6-α-glucosyltransferase has catalytic activities of exo-hydrolysis towards α-1,4-glucan and transglycosylation, and can produce the α-glucan which links α-1,6 glycosidic bonds on the nonreducing end through transglycosylation activity.Therefore, it can be used to produce cyclic alternating sugars and their branched derivatives, as well as cycloisomaltooligosaccharide, which can be used as new functional sugar.To expand the application of 6-α-glucosyltransferase in the food industry, the 6-α-glucosyltransferase from Bacillus globisporus N75 was expressed heterologously in the food safety strain Bacillus subtilis, and the expression level of recombinant protein increased by selecting the host strain and optimizing fermentation condition.These results indicated that the host WHS9 was more beneficial for the recombinant expression of 6-α-glucosyltransferase and the total soluble enzyme activity could achieve 2.11 U/mL at 20 ℃, including intracellular and extracellular.After adding 20 mmol/L trehalose, the total enzyme activity could reach 2.21 U/mL at 25 ℃ for 48 h.Then the fermentation period was optimized, and it was found that the highest enzyme activity could reach 3.14 U/mL at 36 h, which was 196 times higher than in WHS9 before optimization.This study firstly achieves recombinant expression of 6-α-glucosyltransferase in B.subtilis.

Monensin is a kind of polyether antibiotic produced by Streptomyces cinnamonensis, which is widely used in fields including medicine and agriculture due to its environmentally friendly and efficient properties.However, the low oxygen condition commonly existing in the monensin production process strictly limited the monensin fermentation level.Based on the previous integrated expression of the monensin biosynthesis pathway specific regulatory genes monH and monRII, this study attempted to integrating Vitreoscilla hemoglobin gene vgb by heterologous expression to increase the monensin fermentation titer by improving the oxygen uptake capacity of strains.Results showed that the optimized conditions (40 mmol/L Ca²⁺, donor-recipient ratio 100∶1, antibiotics adding time 18 h) significantly improved the conjugation efficiency by 3 times.With successful integration of vgb with monH and monRII, two engineering strains, 2110-monH-vgb and 2110-monH-monRII-vgb were obtained.They produced 18.0% and 21.3% of the monensin higher than that without heterologous expression, respectively, under the extremly weak oxygen shake-flask condition.The biomass of 2110-monH-monRII-vgb in a 5 L bio-fermentor was slightly higher than that of the starting strain, but its monensin titer reached 13.4 kU/mL, which was 55.7% higher than that of the starting strain.In conclusion, by optimizing the conjugation efficiency of S.cinnamonensis and applying it to the genetic engineering of S.cinnamonensis in monensin fermentation, this study successfully obtained a vgb integrated strain by heterologous expression that effectively increased the monensin fermentation level, which would supply a substantial foundation for its subsequent industrial application.

Fermented corn sauce powder is a fermented product with freshening and flavoring effect made of corn and edible salt as the main raw materials, through special strain fermentation and other processes, which can be applied in food to provide umami and salty taste.A variety of volatile and non-volatile compounds work together to determine the flavor characteristics.Therefore, this article uses solid-phase microextraction (SPME) combined with GC-MS and HPLC to quantitatively analyze volatile and non volatile compounds (free amino acids and 5′-nucleotides) in a fermented corn sauce powder on the market, and studies the freshening application characteristics of fermented corn sauce powder in soy sauce.The results showed that fermented corn sauce powder had rich flavor characteristics.A total of 34 volatile compounds were detected.Among them, 12 volatile compounds were OAV≥1.In terms of non-volatile compounds, some amino acids and 5′-nucleotides contribute to the umami taste of sauce powder, amino acids such as Ala can provide sweetness to sauce powder, and amino acids such as Arg provide bitterness.Combined with the orthogonal experiment and sensory evaluation, it was found that the soy sauce prepared by adding white granulated sugar (12%), fermented corn sauce powder (5%) and yeast extract (1%) had the best sensory evaluation, which could increase the flavor and sweetness of soy sauce crude oil while inhibiting its bitter and astringent taste.This study can provide theoretical support for the flavor research of fermented corn sauce powder and its deep application in other seasonings.

