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Ning YN, Tian D, Zhao S, Feng JX. Regulation of genes encoding polysaccharide-degrading enzymes in Penicillium. Appl Microbiol Biotechnol 2024; 108:16. [PMID: 38170318 DOI: 10.1007/s00253-023-12892-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Revised: 10/02/2023] [Accepted: 10/10/2023] [Indexed: 01/05/2024]
Abstract
Penicillium fungi, including Penicillium oxalicum, can secrete a range of efficient plant-polysaccharide-degrading enzymes (PPDEs) that is very useful for sustainable bioproduction, using renewable plant biomass as feedstock. However, the low efficiency and high cost of PPDE production seriously hamper the industrialization of processes based on PPDEs. In Penicillium, the expression of PPDE genes is strictly regulated by a complex regulatory system and molecular breeding to modify this system is a promising way to improve fungal PPDE yields. In this mini-review, we present an update on recent research progress concerning PPDE distribution and function, the regulatory mechanism of PPDE biosynthesis, and molecular breeding to produce PPDE-hyperproducing Penicillium strains. This review will facilitate future development of fungal PPDE production through metabolic engineering and synthetic biology, thereby promoting PPDE industrial biorefinery applications. KEY POINTS: • This mini review summarizes PPDE distribution and function in Penicillium. • It updates progress on the regulatory mechanism of PPDE biosynthesis in Penicillium. • It updates progress on breeding of PPDE-hyperproducing Penicillium strains.
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Affiliation(s)
- Yuan-Ni Ning
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Guangxi Research Center for Microbial and Enzyme Engineering Technology, College of Life Science and Technology, Guangxi University, 100 Daxue Road, Nanning, Guangxi, 530004, People's Republic of China
| | - Di Tian
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Guangxi Research Center for Microbial and Enzyme Engineering Technology, College of Life Science and Technology, Guangxi University, 100 Daxue Road, Nanning, Guangxi, 530004, People's Republic of China
| | - Shuai Zhao
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Guangxi Research Center for Microbial and Enzyme Engineering Technology, College of Life Science and Technology, Guangxi University, 100 Daxue Road, Nanning, Guangxi, 530004, People's Republic of China.
| | - Jia-Xun Feng
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Guangxi Research Center for Microbial and Enzyme Engineering Technology, College of Life Science and Technology, Guangxi University, 100 Daxue Road, Nanning, Guangxi, 530004, People's Republic of China.
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Liu X, Wang Y, Zhang R, Gao Y, Chen H, Dong S, Hu X. Insights into the transcriptomic mechanism and characterization of endoglucanases from Aspergillus terreus in cellulose degradation. Int J Biol Macromol 2024; 263:130340. [PMID: 38387642 DOI: 10.1016/j.ijbiomac.2024.130340] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2023] [Revised: 02/12/2024] [Accepted: 02/19/2024] [Indexed: 02/24/2024]
Abstract
Filamentous fungi are the main industrial source of cellulases which are important in the process of converting cellulose to fermentable sugars. In this study, transcriptome analysis was conducted on Aspergillus terreus NEAU-7 cultivated using corn stover and glucose as carbon sources. Four putative endoglucanases (EG5A, EG7A, EG12A, and EG12C) from A. terreus NEAU-7 were efficiently expressed in Pichia pastoris. Among them, EG7A exhibited the highest enzyme activity (75.17 U/mg) with an optimal temperature of 40 °C and pH 5.0. EG5A and EG12A displayed specific activities of 19.92 U/mg and 14.62 U/mg, respectively, at 50 °C. EG12C showed acidophilic characteristics with an optimal pH of 3.0 and a specific activity of 12.21 U/mg at 40 °C. With CMC-Na as the substrate, the Km value of EG5A, EG7A, EG12A or, EG12C was, 11.08 ± 0.87 mg/mL, 6.82 ± 0.74 mg/mL, 7.26 ± 0.64 mg/mL, and 9.88 ± 0.86 mg/mL, with Vmax values of 1258.23 ± 51.62 μmol∙min-1∙mg-1, 842.65 ± 41.53 μmol∙min-1∙mg-1, 499.38 ± 20.42 μmol∙min-1∙mg-1, and 681.41 ± 30.08 μmol∙min-1∙mg-1, respectively. The co-treatment of EG7A with the commercial cellulase increased the yield of reducing sugar by 155.77 % (filter paper) and 130.49 % (corn stover). Molecular docking assay showed the interaction energy of EG7A with cellotetraose at -10.50 kcal/mol, surpassing EG12A (-10.43 kcal/mol), EG12C (-10.28 kcal/mol), and EG5A (-9.00 kcal/mol). Root Mean Square Deviation (RMSD) and Solvent Accessible Surface Area (SASA) values revealed that the presence of cellotetraose stabilized the molecular dynamics simulation of the cellotetraose-protein complex over a 100 ns time scale. This study provides valuable insights for developing recombinant enzymes and biomass degradation technologies.
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Affiliation(s)
- Xin Liu
- College of Life Science, Northeast Agricultural University, Harbin 150030, China
| | - Yanbo Wang
- College of Life Science, Northeast Agricultural University, Harbin 150030, China
| | - Rui Zhang
- College of Life Science, Northeast Agricultural University, Harbin 150030, China
| | - Yunfei Gao
- Heilongjiang Academy of Agricultural Sciences, Harbin 150086, China
| | - Heshu Chen
- Heilongjiang Academy of Agricultural Sciences, Harbin 150086, China
| | | | - Xiaomei Hu
- College of Life Science, Northeast Agricultural University, Harbin 150030, China.
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Gupta JK, Jain KK, Kaushal M, Upton DJ, Joshi M, Pachauri P, Wood AJ, Yazdani SS, Srivastava S. Marine cyanobacterial biomass is an efficient feedstock for fungal bioprocesses. BIOTECHNOLOGY FOR BIOFUELS AND BIOPRODUCTS 2024; 17:23. [PMID: 38350992 PMCID: PMC10863111 DOI: 10.1186/s13068-024-02469-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2023] [Accepted: 02/02/2024] [Indexed: 02/15/2024]
Abstract
BACKGROUND Marine cyanobacteria offer many sustainability advantages, such as the ability to fix atmospheric CO2, very fast growth and no dependence on freshwater for culture. Cyanobacterial biomass is a rich source of sugars and proteins, two essential nutrients for culturing any heterotroph. However, no previous study has evaluated their application as a feedstock for fungal bioprocesses. RESULTS In this work, we cultured the marine cyanobacterium Synechococcus sp. PCC 7002 in a 3-L externally illuminated bioreactor with working volume of 2 L with a biomass productivity of ~ 0.8 g L-1 day-1. Hydrolysis of the biomass with acids released proteins and hydrolyzed glycogen while hydrolysis of the biomass with base released only proteins but did not hydrolyze glycogen. Among the different acids tested, treatment with HNO3 led to the highest release of proteins and glucose. Cyanobacterial biomass hydrolysate (CBH) prepared in HNO3 was used as a medium to produce cellulase enzyme by the Penicillium funiculosum OAO3 strain while CBH prepared in HCl and treated with charcoal was used as a medium for citric acid by Aspergillus tubingensis. Approximately 50% higher titers of both products were obtained compared to traditional media. CONCLUSIONS These results show that the hydrolysate of marine cyanobacteria is an effective source of nutrients/proteins for fungal bioprocesses.
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Affiliation(s)
- Jai Kumar Gupta
- Systems Biology for Biofuel Group, International Centre for Genetic Engineering and Biotechnology (ICGEB), ICGEB Campus, Aruna Asaf Ali Marg, New Delhi, 110067, India
- Zero Cow Factory, Surat, India
| | - Kavish K Jain
- DBT-ICGEB Centre for Advanced Bioenergy Research, New Delhi, 110067, India
- The Live Green Co., Bangalore, India
| | - Mehak Kaushal
- Systems Biology for Biofuel Group, International Centre for Genetic Engineering and Biotechnology (ICGEB), ICGEB Campus, Aruna Asaf Ali Marg, New Delhi, 110067, India
- Perfect Day India Pvt. Ltd., Bangalore, India
| | - Daniel J Upton
- Department of Biology, University of York, Wentworth Way, York, YO10 5DD, UK
| | - Manish Joshi
- DBT-ICGEB Centre for Advanced Bioenergy Research, New Delhi, 110067, India
- Biocon Limited, Bangalore, India
| | - Piyush Pachauri
- Systems Biology for Biofuel Group, International Centre for Genetic Engineering and Biotechnology (ICGEB), ICGEB Campus, Aruna Asaf Ali Marg, New Delhi, 110067, India
| | - A Jamie Wood
- Department of Biology, University of York, Wentworth Way, York, YO10 5DD, UK
- Department of Mathematics, University of York, York, YO10 5DD, UK
| | - Syed Shams Yazdani
- DBT-ICGEB Centre for Advanced Bioenergy Research, New Delhi, 110067, India
- Microbial Engineering Group, ICGEB, New Delhi, 110067, India
| | - Shireesh Srivastava
- Systems Biology for Biofuel Group, International Centre for Genetic Engineering and Biotechnology (ICGEB), ICGEB Campus, Aruna Asaf Ali Marg, New Delhi, 110067, India.
