The Experts below are selected from a list of 192 Experts worldwide ranked by ideXlab platform
Yuanxing Zhang - One of the best experts on this subject based on the ideXlab platform.
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transcription factor agseb1 affects development osmotic stress response and secondary metabolism in marine derived Aspergillus glaucus
Journal of Basic Microbiology, 2017Co-Authors: Yanna Ren, Menghao Cai, Xiangshan Zhou, Yuanxing ZhangAbstract:Fungi possess sophisticated regulatory systems to respond to a vast array of environmental signals. Among these responsive networks, some genes play critical roles in the regulation of various cellular processes. Here, we identified a putative transcriptional factor Agseb1 in Aspergillus glaucus, a marine-derived filamentous fungus. Agseb1 encodes a protein with two C2 H2 zinc fingers at the C-terminus, similar to the placement of these motifs in msn2/4 of Saccharomyces cerevisia, where they are positioned to allow binding to the CCCCT-box of stress-specific genes. Agseb1 similarly plays a role in stress response and its deletion mutant exhibited decreased sensitivity to hyperosmotic stress (both sorbitol and salt). Agseb1 is also important for mediating morphological development, because ΔAgseb1 formed compact colonies and abnormal hyphal cells with hyperbranching at new sites. Consistent with the observed defects in conidial yield and sporulation, transcription analysis of the central asexual development pathway revealed significant activity changes. Additionally, the strain lacking Agseb1 exhibited a 43% decrease in aspergiolide A biosynthesis. Overall, Agseb1 has significant activity in different cellular pathways, the findings in this study may be generally applicable to the seb1 orthologs of other filamentous ascomycetes.
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de novo transcriptome sequencing of marine derived Aspergillus glaucus and comparative analysis of metabolic and developmental variations in response to salt stress
Genes & Genomics, 2017Co-Authors: Shaomei Liu, Menghao Cai, Xiangshan Zhou, Yanna Ren, Qi Liu, Qiyao Wang, Yuanxing ZhangAbstract:Aspergillus glaucus HB1-19 is a typical marine-derived fungus preferring the dependence on sea water for its growth, asexual development and polyketides biosynthesis. Therein, salt stress greatly functions even in superior to light illumination, which is also a critical regulation signal for fungi. Here, comparative RNA-seq analysis of this strain was performed under conditions of salt-stress + dark (group A), non salt-stress + dark (group B), salt-stress + light (group C). The RNA-seq generated a total of 19,024 unigenes with an average length of 1415 bp. Differentially expressed genes were very similar between group A and group C but greatly differed between group A and group B, proving that salt stress functioned superior to light illumination globally. Salt stress highly enhanced primary metabolism and activated Ras and MAPK signaling pathways. There seems no direct interaction between asexual development and polyketides biosynthesis. Salt stress inhibited terpenoids biosynthesis but showed little influences on polyketide pathway as well as other secondary metabolism pathways. These findings provide a better understanding of marine fungi adapting to marine environment. Also, it indicates that the so-called ‘salt stress-induced’ may truly be a ‘metal ions-induced’ for biosynthesis of secondary metabolites in marine fungi.
