Effects of brewer’s yeast extract on growth performance and health of juvenile pikeperch Sander lucioperca (L.)

Juvenile European pikeperch, Sander lucioperca, were fed commercial feed (group C) or experimental feed supplemented with NuPro^® nucleotide‐rich Saccharomyces cerevisiae yeast protein (extract obtained through a cell wall removal process) in doses of 20, 40 or 60 g kg^?1 feed (groups N2, N4, N6) for 8 weeks. Growth, non‐specific immunity parameters, histological structure of the liver and intestine, proximate whole‐body composition and blood biochemical parameters were assayed. It was noted that brewer’s yeast extract has immunomodulatory proprieties. NuPro^® in doses of 40 and 60 g kg^?1 feed strongly stimulated non‐specific (innate) cellular and humoral immunity in pikeperch. The experimental feed did not have a significant impact on pikeperch growth (P > 0.05). The proximate composition of the fish bodies and the hepatosomatic and viscerosomatic (VSI) indices were also not affected, which indicated that the tested diets had no negative impact on the metabolism or deposition of nutrients in fish tissues. The lower levels of transaminases AST and ALT, which were noted in the groups with the two highest doses of NuPro^® (P < 0.05), might indicate improved liver function. It was also demonstrated that the brewer’s yeast extract stimulates the absorption activity of intestinal epithelial cells.     

The effect of Saccharomyces cerevisiae on digestion and mortality in the volcano rabbit (Romerolagus diazi)

An experiment was conducted to evaluate whether supplementation with a probiotic could enhance digestion and reduce mortality in the volcano rabbit in captivity. Two enclosures at Chapultepec Zoo, Mexico(114 individuals) were used in a crossover design(two periods of 60 days) with the following treatments: control group and supplementation with Saccharomyces cerevisiae(2×108 CFU/exhibit/day). Supplementation with the probiotic negatively affected(P<0.01) the digestibility of dry matter, organic matter, neutral detergent fiber(NDF) and energy. Mortality increased(P<0.04) following supplementation with the probiotic(4.26% vs. 8.89%), primarily in the juvenile rabbits. The results indicate that yeast supplementation in the volcano rabbit negatively affects digestion and mortality in captivity.     

太空诱变复合菌发酵苹果渣玉米秸秆混合料生产饲料蛋白的研究

利用太空诱变获得的优良菌种黑曲霉ZM-8及啤酒酵母YB-6和白地霉、热带假丝酵母配制成的复合菌,固态发酵苹果渣玉米秸秆混合料.结果表明,苹果渣玉米秸秆混合料各成分最适宜的配比为:苹果渣70％,玉米秸秆10％,麸皮15％,辅料5％.通过正交试验确定的最适辅料配方为:尿素2 g,硫铵2 g,食盐1g.复合菌的最佳配方为:黑...     

啤酒糖酵母菌6-磷酸海藻糖合成酶编码基因tps1的cDNA克隆

本工作从抗逆性极强的啤酒糖酵母菌株 Ａ Ｓ２１４１６ 中分离纯化总 Ｒ Ｎ Ａ 和 ｍ Ｒ Ｎ Ａ ,以 Ａ Ｍ Ｖ 逆转录酶合成了单链ｃ Ｄ Ｎ Ａ 。采用保守引物扩增并克隆了该酵母菌的６ － 磷酸海藻糖合成酶编码基因ｔｐｓ１ ,建立了该基因 Ｄ Ｎ Ａ 片段的物理图谱,发现其酶切位点与已见报道的６ － 磷酸海藻糖合成酶编码基因相同。     

绿色木霉AS3.3711的葡聚糖内切酶Ⅰ基因的克隆与表达

采用RTPCR方法克隆到绿色木霉AS3.3711的葡聚糖内切酶Ⅰ(EGⅠ)的cDNA序列,测序后构建到酿酒酵母诱导型表达载体pYES2上,转化酿酒酵母,转化子用2%的βD半乳糖进行诱导,用Northern杂交、刚果红染色法和CMC糖化力法分别对目的基因的转录和表达产物的葡聚糖内切酶活性进行检测.结果表明,EGⅠ的cDNA基因开放阅读框长度为1377bp,编码459个氨基酸,推测蛋白质分子量为48.1kD.刚果红染色显示,转化子可产生明显的水解圈;CMC酶活检测显示该基因能在酿酒酵母中表达有生物活性的EGⅠ并分泌到胞外.发酵液中的酶活在培养60h达到最高0.06UmL,最适酶解温度为50℃,最适pH值为5.4.     

