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Objective: To investigate the effects of cell passage number on the establishment of an oxidative stress model in human colon adenocarcinoma cells (Caco-2) caused by tert-butyl hydroperoxide (t-BHP). Methods: First, by applying various t-BHP concentrations (1, 2 and 3 mmol/L) to the F15 generation of Caco-2 cells for 1, 2, 3, 4, 5 and 6 hours, the content of malondialdehyde (MDA) and 8-hydroxydeoxyguanosine (8-OHdG) in different treatment groups were measured to determine the basic conditions for constructing the oxidative stress model of Caco-2 cells. Then, based on the fundamental parameters, the effect of cell passage number (F14, F15, F18, F19 and F20) on the development of oxidative stress model was investigated using the content of 8-OHdG as an index. Results: When exposed to 1, 2 and 3 mmol/L of t-BHP for 3 to 6 hours, the oxidative stress model of Caco-2 cells from the F15 generation could be established steadily. The content of 8-OHdG in Caco-2 cells of the F14, F15 and F18 generations was significantly higher than that in control group (which had not been treated with t-BHP) after being exposed to 2.0 mmol/L t-BHP for 5 hours (P

Bacteria are the key group of micro-organisms during the fermentation of Paocai. This study applied the high-throughput sequencing technology to trace the dynamics of Paocai brine bacterial community structures at constant temperature (25 ℃) under airtight microcosm condition. The results showed that there were 10 phyla and 205 genera had been detected within 30 days after the experiment setup. Among them, there were 12 dominant genera which accounted for 94.7%~97.8% of the total OTUs. The sub-dominant were 13 genera and accounted for 2.1%~3.3%. The rare genera were 180 genera and accounted for 0.08%~2.7%. During the 1~7 days after the experiment setup, the community was relatively stable (phase A). From the 8~20 days, the sub-dominant and rare genera were continuously changing (phase B), and on the 8th day, the communities of sub-dominant and rare genera were acutely fluctuated. From 22~30 days, all of the genera changed obviously (phase C). Meanwhile, the Chao1, Ace indices were increasing during 1~30 days, in addition, the Shannon and Simpson indices reached the thresholds during phase C. Therefore, phase A and B, phase B and C had the similar communities, but not the phase A and C, while the pH during the three phases changed correspondingly. The results also showed that at 25 ℃, the dynamics of sub-dominant and rare genera were the key factor which caused the dynamic of the bacterial communities in Paocai brine during the 30 days experiment. In addition, the accumulated effect had been detected, the pH and the bacterial communities havd mutual influences. The optimal preservation time for the Paocai brine was one week under airtight condition at 25 ℃. The functional effects of rare genera from Paocai brine need pay more attentions on.

【Objective】The study was conducted to explore the phyllosphere bacterial community structure and diversity of landscaping plants in the niche, and to understand the effects of similar environmental conditions and plant characteristics on microbial community in the niche, with a view to provide references for the health management of garden plants and the exploitation of phyllosphere bacterial resources.【Method】High-throughput sequencing technology was applied to explore the bacterial community structure and diversity of Eriobotyra japonica, Magnolia grandiflora and Ficus altissima leaves facing east within 50 m radius circle of Dali University campus.【Result】Among the three garden plants, E. japonica had the highest phyllosphere bacterial diversity, followed by M. grandiflora and F. altissima. The dominant bacterial phylum of phyllosphere bacteria in different plants was Proteobacteria, and the first dominant bacterial genus was different. However, the top five dominant genera were Sphingopyxis, Methylobacterium, Spirosoma, Hymenobacter and Achromobacter. There were significant differences in phyllosphere bacterial community structure among the three plants, but the bacterial communities were similar among the leaves with different sizes of the same plant. Only E. japonica and M. grandiflora leaves had the largest phylum and genus distribution, indicating that the phyllosphere bacterial communities of evergreen broad-leaved plants was more diverse and complex than those of deciduous broad-leaved plants.【Conclusion】There were differences in the composition and diversity of phyllosphere bacterial communities among different plants, and the primary reasons for these differences were the characteristics of the plants themselves. Therefore, it is urgent to strengthen the researches on the utilization of phyllosphere bacterial resources of plants.

Objective To evaluate the effects of three different serum-free culture systems on the biological function of human umbilical cord mesenchymal stem cells （hUC-MSC） cultured in vitro. Methods Three strains of umbilical cord tissues were obtained，divided into 3 experimental groups and cultured to the 3rd generation （P3） in three different serum-free culture systems （Group A： serum-free culture system synthesized by pure chemical components，group B： serum-free culture system consisting of platelet lysate+basic culture medium，group C： serum-free culture system consisting of fibrinogen coating+recombinant human protein）. The cell proliferation，cell phenotype，three-line differentiation and immunomodulatory function were compared. Results All the cells in three groups were long and flat fusiform，adherent to the wall and uniform in size. The proliferation curve trend was similar，and the proliferation ability of P2 and P3 generations in groups A and B was better than that in group C （both P + CD25+ FOXP3+） was significantly increased in the three experimental groups，but there was no statistical significance among three experimental groups （all P > 0.05）.Conclusions The hUC-MSC in three groups can maintain basic biological characteristics and immunomodulatory activity. The proliferation ability and expression levels of cell surface markers in groups A and B are superior to those in group C.

The effects of different temperature-time regimes of enzymatic retrogradation on the particle size, microscopic morphology, crystal structure, functional groups and epigallocatechin-3-gallate (EGCG)-loading capacity of debranched starch nanoparticles (DBS-NPs) prepared with green banana starch were investigated. Meanwhile, the stability, antioxidant properties and in vitro release behavior of EGCG@DBS-NPs were investigated. It was shown that compared with green banana starch, the particle size of DBS-NPs decreased from (23.4 ± 7.3) μm to (208.5 ± 2.7) nm, and the crystal structure changed from type C to C→B or C→A. Besides, the relative crystallinity and the hydrogen bonding force between molecular chains were enhanced. EGCG showed the highest loading capacity (4.34%) and encapsulation efficiency (86.89%) in DBS-NP50-12, and their combination exhibited synergistic antioxidant activity. EGCG@DBS-NP50-12 was found to be more stable in a near neutral environment than in an acidic environment, and significantly more stable than free EGCG during storage. EGCG@DBS-NP50-12 exhibited excellent slow release behavior in vitro, which was fitted to a first-order kinetic equation. This study provides a reference for the preparation and application of starch nanoparticles, which has potential value in the construction of starch-based bioactive carriers.

The purpose of this study was to explore the effect of treatment with dielectric barrier discharge (DBD) plasma followed by complexation with resveratrol on the physicochemical properties and digestibility of green banana starch. The results showed that DBD plasma treatment improved the complexation between banana starch and resveratrol. Compared with unmodified banana starch, the solubility, retrogradation properties, oil-holding capacity, gelatinization temperature (the onset gelatinization temperature (To), peak gelatinization temperature (Tp) and conclusion gelatinization temperature (Tc) increased from 64.10, 71.14 and 73.92 ℃ to 70.18, 75.79 and 82.53 ℃, respectively) and digestibility of the complex were significantly improved, while the swelling power and freeze-thaw stability were reduced. Scanning electron microscopy (SEM) showed that DBD plasma treatment produced more starch fragments and etched the starch surface. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) showed that resveratrol combined with banana starch through CH-π bond, which made the structure of the complex more compact and orderly, forming a non V-type inclusion complex with high crystallinity. Therefore, plasma treatment and then complexation with polyphenols can improve the processing properties of banana starch, which will contribute to the development of new health foods.