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genetically shaping morphology of the filamentous fungus Aspergillus glaucus for production of antitumor polyketide aspergiolide a
Microbial Cell Factories, 2014Co-Authors: Menghao Cai, Xiangshan Zhou, Ying Zhang, Wei Shen, Weiqiang Zhou, Tao Jiang, Yuanxing ZhangAbstract:For filamentous fungi, the basic growth unit of hyphae usually makes it sensitive to shear stress which is generated from mechanical force and dynamic fluid in bioreactor, and it severely decreases microbial productions. The conventional strategies against shear-sensitive conundrum in fungal fermentation usually focus on adapting agitation, impeller type and bioreactor configuration, which brings high cost and tough work in industry. This study aims to genetically shape shear resistant morphology of shear-sensitive filamentous fungus Aspergillus glaucus to make it adapt to bioreactor so as to establish an efficient fermentation process. Hyphal morphology shaping by modifying polarized growth genes of A. glaucus was applied to reduce its shear-sensitivity and enhance aspergiolide A production. Degenerate PCR and genome walking were used to obtain polarized growth genes AgkipA and AgteaR, followed by construction of gene-deficient mutants by homologous integration of double crossover. Deletion of both genes caused meandering hyphae, for which, ΔAgkipA led to small but intense curves comparing with ΔAgteaR by morphology analysis. The germination of a second germ tube from conidiospore of the mutants became random while colony growth and development almost maintained the same. Morphology of ΔAgkipA and ΔAgteaR mutants turned to be compact pellet and loose clump in liquid culture, respectively. The curved hyphae of both mutants showed no remarkably resistant to glass bead grinding comparing with the wild type strain. However, they generated greatly different broth rheology which further caused growth and metabolism variations in bioreactor fermentations. By forming pellets, the ΔAgkipA mutant created a tank environment with low-viscosity, low shear stress and high dissolved oxygen tension, leading to high production of aspergiolide A (121.7 ± 2.3 mg/L), which was 82.2% higher than the wild type. A new strategy for shaping fungal morphology by modifying polarized growth genes was applied in submerged fermentation in bioreactor. This work provides useful information of shaping fungal morphology for submerged fermentation by genetically modification, which could be valuable for morphology improvement of industrial filamentous fungi.
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roles of cobalt in biosynthesis stimulation of a cytotoxic compound from marine derived Aspergillus glaucus
Process Biochemistry, 2012Co-Authors: Menghao Cai, Xueqian Sun, Xiangshan Zhou, Yuanxing ZhangAbstract:Abstract Effects of trace elements on aspergiolide A biosynthesis by marine-derived filamentous fungus Aspergillus glaucus HB 1–19 were investigated. Cobalt (Co 2+ ) and nickel (Ni 2+ ) stimulated aspergiolide A biosynthesis while zinc (Zn 2+ ) inhibited it. Equal cobalt (Co 2+ ) addition at 48, 72 and 96 h with total amount of 0.052 mM most effectively enhanced aspergiolide A production. The time courses indicated that mycelia growth, sugar utilization and aspergiolide A biosynthesis were enhanced by Co 2+ . Finally, feeding 0.052 mM Co 2+ increased mycelia growth, sugar utilization and aspergiolide A production by 12.2%, 13.7% and 46.7%, respectively. The results of organic acids analysis indicated that extracellular pyruvate increased while fumarate decreased in Co 2+ addition cultures. Moreover, feeding vitamin B 12 , which combined cobalt to be a cofactor form, increased aspergiolide A production by 59.1%. This indicated Co 2+ functioned by facilitating pyruvate accumulation and increasing vitamin B 12 formation that were beneficial to aspergiolide A biosynthesis that is via polyketide pathway.
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improved gene targeting frequency in marine derived filamentous fungus Aspergillus glaucus by disrupting ligd
Journal of Applied Genetics, 2012Co-Authors: Zhe Fang, Menghao Cai, Yuanxing Zhang, Ying Zhang, Jian Zhang, Xiangshan ZhouAbstract:Filamentous fungi from the marine environment have shown great potential as cell factories for the production of pharmacologically active metabolites, but extremely low frequency of homologous recombination brings difficulty to further molecular biology studies. To bypass this problem and develop a highly efficient gene targeting system in marine-derived filamentous fungus Aspergillus glaucus, LigD, a homolog of Neurospora crassa Mus-53 which is considered to play a significant role in nonhomologous end joining (NHEJ), was coloned and deleted, and frequency of targeted gene replacement (TGR) increased dramatically from <2 % to 85 % in comparison with that in the wild type, when containing 1000 bp of homologous flanking sequence. Such results strongly indicate that AgLigD is indeed involved in the repair of NHEJ in A. glaucus and functions in this pathway. Furthermore, the AgLigD-defective mutant has no discernible differences with wild type regarding sensitivity to mutagens and UV, growth characteristics and transformation frequency. The AgligD-deficient transformant, as the first NHEJ-defective mutant in the field of marine-derived filamentous fungus, will help in expediting studies of molecular biology of marine-derived microorganisms.
Shihong Zhang - One of the best experts on this subject based on the ideXlab platform.