- DBT-ICGEB Centre for Advanced Bioenergy Research, New Delhi, 110067, India.
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Randhawa A, A Ogunyewo O, Jawed K, Yazdani SS. Calcium signaling positively regulates cellulase translation and secretion in a Clr-2-overexpressing, catabolically derepressed strain of Penicillium funiculosum. BIOTECHNOLOGY FOR BIOFUELS AND BIOPRODUCTS 2024; 17:21. [PMID: 38336687 PMCID: PMC10858516 DOI: 10.1186/s13068-023-02448-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2023] [Accepted: 12/13/2023] [Indexed: 02/12/2024]
Abstract
BACKGROUND Low-cost cellulase production is vital to sustainable second-generation biorefineries. The catabolically derepressed strain of Penicillium funiculosum NCIM1228 (PfMig188 or ∆Mig1) secretes a superior set of cellulolytic enzymes, that are most suitable for 2G biorefineries. At a 3% (w/w) load, the ∆Mig1 secretome can release > 80% of fermentable sugars from lignocellulose at a 15% (w/v) biomass load, irrespective of the type of biomass and pretreatment. The robustness of the secretome can be further increased by improving the cellulase production capacity of the fungal strain. RESULTS We began by identifying the transcription factor responsible for cellulase production in NCIM1228. An advanced RNA-seq screen identified three genes, clr-2, ctf1a and ctf1b; the genes were cloned under their native promoters and transformed into NCIM1228. Of the three, clr-2 overexpression led to twofold higher cellulase production than the parent strain and was thus identified as the transcriptional activator of cellulase in NCIM1228. Next, we overexpressed clr-2 in ∆Mig1 and expected an exponential increase in cellulolytic attributes accredited to the reinforced activation mechanisms, conjoint with diminished negative regulation. Although clr-2 overexpression increased the transcript levels of cellulase genes in ∆Mig1, there was no increase in cellulase yield. Even a further increase in the transcript levels of clr-2 via a stronger promoter was ineffective. However, when the CaCO3 concentration was increased to 5 g/l in the growth medium, we achieved a 1.5-fold higher activity of 6.4 FPU/ml in the ∆Mig1 strain with clr-2 overexpression. Enthused by the calcium effect, a transcriptomic screen for genes encoding Ca2+-activated kinase identified ssp1, whose overexpression could further increase cellulase yield to ~ 7.5 FPU/ml. Investigation of the mechanism revealed that calcium signaling exclusively enhances the translation and secretion of cellulase in Penicillium funiculosum. CONCLUSIONS Our study identifies for the first time that cellulose activates two discrete signaling events to govern cellulase transcription and posttranscriptional processes (translation, processing and secretion) in P. funiculosum NCIM1228. Whereas Clr-2, the transcriptional activator of cellulase, governs transcription, calcium signaling specifically activates cellulase translation and secretion.
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Affiliation(s)
- Anmoldeep Randhawa
- Microbial Engineering Group, International Centre for Genetic Engineering and Biotechnology, New Delhi, 110067, India.
- DBT-ICGEB Centre for Advanced Bioenergy Research, International Centre for Genetic Engineering and Biotechnology, New Delhi, 110067, India.
- AMITY University, Mohali, Punjab, 140306, India.
| | - Olusola A Ogunyewo
- Microbial Engineering Group, International Centre for Genetic Engineering and Biotechnology, New Delhi, 110067, India
| | - Kamran Jawed
- Microbial Engineering Group, International Centre for Genetic Engineering and Biotechnology, New Delhi, 110067, India
| | - Syed Shams Yazdani
- Microbial Engineering Group, International Centre for Genetic Engineering and Biotechnology, New Delhi, 110067, India.
- DBT-ICGEB Centre for Advanced Bioenergy Research, International Centre for Genetic Engineering and Biotechnology, New Delhi, 110067, India.
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Pasari N, Gupta M, Sinha T, Ogunmolu FE, Yazdani SS. Systematic identification of CAZymes and transcription factors in the hypercellulolytic fungus Penicillium funiculosum NCIM1228 involved in lignocellulosic biomass degradation. BIOTECHNOLOGY FOR BIOFUELS AND BIOPRODUCTS 2023; 16:150. [PMID: 37794424 PMCID: PMC10552389 DOI: 10.1186/s13068-023-02399-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2023] [Accepted: 09/18/2023] [Indexed: 10/06/2023]
Abstract
BACKGROUND Penicillium funiculosum NCIM1228 is a filamentous fungus that was identified in our laboratory to have high cellulolytic activity. Analysis of its secretome suggested that it responds to different carbon substrates by secreting specific enzymes capable of digesting those substrates. This phenomenon indicated the presence of a regulatory system guiding the expression of these hydrolyzing enzymes. Since transcription factors (TFs) are the key players in regulating the expression of enzymes, this study aimed first to identify the complete repertoire of Carbohydrate Active Enzymes (CAZymes) and TFs coded in its genome. The regulation of CAZymes was then analysed by studying the expression pattern of these CAZymes and TFs in different carbon substrates-Avicel (cellulosic substrate), wheat bran (WB; hemicellulosic substrate), Avicel + wheat bran, pre-treated wheat straw (a potential substrate for lignocellulosic ethanol), and glucose (control). RESULTS The P. funiculosum NCIM1228 genome was sequenced, and 10,739 genes were identified in its genome. These genes included a total of 298 CAZymes and 451 TF coding genes. A distinct expression pattern of the CAZymes was observed in different carbon substrates tested. Core cellulose hydrolyzing enzymes were highly expressed in the presence of Avicel, while pre-treated wheat straw and Avicel + wheat bran induced a mixture of CAZymes because of their heterogeneous nature. Wheat bran mainly induced hemicellulases, and the least number of CAZymes were expressed in glucose. TFs also exhibited distinct expression patterns in each of the carbon substrates. Though most of these TFs have not been functionally characterized before, homologs of NosA, Fcr1, and ATF21, which have been known to be involved in fruiting body development, protein secretion and stress response, were identified. CONCLUSIONS Overall, the P. funiculosum NCIM1228 genome was sequenced, and the CAZymes and TFs present in its genome were annotated. The expression of the CAZymes and TFs in response to various polymeric sugars present in the lignocellulosic biomass was identified. This work thus provides a comprehensive mapping of transcription factors (TFs) involved in regulating the production of biomass hydrolyzing enzymes.
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Affiliation(s)
- Nandita Pasari
- Microbial Engineering Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi, India
- National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi, India
| | - Mayank Gupta
- Microbial Engineering Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi, India
- DBT-ICGEB Centre for Advanced Bioenergy Research, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi, India
| | - Tulika Sinha
- Microbial Engineering Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi, India
| | - Funso Emmanuel Ogunmolu
- Microbial Engineering Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi, India
| | - Syed Shams Yazdani
- Microbial Engineering Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi, India.
- DBT-ICGEB Centre for Advanced Bioenergy Research, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi, India.