The production of 1,6-hexanediamine as the synthetic monomer of nylon 66 is mainly monopolized by foreign countries, and the traditional chemical synthesis of hexanediamine contains highly toxic cyanide, high technical barriers, long production process, how to use the biological method to make innovative breakthroughs in the context of carbon neutrality has become a challenge.However, up to now, no natural hexanediamine synthesis pathway has been reported.In this study, 6-aminohexanoic acid, a widely available substrate, was used to construct a synthetic pathway for hexanediamine through component-adapted assembly, and fermentation enhancement was combined to increase the yield of hexanediamine in engineered strains.Finally, excellent carboxylic acid reductase MAB CAR L342E, single transaminase HATA, and double transaminase combination PatA/VFTA were obtained through screening, and the initial hexanediamine yields of the engineered strains after combination could reach 3.01 mg/L (DAH4) and 8.50 mg/L (DAH37), respectively.On this basis, the fermentation conditions were optimized, and the yields of 1,6-hexanediamine reached 64.33 mg/L and 153.93 mg/L, which were 20.37 times and 17.11 times higher than those before optimization, respectively.This study has successfully constructed a pathway for the synthesis of hexanediamine by biological method, which provides technical support for the breakthrough of domestic chemical products.

This study aimed to study the uric acid (UA) lowering activity of Sanghuangporus sanghuang ethanol extract in vitro, the inhibitory activity of free phenol extracts of four different sources of Sanghuangporus sanghuang (wild Phellinus vaninii, cultivated Inonotus hispidus, cultivated Phellinus vaninii, and wild Inonotus hispidus) on xanthine oxidase was determined.Furthermore, the inhibitory effect of free phenol extracts on uric acid production in high uric acid cell models.Additionally, the main compounds in strong active extract were analyzed by UPLC-MS/MS.Results suggested that cultivated Inonotus hispidus, cultivated Phellinus vaninii, and wild Inonotus hispidus showed strong inhibitory effects on xanthine oxidase (XOD), the IC₅₀ values were (94.63±2.73) μg/mL, (99.69±2.50) μg/mL, and (106.32±5.06) μg/mL, respectively.Cultivated Inonotus hispidus and wild Phellinus vaninii showed better UA lowering ability than those of wild Inonotus hispidus and cultivated Phellinus vaninii in the high UA cell model (P<0.05).Results obtained from UPLC-MS/MS showed that the strong active components of flavonoids including hyperoside, (-)-epicatechin, theaflavin, diosmin, and cynaroside, may be the active components for lowering uric acid.This study may provide some theoretical references for the application of uric acid-lowering products of Sanghuangporus sanghuang.

‘Cuixiang’ kiwifruit are usually hard when purchased and need to be stored to soften before they can be eaten.However, kiwifruit are respiratory leaps that are prone to concentrated ripening, and the uncontrollable evolution of kiwifruit fruit quality during home storage can lead to a poor consumer experience and a reduced desire to buy.In this paper, the evolution of fruit quality of ‘Cuixiang’ kiwifruit under home storage conditions was systematically analyzed based on the dimensions of physicochemical characteristics, organoleptic quality, and aroma characteristics.In terms of physicochemical characteristics, titratable acid content and hardness of kiwifruit decreased significantly during home storage, while the content of total soluble solids, sugar-acid ratio, and weight loss tended to increase significantly.Based on the correlation of the above indexes, hardness was chosen to establish a zero-level kinetic shelf-life prediction model, and the model had good accuracy and reliability.Meanwhile, the artificial sensory evaluation showed that, except for the appearance score, which continued to decrease during the storage period, the scores of other sensory indexes, such as color, aroma, taste, texture, etc., increased significantly and peaked on the 11th day.Therefore, the total artificial sensory scores of ‘Cuixiang’ kiwifruit were the highest on the 11th day of home storage, which was the most suitable for consumption at this time.Gas chromatography-mass spectrometry was used to evaluate the aroma profile of kiwifruit, and a total of 513 volatile organic compounds were detected, with ester concentrations accounting for the highest percentage of kiwifruit samples at different stages of home storage, and terpenes showing the highest percentage of species.On the 1st day and the 7th day, the volatiles were more abundant and the aroma was more complex, with the highest content of aldehydes and a prominent herbaceous note.On the 11th day, the proportion of esters in the total volatiles was significantly higher than that on the 1st day and the 7th day, and the fruity and sweet flavors were more intense.