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genome sequencing of Aspergillus glaucus ccha provides insights into salt stress adaptation
PeerJ, 2020Co-Authors: Wenmin Qiu, Yi Wei, Feiyu Fan, Jing Jiang, Mingying Liu, Xiaojiao Han, Chaoguang Tian, Shihong Zhang, Renying ZhuoAbstract:Aspergillus, as a genus of filamentous fungi, has members that display a variety of different behavioural strategies, which are affected by various environmental factors. The decoded genomic sequences of many species vary greatly in their evolutionary similarities, encouraging studies on the functions and evolution of the Aspergillus genome in complex natural environments. Here, we present the 26 Mb de novo assembled high-quality reference genome of Aspergillus glaucus 'China Changchun halophilic Aspergillus' (CCHA), which was isolated from the surface of plants growing near a salt mine in Jilin, China, based on data from whole-genome shotgun sequencing using Illumina Solexa technology. The sequence, coupled with data from comprehensive transcriptomic survey analyses, indicated that the redox state and transmembrane transport might be critical molecular mechanisms for the adaptation of A. glaucus 'CCHA' to the high-salt environment of the saltern. The isolation of salt tolerance-related genes, such as CCHA-2114, and their overexpression in Escherichia coli demonstrated that A. glucus 'CCHA' is an excellent organism for the isolation and identification of salt tolerant-related genes. These data expand our understanding of the evolution and functions of fungal and microbial genomes, and offer multiple target genes for crop salt-tolerance improvement through genetic engineering.
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statistical optimization of a cellulase from Aspergillus glaucus ccha for hydrolyzing corn and rice straw by rsm to enhance yield of reducing sugar
Biotechnology Letters, 2020Co-Authors: Yi Wei, Lina Chen, Mao Shi, Shihong ZhangAbstract:The unique GH5 cellulase, AgCMCase, from Aspergillus glaucus CCHA was identified and characterized as having high cellulose and straw hydrolysis activities that were thermostable, pH stable and salt-tolerant. Therefore, it is a potential straw-degradation enzyme that can release reducing sugars in industrial applications. To increase the efficiency of the AgCMCase’ hydrolysis of straw to release simple sugars, response surface methodology (RSM) was introduced to optimize hydrolysis parameters such as pH, temperature, reaction time and enzyme dose. The enzyme showed only one major protein band from the fermentation broth by the Pichia pastoris GS115 expression. The crude enzyme (without purification) showed a satisfactory capability to hydrolyze CMC-Na after 4 days of production. Here, the crude AgCMCase also showed cellulose and straw hydrolysis capabilities as assessed by scanning electron microscopic and Fourier-transform infrared spectroscopic analyses. A high-performance liquid chromatographic analysis demonstrated that the degradation of corn and rice straw by crude AgCMCase mainly produced glucose and cellobiose. Temperature, reaction time and enzyme dose were the significant variables affecting corn and rice straw degradation. After the optimization of RSM, a model was proposed to predict 1.48% reducing sugar yield with the optimum temperature (51.45 °C) and reaction time (3.84 h) from the straw degradation. The reaction of crude AgCMCase and rice straw in the optimized condition resulted in reducing sugar production of 1.61% that agrees the prediction. Our findings suggest that the crude AgCMCase is suitable to be used in straw conversion.
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the unique gh5 cellulase member in the extreme halotolerant fungus Aspergillus glaucus ccha is an endoglucanase with multiple tolerance to salt alkali and heat prospects for straw degradation applications
Extremophiles, 2018Co-Authors: Xue Pei, Yi Wei, Ziyu Zhang, Yanyue Song, Lina Chen, Shouan Liu, Shihong ZhangAbstract:In a halotolerant fungus Aspergillus glaucus CCHA, several functional proteins with stress-tolerant activity have been studied, but no secretory enzymes have been identified yet. The unique GH5 cellulase candidate from A. glaucus, an endoglucanase termed as AgCMCase, was cloned, expressed in the Pichia pastoris system and the purified enzyme was characterized. A large amount of recombinant enzyme secreted by the P. pastoris GS115 strain was purified to homogeneity. The molecular weight of the purified endoglucanase is about 55.0 kDa. The AgCMCase exhibited optimum catalytic activity at pH 5.0 and 55 °C. However, it remained relatively stable at temperatures ranging from 45 to 80 °C and pH ranging from 4.0 to 9.0. In addition, it showed higher activity at extreme NaCl concentrations from 1.0 to 4.0 M, suggesting it is an enzyme highly stable under heat, acid, alkaline and saline conditions. To evaluate the catalytic activity of AgCMCase, the hydrolysis products of rice and corn straws were successfully studied. In conclusion, the AgCMCase is a thermostable and salt-tolerant cellulase with potential for industrial application.
