Abstract:Alzheimer’s disease (AD) is a chronic neurodegenerative disease, which is considered as one of the most intractable medical problems with heavy social and economic burden. Currently, the therapeutic strategies development based on Aβ hypothesis is a research hotspot. The research progress on therapeutic strategies developed based on the mechanism of reducing Aβ synthesis, increasing Aβ degradation, blocking the interaction of Aβ and neurons, and inhibiting Aβ aggregation are reviewed to provide basis for the further development of anti-AD drugs.

Abstract:The high-yielding strain of sisomicin was selected by protoplast normal pressure and room temperature plasma mutagenesis. A high-yielding strain I4-10 was obtained through mutagenesis and the biological titer of sisomicin reached 1 389 U/mL, which was 35.4% higher than the original strain. By optimizing the carbon source and nitrogen source of the high-yielding strain I4-10, it was determined that the soluble starch and beef meal were the most suitable carbon and nitrogen sources for the mutant strain I4-10. The response surface method was further used to optimize the fermentation medium. Results showed that the mass concentrations of soybean meal and DL-methionine were significant influencing factors, and the optimal addition concentrations were 32.78 g/L and 1.75 g/L, respectively. Under this optimal condition, the biological titer of sisomicin was increased to 1 849 U/mL, which was 80% higher compared to the original strain. Finally, the authors compared the transcription level of the key enzymes related to the metabolic pathway of sisomicin, the growth of the high-yielding mutant strain and the strain in the starting bacteria, and preliminarily analyzed the high production mechanism of sisomicin by the mutant strain I4-10.

Abstract:The antifungal effect of rhamnolipids (RLS) on the vegetative growth of Alternaria alternata and on the black spot control were studied, and the possible mechanism of its antifungal activity was evaluated. The results showed that RLS significantly inhibited the growth of A. alternata, and the inhibition effect was significantly increased with the increase of RLS concentration. The mycelium diameters of A. alternata treated with 30 mg/mL RLS was only 19.22% of the control group after 7 days' incubation, and mycelium was white and ball in shape. The development of black spot in pear fruit treated with RLS was also inhibited, lesion diameter of 50 mg/mL RLS treatment group was only 21.42% of that in the control group. Further research showed that the RLS treatment severely damaged the integrity of A. alternata cell membranes and mitochondria, increased membrane conductivity, and promoted the generation and accumulation of reactive oxygen species. Ultramicroscopic observation showed that the hyphae morphology and cellular structure of A. alternata were significantly destroyed by RLS treatment.

Abstract:To expand the strain pool of oil degradation and to improve the biotransformation efficiency of oil in food waste, 4 microbial strains preserved in the laboratory were used as lipase degrading bacteria, the compound oil-removing microbial agent was obtained by equal proportion mixture of the 4 strains. The factors affecting oil removal and lipase production ability of the different strains were investigated. The results showed that the compound oil-removing microbial agent had oil-removing ability at temperature 25~55 ℃, pH 4~9, salt content 5~90 g/L, oil concentration 1%~5%, inoculum 1%~9%, and the degradation rate of oil can reach up to 84.75%. The results of the single strain experiments showed that the strain B501 had the highest lipase activity, while strain 009 had the strongest oil removal ability because of its longer duration of high lipase activity. Also, the oil removal effect of compound bacteria is better than that of a single strain.

Abstract:Halophilic microorganisms live in hypersaline environments, i.e. salted products, seafood and other high-salt foods. Salted-food is an important hypersaline environment rich in extremophiles. the authors collected 7 kinds of salted-foods collected from supermarkets in Wuhu, Anhui Province were used to isolate the halophilic microorganisms. According to the difference incolony morphology, 43 strains were selected for further identification based on the similarity of 16S rRNA gene sequence. After determination their classification status, representative strains from different species were selected for the detection of extracellular enzyme activities. Finally, it was determined that the 43 halophilic microorganisms contained 21 species in 13 genera in domains bacteria and archaea. There are 7 species in 4 genera belonging to halophilic archaea, while 14 species in 9 genera belonging to halophilic bacteria. This study isolated 3 strains produce extracellular amylase, 7 strains produce esterase, 1 strain produces gelatinase, and 8 strains produce catalase, which indicates that halophilic microorganisms are prevalent in the salted-food in the market. Extracellular enzymes produced by these halophilic microorganisms with strong salt-tolerance activity have potential applications in the biological industry.

Abstract:The biomass of Bacillus cereus has an important effect on its biological function. In order to increase the yield and spore rate of Bacillus cereus, the optimum carbon and nitrogen source were screened by single factor experiment. The optimal carbon source was 1∶1(mass ratio) mixed glucose and water-soluble starch, and the optimal nitrogen source was 1∶1(mass ratio) mixed soybean peptone and yeast extract. The effects of feeding method, pH, stirring speed and ventilatory capacity on the biomass and spore rate were studied in a 7 L bioreactor. The optimal fermentation conditions were as follows: in 0~9 h, the stirring speed, aeration ratio and pH were 250 r/min, 3 L/min and 6.5, respectively; in 9~18 h, the stirring speed and ventilatory capacity were 350 r/min and 4.5 L/min, respectively and the concentrated medium was added at a flow rate of 0.45 mL/min; at 18 h, the stirring speed, ventilatory capacity and pH were changed to 150 r/min, 2.25 L/min and 7.5 respectively, and the feeding was stopped till the end of fermentation. Based on the above fermentation strategies, the number of viable Bacillus cereus reached 2.2×10¹⁰ CFU/mL at 18 h, which was 4.88 times of that before the optimization. At the end of fermentation, the spore rate was over 90%. This study provided basis for the industrial applications of Bacillus cereus.

