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Zhao S, Tan MZ, Wang RX, Ye FT, Chen YP, Luo XM, Feng JX. Combination of genetic engineering and random mutagenesis for improving production of raw-starch-degrading enzymes in Penicillium oxalicum. Microb Cell Fact 2022; 21:272. [PMID: 36566178 DOI: 10.1186/s12934-022-01997-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Accepted: 12/17/2022] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND Raw starch-degrading enzyme (RSDE) is applied in biorefining of starch to produce biofuels efficiently and economically. At present, RSDE is obtained via secretion by filamentous fungi such as Penicillium oxalicum. However, high production cost is a barrier to large-scale industrial application. Genetic engineering is a potentially efficient approach for improving production of RSDE. In this study, we combined genetic engineering and random mutagenesis of P. oxalicum to enhance RSDE production. RESULTS A total of 3619 mutated P. oxalicum colonies were isolated after six rounds of ethyl methanesulfonate and Co60-γ-ray mutagenesis with the strain A2-13 as the parent strain. Mutant TE4-10 achieved the highest RSDE production of 218.6 ± 3.8 U/mL with raw cassava flour as substrate, a 23.2% compared with A2-13. Simultaneous deletion of transcription repressor gene PoxCxrC and overexpression of activator gene PoxAmyR in TE4-10 resulted in engineered strain GXUR001 with an RSDE yield of 252.6 U/mL, an increase of 15.6% relative to TE4-10. Comparative transcriptomics and real-time quantitative reverse transcription PCR revealed that transcriptional levels of major amylase genes, including raw starch-degrading glucoamylase gene PoxGA15A, were markedly increased in GXUR001. The hydrolysis efficiency of raw flour from cassava and corn by crude RSDE of GXUR001 reached 93.0% and 100%, respectively, after 120 h and 84 h with loading of 150 g/L of corresponding substrate. CONCLUSIONS Combining genetic engineering and random mutagenesis efficiently enhanced production of RSDE by P. oxalicum. The RSDE-hyperproducing mutant GXUR001 was generated, and its crude RSDE could efficiently degrade raw starch. This strain has great potential for enzyme preparation and further genetic engineering.
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Affiliation(s)
- Shuai Zhao
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangxi Research Centre for Microbial and Enzyme Engineering Technology, College of Life Science and Technology, Guangxi University, Nanning, China.
| | - Ming-Zhu Tan
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangxi Research Centre for Microbial and Enzyme Engineering Technology, College of Life Science and Technology, Guangxi University, Nanning, China
| | - Rui-Xian Wang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangxi Research Centre for Microbial and Enzyme Engineering Technology, College of Life Science and Technology, Guangxi University, Nanning, China
| | - Fa-Ting Ye
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangxi Research Centre for Microbial and Enzyme Engineering Technology, College of Life Science and Technology, Guangxi University, Nanning, China
| | - Yuan-Peng Chen
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangxi Research Centre for Microbial and Enzyme Engineering Technology, College of Life Science and Technology, Guangxi University, Nanning, China
| | - Xue-Mei Luo
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangxi Research Centre for Microbial and Enzyme Engineering Technology, College of Life Science and Technology, Guangxi University, Nanning, China
| | - Jia-Xun Feng
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangxi Research Centre for Microbial and Enzyme Engineering Technology, College of Life Science and Technology, Guangxi University, Nanning, China
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Gu LS, Tan MZ, Li SH, Zhang T, Zhang QQ, Li CX, Luo XM, Feng JX, Zhao S. ARTP/EMS-combined multiple mutagenesis efficiently improved production of raw starch-degrading enzymes in Penicillium oxalicum and characterization of the enzyme-hyperproducing mutant. BIOTECHNOLOGY FOR BIOFUELS 2020; 13:187. [PMID: 33292496 PMCID: PMC7661180 DOI: 10.1186/s13068-020-01826-5] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2020] [Accepted: 10/30/2020] [Indexed: 05/30/2023]
Abstract