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Aspergillus glaucus aquaglyceroporin gene glpf confers high osmosis tolerance in heterologous organisms
Applied and Environmental Microbiology, 2015Co-Authors: Xiaodan Liu, Yi Wei, Xiaoyang Zhou, Xue Pei, Shihong ZhangAbstract:ABSTRACT Aquaglyceroporins (GlpFs) that transport glycerol along with water and other uncharged solutes are involved in osmoregulation in myriad species. Fungal species form a large group of eukaryotic organisms, and their GlpFs may be diverse, exhibiting various activities. However, few filamentous fungal GlpFs have been biologically investigated. Here, a glpF gene from the halophilic fungus Aspergillus glaucus ( AgglpF ) was verified to be a channel of water or glycerol in Xenopus laevis oocytes and was further functionally analyzed in three heterologous systems. In Saccharomyces cerevisiae, cells overexpressing AgglpF possessed significant tolerance of drought, salt, and certain metal ions. AgglpF was then characterized in the filamentous fungus of Neurospora crassa. Based on the N. crassa aquaporin gene ( NcAQP ) disruption mutant (the Δ aqp mutant), a series of complementary strains carrying NcAQP and AgglpF and three asparagine-proline-alanine-gene ( NPA )-deleted AgglpF fragments were created. As revealed by salt resistance analysis, the AgglpF complementary strain possessed the highest salt resistance among the tested strains. In addition, the intracellular glycerol content in the AgglpF complementary strain was markedly higher than that in the other strains. The AgGlpF-green fluorescent protein (GFP) fusion protein was subcellularly localized in the plasma membrane of onion epidermal cells, suggesting that AgglpF functions in plants. Indeed, when AgglpF was expressed in Arabidopsis thaliana, transgenic lines survived under conditions of high osmotic stress and under conditions of drought stress in particular. Overall, our results revealed that AgGlpF as a water/glycerol transporter is required for survival of both fungi and plants under conditions of high osmotic stress and may have value in applications in genetic engineering for generating high salt and drought resistance.
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a ribosomal protein agrps3ae from halophilic Aspergillus glaucus confers salt tolerance in heterologous organisms
International Journal of Molecular Sciences, 2015Co-Authors: Xilong Liang, Yi Wei, Yiling Liu, Lixia Xie, Xiaodan Liu, Xiaoyang Zhou, Shihong ZhangAbstract:High salt in soils is one of the abiotic stresses that significantly reduces crop yield, although saline lands are considered potential resources arable for agriculture. Currently, genetic engineering for enhancing salt tolerance is being tested as an efficient and viable strategy for crop improvement. We previously characterized a large subunit of the ribosomal protein RPL44, which is involved in osmotic stress in the extremely halophilic fungus Aspergillus glaucus. Here, we screened another ribosomal protein (AgRPS3aE) that also produced high-salt tolerance in yeast. Bioinformatics analysis indicated that AgRPS3aE encodes a 29.2 kDa small subunit of a ribosomal protein belonging to the RPS3Ae family in eukaryotes. To further confirm its protective function against salinity, we expressed AgRPS3aE in three heterologous systems, the filamentous fungus Magnaporthe oryzae and two model plants Arabidopsis and tobacco. Overexpression of AgRPS3aE in all tested transformants significantly alleviated stress symptoms compared with controls, suggesting that AgRPS3aE functions not only in fungi but also in plants. Considering that ribosomal proteins are housekeeping components in organisms from prokaryotes to eukaryotes, we propose that AgRPS3aE is one of the optimal genes for improving high-salt tolerance in crops.
Menghao Cai - One of the best experts on this subject based on the ideXlab platform.
