褐藻胶低聚糖生物活性研究进展

综述近年来褐藻胶低聚糖在抑菌、抗肿瘤、调节免疫、促生长、抗氧化等生物活性方面的研究,展望褐藻胶低聚糖的应用前景。     

海藻酸钠包埋保藏对食药用菌种活性的影响

采用海藻酸钠包埋食药用菌种 ,并于液体石蜡中封藏 3年后测定其活性。结果表明 :食药用菌种平均萌发率为 84.0 % ,平均萌发时间为 3 2h ,菌丝生长速度为 0 .75 8cm/d。     

益生素、寡糖对三黄鸡生产性能及免疫机能的影响

将1日龄广东三黄鸡160只，随机分成5组，即对照组，试验1组(添加0．3％的益生素)，试验2组(添加0．2％的寡糖)，试验3组(添加0．3％的益生素和0．2％的寡糖)，试验4组(添加0.2％的益生素和0．1％的寡糖)，研究益生素和寡糖对肉鸡生产性能与免疫机能的影响。结果表明：饲料中添加益生素或寡糖均能显著提高肉鸡的平均日增重、饲料转化率、免疫器官指数、白细胞吞噬率及新城疫抗体效价，降低肉鸡死亡率。寡糖的作用效果前4周较明显．而益生素4周后较明显。同时添加益生素和寡糖对提高肉鸡生产性能与免疫机能具有协同作用。     

Simultaneous Extraction and Depolymerization of Fucoidan from Sargassum muticum in Aqueous Media

The biomass components of the invasive seaweed Sargassum muticum were fractionated to allow their separate valorization. S. muticum (Sm) and the solid residue remaining after alginate extraction of this seaweed (AESm) were processed with hot, compressed water (hydrothermal processing) to assess the effects of temperature on fucoidan solubilization. Fucose-containing oligosaccharides were identified as reaction products. Operating under optimal conditions (170 °C), up to 62 and 85 wt% of the dry mass of Sm and AESm were solubilized, respectively. The reaction media were subjected to precipitation, nanofiltration and freeze-drying. The dried products contained 50% and 85% of the fucoidan present in Sm and AESm, respectively; together with other components such as phenolics and inorganic components. The saccharidic fraction, accounting for up to 35% of the dried extracts, contained fucose as the main sugar, and also galactose, xylose, glucose and mannose. The concentrates were characterized for antioxidant activity using the TEAC assay.     

Effect of ensiling moist field bean (Vicia faba), pea (Pisum sativum) and lupine (Lupinus spp.) grains on the contents of alkaloids,oligosaccharides and tannins

Ensiling legume grain may be an inexpensive and ecologically interesting method to produce a high‐protein feed of local origin. The typically patchy maturation recommends harvesting and ensiling the seeds in moist condition. Developing a method for preserving legume grains harvested before maturation by lactic acid fermentation would have several advantages. Under laboratory conditions, crushed legume seeds of beans, peas and lupines with high moisture content of 35 % were ensiled with different additives (molasses and lactic acid bacteria). To characterize the final silages, contents of proximate nutrients and antinutritional factors (alkaloids, oligosaccharides, tannins) were analysed. The addition of lactic acid bacteria ensured a fast and pronounced lactic acid production and decreased contents of undesired fermentation products like ethanol. An additional use of molasses for ensilage did not provide a remarkable additional benefit. Excluding sugar and starch, the contents of proximate nutrients were not remarkably altered after ensiling. As an overall effect, lactic acid fermentation reduced tannins and oligosaccharides. It can be supposed that the oligosaccharides after breakdown of the complex molecules acted as a source of fermentable carbohydrates. A relevant reduction of alkaloids did not occur. The lactic acid fermentation of legume grains can be recommended as an appropriate method for conservation. With respect to the economic advantages and compared with methods of chemical preservation, the lactic acid fermentation of legume grains under anaerobic conditions is an environmentally compliant procedure and therefore also an option for organic farming.     

