The objective of this study was to assess in vitro probiotic potential of Lactobacillus strains derived from artisanal fermented vegetables in Shaanxi, China. In total, 74 acid-producing Gram-positive strains with rod-shaped under the microscope were isolated from 16 samples of spontaneously fermented vegetables. Out of 74 strains, 26 showed high survival rate under low pH and high bile salts conditions and were subjected to molecular identification by 16S rRNA gene sequencing analysis. The results showed that 15 isolates belonged to Lactobacillus plantarum, 9 isolates belonged to Lactobacillus brevis, and the 2 remaining strains belonged to Weissella viridescens. The 24 Lactobacillus strains were investigated for their survival rate to transit simulated gastrointestinal tract, cell surface hydrophobicity, auto-aggregation, co-aggregation with pathogen, adhesion to Caco-2, antimicrobial activity, antibiotics susceptibility, radical scavenging ability, α-glucosidase inhibition, and the cholesterol assimilation. The results showed that the probiotic characteristics were strain-dependent, and several strains exhibited great probiotic potential with specific health benefits, which indicated that they might be excellent candidates for production of functional foods. Interestingly, it was first found that L. plantarum generally had higher antibacterial activities, α-glucosidase inhibition ability, and antibiotics susceptibility compared to L. brevis in this study. The results indicated that Lactobacillus strains isolated from fermented vegetables in Shaanxi, China, could be exploited as a promising novel probiotic source.

Pullulan is a natural exopolysaccharide with many useful characteristics. However, pullulan is more costly than other exopolysaccharides, which limits its effective application. The purpose of this study was to adopt a novel mixed-sugar strategy for maximizing pullulan production, mainly using potato starch hydrolysate as a low-cost substrate for liquid-state fermentation by Aureobasidium pullulans. Based on fermentation kinetics evaluation of pullulan production by A. pullulans 201253, the pullulan production rate of A. pullulans with mixtures of potato starch hydrolysate and sucrose (potato starch hydrolysate:sucrose=80:20) was 0.212h-1, which was significantly higher than those of potato starch hydrolysate alone (0.146h-1) and mixtures of potato starch hydrolysate, glucose, and fructose (potato starch hydrolysate:glucose:fructose=80:10:10, 0.166h-1) with 100gL-1 total carbon source. The results suggest that mixtures of potato starch hydrolysate and sucrose could promote pullulan synthesis and possibly that a small amount of sucrose stimulated the enzyme responsible for pullulan synthesis and promoted effective potato starch hydrolysate conversion effectively. Thus, mixed sugars in potato starch hydrolysate and sucrose fermentation might be a promising alternative for the economical production of pullulan.

Novel hydrogels (termed HCD hydrogels) were synthesized based on human-like collagen (HLC) and chitosan (CS) cross-linked with dialdehyde starch (DAS). The biological stability and biocompatibility of HCD hydrogels were determined through in vitro and in vivo tests. The mechanism of hydrogel formation was studied using Fourier transform infrared spectroscopy (FTIR), which showed that covalent bonds formed via acetalization and Schiff base reactions. Biological stability was evaluated in vitro by degrading HCD hydrogels with class I collagenase, class II collagenase, and both class I and class II collagenases and in vivo after subcutaneously injecting HCD into an animal model. The biological characteristics of HCD hydrogels was studied by two methods: (i) MTT and cytomorphology cytotoxicity and cytocompatibility and (ii) in vivo, whereby histomorphometry, transmission electron microscopy (TEM), and immunohistochemistry were used to compare different types of surgically introduced hydrogels, our HCD hydrogels, SunMax Collagen Implant hydrogels (SUM hydrogels), and OUTLINE&EVOLUTION Injectable Synthetic Gel hydrogels (EVL hydrogels). The in vivo analyses were performed at 1, 9, 12, and 28 weeks after surgery. The hydrogel biodegradation results showed that the normalized residual weight (W_R) of HCD hydrogels varied with DAS content. In vitro, we found that the minimum W_R of HCD hydrogels was 42.19% after 28 weeks when degraded by both types of class I and class II collagenase. The MTT assay indicated that the minimum relative growth rate (RGR) of cells was 93% after they were incubated with HCD hydrogels for 7 days, suggesting good cytocompatibility. In vivo histomorphometry results indicated that HCD hydrogels effectively filled tissue voids and did not cause redness, edema, festering, or color changes. In addition, a few vessels grew into the hydrogel and a thin fibrous capsule was eventually produced. TEM and immunohistochemistry studies suggested that HCD hydrogels produced less intense inflammatory responses than those produced by SUM hydrogels and EVL hydrogels. Overall, HCD hydrogels afford both enhanced biological stability and excellent biocompatibility, making them potentially promising for skin patch scaffolds, wrinkle treatments, and tissue cavity fillers.