BACKGROUND Application of raw starch-degrading enzymes (RSDEs) in starch processing for biofuel production can effectively reduce energy consumption and processing costs. RSDEs are generally produced by filamentous fungi, such as Penicillium oxalicum, but with very low yields, which seriously hampers industrialization of raw starch processing. Breeding assisted by random mutagenesis is an efficient way to improve fungal enzyme production. RESULTS A total of 3532 P. oxalicum colonies were generated after multiple rounds of mutagenesis, by atmospheric and room-temperature plasma (ARTP) and/or ethyl methanesulfonate (EMS). Of these, one mutant A2-13 had the highest RSDE activity of 162.7 U/mL, using raw cassava flour as substrate, a yield increase of 61.1%, compared with that of the starting strain, OXPoxGA15A. RSDE activity of A2-13 further increased to 191.0 U/mL, through optimization of culture conditions. Increased expression of major amylase genes, including the raw starch-degrading glucoamylase gene, PoxGA15A, and its regulatory gene, PoxAmyR, as well as several single-nucleotide polymorphisms in the A2-13 genome, were detected by real-time reverse transcription quantitative PCR and genomic re-sequencing, respectively. In addition, crude RSDEs produced by A2-13, combined with commercial α-amylase, could efficiently digest raw corn flour and cassava flour at 40 °C. CONCLUSIONS Overall, ARTP/EMS-combined mutagenesis effectively improved fungal RSDE yield. An RSDE-hyperproducing mutant, A2-13, was obtained, and its RSDEs could efficiently hydrolyze raw starch, in combination with commercial α-amylase at low temperature, which provides a useful RSDE resource for future starch processing.
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Affiliation(s)
- Li-Sha Gu
- 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, 530004 Guangxi People’s Republic of China
| | - Ming-Zhu Tan
- 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, 530004 Guangxi People’s Republic of China
| | - Shi-Huan Li
- 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, 530004 Guangxi People’s Republic of China
| | - Ting Zhang
- 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, 530004 Guangxi People’s Republic of China
| | - Qi-Qiang Zhang
- 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, 530004 Guangxi People’s Republic of China
| | - Cheng-Xi Li
- 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, 530004 Guangxi People’s Republic of China
| | - Xue-Mei Luo
- 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, 530004 Guangxi 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, 530004 Guangxi 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, 530004 Guangxi People’s Republic of China
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Fang W, Xue S, Deng P, Zhang X, Wang X, Xiao Y, Fang Z. AmyZ1: a novel α-amylase from marine bacterium Pontibacillus sp. ZY with high activity toward raw starches. BIOTECHNOLOGY FOR BIOFUELS 2019; 12:95. [PMID: 31044008 PMCID: PMC6477751 DOI: 10.1186/s13068-019-1432-9] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2019] [Accepted: 04/12/2019] [Indexed: 05/03/2023]
Abstract
BACKGROUND Starch is an inexpensive and renewable raw material for numerous industrial applications. However, most starch-based products are not cost-efficient due to high-energy input needed in traditional enzymatic starch conversion processes. Therefore, α-amylase with high efficiency to directly hydrolyze high concentration raw starches at a relatively lower temperature will have a profound impact on the efficient application of starch. RESULTS A novel raw starch digesting α-amylase (named AmyZ1) was screened and cloned from a deep-sea bacterium Pontibacillus sp. ZY. Phylogenetic analysis showed that AmyZ1 was a member of subfamily 5 of glycoside hydrolase family 13. When expressed in Escherichia coli, the recombinant AmyZ1 showed high activity at pH 6.0-7.5 and 25-50 °C. Its optimal pH and temperature were 7.0 and 35 °C, respectively. Similar to most α-amylases, AmyZ1 activity was enhanced (2.4-fold) by 1.0 mM Ca2+. Its half-life time at 35 °C was also extended from about 10 min to 100 min. In comparison, AmyZ1 showed a broad substrate specificity toward raw starches, including those derived from rice, corn, and wheat. The specific activity of AmyZ1 towards raw rice starch was 12,621 ± 196 U/mg, much higher than other reported raw starch hydrolases. When used in raw starch hydrolyzing process, AmyZ1 hydrolyzed 52%, 47% and 38% of 30% (w/v) rice, corn, and wheat starch after 4 h incubation. It can also hydrolyze marine raw starch derived from Chlorella pyrenoidosa, resulting in 50.9 mg/g DW (dry weight of the biomass) of reducing sugars after 4 h incubation at 35 °C. Furthermore, when hydrolyzing raw corn starch using the combination of AmyZ1 and commercial glucoamylase, the hydrolysis rate reached 75% after 4.5 h reaction, notably higher than that obtained in existing starch-processing industries. CONCLUSIONS As a novel raw starch-digesting α-amylase with high specific activity, AmyZ1 efficiently hydrolyzed raw starches derived from both terrestrial and marine environments at near ambient temperature, suggesting its application potential in starch-based industrial processes.