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Okereke OE, Gupta M, Ogunyewo OA, Sharma K, Kapoor S, Sinha T, Yazdani SS. Profiling of the β-glucosidases identified in the genome of Penicillium funiculosum: insights from genomics, transcriptomics, proteomics, and homology-modeling studies. Appl Environ Microbiol 2023; 89:e0070423. [PMID: 37610233 PMCID: PMC10537656 DOI: 10.1128/aem.00704-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2023] [Accepted: 07/14/2023] [Indexed: 08/24/2023] Open
Abstract
The enzymatic conversion of lignocellulosic biomass to bioethanol depends on efficient enzyme systems with β-glucosidase as one of the key components. In this study, we performed in-depth profiling of the various β-glucosidases present in the genome of the hypercellulolytic fungus Penicillium funiculosum using genomics, transcriptomics, proteomics, and molecular dynamics simulation approaches. Of the eight β-glucosidase genes identified in the P. funiculosum genome, three were predicted to be extracellular based on signal peptide prediction and abundance in the secretome. Among the three secreted β-glucosidases, two belonged to the GH3 family and one belonged to the GH1 family. Homology models of these proteins predicted a deep and narrow active site for the GH3 β-glucosidases (PfBgl3A and PfBgl3B) and a shallow open active site for the GH1 β-glucosidase (PfBgl1A). The enzymatic assays indicated that P. funiculosum-secreted proteins showed high β-glucosidase activities with prominent bands on the 4-methylumbelliferyl β-D-glucopyranoside zymogram. To understand the contributory effects of each of the three secreted β-glucosidases (PfBgls), the corresponding gene was deleted separately, and the effect of the deletion on the β-glucosidase activity of the secretome was examined. Although not the most abundant, PfBgl3A was found to be one of the most important β-glucosidases, as evidenced by a 42% reduction in β-glucosidase activity in the ΔPfBgl3A strain. Our results advance the understanding of the genetic and biochemical nature of all β-glucosidases produced by P. funiculosum and pave the way to design a superior biocatalyst for the hydrolysis of lignocellulosic biomass. IMPORTANCE Commercially available cellulases are primarily produced from Trichoderma reesei. However, external supplementation of the cellulase cocktail from this host with exogenous β-glucosidase is often required to achieve the desired optimal saccharification of cellulosic feedstocks. This challenge has led to the exploration of other cellulase-producing strains. The nonmodel hypercellulolytic fungus Penicillium funiculosum has been studied in recent times and identified as a promising source of industrial cellulases mainly due to its ability to produce a balanced concoction of cellulolytic enzymes, including β-glucosidases. Various genetic interventions targeted at strain improvement for cellulase production have been performed; however, the β-glucosidases of this strain have remained largely understudied. This study, therefore, reports profiling of all eight β-glucosidases of P. funiculosum via molecular and computational approaches. The results of this study provide useful insights that will establish the background for future engineering strategies to transform this fungus into an industrial workhorse.
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Affiliation(s)
- Omoaruemike Ebele Okereke
- Microbial Engineering Group, International Centre for Genetic Engineering and Biotechnology, New Delhi, India
- Biotechnology Advanced Research Centre, Sheda Science and Technology Complex (SHESTCO), Abuja, Nigeria
| | - Mayank Gupta
- Microbial Engineering Group, International Centre for Genetic Engineering and Biotechnology, New Delhi, India
- DBT-ICGEB Centre for Advanced Bioenergy Research, International Centre for Genetic Engineering and Biotechnology, New Delhi, India
| | - Olusola A. Ogunyewo
- Microbial Engineering Group, International Centre for Genetic Engineering and Biotechnology, New Delhi, India
- DBT-ICGEB Centre for Advanced Bioenergy Research, International Centre for Genetic Engineering and Biotechnology, New Delhi, India
| | - Kanika Sharma
- Microbial Engineering Group, International Centre for Genetic Engineering and Biotechnology, New Delhi, India
- DBT-ICGEB Centre for Advanced Bioenergy Research, International Centre for Genetic Engineering and Biotechnology, New Delhi, India
| | - Sonal Kapoor
- Microbial Engineering Group, International Centre for Genetic Engineering and Biotechnology, New Delhi, India
| | - Tulika Sinha
- Microbial Engineering Group, International Centre for Genetic Engineering and Biotechnology, New Delhi, India
| | - Syed Shams Yazdani
- Microbial Engineering Group, International Centre for Genetic Engineering and Biotechnology, New Delhi, India
- DBT-ICGEB Centre for Advanced Bioenergy Research, International Centre for Genetic Engineering and Biotechnology, New Delhi, India
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Zhao Z, Gu S, Liu D, Liu D, Chen B, Li J, Tian C. The putative methyltransferase LaeA regulates mycelium growth and cellulase production in Myceliophthora thermophila. BIOTECHNOLOGY FOR BIOFUELS AND BIOPRODUCTS 2023; 16:58. [PMID: 37013645 PMCID: PMC10071736 DOI: 10.1186/s13068-023-02313-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Accepted: 03/28/2023] [Indexed: 04/05/2023]
Abstract
BACKGROUND Filamentous fungi with the ability to use complex carbon sources has been developed as platforms for biochemicals production. Myceliophthora thermophila has been developed as the cell factory to produce lignocellulolytic enzymes and plant biomass-based biofuels and biochemicals in biorefinery. However, low fungal growth rate and cellulose utilization efficiency are significant barriers to the satisfactory yield and productivity of target products, which needs our further exploration and improvement. RESULTS In this study, we comprehensively explored the roles of the putative methyltransferase LaeA in regulating mycelium growth, sugar consumption, and cellulases expression. Deletion of laeA in thermophile fungus Myceliophthora thermophila enhanced mycelium growth and glucose consumption significantly. Further exploration of LaeA regulatory network indicated that multiple growth regulatory factors (GRF) Cre-1, Grf-1, Grf-2, and Grf-3, which act as negative repressors of carbon metabolism, were regulated by LaeA in this fungus. We also determined that phosphoenolpyruvate carboxykinase (PCK) is the core node of the metabolic network related to fungal vegetative growth, of which enhancement partially contributed to the elevated sugar consumption and fungal growth of mutant ΔlaeA. Noteworthily, LaeA participated in regulating the expression of cellulase genes and their transcription regulator. ΔlaeA exhibited 30.6% and 5.5% increases in the peak values of extracellular protein and endo-glucanase activity, respectively, as compared to the WT strain. Furthermore, the global histone methylation assays indicated that LaeA is associated with modulating H3K9 methylation levels. The normal function of LaeA on regulating fungal physiology is dependent on methyltransferase activity. CONCLUSIONS The research presented in this study clarified the function and elucidated the regulatory network of LaeA in the regulation of fungal growth and cellulase production, which will significantly deepen our understanding about the regulation mechanism of LaeA in filamentous fungi and provides the new strategy for improvement the fermentation properties of industrial fungal strain by metabolic engineering.
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Affiliation(s)
- Zhen Zhao
- Key Laboratory of Engineering Biology for Low-carbon Manufacturing, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308, China
- National Technology Innovation Center of Synthetic Biology, Tianjin, 300308, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Shuying Gu
- Key Laboratory of Engineering Biology for Low-carbon Manufacturing, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308, China
- National Technology Innovation Center of Synthetic Biology, Tianjin, 300308, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Defei Liu
- Key Laboratory of Engineering Biology for Low-carbon Manufacturing, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308, China
- National Technology Innovation Center of Synthetic Biology, Tianjin, 300308, China
| | - Dandan Liu
- Key Laboratory of Engineering Biology for Low-carbon Manufacturing, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308, China
- National Technology Innovation Center of Synthetic Biology, Tianjin, 300308, China
| | - Bingchen Chen
- Key Laboratory of Engineering Biology for Low-carbon Manufacturing, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308, China
- National Technology Innovation Center of Synthetic Biology, Tianjin, 300308, China
| | - Jingen Li
- Key Laboratory of Engineering Biology for Low-carbon Manufacturing, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308, China.
- National Technology Innovation Center of Synthetic Biology, Tianjin, 300308, China.
| | - Chaoguang Tian
- Key Laboratory of Engineering Biology for Low-carbon Manufacturing, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308, China.
- National Technology Innovation Center of Synthetic Biology, Tianjin, 300308, China.
