Effects of fish protein hydrolysate on growth performance and humoral immune response in large yellow croaker (Pseudosciaena crocea R.)

We investigated the effects of fish protein hydrolysate (FPH) on growth performance and humoral immune response of the large yellow croaker (Pseudosciaena crocea R.). One thousand and two hundred large yellow croakers [initial average weight: (162.75±23.85) g] were divided into four groups and reared in floating sea cages (3 m×3 m×3 m). The animals were fed with 4 diets: basal diet only (control) or diets supplemented with 5%, 10% and 15% (w/w) FPH. The results show that dietary FPH levels significantly influenced the growth and immunity of the large yellow croaker. Compared with the control group, total weight gain (TWG) in all treatment groups, relative weight gain (RWG) and specific growth rate (SGR) in fish fed with diets supplemerited with 10% and 15% FPH were significantly increased (P＜0.05). Similar results were observed in immune parameters [lysozyme activity, serum complements, immunoglobulin M (IgM)]. Lysozyme activity, complement C4 and IgM were also significantly increased (P＜0.05) in fish fed with diets supplemented with 10% and 15% FPH, while complement C3 level was significantly increased (P＜0.05) in all treatment groups. In general, with the supplementation of FPH, particularly at dose of 10%,the growth performance and immunity of the large yellow croaker can be improved effectively.     

高产柠檬酸突变菌株以玉米粉为原料的生物反应器扩大生产研究

研究目的：研究高产黑曲霉突变菌株以玉米粉为原料的生物反应器扩大发酵,以期获得适合于工业化生产柠檬酸的发酵工艺。 创新要点：以玉米粉为原料,系统地研究了筛选得到的高产菌株在50L生物反应器中不同糖浓度发酵生产柠檬酸的特性,最终优化出适合于工业化生产柠檬酸的发酵工艺。 研究方法：（1）利用淀粉酶对粉碎后的玉米进行液化,然后过滤,最终得上清液;（2）以50L生物反应器作为发酵设备,对筛选得到的高产柠檬酸菌株进行扩大培养;（3）通过测定不同培养时期中积累的柠檬酸含量和剩余的残总糖,最终优化出高效率生产柠檬酸的发酵工艺。 重要结论：以不同糖浓度的液化玉米粉上清液作为碳源,突变菌株H4002能积累177．7--196．0g,L的柠檬酸,效率能达到2．96～3．27g/（L·h）,尤其当糖浓度为210g／L,H4002菌株表现出最佳的柠檬酸生产水平,如柠檬酸积累187．5g/L,生产效率达3．13g／（L·h）。上述结果说明了突变菌株H4002拥有快速生产柠檬酸的能力。     

Collagen as a source of bioactive peptides: A bioinformatics approach

BackgroundCollagen is the most abundant protein in animals and can be obtained from residues of the food industry. Its hydrolysate has many desirable properties that make it suitable as an additive in foods and cosmetics, or as a component of scaffold materials to be used in biomedicine.ResultsWe report here the characterization of type I collagen from five different sources, namely bovine, porcine, chicken, trout and salmon, as well as their hydrolysates by means of bioinformatics tools. As expected, the results showed that bovine and porcine collagen, as well as trout and salmon collagen, can be used interchangeably due to their high identity. This result is consistent with the evolution of proteins with highly identical sequences between related species. Also, 156 sequences were found as potential bioactive peptides, 126 from propeptide region and 30 from the central domain, according to the comparison with reported active sequences.ConclusionsCollagen analysis from a bioinformatic approach allowed us to classify collagen from 5 different animal sources, to establish its interchangeability as potential additive in diverse fields and also to determine the content of bioactive peptides from its in silico hydrolysis.How to citeNuñez SM, Guzmán F, Valencia P, et al. Collagen as a source of bioactive peptides: a bioinformatics approach. Electron J Biotechnol 2020; 48. https://doi.org/10.1016/j.ejbt.2020.09.009.     

发酵玉米芯酶水解液生产木糖醇的研究

假丝酵母(Candida sp.)菌株经驯化后显著地提高了对水解液中发酵抑制物质的耐受力,从而增加了木糖利用率和木糖醇得率。玉米芯经酶水解得到水解液,在30℃下采用假丝酵母菌株直接发酵生产木糖醇。对发酵条件进行了优化,优化结果为:接种量5%(体积比),种子龄20 h,氮源组成:2.5 g/L的酵母浸膏,2.5 g/L的胰蛋白胨,250 mL三角瓶装液100 mL,初始pH值6。在此条件下,木糖醇得率达65%。该方法大大降低了预处理的成本,显示了良好的应用前景。