Diacetyl is one of the most important substances in dairy products and contributes to buttery flavor in cheese.Based on the biosynthesis pathway of diacetyl, 23 strains of lactic acid bacteria were screened according to the ability to produce diacetyl, activities of acetoin reductase, α-acetolactate decarboxylase, and diacetyl reductase for adjunct culture, the growth ability in ripening environment of cheddar cheese, and autolysis degree.The impact of the selected adjunct culture on the properties of cheddar cheese was evaluated with a rapid ripening model.The ripening experimental results showed that the addition of adjunct cultures did not result in significant difference in the physical and chemical indicators, proteolysis, and texture of cheddar cheese except the flavor profile.Compared to the other groups, diacetyl content and buttery flavor was higher in the cheddar cheese prepared with CCFM 601, and the decline of diacetyl was slower during ripening.Therefore, the addition of adjunct cultures in cheddar cheese with high production ability of diacetyl could enhance the milky flavor of cheddar cheese during ripening.

Fresh meat, legumes, aquatic products, and vegetables transformed into fermented foods with significantly different flavor after a period of time of microbial fermentation naturally or artificially, which have been widely loved by people all around the world since ancient times.Organic acids, amino acids, peptides, and sugars formed in the fermentation process of food raw materials are important flavor substances, which determine the taste and flavor of fermented food.Based on extensive literature review, this paper reviewed the research progress of six main taste substances of fermented food, such as sourness, sweetness, bitterness, saltiness, umami, and kokumi, mainly focused on the formation mechanism of six taste substances, and the foreground of its application and development were pointed out, for the purpose of providing reference for the quality control of high-quality fermented foods.

To study the sensory characteristics and different aroma compounds of wines made from grapes with different maturities, grapes with four maturities of 20, 23, 25 and 27.5 °Brix were selected for small-scale fermentation, and the wines with different maturities were analyzed by GC-MS and flash profile (FP).Results showed that with increasing maturity, the alcohol content in the wine body increased, the total acid content decreased, and the alcohol content showed an overall increasing trend, while the acid content showed an initial increasing and then decreasing trend.The content of 2-methylbutanol and ethyl butyrate in T27.5 wine sample was highest (620.62 mg/L, 5.45 mg/L) and the wine body showed the strongest fruit and fat aroma.The content of ethyl isobutyrate in T25 was highest (2.77 mg/L) and the wine body showed the strongest floral and sweet aroma, while T23 and T20 had no prominent aroma characteristics.Sensory evaluation analysis showed that the grass aroma was prominent in T27.5 wine sample, the red berry aroma was prominent in T25, and T23 and T20 had obvious sensory characteristics in acidity and color.In summary, among the four maturity wines, the appearance and flavor of T20 and T23 wine samples were the best, and the active aroma compounds of T25 and T27.5 wine samples were the most.This study provides a theoretical basis for the scientific control of grape maturity and the production of diversified wines.

The effects of adding cellulose with different particle sizes and proportions on the gel properties of three common surimi products, namely fish balls, fish intestines, and fish cakes, were studied, and the best particle sizes and proportions were selected.This experiment determined the best particle size and proportion by studying the effects of adding different particle sizes and proportions of cellulose on the whiteness, water holding capacity, gel strength, total texture analysis, water distribution, and sensory aspects of fish balls, fish intestines, and fish cakes.The experiment found that the addition of cellulose could effectively improve the whiteness, water retention, gel strength, and texture characteristics of three common surimi products, and reduce the content of free water.The water holding capacity of fish balls, fish intestines, and fish cakes, gel strength, hardness, chewiness, and the proportion of water that was difficult to flow would increase with the increase of cellulose particle size, and first increase and then decrease with the increase of the addition proportion.It was found that the particle size of cellulose was 200 μm.When the addition ratio was 2%, the sensory evaluation would be more popular with consumers.After comprehensive consideration, the particle size of added cellulose was 200 μm.When the addition ratio was 2%, the quality of three common surimi products could be improved to the greatest extent, and the water holding capacity of fish balls, fish intestines and fish cakes can be increased by 14.5%, 22.1%, and 8.9% respectively.Gel strength increased by 121.9%, 108.7%, and 65.5%.Hardness increased by 97.5%, 107.0%, and 158.8%.The proportion of non-flowing water increased by 0.8%, 1.7%, and 1.7%.