菊芋替代玉米发酵生产乙醇的初步研究

对以果糖基能源植物——菊芋作为唯一碳源,发酵生产乙醇的可行性进行了探讨。结果显示,酿酒酵母BY4742可以良好地利用菊芋水解产物生长和代谢,生物量和乙醇产量和葡萄糖或果糖做底物时相比无明显差异。当底物浓度较高时,菌种对糖化菊芋汁中还原糖的利用率明显下降,但是乙醇产量没有下降,说明菊芋中含有的一些可溶性蛋白、氨基酸和矿物质有可能被菌种代谢利用转化成乙醇。另外,还从经济角度简单分析了菊芋替代玉米发酵生产乙醇的优势和不足。     

灭活黑曲霉与中期啤酒酵母原生质体融合的研究

用ＰＥＧ促融剂使经硫酸二乙酯灭活的黑曲霉ＡＭＳ－１１的原生质体与细胞分裂中期折啤酒酵母ＲａｓｓｅⅫ原生质体融合，在选择性培养基上获得了能利用羧甲纤维素作唯一碳源的杂种酵母菌株ＦＡＳＳ１及ＦＡＳＣ１，经测定其ＤＮＡ量，蛋白质电泳谱带，生长曲线和碳源同化等项目，它们将具有双亲菌株的特征性状。     

酿酒酵母DCCS101脱除荔枝酒挥发醋酸的效果研究

以酿酒酵母DCCS101为出发菌株,研究其在不同条件下脱除挥发醋酸的效果。结果表明：以新鲜的荔枝汁作为发酵基质,酿酒酵母脱除外源醋酸的能力最大可达45%,但外源醋酸浓度高达2 g/L时,发酵终了醋酸浓度仍然达不到荔枝酒挥发酸最低标准的要求;酿酒酵母DCCS101脱除醋酸的速度与酵母生长繁殖速度有关。在以新鲜荔枝汁作为发酵基质的情况下,酵母生长繁殖指数期时脱除醋酸的速度最快;用新鲜荔枝汁调整荔枝酸酒作为发酵基质,在低糖高酒精度增氧条件下醋酸脱除率高达86.3%;以荔枝酸酒直接作为发酵基质,酿酒酵母DCCS101在增氧条件下能较好地生长繁殖,并将起始醋酸浓度1.5 g/L降低至0.53 g/L的水平,有效地提高了荔枝酒的品质。     

豆腐渣混合苹果渣固态发酵改善纤维适口性

为了改善豆腐渣发酵后膳食纤维的适口性,适量混合部分苹果渣,利用其糖分提高酿酒酵母的发酵效率,并对其固态发酵工艺条件进行优化。采用单因素和正交试验方法优化的较佳发酵条件为pH值为8、发酵温度22℃、豆腐渣与苹果渣质量比2∶1、酿酒酵母接种量8%、发酵时间48 h。在优化发酵条件下,豆腐渣和苹果渣混合物中粗纤维的质量分数由发酵前的107.8 mg/g下降到发酵后的64.2 mg/g,降解率为40.45%。混合苹果渣的固态发酵极大地改善了膳食纤维的适口性,可以作为健康食品原料广泛使用。     

酿酒酵母制备固态发酵饲料的参数优化及品质评价

试验旨在研究利用酿酒酵母(Saccharomyces cerevisiae)Yn制备发酵饲料的合适参数及发酵后饲料品质。试验以酵母活菌数为检测指标,对发酵原料添加量、糖化酶添加量、接种量、料水比和发酵温度等参数进行单因素试验,通过响应面设计进一步确定糖化酶添加量、接种量和发酵温度的最优条件,同时评价最优固态发酵条件下发酵饲料的营养品质。结果表明:最适的发酵配方为玉米粉50%,豆粕20%;酵母菌Yn最佳的发酵条件为糖化酶添加量220 U/g、接种量1.4%(w/w)、料水比1:0.8(w/v),优化后的酵母菌数(折算干重)达到1.30×10~(10) CFU/g;粗蛋白、总酚、维生素B_2和低分子量肽含量在发酵后显著提高(P0.05),而粗脂肪含量显著降低(P0.05)。以上结果表明,该发酵条件在饲料发酵方面具有较好的应用前景。