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transcription factor agseb1 affects development osmotic stress response and secondary metabolism in marine derived Aspergillus glaucus
Journal of Basic Microbiology, 2017Co-Authors: Yanna Ren, Menghao Cai, Xiangshan Zhou, Yuanxing ZhangAbstract:Fungi possess sophisticated regulatory systems to respond to a vast array of environmental signals. Among these responsive networks, some genes play critical roles in the regulation of various cellular processes. Here, we identified a putative transcriptional factor Agseb1 in Aspergillus glaucus, a marine-derived filamentous fungus. Agseb1 encodes a protein with two C2 H2 zinc fingers at the C-terminus, similar to the placement of these motifs in msn2/4 of Saccharomyces cerevisia, where they are positioned to allow binding to the CCCCT-box of stress-specific genes. Agseb1 similarly plays a role in stress response and its deletion mutant exhibited decreased sensitivity to hyperosmotic stress (both sorbitol and salt). Agseb1 is also important for mediating morphological development, because ΔAgseb1 formed compact colonies and abnormal hyphal cells with hyperbranching at new sites. Consistent with the observed defects in conidial yield and sporulation, transcription analysis of the central asexual development pathway revealed significant activity changes. Additionally, the strain lacking Agseb1 exhibited a 43% decrease in aspergiolide A biosynthesis. Overall, Agseb1 has significant activity in different cellular pathways, the findings in this study may be generally applicable to the seb1 orthologs of other filamentous ascomycetes.
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de novo transcriptome sequencing of marine derived Aspergillus glaucus and comparative analysis of metabolic and developmental variations in response to salt stress
Genes & Genomics, 2017Co-Authors: Shaomei Liu, Menghao Cai, Xiangshan Zhou, Yanna Ren, Qi Liu, Qiyao Wang, Yuanxing ZhangAbstract:Aspergillus glaucus HB1-19 is a typical marine-derived fungus preferring the dependence on sea water for its growth, asexual development and polyketides biosynthesis. Therein, salt stress greatly functions even in superior to light illumination, which is also a critical regulation signal for fungi. Here, comparative RNA-seq analysis of this strain was performed under conditions of salt-stress + dark (group A), non salt-stress + dark (group B), salt-stress + light (group C). The RNA-seq generated a total of 19,024 unigenes with an average length of 1415 bp. Differentially expressed genes were very similar between group A and group C but greatly differed between group A and group B, proving that salt stress functioned superior to light illumination globally. Salt stress highly enhanced primary metabolism and activated Ras and MAPK signaling pathways. There seems no direct interaction between asexual development and polyketides biosynthesis. Salt stress inhibited terpenoids biosynthesis but showed little influences on polyketide pathway as well as other secondary metabolism pathways. These findings provide a better understanding of marine fungi adapting to marine environment. Also, it indicates that the so-called ‘salt stress-induced’ may truly be a ‘metal ions-induced’ for biosynthesis of secondary metabolites in marine fungi.
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genetically shaping morphology of the filamentous fungus Aspergillus glaucus for production of antitumor polyketide aspergiolide a
Microbial Cell Factories, 2014Co-Authors: Menghao Cai, Xiangshan Zhou, Ying Zhang, Wei Shen, Weiqiang Zhou, Tao Jiang, Yuanxing ZhangAbstract:For filamentous fungi, the basic growth unit of hyphae usually makes it sensitive to shear stress which is generated from mechanical force and dynamic fluid in bioreactor, and it severely decreases microbial productions. The conventional strategies against shear-sensitive conundrum in fungal fermentation usually focus on adapting agitation, impeller type and bioreactor configuration, which brings high cost and tough work in industry. This study aims to genetically shape shear resistant morphology of shear-sensitive filamentous fungus Aspergillus glaucus to make it adapt to bioreactor so as to establish an efficient fermentation process. Hyphal morphology shaping by modifying polarized growth genes of A. glaucus was applied to reduce its shear-sensitivity and enhance aspergiolide A production. Degenerate PCR and genome walking were used to obtain polarized growth genes AgkipA and AgteaR, followed by construction of gene-deficient mutants by homologous integration of double crossover. Deletion of both genes caused meandering hyphae, for which, ΔAgkipA led to small but intense curves comparing with ΔAgteaR by morphology analysis. The germination of a second germ tube from conidiospore of the mutants became random while colony growth and development almost maintained the same. Morphology of ΔAgkipA and ΔAgteaR mutants turned to be compact pellet and loose clump in liquid culture, respectively. The curved hyphae of both mutants showed no remarkably resistant to glass bead grinding comparing with the wild type strain. However, they generated greatly different broth rheology which further caused growth and metabolism variations in bioreactor fermentations. By forming pellets, the ΔAgkipA mutant created a tank environment with low-viscosity, low shear stress and high dissolved oxygen tension, leading to high production of aspergiolide A (121.7 ± 2.3 mg/L), which was 82.2% higher than the wild type. A new strategy for shaping fungal morphology by modifying polarized growth genes was applied in submerged fermentation in bioreactor. This work provides useful information of shaping fungal morphology for submerged fermentation by genetically modification, which could be valuable for morphology improvement of industrial filamentous fungi.