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Characterization of a GH5 endoxylanase from Penicillium funiculosum and its synergism with GH16 endo-1,3(4)-glucanase in saccharification of sugarcane bagasse. Sci Rep 2022; 12:17219. [PMID: 36241677 PMCID: PMC9568505 DOI: 10.1038/s41598-022-21529-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2022] [Accepted: 09/28/2022] [Indexed: 01/06/2023] Open
Abstract
The production of second-generation fuels from lignocellulosic residues such as sugarcane bagasse (SCB) requires the synergistic interaction of key cellulose-degrading enzymes and accessory proteins for their complete deconstruction to useful monomeric sugars. Here, we recombinantly expressed and characterized unknown GH5 xylanase from P. funiculosum (PfXyn5) in Pichia pastoris, which was earlier found in our study to be highly implicated in SCB saccharification. The PfXyn5 has a molecular mass of ~ 55 kDa and showed broad activity against a range of substrates like xylan, xyloglucan, laminarin and p-nitrophenyl-β-D-xylopyranoside, with the highest specific activity of 0.7 U/mg against xylan at pH 4.5 and 50 °C. Analysis of the degradation products of xylan and SCB by PfXyn5 showed significant production of xylooligosaccharides (XOS) with a degree of polymerization (DP) ranging from two (DP2) to six (DP6), thus, suggesting that the PfXyn5 is an endo-acting enzyme. The enzyme synergistically improved the saccharification of SCB when combined with the crude cellulase cocktail of P. funiculosum with a degree of synergism up to 1.32. The PfXyn5 was further expressed individually and simultaneously with a notable GH16 endoglucanase (PfEgl16) in a catabolite-derepressed strain of P. funiculosum, PfMig188, and the saccharification efficiency of the secretomes from the resulting transformants were investigated on SCB. The secretome of PfMig188 overexpressing Xyn5 or Egl16 increased the saccharification of SCB by 9% or 7%, respectively, over the secretome of PfMig188, while the secretome of dual transformant increased SCB saccharification by ~ 15% at the same minimal protein concentration.
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Mattam AJ, Chaudhari YB, Velankar HR. Factors regulating cellulolytic gene expression in filamentous fungi: an overview. Microb Cell Fact 2022; 21:44. [PMID: 35317826 PMCID: PMC8939176 DOI: 10.1186/s12934-022-01764-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Accepted: 02/27/2022] [Indexed: 12/19/2022] Open
Abstract
The growing demand for biofuels such as bioethanol has led to the need for identifying alternative feedstock instead of conventional substrates like molasses, etc. Lignocellulosic biomass is a relatively inexpensive feedstock that is available in abundance, however, its conversion to bioethanol involves a multistep process with different unit operations such as size reduction, pretreatment, saccharification, fermentation, distillation, etc. The saccharification or enzymatic hydrolysis of cellulose to glucose involves a complex family of enzymes called cellulases that are usually fungal in origin. Cellulose hydrolysis requires the synergistic action of several classes of enzymes, and achieving the optimum secretion of these simultaneously remains a challenge. The expression of fungal cellulases is controlled by an intricate network of transcription factors and sugar transporters. Several genetic engineering efforts have been undertaken to modulate the expression of cellulolytic genes, as well as their regulators. This review, therefore, focuses on the molecular mechanism of action of these transcription factors and their effect on the expression of cellulases and hemicellulases.
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Affiliation(s)
- Anu Jose Mattam
- Hindustan Petroleum Green R and D Centre (HPGRDC), KIADB Industrial Area, Tarabanahalli, Devanagundi, Hoskote, Bangalore, 560067, India
| | - Yogesh Babasaheb Chaudhari
- Hindustan Petroleum Green R and D Centre (HPGRDC), KIADB Industrial Area, Tarabanahalli, Devanagundi, Hoskote, Bangalore, 560067, India
| | - Harshad Ravindra Velankar
- Hindustan Petroleum Green R and D Centre (HPGRDC), KIADB Industrial Area, Tarabanahalli, Devanagundi, Hoskote, Bangalore, 560067, India.
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Zinc finger protein LipR represses docosahexaenoic acid and lipid biosynthesis in Schizochytrium sp. Appl Environ Microbiol 2022; 88:e0206321. [PMID: 35108079 DOI: 10.1128/aem.02063-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The heterotrophic marine microalgae Schizochytrium sp. is an important industrial producer of docosahexaenoic acid (DHA). Increased production of DHA and lipids in Schizochytrium sp. have been achieved by standard fermentation optimization and metabolic engineering methods; however, regulatory mechanisms for DHA and lipid biosynthesis remain unknown. In this study, the C2H2 zinc finger protein LipR was identified in Schizochytrium sp. ATCC20888 by transcriptional analysis. Deletion of the lipR gene significantly (p< 0.001) increased production of total lipids and DHA by (respectively) 33% and 48%. LipR repressed DHA and lipid production by directly inhibiting transcription of polyunsaturated fatty acid (PUFA) and fatty acid synthase (FAS) genes (pfa1, pfa2, pfa3, fas). Specific binding of LipR to 9-bp recognition sequence 5'-(C/A)(A/G)CCATCTT-3' in upstream regions of target genes was demonstrated by electrophoretic mobility shift assays (EMSAs) and DNase I footprinting assays. Expression of several key genes (acc, acl, ampD, fabD, mae, zwf, dga1) related to levels of precursors and NADPH, and to triacylglycerol storage rate, were also directly repressed by LipR. Our findings, taken together, indicate that the evolutionarily unique regulator LipR is an essential repressor of DHA and saturated fatty acid biosynthesis in Schizochytrium sp. Importance Regulatory mechanisms for DHA and saturated fatty acid biosynthesis in the heterotrophic marine microalgae Schizochytrium sp. are unclear. We demonstrate here that deletion of the gene (lipR) encoding the C2H2 zinc finger protein LipR promotes DHA and saturated fatty acid production in this genus. LipR acts as a key repressor of such production by binding to 9-bp consensus sequence 5'-(C/A)(A/G)CCATCTT-3' in the upstream regions of polyunsaturated fatty acid and fatty acid synthase genes (pfa1, pfa2, pfa3, fas), and genes related to levels of precursors and NADPH (acc, acl, ampD, fabD, mae, zwf), and to triacylglycerol storage rate (dga1). This is the first demonstration that a regulator inhibits synthesis of DHA and lipids in Schizochytrium sp. by directly controlling transcription of PUFA synthase and fas genes. Manipulation of the lipR gene provides a potential strategy for enhancing accumulation of polyunsaturated fatty acids and lipids in thraustochytrids.
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Mohamed RA, Ren K, Mou YN, Ying SH, Feng MG. Genome-Wide Insight into Profound Effect of Carbon Catabolite Repressor (Cre1) on the Insect-Pathogenic Lifecycle of Beauveriabassiana. J Fungi (Basel) 2021; 7:jof7110895. [PMID: 34829184 PMCID: PMC8622151 DOI: 10.3390/jof7110895] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Revised: 10/19/2021] [Accepted: 10/20/2021] [Indexed: 11/16/2022] Open
Abstract
Carbon catabolite repression (CCR) is critical for the preferential utilization of glucose derived from environmental carbon sources and regulated by carbon catabolite repressor A (Cre1/CreA) in filamentous fungi. However, a role of Cre1-mediated CCR in insect-pathogenic fungal utilization of host nutrients during normal cuticle infection (NCI) and hemocoel colonization remains explored insufficiently. Here, we report an indispensability of Cre1 for Beauveriabassiana's utilization of nutrients in insect integument and hemocoel. Deletion of cre1 resulted in severe defects in radial growth on various media, hypersensitivity to oxidative stress, abolished pathogenicity via NCI or intrahemocoel injection (cuticle-bypassing infection) but no change in conidial hydrophobicity and adherence to insect cuticle. Markedly reduced biomass accumulation in the Δcre1 cultures was directly causative of severe defect in aerial conidiation and reduced secretion of various cuticle-degrading enzymes. The majority (1117) of 1881 dysregulated genes identified from the Δcre1 versus wild-type cultures were significantly downregulated, leading to substantial repression of many enriched function terms and pathways, particularly those involved in carbon and nitrogen metabolisms, cuticle degradation, antioxidant response, cellular transport and homeostasis, and direct/indirect gene mediation. These findings offer a novel insight into profound effect of Cre1 on the insect-pathogenic lifestyle of B. bassiana.