Abstract:To obtain fruit and vegetable starters with good growth ability and gastrointestinal tolerance, 3 strains of Lactobacillus were isolated and identified (named L1, L2 and L3) from tomato fermentation broth that was naturally fermented for 60 days by morphology and 16S rDNA gene sequence analysis, and the growth characteristics and the tolerance to simulated gastrointestinal environment were studied. L1 and L3 belong to Lactobacillus plantarum, while L2 is Lactobacillus brevis. The optimum pH value for growth of the three strains was 6.6, and the optimum growth temperature was 30~38 ℃. The tolerance study results showed that L1 and L3 had stronger high temperature and high salt tolerance, while L2 has better bile salt tolerance. The 3 Lactobacillus had good tolerance to the artificial gastric fluid environment, especially L3, and the survival rates were over 96%. In the artificial intestinal fluid environment, the survival rates of the 3 Lactobacillus strains were over 90%, especially L1 showed better stability. The results showed that the 3 Lactobacillus strains had good growth characteristics and gastrointestinal tolerance, which can provide reference for the development of starter culture and fermented products of fruit and vegetable.

Abstract:To investigate the functional components and biological activities of 24 fermented juice of edible plants, the contents of total flavonoids and total polyphenols were determined by UV/Vis spectrophotometry, and 6 organic acids in the fermented juice were determined by Ultra Performance Liquid Chromatography (UPLC). The optical density(OD) value was measured to evaluate the effect of fermented juice on the growth of Staphylococcus aureus, and compared the inhibitory effects of the fermented juice on the cell growth of human liver cancer cell line Hep G2. The results showed that the total flavonoid content in Lycium barbarum fermented juice was the highest among the 24 fermented juice. The total polyphenol content of Rosa rugosa fermented juice and Syzygium aromaticum fermented juice was significantly higher than that of others. The types of organic acids contained in different fermented juice were similar, but their content was quite different. Among them, the total acid content of Phyllanthus emblica fermented juice was the highest. All the 24 fermented juice had strong inhibitory effects on the growth of Staphylococcus aureus, and had an inhibitory effect on the growth of Hep G2 cells. In conclusion, the contents of polyphenols, flavonoids, organic acids and biological activities of the 24 kinds of fermented juice were compared, which provided direction for further research and development of functional fermented juice products.

Abstract:This study investigated the effect of subculture of species on the viability of extracellular enzymes and the morphology, yield and quality of Ganoderma lucidum fruiting bodies during cultivation. The effects of subculture of species on the viability of extracellular enzymes, the biological efficiency of dry basis of fruiting bodies, and the contents of leachables, polysaccharides, triterpenes and sterols, and components of G. lucidum acid were investigated by colorimetry and HPLC. Correlation analysis was performed to explore the correlation between extracellular enzyme activity and quality of G. lucidum. The investigation showed that the activities of G. laccase, filter paper enzyme, cellulase and amylase showed a decreasing trend with the increase of subculture number of species. Correlation analysis showed that laccase, filter paper enzyme, cellulase and amylase activities were positively correlated with fruiting body dry based biological efficiency and the contents of leachables, polysaccharides, ganoderic acid A, ganoderic acid D, ganoderic acid F, ganoderenic acid A and ganoderenic acid D. Further pathway analysis identified the filter paper enzyme was the key extracellular enzyme affecting the biological efficiency of G. lucidum stem-based substrates, the content of polysaccharide and ganoderic acid F, and cellulase was the key extracellular enzyme affecting the content of ganoderenic acid A. Therefore, the subculture number of G. lucidum species should be controlled within 5 generations in practical production, so that the main extracellular enzymes in the matrix can maintain high viability, and the G. lucidum stem-based biology is of high efficiency and quality.

Abstract:To investigate the influence of cold plasma technology on microbial decontamination and quality of sugarcane juice, the sterilizing rate, polyphenol oxidase (PPO), sugar composition, total phenolic content, free amino acid content, color and pH were selected as the evaluation indicators and the changes of these indicators at different electronic voltage and handling time were analyzed. The results showed that the highest bacteria sterilizing rate, 1.31 lg(N₀/N), and the mold sterilizing rate, 2.34 lg(N₀/N), were obtained in the juice treated at 70 kV, 4 min. The activity of PPO could be inhibited significantly after treated for 1 min (P<0.05). When the voltage was higher than 50 kV, the content of sucrose decreased rapidly in 1 min，while the content of glucose and fructose were increased. The variation trends of total phenolic and free amino acid content decreased first and then increased along with the handling time. While the total phenolic content increased with the increase of electronic voltage, the free amino acid content decreased. The changes of color were significant when the electronic voltage was set at 60 kV and 70 kV(P<0.05). The pH decreased significantly during the cold plasma treatment(P<0.05), and the decrease speed under high voltage was greater than that under low voltage. Comprehensively, the juice treated under 40 kV, 4 min had the best quality, but the sterilizing efficiency was lower than that of the other treatments. In conclusion, prolong the handling time can obtain safer sugarcane juice with higher quality.