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Affiliation(s)
- Wei Fang
- School of Life Sciences, Anhui University, Hefei, 230601 Anhui China
- Anhui Key Laboratory of Modern Biomanufacturing, Hefei, 230601 Anhui China
- Anhui Provincial Engineering Technology Research Center of Microorganisms and Biocatalysis, Hefei, 230601 Anhui China
| | - Saisai Xue
- School of Life Sciences, Anhui University, Hefei, 230601 Anhui China
- Anhui Key Laboratory of Modern Biomanufacturing, Hefei, 230601 Anhui China
- Anhui Provincial Engineering Technology Research Center of Microorganisms and Biocatalysis, Hefei, 230601 Anhui China
| | - Pengjun Deng
- School of Life Sciences, Anhui University, Hefei, 230601 Anhui China
- Anhui Key Laboratory of Modern Biomanufacturing, Hefei, 230601 Anhui China
- Anhui Provincial Engineering Technology Research Center of Microorganisms and Biocatalysis, Hefei, 230601 Anhui China
| | - Xuecheng Zhang
- School of Life Sciences, Anhui University, Hefei, 230601 Anhui China
- Anhui Key Laboratory of Modern Biomanufacturing, Hefei, 230601 Anhui China
- Anhui Provincial Engineering Technology Research Center of Microorganisms and Biocatalysis, Hefei, 230601 Anhui China
| | - Xiaotang Wang
- Department of Chemistry & Biochemistry, Florida International University, Miami, FL 33199 USA
| | - Yazhong Xiao
- School of Life Sciences, Anhui University, Hefei, 230601 Anhui China
- Anhui Key Laboratory of Modern Biomanufacturing, Hefei, 230601 Anhui China
- Anhui Provincial Engineering Technology Research Center of Microorganisms and Biocatalysis, Hefei, 230601 Anhui China
| | - Zemin Fang
- School of Life Sciences, Anhui University, Hefei, 230601 Anhui China
- Anhui Key Laboratory of Modern Biomanufacturing, Hefei, 230601 Anhui China
- Anhui Provincial Engineering Technology Research Center of Microorganisms and Biocatalysis, Hefei, 230601 Anhui China
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Wang L, Zhao S, Chen XX, Deng QP, Li CX, Feng JX. Secretory overproduction of a raw starch-degrading glucoamylase in Penicillium oxalicum using strong promoter and signal peptide. Appl Microbiol Biotechnol 2018; 102:9291-9301. [PMID: 30155751 DOI: 10.1007/s00253-018-9307-8] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2018] [Revised: 07/27/2018] [Accepted: 08/02/2018] [Indexed: 02/05/2023]
Abstract
Raw starch-degrading enzymes (RSDEs) are capable of directly degrading raw starch granules below the gelatinization temperature of starch, which may significantly reduce the cost of starch-based biorefining. However, low yields of natural RSDEs from filamentous fungi limit their industrial application. In this study, transcriptomic and secretomic profiling was employed to screen strongest promoters and signal peptides for use in overexpression of a RSDE gene in Penicillium oxalicum. Top five strong promoters and three signal peptides were detected. Using a green fluorescent protein (GFP) as the reporter, the inducible promoter pPoxEgCel5B of an endoglucanase gene PoxEgCel5B and the signal peptide spPoxGA15A of a raw starch-degrading glucoamylase PoxGA15A were respectively identified as driving the highest GFP production in P. oxalicum. PoxGA15A-overexpressed P. oxalicum strain OXPoxGA15A, which was constructed based on both pPoxEgCel5B and spPoxGA15A, produced significantly higher amounts of recombinant PoxGA15A than the parental strain ∆PoxKu70. Furthermore, crude enzyme from the OXPoxGA15A strain exhibited high activities towards raw starch from cassava, potato, and uncooked soluble starch. Specifically, raw cassava starch-degrading enzyme activity reached 241.6 U/mL in the OXPoxGA15A, which was 3.4-fold higher than that of the ∆PoxKu70. This work provides a feasible method for hyperproduction of RSDEs in P. oxalicum.