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Ogunyewo OA, Upadhyay P, Rajacharya GH, Okereke OE, Faas L, Gómez LD, McQueen-Mason SJ, Yazdani SS. Accessory enzymes of hypercellulolytic Penicillium funiculosum facilitate complete saccharification of sugarcane bagasse. BIOTECHNOLOGY FOR BIOFUELS 2021; 14:171. [PMID: 34446097 PMCID: PMC8394629 DOI: 10.1186/s13068-021-02020-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Accepted: 08/15/2021] [Indexed: 05/26/2023]
Abstract
BACKGROUND Sugarcane bagasse (SCB) is an abundant feedstock for second-generation bioethanol production. This complex biomass requires an array of carbohydrate active enzymes (CAZymes), mostly from filamentous fungi, for its deconstruction to monomeric sugars for the production of value-added fuels and chemicals. In this study, we evaluated the repertoire of proteins in the secretome of a catabolite repressor-deficient strain of Penicillium funiculosum, PfMig188, in response to SCB induction and examined their role in the saccharification of SCB. RESULTS A systematic approach was developed for the cultivation of the fungus with the aim of producing and understanding arrays of enzymes tailored for saccharification of SCB. To achieve this, the fungus was grown in media supplemented with different concentrations of pretreated SCB (0-45 g/L). The profile of secreted proteins was characterized by enzyme activity assays and liquid chromatography-tandem mass spectrometry (LC-MS/MS). A total of 280 proteins were identified in the secretome of PfMig188, 46% of them being clearly identified as CAZymes. Modulation of the cultivation media with SCB up to 15 g/L led to sequential enhancement in the secretion of hemicellulases and cell wall-modifying enzymes, including endo-β-1,3(4)-glucanase (GH16), endo-α-1,3-glucanase (GH71), xylanase (GH30), β-xylosidase (GH5), β-1,3-galactosidase (GH43) and cutinase (CE5). There was ~ 122% and 60% increases in β-xylosidase and cutinase activities, respectively. There was also a 36% increase in activities towards mixed-linked glucans. Induction of these enzymes in the secretome improved the saccharification performance to 98% (~ 20% increase over control), suggesting their synergy with core cellulases in accessing the recalcitrant region of SCB. CONCLUSION Our findings provide an insight into the enzyme system of PfMig188 for degradation of complex biomass such as SCB and highlight the importance of adding SCB to the culture medium to optimize the secretion of enzymes specific for the saccharification of sugarcane bagasse.
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Affiliation(s)
- Olusola A Ogunyewo
- Microbial Engineering Group, International Centre for Genetic Engineering and Biotechnology, New Delhi, 110067, India
- DBT-ICGEB Centre for Advanced Bioenergy Research, International Centre for Genetic Engineering and Biotechnology, New Delhi, 110067, India
| | - Pooja Upadhyay
- Microbial Engineering Group, International Centre for Genetic Engineering and Biotechnology, New Delhi, 110067, India
| | - Girish H Rajacharya
- Microbial Engineering Group, International Centre for Genetic Engineering and Biotechnology, New Delhi, 110067, India
- DBT-ICGEB Centre for Advanced Bioenergy Research, International Centre for Genetic Engineering and Biotechnology, New Delhi, 110067, India
| | - Omoaruemike E Okereke
- Microbial Engineering Group, International Centre for Genetic Engineering and Biotechnology, New Delhi, 110067, India
- Biotechnology Advanced Research Centre, Sheda Science and Technology Complex (SHESTCO), Abuja, Nigeria
| | - Laura Faas
- Department of Biology, Centre for Novel Agricultural Products, CNAP, University of York, York, YO10 5DD, UK
| | - Leonardo D Gómez
- Department of Biology, Centre for Novel Agricultural Products, CNAP, University of York, York, YO10 5DD, UK
| | - Simon J McQueen-Mason
- Department of Biology, Centre for Novel Agricultural Products, CNAP, University of York, York, YO10 5DD, UK
| | - Syed Shams Yazdani
- Microbial Engineering Group, International Centre for Genetic Engineering and Biotechnology, New Delhi, 110067, India.
- DBT-ICGEB Centre for Advanced Bioenergy Research, International Centre for Genetic Engineering and Biotechnology, New Delhi, 110067, India.
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Xu W, Fan J, Wang Y, Wang Y, Zhu J, Ren A, Yu H, Shi L, Zhao M. Mitochondrial pyruvate carrier regulates the lignocellulosic decomposition rate through metabolism in Ganoderma lucidum. FEMS Microbiol Lett 2021; 368:6316105. [PMID: 34227669 DOI: 10.1093/femsle/fnab088] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Accepted: 07/02/2021] [Indexed: 11/14/2022] Open
Abstract
The activity of mitochondrial pyruvate carrier (MPC) can be modulated to regulate intracellular metabolism under different culture conditions. In Ganoderma lucidum, the role of MPC in regulating carbon sources remains unknown. By knocking down MPC genes (MPC1 and MPC2), this research found that the loss of MPC increased the growth rate of G. lucidum by ~30% in a medium with wood chips as a carbon source. Then cellulase and laccase activities were tested. Endoglucanase and laccase activity increased by ~50% and ~35%, respectively, in MPC knockdown mutants compared with that in the wild type strain. Finally, the expression levels of genes related to glycolysis were assayed, and the transcription levels of these enzymes were found to be increased by ~250% compared with the wild type strain. In conclusion, the regulation of intracellular metabolism by MPC provides a new way to improve the use of nondominant carbon sources such as lignocellulose.
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Affiliation(s)
- Wenzhao Xu
- Key Laboratory of Microbiological Engineering of Agricultural Environment, Ministry of Agriculture, Department of Microbiology, College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, Jiangsu, P.R. China
| | - Junpei Fan
- Key Laboratory of Microbiological Engineering of Agricultural Environment, Ministry of Agriculture, Department of Microbiology, College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, Jiangsu, P.R. China
| | - Yihong Wang
- Key Laboratory of Microbiological Engineering of Agricultural Environment, Ministry of Agriculture, Department of Microbiology, College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, Jiangsu, P.R. China
| | - Yunxiao Wang
- Key Laboratory of Microbiological Engineering of Agricultural Environment, Ministry of Agriculture, Department of Microbiology, College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, Jiangsu, P.R. China
| | - Jing Zhu
- Key Laboratory of Microbiological Engineering of Agricultural Environment, Ministry of Agriculture, Department of Microbiology, College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, Jiangsu, P.R. China
| | - Ang Ren
- Key Laboratory of Microbiological Engineering of Agricultural Environment, Ministry of Agriculture, Department of Microbiology, College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, Jiangsu, P.R. China
| | - Hanshou Yu
- Key Laboratory of Microbiological Engineering of Agricultural Environment, Ministry of Agriculture, Department of Microbiology, College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, Jiangsu, P.R. China
| | - Liang Shi
- Key Laboratory of Microbiological Engineering of Agricultural Environment, Ministry of Agriculture, Department of Microbiology, College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, Jiangsu, P.R. China
| | - Mingwen Zhao
- Key Laboratory of Microbiological Engineering of Agricultural Environment, Ministry of Agriculture, Department of Microbiology, College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, Jiangsu, P.R. China
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Randhawa A, Pasari N, Sinha T, Gupta M, Nair AM, Ogunyewo OA, Verma S, Verma PK, Yazdani SS. Blocking drug efflux mechanisms facilitate genome engineering process in hypercellulolytic fungus, Penicillium funiculosum NCIM1228. BIOTECHNOLOGY FOR BIOFUELS 2021; 14:31. [PMID: 33494787 PMCID: PMC7836482 DOI: 10.1186/s13068-021-01883-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Accepted: 01/09/2021] [Indexed: 06/12/2023]
Abstract
BACKGROUND Penicillium funiculosum NCIM1228 is a non-model filamentous fungus that produces high-quality secretome for lignocellulosic biomass saccharification. Despite having desirable traits to be an industrial workhorse, P. funiculosum has been underestimated due to a lack of reliable genetic engineering tools. Tolerance towards common fungal antibiotics had been one of the major hindrances towards development of reliable transformation tools against the non-model fungi. In this study, we sought to understand the mechanism of drug tolerance of P. funiculosum and the provision to counter it. We then attempted to identify a robust method of transformation for genome engineering of this fungus. RESULTS Penicillium funiculosum showed a high degree of drug tolerance towards hygromycin, zeocin and nourseothricin, thereby hindering their use as selectable markers to obtain recombinant transformants. Transcriptome analysis suggested a high level expression of efflux pumps belonging to ABC and MFS family, especially when complex carbon was used in growth media. Antibiotic selection medium was optimized using a combination of efflux pump inhibitors and suitable carbon source to prevent drug tolerability. Protoplast-mediated and Agrobacterium-mediated transformation were attempted for identifying efficiencies of linear and circular DNA in performing genetic manipulation. After finding Ti-plasmid-based Agrobacterium-mediated transformation more suitable for P. funiculosum, we improvised the system to achieve random and homologous recombination-based gene integration and deletion, respectively. We found single-copy random integration of the T-DNA cassette and could achieve 60% efficiency in homologous recombination-based gene deletions. A faster, plasmid-free, and protoplast-based CRISPR/Cas9 gene-editing system was also developed for P. funiculosum. To show its utility in P. funiculosum, we deleted the gene coding for the most abundant cellulase Cellobiohydrolase I (CBH1) using a pair of sgRNA directed towards both ends of cbh1 open reading frame. Functional analysis of ∆cbh1 strain revealed its essentiality for the cellulolytic trait of P. funiculosum secretome. CONCLUSIONS In this study, we addressed drug tolerability of P. funiculosum and developed an optimized toolkit for its genome modification. Hence, we set the foundation for gene function analysis and further genetic improvements of P. funiculosum using both traditional and advanced methods.