Abstract:To study the effect of compound enzyme (pectinase and cellulase) treatment on the quality of mixed fermented juice of Rosa roxburghii Tratt and Malus pumila Mill, the conditions of compound enzyme treatment of mixed fruit juice were optimized first. Then the mixed juice with (test group) and without compound enzyme treatment (control group) were fermented with Lactobacillus paracasei to study their differences in physical and chemical properties, antioxidant properties, and sensory evaluation. The results showed that when the amount of compound enzyme added was 3 g/L (the mass ratio of pectinase to cellulase was 3∶2), the treatment temperature was 35 ℃, and the treatment time was 1.5 h, the maximum light transmittance of the mixed juice was obtained, which was 97.97%. The compound enzyme treatment resulted in a significant decrease in the mass concentrations of carotenoids and increase in reducing sugars in the test group. However, there was no significant difference in pH, acidity, total phenols, total flavonoids, and vitamin C between the test and the control group. The scavenging rates of hydroxyl free radicals and superoxide anion free radicals in the test group were 72.86% and 81.94%, respectively, which were extremely and significantly higher than those of the control group. In terms of sensory evaluation, the color, aroma, tissue state and taste of the test group were better than those of the control group. Therefore, the treatment of compound enzyme can significantly improve the light transmittance of the mixed juice. Moreover, the treatment of complex enzyme had no significant effect on the mass concentration of nutrients like vitamin C and flavonoids in the mixed fermented juice, and improved the antioxidant property and sensory quality of the mixed fermented juice.

Abstract:To study the effects of flavonoids on the activity of α-glucosidase and their inhibitory kinetic characteristics in different polar extraction phases of the alcohol extract of Opisthopappus taihangensis (Ling) Shih, the ethyl acetate phase, n-butanol phase, residual water phase and petroleum ether phase of flavonoids from Opisthopappus taihangensis were extracted. A screening model of α-glucosidase activity inhibition was established by in vitro (PNPG) method. Lineweaver-Burk curves were drawn to analyze the type of inhibition of α-glucosidase by flavonoids from Opisthopappus taihangensis. Flavonoids from Opisthopappus taihangensis in different polar extraction phases showed different degrees of inhibition on α-glucosidase, and a significant dose-effect relationship was found between the inhibitory activity and the concentration of flavonoids. Among them, the flavonoid content and α-glucosidase inhibitory activity in the ethyl acetate phase and n-butanol phase were significantly higher than those in the other extraction phases and higher than that of the acarbose, while the inhibitory activity of glucosidase is lower than that of acarbose. The inhibitory activity was: ethyl acetate (IC₅₀=1.01 mg/mL) ＜n-butanol (IC₅₀=1.25 mg/mL) ＜acarbose (IC₅₀=1.47 mg/mL) ＜residual water (IC₅₀=1.77 mg/mL) ＜petroleum ether (IC₅₀=2.12 mg/mL). Enzyme inhibition kinetics studies found that α-glucosidase of flavonoids from Opisthopappus taihangensis in ethyl acetate phase and n-butanol phase is competitive and non-competitive mixed type; flavonoids from Opisthopappus taihangensis in residual water phase and petroleum ether phase α-glucosidase is a mixed type of competition and anti-competition. The flavonoids of different polar extraction phases of Opisthopappus taihangensis have α-glucosidase inhibitory activity, and have good potential in developing health foods or medicines that assist in lowering blood sugar. Ethyl acetate phase and n-butanol phase flavonoids can be developed as novel α-glucosidase inhibitors.

Abstract:To obtain an adsorbent with high efficiency for the decolorization of dyes, sodium alginate, polyvinyl alcohol and zeolite are used as adsorption materials. Based on the results of the single factor experiment, Box-Behnken experimental design is adopted to conduct a three-factor and three-level response surface test. Decolorization rate is taken as the response; sodium alginate (SA), polyvinyl alcohol (PVA) and zeolite concentration are selected as the influencing factors to optimize the preparation conditions. The results show that the optimum preparation conditions of SPZ are: SA 11 g/L, PVA 21 g/L, zeolite 52 g/L, and the actual decolorization rate is 88.57%. SEM result shows that methylene blue (MB) is successfully adsorbed on SPZ surface. FTIR result shows that there are hydrogen bonds and electrostatic interactions between SPZ and MB. The adsorption process follows the quasi-second-order kinetics and fitts Langmuir isothermal adsorption model, which indicates that the adsorption process can be described as physical diffusion accompanied by chemical adsorption. The results indicate that the SPZ adsorbent has good stability and high decolorization rate. This study will offer references to the application of sodium alginate composite material in the treatment of dye wastewater.