壳寡糖叶面喷施对玉米耐旱性的调节

针对壳寡糖持续时间不长的作用机制,本研究在自然干旱条件下多次叶面喷施不同浓度的壳寡糖,调查其对不同玉米杂交种抗旱相关生理指标、产量及其构成因素的影响。结果表明,在5叶期、10叶期和15叶期叶面喷施壳寡糖,叶片相对含水量均较清水对照显著提高,电导率和丙二醛含量较清水对照显著降低,吐丝期、生育期、株高、穗位高、穗行数和百粒重的影响不显著,行粒数和穗粒重较清水对照显著提高,而且以0.3%浓度壳寡糖处理的作用更为明显。由此说明,在干旱胁迫下叶面喷施壳寡糖对细胞膜具有保护作用,可通过对行粒数的影响而提高玉米产量。     

Preparation of Alginate-Based Biomaterials and Their Applications in Biomedicine

Alginates are naturally occurring polysaccharides extracted from brown marine algae and bacteria. Being biocompatible, biodegradable, non-toxic and easy to gel, alginates can be processed into various forms, such as hydrogels, microspheres, fibers and sponges, and have been widely applied in biomedical field. The present review provides an overview of the properties and processing methods of alginates, as well as their applications in wound healing, tissue repair and drug delivery in recent years.     

Effect of fructo‐oligosaccharides on nutrient digestibility and digesta retention time in adult guinea pigs

A previous study suggested that addition of fructo‐oligosaccharides (FOS) to the diet improved nitrogen (N) utilization and decreased acid detergent fiber (ADF) digestibility in guinea pigs. The present study was conducted to clarify the relationship between ADF digestibility and gastrointestinal mean retention time (MRT) in guinea pigs under FOS supplementation. Adult male guinea pigs were fed a commercial diet (50 g/day) with either 5% glucose (glucose group) or 5% FOS (FOS group) for 12 days in individual metabolism cages. Unlike the glucose group, N utilization improved, but ADF digestibility significantly (P < 0.05) decreased in the FOS group. MRT of solid digesta also significantly (P < 0.05) decreased in the FOS group compared with that in the glucose group. We concluded that reduction of MRT of solid digesta containing FOS decreased ADF digestibility in guinea pigs.     

Purification and Characterization of a Novel Alginate Lyase from a Marine Streptomyces Species Isolated from Seaweed

Alginate, a natural polysaccharide derived from brown seaweed, is finding multiple applications in biomedicine via its transformation through chemical, physical, and, increasingly, enzymatic processes. In this study a novel alginate lyase, AlyDS44, was purified and characterized from a marine actinobacterium, Streptomyces luridiscabiei, which was isolated from decomposing seaweed. The purified enzyme had a specific activity of 108.6 U/mg, with a molecular weight of 28.6 kDa, and was composed of 260 amino acid residues. AlyDS44 is a bifunctional alginate lyase, active on both polyguluronate and polymannuronate, though it preferentially degrades polyguluronate. The optimal pH of this enzyme is 8.5 and the optimal temperature is 45 °C. It is a salt-tolerant alginate lyase with an optimal activity at 0.6 M NaCl. Metal ions Mn²⁺, Co²⁺, and Fe²⁺ increased the alginate degrading activity, but it was inhibited in the presence of Zn²⁺ and Cu²⁺. The highly conserved regions of its amino acid sequences indicated that AlyDS44 belongs to the polysaccharide lyase family 7. The main breakdown products of the enzyme on alginate were disaccharides, trisaccharides, and tetrasaccharides, which demonstrated that this enzyme acted as an endo-type alginate lyase. AlyDS44 is a novel enzyme, with the potential for efficient production of alginate oligosaccharides with low degrees of polymerization.     

Advanced Strategies for 3D Bioprinting of Tissue and Organ Analogs Using Alginate Hydrogel Bioinks

Alginate is a natural polysaccharide that typically originates from various species of algae. Due to its low cost, good biocompatibility, and rapid ionic gelation, the alginate hydrogel has become a good option of bioink source for 3D bioprinting. However, the lack of cell adhesive moieties, erratic biodegradability, and poor printability are the critical limitations of alginate hydrogel bioink. This review discusses the pivotal properties of alginate hydrogel as a bioink for 3D bioprinting technologies. Afterward, a variety of advanced material formulations and biofabrication strategies that have recently been developed to overcome the drawbacks of alginate hydrogel bioink will be focused on. In addition, the applications of these advanced solutions for 3D bioprinting of tissue/organ mimicries such as regenerative implants and in vitro tissue models using alginate-based bioink will be systematically summarized.