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Affiliation(s)
- Long Wang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Life Science and Technology, Guangxi University, 100 Daxue Road, Nanning, 530004, Guangxi, People's Republic of China
| | - Shuai Zhao
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Life Science and Technology, Guangxi University, 100 Daxue Road, Nanning, 530004, Guangxi, People's Republic of China.
| | - Xing-Xiang Chen
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Life Science and Technology, Guangxi University, 100 Daxue Road, Nanning, 530004, Guangxi, People's Republic of China
| | - Qiao-Ping Deng
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Life Science and Technology, Guangxi University, 100 Daxue Road, Nanning, 530004, Guangxi, People's Republic of China
| | - Cheng-Xi Li
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Life Science and Technology, Guangxi University, 100 Daxue Road, Nanning, 530004, Guangxi, People's Republic of China
| | - Jia-Xun Feng
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Life Science and Technology, Guangxi University, 100 Daxue Road, Nanning, 530004, Guangxi, People's Republic of China.
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Trakarnpaiboon S, Srisuk N, Piyachomkwan K, Sakai K, Kitpreechavanich V. Enhanced production of raw starch degrading enzyme using agro-industrial waste mixtures by thermotolerant Rhizopus microsporus for raw cassava chip saccharification in ethanol production. Prep Biochem Biotechnol 2017. [PMID: 28636431 DOI: 10.1080/10826068.2017.1342264] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
In the present study, solid-state fermentation for the production of raw starch degrading enzyme was investigated by thermotolerant Rhizopus microsporus TISTR 3531 using a combination of agro-industrial wastes as substrates. The obtained crude enzyme was applied for hydrolysis of raw cassava starch and chips at low temperature and subjected to nonsterile ethanol production using raw cassava chips. The agro-industrial waste ratio was optimized using a simplex axial mixture design. The results showed that the substrate mixture consisting of rice bran:corncob:cassava bagasse at 8 g:10 g:2 g yielded the highest enzyme production of 201.6 U/g dry solid. The optimized condition for solid-state fermentation was found as 65% initial moisture content, 35°C, initial pH of 6.0, and 5 × 106 spores/mL inoculum, which gave the highest enzyme activity of 389.5 U/g dry solid. The enzyme showed high efficiency on saccharification of raw cassava starch and chips with synergistic activities of commercial α-amylase at 50°C, which promotes low-temperature bioethanol production. A high ethanol concentration of 102.2 g/L with 78% fermentation efficiency was achieved from modified simultaneous saccharification and fermentation using cofermentation of the enzymatic hydrolysate of 300 g raw cassava chips/L with cane molasses.