Recombinant collagen is a biopolymer with broad potential applications in various fields, such as biomedicine and tissue engineering.The triple-helix structure of collagen imparts unique biological functions and biocompatibilit but also increases the complexity of its expression in microbial systems.In this study, bacterial collagen V-B was used as a model protein to promote the expression of recombinant collagen in Corynebacterium glutamicum through optimization of expression elements.Firstly, the most efficient promoter tac-R0 was obtained through promoter screening and fermentation duration optimization.Subsequently, the RBS calculator was used to design a mutation library for ribosome binding sites (RBS) and aligned spacing (AS).The RBS and AS with the highest strength were identified, which increased the yield of V-B to 514 mg/L.Furthermore, through the tandem combination of multi-gene expression cassettes, the final yield of V-B increased by 8.4-fold compared to the initial level, reaching 697 mg/L.This study lays a foundation for the industrial production of recombinant collagen.

To study the fresh-keeping effect of nutmeg essential oil/hydroxypropyl-β-cyclodextrin (NEO/HP-β-CD) inclusion complex on chilled pork, the chilled pork was treated with different concentrations of NEO/HP-β-CD inclusion compound in combination with the soaking method, smear method, and non-woven fabric method.The indexes including total bacterial count, pH, volatile basic nitrogen, thiobarbituric acid value, texture, juice loss rate, color, and sensory indicators were measured every two days.Results showed that the non-woven fabric method containing 1% NEO/HP-β-CD inclusion complex could effectively reduce the total bacterial count, pH value, and volatile basic nitrogen content of chilled pork during storage, delay the deterioration of texture and color of pork, and improve sensory quality.Compared with the control group (6 days), the storage period of this group could be extended by 6 days.Therefore, the non-woven method containing 1% NEO/HP-β-CD inclusion complex has a good preservation effect on chilled pork.

Squid belongs to the cephalopod class of mollusks, with short survival time, fast reproduction speed, comprehensive nutrition, high protein content, low-fat content, and low-calorie content.Squid skin accounts for 8%-13% of squid processing waste, and full utilization of squid skin can prevent resource waste.This article reviewed the nutritional components, peeling methods, extraction methods of collagen and gelatin from squid skin, as well as the preparation methods of squid skin collagen peptides with antioxidant activity, anti-hypertension, anti-skin aging, anti-tumor activity, and anti-freezing activity.The application of squid skin collagen products in industries such as food, medicine, cosmetics, and cosmeceuticals was also introduced.This article provided a systematic introduction to the research progress in the processing and utilization of squid skin, aiming to provide a theoretical basis for the deep processing of squid skin and promote the sustainable and healthy development of China’s aquatic product processing industry.In the future, the research should focus on optimizing the extraction process of squid skin collagen, improving the targeting of its target peptide screening, and conducting active clinical validation studies, to provide reference for the development and high-value utilization of squid skin.

The combination of meal and wine has always been one of people’s pursuits for a better life.The academic community’s interest in the study of meal and wine pairing is rapidly growing, but there is still a lack of scientific empirical evidence.For the first time, this study adopted a within-subjects design and used correlation analysis, ANOVA and other methods to explore consumer preferences for taste and Baijiu pairings.Results showed that four typical Baijiu (elegant-flavor Baijiu, chi-flavor Baijiu, strong-flavor Baijiu, and sauce-flavor Baijiu) could significantly weaken sweet and sour taste.In addition, strong-flavor Baijiu could weaken bitter taste, while sauce-flavor Baijiu could weaken umami taste.Consumer preferences for different types of Baijiu and taste pairings were significantly different, and preferences were significantly related to taste intensity changes, purchase intention, and recommendation.Four types of Baijiu had the highest preference for pairing with a sour taste, but there were differences in other tastes suitable for different types of Baijiu.In addition to the sour taste, the combinations of chi-flavor Baijiu and elegant-flavor Baijiu with sweet and salty taste were more satisfactory, while strong-flavor Baijiu and sauce-flavor Baijiu were more suitable for sweet and umami taste.In this study, a taste solution was used to induce a basic taste experience and to explore the matching preference between it and different types of Baijiu, which laid the foundation for further research on meal and wine pairing.