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roles of cobalt in biosynthesis stimulation of a cytotoxic compound from marine derived Aspergillus glaucus
Process Biochemistry, 2012Co-Authors: Menghao Cai, Xueqian Sun, Xiangshan Zhou, Yuanxing ZhangAbstract:Abstract Effects of trace elements on aspergiolide A biosynthesis by marine-derived filamentous fungus Aspergillus glaucus HB 1–19 were investigated. Cobalt (Co 2+ ) and nickel (Ni 2+ ) stimulated aspergiolide A biosynthesis while zinc (Zn 2+ ) inhibited it. Equal cobalt (Co 2+ ) addition at 48, 72 and 96 h with total amount of 0.052 mM most effectively enhanced aspergiolide A production. The time courses indicated that mycelia growth, sugar utilization and aspergiolide A biosynthesis were enhanced by Co 2+ . Finally, feeding 0.052 mM Co 2+ increased mycelia growth, sugar utilization and aspergiolide A production by 12.2%, 13.7% and 46.7%, respectively. The results of organic acids analysis indicated that extracellular pyruvate increased while fumarate decreased in Co 2+ addition cultures. Moreover, feeding vitamin B 12 , which combined cobalt to be a cofactor form, increased aspergiolide A production by 59.1%. This indicated Co 2+ functioned by facilitating pyruvate accumulation and increasing vitamin B 12 formation that were beneficial to aspergiolide A biosynthesis that is via polyketide pathway.
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improved gene targeting frequency in marine derived filamentous fungus Aspergillus glaucus by disrupting ligd
Journal of Applied Genetics, 2012Co-Authors: Zhe Fang, Menghao Cai, Yuanxing Zhang, Ying Zhang, Jian Zhang, Xiangshan ZhouAbstract:Filamentous fungi from the marine environment have shown great potential as cell factories for the production of pharmacologically active metabolites, but extremely low frequency of homologous recombination brings difficulty to further molecular biology studies. To bypass this problem and develop a highly efficient gene targeting system in marine-derived filamentous fungus Aspergillus glaucus, LigD, a homolog of Neurospora crassa Mus-53 which is considered to play a significant role in nonhomologous end joining (NHEJ), was coloned and deleted, and frequency of targeted gene replacement (TGR) increased dramatically from <2 % to 85 % in comparison with that in the wild type, when containing 1000 bp of homologous flanking sequence. Such results strongly indicate that AgLigD is indeed involved in the repair of NHEJ in A. glaucus and functions in this pathway. Furthermore, the AgLigD-defective mutant has no discernible differences with wild type regarding sensitivity to mutagens and UV, growth characteristics and transformation frequency. The AgligD-deficient transformant, as the first NHEJ-defective mutant in the field of marine-derived filamentous fungus, will help in expediting studies of molecular biology of marine-derived microorganisms.
Qing-xi Chen - One of the best experts on this subject based on the ideXlab platform.
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purification and characterization of b 1 4 glucosidase from Aspergillus glaucus
African Journal of Biotechnology, 2011Co-Authors: Bo Leng, Yi-ming Tao, Xiang-zhi Zhu, Minnan Long, Yan Shi, Shaoxuan Chen, Qing-xi ChenAbstract:National Key Basic Research Program (NKBRP) [2010CB732201]; Natural Science Foundation of Fujian Province [2009J01196]; National Foundation for fostering talents of basic science [J1030626]
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Purification and Properties of Endoglucanase from a Sugar Cane Bagasse Hydrolyzing Strain, Aspergillus glaucus XC9
Journal of agricultural and food chemistry, 2010Co-Authors: Yi-ming Tao, Xiang-zhi Zhu, Jian-zhong Huang, Minnan Long, Qing-xi ChenAbstract:An endoglucanase (EG) from Aspergillus glaucus XC9 grown on 0.3% sugar cane bagasse as a carbon source was purified from the culture filtrate using ammonium sulfate, an anion exchange DEAE Sepharos...