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Affiliation(s)
- Srisakul Trakarnpaiboon
- a Department of Microbiology, Faculty of Science , Kasetsart University , Chatuchak , Bangkok , Thailand
| | - Nantana Srisuk
- a Department of Microbiology, Faculty of Science , Kasetsart University , Chatuchak , Bangkok , Thailand
| | - Kuakoon Piyachomkwan
- b Cassava and Starch Technology Research Laboratory , National Center for Genetic Engineering and Biotechnology , Pathum Thani , Thailand
| | - Kenji Sakai
- c Laboratory of Soil Microbiology, Division of Systems Bioengineering, Department of Bioscience and Biotechnology, Faculty of Agriculture, Graduate School of Bioresource and Bioenvironmental Sciences , Kyushu University , Higashi-ku , Fukuoka , Japan
| | - Vichien Kitpreechavanich
- a Department of Microbiology, Faculty of Science , Kasetsart University , Chatuchak , Bangkok , Thailand
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Sun H, Peng M. Improvement of glucoamylase production for raw-starch digestion in Aspergillus niger F-01 by maltose stearic acid ester. Biotechnol Lett 2017; 39:561-566. [DOI: 10.1007/s10529-016-2277-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Accepted: 12/20/2016] [Indexed: 10/20/2022]
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Yang P, Zhang H, Cao L, Zheng Z, Jiang S. Construction of Aspergillus niger integrated with cellulase gene from Ampullaria gigas Spix for improved enzyme production and saccharification of alkaline-pretreated rice straw. 3 Biotech 2016; 6:236. [PMID: 28330308 PMCID: PMC5095100 DOI: 10.1007/s13205-016-0545-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2016] [Accepted: 10/07/2016] [Indexed: 11/27/2022] Open
Abstract
Aspergillus niger is an important microorganism that has been used for decades to produce extracellular enzymes. In this study, a novel Aspergillus niger strain integrated with a eukaryotic expression vector harboring the gpd-Shi promoter of shiitake mushrooms and cellulase gene of Ampullaria gigas Spix was engineered to improve cellulase production for the achievement of highly efficient saccharification of agricultural residues. In one strain, designated ACShi27, which exhibited the highest total cellulase expression, total cellulase, endoglucanase, exoglucanase, and xylanase expression levels were 1.73, 16.23, 17.73, and 150.83 U ml−1, respectively; these values were 14.5, 22.3, 24.6, and 17.3% higher than those of the wild-type Aspergillus niger M85 using wheat bran as an induction substrate. Production of cellulases and xylanase by solid-state fermentation followed by in situ saccharification of ACShi27 was investigated with alkaline-pretreated rice straw as a substrate. After 2 days of enzyme induction at 30 °C, followed by 48 h of saccharification at 50 °C, the conversion rate of carbon polymers into reducing sugar reached 293.2 mg g−1, which was 1.23-fold higher than that of the wild-type strain. The expression of sestc in Aspergillus niger can improve the total cellulase and xylanase activity and synergism, thereby enhancing the lignocellulose in situ saccharification.
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Affiliation(s)
- Peizhou Yang
- College of Food Science and Engineering, Hefei University of Technology, Hefei, 230009, China.
- Anhui Key Laboratory of Intensive Processing of Agricultural Products, Hefei University of Technology, Hefei, 230009, China.
| | - Haifeng Zhang
- College of Food Science and Engineering, Hefei University of Technology, Hefei, 230009, China
- Anhui Key Laboratory of Intensive Processing of Agricultural Products, Hefei University of Technology, Hefei, 230009, China
| | - Lili Cao
- College of Food Science and Engineering, Hefei University of Technology, Hefei, 230009, China
- Anhui Key Laboratory of Intensive Processing of Agricultural Products, Hefei University of Technology, Hefei, 230009, China
| | - Zhi Zheng
- College of Food Science and Engineering, Hefei University of Technology, Hefei, 230009, China
- Anhui Key Laboratory of Intensive Processing of Agricultural Products, Hefei University of Technology, Hefei, 230009, China
| | - Shaotong Jiang
- College of Food Science and Engineering, Hefei University of Technology, Hefei, 230009, China
- Anhui Key Laboratory of Intensive Processing of Agricultural Products, Hefei University of Technology, Hefei, 230009, China
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