To explore the protective effect of component from Poria cocos polysaccharide (PCP) on freeze-drying of compound lactic acid bacteria, purified component from Poria cocos polysaccharide was prepared successfully and its structure was characterized, studying its protective effect and mechanism on freeze-drying of compound lactic acid bacteria.Results showed that PCP-1 with total sugar content of (96.21±0.39)% was obtained after isolation and purification, and the weight average molecular weight of PCP-1 was 11 732 Da.PCP-1 is mainly composed of glucose and glucuronic acid, with the molar ratio of 0.989∶0.011.Moreover, there are hydroxyl groups and both α and β glycosidic bonds in PCP-1.Adding PCP-1 into the basic protective agent increased the freeze-dried survival rate of compound lactic acid bacteria by 11.29% when compared with PCP.The surface of lactic acid bacteria powder with PCP-1 was denser by observed with scanning electron microscope.Furthermore, the activities of Na⁺-K⁺-ATPase and lactate dehydrogenase of compound lactic acid bacteria were significantly enhanced by adding PCP-1 to the basic protective agent, which increased by 0.66 U/mg prot and 1.46 U/mg prot, respectively.The cell membrane integrity of the compound lactic acid bacteria added with PCP-1 was better maintained after double staining with propidium iodide and fluorescein diacetate.In conclusion, PCP-1 may reduce the freeze-drying damage of compound lactic acid bacteria by forming hydrogen bonds through the existence of hydroxyl groups, and improve the freeze-drying survival rate of compound lactic acid bacteria.

Acidic stress has limited the development of industrial microorganisms during the fermentation process.Fine regulation of biofilm formation is an effective strategy to improve the acid tolerance of Escherichia coli.A dual-plasmid regulatory system based on the EL222 blue light-inducible protein was successfully constructed with an 8.6-fold increase in regulatory efficiency.This dual-plasmid expression system was further used to regulate the expressions of a biofilm formation key regulatory factor CsgD and diguanylate cyclase M (DgcM) proteins.The results indicated that the acid resistance of CsgD and DgcM overexpressed strains was improved by 22.3% and 16.4% under conditions of pH 5.0 and 15 mW/cm² blue light irradiation.Moreover, the biofilm content was increased by 2.7 and 3.4 times, respectively.The analysis of biofilm composition revealed that the level of polysaccharides and proteins increased, while the soluble microbial products decreased under acid stress.These changes promoted bacterial aggregation, contributing to the formation of a more stable biofilm structure.Quantitative reverse transcription PCR (RT-qPCR) results further showed a significant upregulation in the transcription levels of biofilm formation-related genes.This blue light-regulated system successfully improved the acid resistance of E.coli by controlling key genes for biofilm formation, which will offer potential references and guidance for microbial organic acid fermentation.

In order to investigate the inhibitory activity of oyster peptides against dipeptidyl peptidase Ⅳ (DPP-Ⅳ), as well as their synergistic effects with anthocyanins, oyster peptides were obtained using the enzymatic hydrolysis method, and their structures were characterized.Furthermore, an in vitro DPP-Ⅳ activity inhibition model and the Compusyn collaborative calculation model were used to analyze the synergistic effect of oyster DPP-Ⅳ inhibitory peptides and anthocyanins in inhibiting DPP-Ⅳ activity.The results indicated that the molecular weight of oyster peptides was primarily below 3 kDa (55.44%), with branched-chain amino acids (BCAAs) and proline (Pro) accounting for 60.84% of the total hydrophobic amino acids.Peptide profiling analysis revealed that the predominant 17 peptide segments in oyster peptides were significantly enriched in BCAAs and Pro at the N-terminus, displaying significant structural characteristics of DPP-Ⅳ inhibitory peptides.Among the five peptides synthesized through screening (FPVGR, APPNIT, IAPPERK, LDFYLDIP, LAIL), FPVGR exhibited the strongest DPP-Ⅳ inhibitory activity (P<0.05).Moreover, among the six common anthocyanins (peonidin/cyanidin/malvidin/delphinidin/pelargonidin/petunidin-3-O-glucoside:Pn3G, C3G, Mv3G, D3G, Pg3G, Pt3G), Pn3G, C3G, and Mv3G demonstrated the strongest DPP-Ⅳ inhibitory activity (P<0.05).Synergy studies revealed that FPVGR and Pn3G/C3G/Mv3G displayed synergistic inhibitory effects against DPP-Ⅳ (with CI values of 0.89, 0.93, and 0.89, respectively, at a 50% inhibition rate).This study provides a scientific foundation for further research on the synergistic activity of DPP-Ⅳ inhibitory peptides and anthocyanins.

