excellent protein secretion systems. A series of food enzymes such as glucoamylase have been commercially produced by A. niger strains, making this species a suitable platform for the engineered of strains with improved enzyme production. However, difficulties in genetic manipulations and shortage of expression strategies limit the progress in this regard. Moreover, several mycotoxins have recently been detected in some A. niger strains, which raises the necessity for a regulatory approval process for food enzyme production. With robust strains, processing engineering strategies are also needed for producing the enzymes on a large scale, which is also challenging for A. niger, since its culture is aerobic, and non-Newtonian fluid properties are developed during submerged culture, making mixing and aeration very energy-intensive. In this article, the progress and challenges of developing A. niger for the production of food enzymes are reviewed, including its genetic manipulations, strategies for more efficient production of food enzymes, and elimination of mycotoxins for product safety.
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Affiliation(s)
- Cen Li
- National Engineering Laboratory for Cereal Fermentation Technology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China; School of Biotechnology and Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China.
| | - Jingwen Zhou
- National Engineering Laboratory for Cereal Fermentation Technology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China; School of Biotechnology and Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China; Jiangsu Provisional Research Center for Bioactive Product Processing Technology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China.
| | - Guocheng Du
- School of Biotechnology and Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China; The Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China.
| | - Jian Chen
- National Engineering Laboratory for Cereal Fermentation Technology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China; School of Biotechnology and Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China; Jiangsu Provisional Research Center for Bioactive Product Processing Technology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China.
| | - Shunji Takahashi
- Natural Product Biosynthesis Research Unit, RIKEN Center for Sustainable Resource Science, 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan.
| | - Song Liu
- National Engineering Laboratory for Cereal Fermentation Technology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China; School of Biotechnology and Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China.
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