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Affiliation(s)
- Anmoldeep Randhawa
- Microbial Engineering Group, International Centre for Genetic Engineering and Biotechnology, New Delhi, 110067, India
- DBT-ICGEB Centre for Advanced Bioenergy Research, International Centre for Genetic Engineering and Biotechnology, New Delhi, 110067, India
| | - Nandita Pasari
- Microbial Engineering Group, International Centre for Genetic Engineering and Biotechnology, New Delhi, 110067, India
- National Institute of Plant Genome Research, New Delhi, 110067, India
| | - Tulika Sinha
- Microbial Engineering Group, International Centre for Genetic Engineering and Biotechnology, New Delhi, 110067, India
| | - Mayank Gupta
- Microbial Engineering Group, International Centre for Genetic Engineering and Biotechnology, New Delhi, 110067, India
- DBT-ICGEB Centre for Advanced Bioenergy Research, International Centre for Genetic Engineering and Biotechnology, New Delhi, 110067, India
| | - Anju M Nair
- Microbial Engineering Group, International Centre for Genetic Engineering and Biotechnology, New Delhi, 110067, India
- DBT-ICGEB Centre for Advanced Bioenergy Research, International Centre for Genetic Engineering and Biotechnology, New Delhi, 110067, India
| | - Olusola A Ogunyewo
- Microbial Engineering Group, International Centre for Genetic Engineering and Biotechnology, New Delhi, 110067, India
| | - Sandhya Verma
- National Institute of Plant Genome Research, New Delhi, 110067, India
| | | | - Syed Shams Yazdani
- Microbial Engineering Group, International Centre for Genetic Engineering and Biotechnology, New Delhi, 110067, India.
- DBT-ICGEB Centre for Advanced Bioenergy Research, International Centre for Genetic Engineering and Biotechnology, New Delhi, 110067, India.
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Bhagwat P, Amobonye A, Singh S, Pillai S. A comparative analysis of GH18 chitinases and their isoforms from Beauveria bassiana: An in-silico approach. Process Biochem 2021. [DOI: 10.1016/j.procbio.2020.10.012] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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16
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Synergistic Action of a Lytic Polysaccharide Monooxygenase and a Cellobiohydrolase from Penicillium funiculosum in Cellulose Saccharification under High-Level Substrate Loading. Appl Environ Microbiol 2020; 86:AEM.01769-20. [PMID: 32978122 DOI: 10.1128/aem.01769-20] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Accepted: 09/15/2020] [Indexed: 12/25/2022] Open
Abstract
Lytic polysaccharide monooxygenases (LPMOs) are crucial industrial enzymes required in the biorefinery industry as well as in the natural carbon cycle. These enzymes, known to catalyze the oxidative cleavage of glycosidic bonds, are produced by numerous bacterial and fungal species to assist in the degradation of cellulosic biomass. In this study, we annotated and performed structural analysis of an uncharacterized LPMO from Penicillium funiculosum (PfLPMO9) based on computational methods in an attempt to understand the behavior of this enzyme in biomass degradation. PfLPMO9 exhibited 75% and 36% sequence identities with LPMOs from Thermoascus aurantiacus (TaLPMO9A) and Lentinus similis (LsLPMO9A), respectively. Furthermore, multiple fungal genetic manipulation tools were employed to simultaneously overexpress LPMO and cellobiohydrolase I (CBH1) in a catabolite-derepressed strain of Penicillium funiculosum, PfMig188 (an engineered variant of P. funiculosum), to improve its saccharification performance toward acid-pretreated wheat straw (PWS) at 20% substrate loading. The resulting transformants showed improved LPMO and CBH1 expression at both the transcriptional and translational levels, with ∼200% and ∼66% increases in ascorbate-induced LPMO and Avicelase activities, respectively. While the secretome of PfMig88 overexpressing LPMO or CBH1 increased the saccharification of PWS by 6% or 13%, respectively, over the secretome of PfMig188 at the same protein concentration, the simultaneous overexpression of these two genes led to a 20% increase in saccharification efficiency over that observed with PfMig188, which accounted for 82% saccharification of PWS under 20% substrate loading.IMPORTANCE The enzymatic hydrolysis of cellulosic biomass by cellulases continues to be a significant bottleneck in the development of second-generation biobased industries. While increasing efforts are being made to obtain indigenous cellulases for biomass hydrolysis, the high production cost of this enzyme remains a crucial challenge affecting its wide availability for the efficient utilization of cellulosic materials. This is because it is challenging to obtain an enzymatic cocktail with balanced activity from a single host. This report describes the annotation and structural analysis of an uncharacterized lytic polysaccharide monooxygenase (LPMO) gene in Penicillium funiculosum and its impact on biomass deconstruction upon overexpression in a catabolite-derepressed strain of P. funiculosum Cellobiohydrolase I (CBH1), which is the most important enzyme produced by many cellulolytic fungi for the saccharification of crystalline cellulose, was further overexpressed simultaneously with LPMO. The resulting secretome was analyzed for enhanced LPMO and exocellulase activities and the corresponding improvement in saccharification performance (by ∼20%) under high-level substrate loading using a minimal amount of protein.
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Zhang T, Liu H, Lv B, Li C. Regulating Strategies for Producing Carbohydrate Active Enzymes by Filamentous Fungal Cell Factories. Front Bioeng Biotechnol 2020; 8:691. [PMID: 32733865 PMCID: PMC7360787 DOI: 10.3389/fbioe.2020.00691] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2020] [Accepted: 06/03/2020] [Indexed: 12/17/2022] Open
Abstract
Filamentous fungi are important eukaryotic organisms crucial in substrate degradation and carbon cycle on the earth and have been harnessed as cell factories for the production of proteins and other high value-added products in recent decades. As cell factories, filamentous fungi play a crucial role in industrial protein production as both native hosts and heterologous hosts. In this review, the regulation strategies of carbohydrate active enzyme expression at both transcription level and protein level are introduced, and the transcription regulations are highlighted with induction mechanism, signaling pathway, and promoter and transcription factor regulation. Afterward, the regulation strategies in protein level including suitable posttranslational modification, protein secretion enhancement, and protease reduction are also presented. Finally, the challenges and perspectives in this field are discussed. In this way, a comprehensive knowledge regarding carbohydrate active enzyme production regulation at both transcriptional and protein levels is provided with the particular goal of aiding in the practical application of filamentous fungi for industrial protein production.