Lactic acid bacteria (LAB) fermentation of oats is a new processing method for oat products.However,there is still lack of suitable strains for oak, and the quality traits were not well characterized.This study evaluated the fermentation performance of 20 different strains of LAB in MRS broth, and two optimal strains (Lactobacillus plantarum) were screened.These two strains were combined with common milk fermentation strains Streptococcus thermophilus and Lactobacillus bulgaricus to ferment oat.The fermentation performance of different stains combinations in oat and their effects on physicochemical parameters and flavor quality of oat were studied.Results showed that L.plantarum generally exhibited higher growth and acid production performance, and the amylase activity of L.plantarum was above 7.69 U/mL.The viable count of fermented oat increased to above 10⁹ CFU/mL.Fermentation significantly reduced the reducing sugar, accumulated organic acids, promoted the release of polyphenols and flavonoids, and improved the antioxidant activities of oat.Fermentation increased the water holding capacity of oat and produced more volatile substances.The fermentation with L.plantarum improved the phytochemistry content and antioxidant capacity of mixed stains fermentation group.Fermentation increased the water holding capacity of oat pulp and produced a large number of volatile substances.Compared to pure fermentation of L.plantarum, the mixed fermentation group contained a higher content of 3-hydroxy-2-butanone with a creamy aroma.Among them, L1-L4-F showed the best overall sensory quality, antioxidant activities, and flavor quality, making it a suitable fermenting combination for oat, with greater research and development value.

Oxidative stress is one of the important pathogenesis of Parkinson's disease (PD), and chitosan oligosaccharides have good antioxidant activity and protective effects in neuropathic diseases such as PD.The mice were divided into a control group, model group, low dose group (35 mg/kg), medium dose group (70 mg/kg), and high dose group (140 mg/kg).The mice were intraperitoneally injected with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) to induce PD mice models.To explore the dose-effect relationship and protective mechanism of chitotriose in PD mice, the mice in each group were evaluated by behavioral and pathological indexes and the related indexes of oxidative stress.Results showed that low, middle, and high doses of chitotriose could alleviate the behavioral disorder and the decrease of tyrosine hydroxylase (TH) expression in the striatum of PD mice, and the middle dose group had the best effect.The chitotriose intervention significantly reduced the content of malondialdehyde (MDA) in the striatum of PD mice, significantly increased the levels of glutathione (GSH), total antioxidant capacity (T-AOC), catalase (CAT), and superoxide dismutase (SOD), and up-regulated the nuclear factor E2 related factor (Nrf2)/heme oxygenase (HO-1) signal pathway.Results indicated that the middle dose of chitotriose had a more obvious alleviating effect on MPTP-induced PD mice.The mechanism of its action may be to reduce oxidative stress and alleviate PD by increasing the expression of antioxidant enzymes and up-regulating the Nrf2/HO-1 signaling pathway.

Triacetic acid lactone (TAL) is a promising platform polyketide with broad applications, especially it can be used as a precursor for the synthesis of various organic compounds.This study characterized the repeating sequences on the yeast genome to integrate the TAL biosynthesis pathway into these sites for enhanced gene expression and TAL production by Saccharomyces cerevisiae.Firstly, this study used the green fluorescent protein as the reporter to characterize multi-copy integration by the Delta1 site.It showed that truncating the promoter of a selection marker gene (for geneticin or hygromycin B) or increasing the antibiotic concentration, were effective in improving the integration efficiency and copy numbers.The highest copy number of multi-copy integration was obtained when truncating the antibiotic gene promoter to 15 bp, and using an antibiotic at 160 μg/mL.The optimization system was subsequently used to characterize the second multi-copy integration site, Delta2, with similar results.Then, the optimized multi-copy integration system was applied to introduce the TAL biosynthesis pathway into S.cerevisiae.The highest pathway copies using Delta1 and Delta2 sequences were 10 and 7, respectively, with Delta1 slightly better than Delta2.After 48 h fermentation in YTD medium, TAL titers of the Delta1-integration strain and the Delta2-integration strain were 1.50 mmol/L and 1.17 mmol/L, respectively, 460% and 337% higher than the single-copy integration strain.This study demonstrates that the multi-copy integration system is an efficient approach to introducing heterologous pathways into S.cerevisiae to improve biocatalytic efficiency.