Xiangshan Zhou - One of the best experts on this subject based on the ideXlab platform.
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transcription factor agseb1 affects development osmotic stress response and secondary metabolism in marine derived Aspergillus glaucus
Journal of Basic Microbiology, 2017Co-Authors: Yanna Ren, Menghao Cai, Xiangshan Zhou, Yuanxing ZhangAbstract:Fungi possess sophisticated regulatory systems to respond to a vast array of environmental signals. Among these responsive networks, some genes play critical roles in the regulation of various cellular processes. Here, we identified a putative transcriptional factor Agseb1 in Aspergillus glaucus, a marine-derived filamentous fungus. Agseb1 encodes a protein with two C2 H2 zinc fingers at the C-terminus, similar to the placement of these motifs in msn2/4 of Saccharomyces cerevisia, where they are positioned to allow binding to the CCCCT-box of stress-specific genes. Agseb1 similarly plays a role in stress response and its deletion mutant exhibited decreased sensitivity to hyperosmotic stress (both sorbitol and salt). Agseb1 is also important for mediating morphological development, because ΔAgseb1 formed compact colonies and abnormal hyphal cells with hyperbranching at new sites. Consistent with the observed defects in conidial yield and sporulation, transcription analysis of the central asexual development pathway revealed significant activity changes. Additionally, the strain lacking Agseb1 exhibited a 43% decrease in aspergiolide A biosynthesis. Overall, Agseb1 has significant activity in different cellular pathways, the findings in this study may be generally applicable to the seb1 orthologs of other filamentous ascomycetes.
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de novo transcriptome sequencing of marine derived Aspergillus glaucus and comparative analysis of metabolic and developmental variations in response to salt stress
Genes & Genomics, 2017Co-Authors: Shaomei Liu, Menghao Cai, Xiangshan Zhou, Yanna Ren, Qi Liu, Qiyao Wang, Yuanxing ZhangAbstract:Aspergillus glaucus HB1-19 is a typical marine-derived fungus preferring the dependence on sea water for its growth, asexual development and polyketides biosynthesis. Therein, salt stress greatly functions even in superior to light illumination, which is also a critical regulation signal for fungi. Here, comparative RNA-seq analysis of this strain was performed under conditions of salt-stress + dark (group A), non salt-stress + dark (group B), salt-stress + light (group C). The RNA-seq generated a total of 19,024 unigenes with an average length of 1415 bp. Differentially expressed genes were very similar between group A and group C but greatly differed between group A and group B, proving that salt stress functioned superior to light illumination globally. Salt stress highly enhanced primary metabolism and activated Ras and MAPK signaling pathways. There seems no direct interaction between asexual development and polyketides biosynthesis. Salt stress inhibited terpenoids biosynthesis but showed little influences on polyketide pathway as well as other secondary metabolism pathways. These findings provide a better understanding of marine fungi adapting to marine environment. Also, it indicates that the so-called ‘salt stress-induced’ may truly be a ‘metal ions-induced’ for biosynthesis of secondary metabolites in marine fungi.