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Affiliation(s)
- Teng Zhang
- Institute for Synthetic Biosystem/Department of Biochemical Engineering, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing, China
| | - Hu Liu
- Institute for Synthetic Biosystem/Department of Biochemical Engineering, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing, China
| | - Bo Lv
- Institute for Synthetic Biosystem/Department of Biochemical Engineering, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing, China
| | - Chun Li
- Institute for Synthetic Biosystem/Department of Biochemical Engineering, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing, China
- Key Laboratory of Systems Bioengineering (Ministry of Education), Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), School of Chemical Engineering and Technology, Tianjin University, Tianjin, China
- Key Lab for Industrial Biocatalysis, Ministry of Education, Department of Chemical Engineering, Tsinghua University, Beijing, China
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Wang S, Han J, Xia J, Hu Y, Shi L, Ren A, Zhu J, Zhao M. Overexpression of nicotinamide mononucleotide adenylyltransferase (nmnat) increases the growth rate, Ca 2+ concentration and cellulase production in Ganoderma lucidum. Appl Microbiol Biotechnol 2020; 104:7079-7091. [PMID: 32632475 DOI: 10.1007/s00253-020-10763-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Revised: 06/08/2020] [Accepted: 06/16/2020] [Indexed: 12/13/2022]
Abstract
Identifying new and economical means to utilize diverse lignocellulosic biomass is an urgent task. Ganoderma lucidum is a well-known edible and medicinal basidiomycete with an excellent ability to degrade a wide range of cellulosic biomass, and its nutrient use efficiency is closely related to the activity of extracellular cellulase. Intracellular nicotinamide adenine dinucleotide (NAD+) biosynthesis is controlled in response to nutritional status, and NAD+ is an essential metabolite involved in diverse cellular processes. Nicotinamide mononucleotide adenylyltransferase (NMNAT) is a common enzyme in three NAD+ synthesis pathways. In this study, a homologous gene of nmnat was cloned from G. lucidum and two G. lucidum overexpression strains, OE::nmnat4 and OE::nmnat19, were constructed using an Agrobacterium tumefaciens-mediated transformation method. The G. lucidum nmnat overexpression strains showed obviously increased colony growth on different carbon sources, and intracellular Ca2+ concentrations in the G. lucidum OE::nmnat4 and OE::nmnat19 strains were increased by 2.04- and 2.30-fold, respectively, compared with those in the wild-type (WT) strains. In the G. lucidum OE::nmnat4 and OE::nmnat19 strains, endo-β-glucanase (CMCase) activity increased by approximately 2.8- and 3-fold, while β-glucosidase (pNPGase) activity increased by approximately 1.9- and 2.1-fold, respectively, compared with the activity in the WT strains. Furthermore, overexpression of NAD+ synthesis pathways was found to elicit cellulase production by increasing the intracellular Ca2+ concentration. In summary, this study is the first to demonstrate that increased intracellular NAD+ contents through overexpression of the nmnat gene of NAD+ synthesis pathways may increase cellulase production by increasing intracellular Ca2+ concentrations in G. lucidum. KEY POINTS: • The concentration of NAD+influences cellulase production in G. lucidum. • The concentration of NAD+influences the intracellular Ca2+concentration in G. lucidum. • The concentration of NAD+influences cellulase production by eliciting a change in intracellular Ca2+in G. lucidum.
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Affiliation(s)
- Shengli Wang
- Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture, Microbiology Department, College of Life Sciences, Nanjing Agricultural University, Nanjing, 210095, Jiangsu, People's Republic of China
| | - Jing Han
- Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture, Microbiology Department, College of Life Sciences, Nanjing Agricultural University, Nanjing, 210095, Jiangsu, People's Republic of China
| | - Jiale Xia
- Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture, Microbiology Department, College of Life Sciences, Nanjing Agricultural University, Nanjing, 210095, Jiangsu, People's Republic of China
| | - Yanru Hu
- Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture, Microbiology Department, College of Life Sciences, Nanjing Agricultural University, Nanjing, 210095, Jiangsu, People's Republic of China
| | - Liang Shi
- Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture, Microbiology Department, College of Life Sciences, Nanjing Agricultural University, Nanjing, 210095, Jiangsu, People's Republic of China
| | - Ang Ren
- Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture, Microbiology Department, College of Life Sciences, Nanjing Agricultural University, Nanjing, 210095, Jiangsu, People's Republic of China
| | - Jing Zhu
- Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture, Microbiology Department, College of Life Sciences, Nanjing Agricultural University, Nanjing, 210095, Jiangsu, People's Republic of China
| | - Mingwen Zhao
- Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture, Microbiology Department, College of Life Sciences, Nanjing Agricultural University, Nanjing, 210095, Jiangsu, People's Republic of China.
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Valente S, Cometto A, Piombo E, Meloni GR, Ballester AR, González-Candelas L, Spadaro D. Elaborated regulation of griseofulvin biosynthesis in Penicillium griseofulvum and its role on conidiation and virulence. Int J Food Microbiol 2020; 328:108687. [PMID: 32474227 DOI: 10.1016/j.ijfoodmicro.2020.108687] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2019] [Revised: 05/14/2020] [Accepted: 05/23/2020] [Indexed: 10/24/2022]
Abstract
Penicilium griseofulvum, the causal agent of apple blue mold, is able to produce in vitro and on apple a broad spectrum of secondary metabolites (SM), including patulin, roquefortine C and griseofulvin. Among them, griseofulvin is known for its antifungal and antiproliferative activity, and has received interest in many sectors, from medicine to agriculture. The biosynthesis of SM is finely regulated by filamentous fungi and can involve global regulators and pathway specific regulators, which are usually encoded by genes present in the same gene cluster as the backbone gene and tailoring enzymes. In the griseofulvin gene cluster, two putative transcription factors were previously identified, encoded by genes gsfR1 and gsfR2, and their role has been investigated in the present work. Analysis of P. griseofulvum knockout mutants lacking either gene suggest that gsfR2 forms part of a different pathway and gsfR1 exhibits many spectra of action, acting as regulator of griseofulvin and patulin biosynthesis and influencing conidia production and virulence on apple. The analysis of gsfR1 promoter revealed that the regulation of griseofulvin biosynthesis is also controlled by global regulators in response to many environmental stimuli, such as carbon and nitrogen. The influence of carbon and nitrogen on griseofulvin production was further investigated and verified, revealing a complex network of response and confirming the central role of gsfR1 in many processes in P. griseofulvum.
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Affiliation(s)
- Silvia Valente
- Dept. Agricultural, Forest and Food Sciences (DISAFA), Università degli Studi di Torino, Largo Paolo Braccini 2, 10095 Grugliasco, Italy
| | - Agnese Cometto
- Dept. Agricultural, Forest and Food Sciences (DISAFA), Università degli Studi di Torino, Largo Paolo Braccini 2, 10095 Grugliasco, Italy
| | - Edoardo Piombo
- Dept. Agricultural, Forest and Food Sciences (DISAFA), Università degli Studi di Torino, Largo Paolo Braccini 2, 10095 Grugliasco, Italy
| | - Giovanna Roberta Meloni
- Dept. Agricultural, Forest and Food Sciences (DISAFA), Università degli Studi di Torino, Largo Paolo Braccini 2, 10095 Grugliasco, Italy
| | - Ana-Rosa Ballester
- IATA-CSIC - Instituto de Agroquímica y Tecnología de Alimentos, Calle Catedrático Agustín Escardino 7, Paterna 46980, Valencia, Spain
| | - Luis González-Candelas
- IATA-CSIC - Instituto de Agroquímica y Tecnología de Alimentos, Calle Catedrático Agustín Escardino 7, Paterna 46980, Valencia, Spain.
| | - Davide Spadaro
- Dept. Agricultural, Forest and Food Sciences (DISAFA), Università degli Studi di Torino, Largo Paolo Braccini 2, 10095 Grugliasco, Italy.
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Ogunyewo OA, Randhawa A, Joshi M, Jain KK, Wadekar P, Odaneth AA, Lali AM, Yazdani SS. Engineered Penicillium funiculosum produces potent lignocellulolytic enzymes for saccharification of various pretreated biomasses. Process Biochem 2020. [DOI: 10.1016/j.procbio.2020.02.029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Hu Y, Xu W, Hu S, Lian L, Zhu J, Shi L, Ren A, Zhao M. InGanoderma lucidum, Glsnf1 regulates cellulose degradation by inhibiting GlCreA during the utilization of cellulose. Environ Microbiol 2019; 22:107-121. [DOI: 10.1111/1462-2920.14826] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Accepted: 10/05/2019] [Indexed: 01/16/2023]
Affiliation(s)
- Yanru Hu
- Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture, Microbiology Department, College of Life SciencesNanjing Agricultural University Jiangsu 210095 Nanjing People's Republic of China
| | - Wenzhao Xu
- Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture, Microbiology Department, College of Life SciencesNanjing Agricultural University Jiangsu 210095 Nanjing People's Republic of China
| | - Shishan Hu
- Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture, Microbiology Department, College of Life SciencesNanjing Agricultural University Jiangsu 210095 Nanjing People's Republic of China
| | - Lingdan Lian
- Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture, Microbiology Department, College of Life SciencesNanjing Agricultural University Jiangsu 210095 Nanjing People's Republic of China
| | - Jing Zhu
- Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture, Microbiology Department, College of Life SciencesNanjing Agricultural University Jiangsu 210095 Nanjing People's Republic of China
| | - Liang Shi
- Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture, Microbiology Department, College of Life SciencesNanjing Agricultural University Jiangsu 210095 Nanjing People's Republic of China
| | - Ang Ren
- Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture, Microbiology Department, College of Life SciencesNanjing Agricultural University Jiangsu 210095 Nanjing People's Republic of China
| | - MingWen Zhao
- Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture, Microbiology Department, College of Life SciencesNanjing Agricultural University Jiangsu 210095 Nanjing People's Republic of China
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Champreda V, Mhuantong W, Lekakarn H, Bunterngsook B, Kanokratana P, Zhao XQ, Zhang F, Inoue H, Fujii T, Eurwilaichitr L. Designing cellulolytic enzyme systems for biorefinery: From nature to application. J Biosci Bioeng 2019; 128:637-654. [PMID: 31204199 DOI: 10.1016/j.jbiosc.2019.05.007] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Revised: 05/06/2019] [Accepted: 05/11/2019] [Indexed: 12/14/2022]
Abstract
Cellulolytic enzymes play a key role on conversion of lignocellulosic plant biomass to biofuels and biochemicals in sugar platform biorefineries. In this review, we survey composite carbohydrate-active enzymes (CAZymes) among groups of cellulolytic fungi and bacteria that exist under aerobic and anaerobic conditions. Recent advances in designing effective cellulase mixtures are described, starting from the most complex microbial consortium-based enzyme preparations, to single-origin enzymes derived from intensively studied cellulase producers such as Trichoderma reesei, Talaromyces cellulolyticus, and Penicellium funiculosum, and the simplest minimal enzyme systems comprising selected sets of mono-component enzymes tailor-made for specific lignocellulosic substrates. We provide a comprehensive update on studies in developing high-performance cellulases for biorefineries.
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Affiliation(s)
- Verawat Champreda
- National Center for Genetic Engineering and Biotechnology, 113 Thailand Science Park, Phahonyothin Road, Khlong Luang, Pathumthani 12120, Thailand.
| | - Wuttichai Mhuantong
- National Center for Genetic Engineering and Biotechnology, 113 Thailand Science Park, Phahonyothin Road, Khlong Luang, Pathumthani 12120, Thailand
| | - Hataikarn Lekakarn
- Department of Biotechnology, Faculty of Science and Technology, Thammasat University, Rangsit Campus, Phahonyothin Road, Khlong Luang, Pathumthani 12120, Thailand
| | - Benjarat Bunterngsook
- National Center for Genetic Engineering and Biotechnology, 113 Thailand Science Park, Phahonyothin Road, Khlong Luang, Pathumthani 12120, Thailand
| | - Pattanop Kanokratana
- National Center for Genetic Engineering and Biotechnology, 113 Thailand Science Park, Phahonyothin Road, Khlong Luang, Pathumthani 12120, Thailand
| | - Xin-Qing Zhao
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Fei Zhang
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Hiroyuki Inoue
- Research Institute for Sustainable Chemistry, National Institute of Advanced Industrial Science and Technology, 3-11-32 Kagamiyama, Hiroshima 739-0046, Japan
| | - Tatsuya Fujii
- Research Institute for Sustainable Chemistry, National Institute of Advanced Industrial Science and Technology, 3-11-32 Kagamiyama, Hiroshima 739-0046, Japan
| | - Lily Eurwilaichitr
- National Center for Genetic Engineering and Biotechnology, 113 Thailand Science Park, Phahonyothin Road, Khlong Luang, Pathumthani 12120, Thailand
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Llanos A, Déjean S, Neugnot-Roux V, François JM, Parrou JL. Carbon sources and XlnR-dependent transcriptional landscape of CAZymes in the industrial fungus Talaromyces versatilis: when exception seems to be the rule. Microb Cell Fact 2019; 18:14. [PMID: 30691469 PMCID: PMC6348686 DOI: 10.1186/s12934-019-1062-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2018] [Accepted: 01/13/2019] [Indexed: 11/19/2022] Open
Abstract
Background Research on filamentous fungi emphasized the remarkable redundancy in genes encoding hydrolytic enzymes, the similarities but also the large differences in their expression, especially through the role of the XlnR/XYR1 transcriptional activator. The purpose of this study was to evaluate the specificities of the industrial fungus Talaromyces versatilis, getting clues into the role of XlnR and the importance of glucose repression at the transcriptional level, to provide further levers for cocktail production. Results By studying a set of 62 redundant genes representative of several categories of enzymes, our results underlined the huge plasticity of transcriptional responses when changing nutritional status. As a general trend, the more heterogeneous the substrate, the more efficient to trigger activation. Genetic modifications of xlnR led to significant reorganisation of transcriptional patterns. Just a minimal set of genes actually fitted in a simplistic model of regulation by a transcriptional activator, and this under specific substrates. On the contrary, the diversity of xlnR+ versus ΔxlnR responses illustrated the existence of complex and unpredicted patterns of co-regulated genes that were highly dependent on the culture condition, even between genes that encode members of a functional category of enzymes. They notably revealed a dual, substrate-dependant repressor-activator role of XlnR, with counter-intuitive transcripts regulations that targeted specific genes. About glucose, it appeared as a formal repressive sugar as we observed a massive repression of most genes upon glucose addition to the mycelium grown on wheat straw. However, we also noticed a positive role of this sugar on the basal expression of a few genes, (notably those encoding cellulases), showing again the strong dependence of these regulatory mechanisms upon promoter and nutritional contexts. Conclusions The diversity of transcriptional patterns appeared to be the rule, while common and stable behaviour, both within gene families and with fungal literature, the exception. The setup of a new biotechnological process to reach optimized, if not customized expression patterns of enzymes, hence appeared tricky just relying on published data that can lead, in the best scenario, to approximate trends. We instead encourage preliminary experimental assays, carried out in the context of interest to reassess gene responses, as a mandatory step before thinking in (genetic) strategies for the improvement of enzyme production in fungi.![]() Electronic supplementary material The online version of this article (10.1186/s12934-019-1062-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Agustina Llanos
- LISBP, Université de Toulouse, INSA, INRA, CNRS, Toulouse, France.,Adisseo France S.A.S, 135 Avenue de Rangueil, 31077, Toulouse, France
| | - Sébastien Déjean
- Institut de Mathématiques de Toulouse, UMR5219-Université de Toulouse; CNRS-UPS, 31062, Toulouse Cedex 9, France
| | | | - Jean M François
- LISBP, Université de Toulouse, INSA, INRA, CNRS, Toulouse, France
| | - Jean-Luc Parrou
- LISBP, Université de Toulouse, INSA, INRA, CNRS, Toulouse, France.
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Quantitative multiplexed profiling of Penicillium funiculosum secretome grown on polymeric cellulase inducers and glucose. J Proteomics 2018; 179:150-160. [PMID: 29597011 DOI: 10.1016/j.jprot.2018.03.025] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Revised: 02/16/2018] [Accepted: 03/20/2018] [Indexed: 11/22/2022]
Abstract
Filamentous fungi respond to the need to secure utilisable carbon from their growth milieu by secreting unique extracellular proteins depending upon the types of polymeric substrates. We have here profiled the variations in the secretome pattern of a non-model hypercellulolytic fungus - Penicillium funiculosum, grown in minimal media containing four different polymeric cellulase inducers, i.e., Avicel, wheat bran, ammonium-pretreated wheat straw and Avicel & wheat bran, and glucose over its early and late log phases of growth. Of the 137 secreted proteins validated at 1% FDR, we identified the quantified proteins in three clusters as early, persistently or lately expressed. The type of carbon substrate present in the culture media significantly affected the levels of cellulolytic enzymes expression by the fungus. The top abundant proteins quantified in the secretome for Avicel and wheat bran were cellobiohydrolaseI [GH7-CBM1], cellobiohydrolaseII [GH6-CBM1], β-glucosidase [GH3], arabinofuranosidase [GH51] and β-xylosidase [GH3], with bicupin being highest in case of wheat straw. Our results further suggested that the fungus secreted the extracellular proteins in waves, such that the initial responders act to hydrolyse the composite substrates in the culture environment before the second wave of proteins which tend to be more tailored to the specific substrate in the cultivating media. BIOLOGICAL SIGNIFICANCE In this article, we have comprehensively examined the dynamics of the secretome of a non-model hypercellulolytic fungus produced in response to model and composite cellulase inducers. Our study has provided additional insights into how the fungus enzyme machinery responds to the presence of different polymeric cellulase inducers over the two different growth phases (early growth and late growth phase). The comprehensive typing and quantification of the different proteins present in the secretomes of the cellulolytic fungal strains in response to diverse nutrient sources hold many prospects in understanding the fungus unique enzyme machinery and dynamics for the downstream biotechnological applications.
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