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genetically shaping morphology of the filamentous fungus Aspergillus glaucus for production of antitumor polyketide aspergiolide a
Microbial Cell Factories, 2014Co-Authors: Menghao Cai, Xiangshan Zhou, Ying Zhang, Wei Shen, Weiqiang Zhou, Tao Jiang, Yuanxing ZhangAbstract:For filamentous fungi, the basic growth unit of hyphae usually makes it sensitive to shear stress which is generated from mechanical force and dynamic fluid in bioreactor, and it severely decreases microbial productions. The conventional strategies against shear-sensitive conundrum in fungal fermentation usually focus on adapting agitation, impeller type and bioreactor configuration, which brings high cost and tough work in industry. This study aims to genetically shape shear resistant morphology of shear-sensitive filamentous fungus Aspergillus glaucus to make it adapt to bioreactor so as to establish an efficient fermentation process. Hyphal morphology shaping by modifying polarized growth genes of A. glaucus was applied to reduce its shear-sensitivity and enhance aspergiolide A production. Degenerate PCR and genome walking were used to obtain polarized growth genes AgkipA and AgteaR, followed by construction of gene-deficient mutants by homologous integration of double crossover. Deletion of both genes caused meandering hyphae, for which, ΔAgkipA led to small but intense curves comparing with ΔAgteaR by morphology analysis. The germination of a second germ tube from conidiospore of the mutants became random while colony growth and development almost maintained the same. Morphology of ΔAgkipA and ΔAgteaR mutants turned to be compact pellet and loose clump in liquid culture, respectively. The curved hyphae of both mutants showed no remarkably resistant to glass bead grinding comparing with the wild type strain. However, they generated greatly different broth rheology which further caused growth and metabolism variations in bioreactor fermentations. By forming pellets, the ΔAgkipA mutant created a tank environment with low-viscosity, low shear stress and high dissolved oxygen tension, leading to high production of aspergiolide A (121.7 ± 2.3 mg/L), which was 82.2% higher than the wild type. A new strategy for shaping fungal morphology by modifying polarized growth genes was applied in submerged fermentation in bioreactor. This work provides useful information of shaping fungal morphology for submerged fermentation by genetically modification, which could be valuable for morphology improvement of industrial filamentous fungi.
-
roles of cobalt in biosynthesis stimulation of a cytotoxic compound from marine derived Aspergillus glaucus
Process Biochemistry, 2012Co-Authors: Menghao Cai, Xueqian Sun, Xiangshan Zhou, Yuanxing ZhangAbstract:Abstract Effects of trace elements on aspergiolide A biosynthesis by marine-derived filamentous fungus Aspergillus glaucus HB 1–19 were investigated. Cobalt (Co 2+ ) and nickel (Ni 2+ ) stimulated aspergiolide A biosynthesis while zinc (Zn 2+ ) inhibited it. Equal cobalt (Co 2+ ) addition at 48, 72 and 96 h with total amount of 0.052 mM most effectively enhanced aspergiolide A production. The time courses indicated that mycelia growth, sugar utilization and aspergiolide A biosynthesis were enhanced by Co 2+ . Finally, feeding 0.052 mM Co 2+ increased mycelia growth, sugar utilization and aspergiolide A production by 12.2%, 13.7% and 46.7%, respectively. The results of organic acids analysis indicated that extracellular pyruvate increased while fumarate decreased in Co 2+ addition cultures. Moreover, feeding vitamin B 12 , which combined cobalt to be a cofactor form, increased aspergiolide A production by 59.1%. This indicated Co 2+ functioned by facilitating pyruvate accumulation and increasing vitamin B 12 formation that were beneficial to aspergiolide A biosynthesis that is via polyketide pathway.
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improved gene targeting frequency in marine derived filamentous fungus Aspergillus glaucus by disrupting ligd
Journal of Applied Genetics, 2012Co-Authors: Zhe Fang, Menghao Cai, Yuanxing Zhang, Ying Zhang, Jian Zhang, Xiangshan ZhouAbstract:Filamentous fungi from the marine environment have shown great potential as cell factories for the production of pharmacologically active metabolites, but extremely low frequency of homologous recombination brings difficulty to further molecular biology studies. To bypass this problem and develop a highly efficient gene targeting system in marine-derived filamentous fungus Aspergillus glaucus, LigD, a homolog of Neurospora crassa Mus-53 which is considered to play a significant role in nonhomologous end joining (NHEJ), was coloned and deleted, and frequency of targeted gene replacement (TGR) increased dramatically from <2 % to 85 % in comparison with that in the wild type, when containing 1000 bp of homologous flanking sequence. Such results strongly indicate that AgLigD is indeed involved in the repair of NHEJ in A. glaucus and functions in this pathway. Furthermore, the AgLigD-defective mutant has no discernible differences with wild type regarding sensitivity to mutagens and UV, growth characteristics and transformation frequency. The AgligD-deficient transformant, as the first NHEJ-defective mutant in the field of marine-derived filamentous fungus, will help in expediting studies of molecular biology of marine-derived microorganisms.
