自然发酵面团中乳酸菌菌株的分离与鉴定

利用MRS和M17培养基,从自然发酵面团中分离纯化出2株乳酸菌菌株,通过菌落形态、菌体形态观察和生理生化试验鉴定,菌株1为植物乳杆菌(Lactobacillus plantarum),菌株2为嗜热链球菌(Streptococcus thermophilus)。     

方波脉冲电场增强乳酸菌细胞通透性的条件优化

利用方波脉冲电场增强乳酸菌细胞通透性,通过将乳酸菌细胞离心,制成浓度为108cfu.mL-1菌悬液,采用不同方波电脉冲条件对其进行处理。结果表明,在0.5 mol.L-1蔗糖的等渗脉冲介质中,电场强度2.25kV.cm-1,脉冲宽度15μs,脉冲数5,间隔时间2 s,此时,乳酸菌细胞的存活率平均为78.24%,细胞内平均荧光强度为5 480。表明脉冲电场可有效增强乳酸菌细胞通透性。     

复合乳酸杆菌制剂对蛋种鸡产蛋性能、免疫机能和盲肠微生物的影响

为研究复合乳酸杆菌制剂对蛋种鸡产蛋性能、免疫机能和盲肠微生物区系的影响,试验选用170日龄蛋种鸡288只,随机分为4组,每组6个重复,每个重复12只鸡.对照组饲喂基础饲粮,试验组饲喂在基础饲粮中分别添加0.05％、0.10％和0.20％复合乳酸杆菌制剂的试验饲粮.试验期30 d.结果表明:1)各组蛋种鸡平均日采食量、平均蛋重和料蛋比均差异不显著(P＞0.05);饲粮添加复合乳酸杆菌制剂可显著影响蛋种鸡的产蛋率(P＜0.05),其中0.05％乳酸杆菌添加组显著高于对照组(P＜0.05).2)饲粮添加复合乳酸杆菌制剂显著提高了蛋种鸡对粗蛋白质的表观消化率(P＜0.05),但对钙和磷的表观消化率无显著影响(P＞0.05).3)饲粮添加0.05％复合乳酸杆菌制剂显著提高了蛋种鸡的禽流感抗体效价(P＜0.05),添加0.05％、0.10％和0.20％复合乳酸杆菌制剂均显著降低了盲肠大肠杆菌和产气荚膜梭菌的数量(P＜0.05),显著提高了盲肠双歧杆菌和乳酸菌数量(P＜0.05).综上所述,饲粮中添加复合乳酸杆菌制剂对蛋种鸡的产蛋性能、营养物质消化率、免疫机能都有一定提高作用,并改善了肠道微生物区系,其适宜添加水平为0.05％.     

乳酸菌发酵玉米秸秆条件的优化

以玉米秸秆为材料,采用L9(33)正交试验设计,秸秆含水量、温度、接种量为主要影响因素,以发酵7 d、12 d、17 d后玉米秸秆中的粗蛋白和粗纤维含量为指标,确定乳酸菌发酵玉米秸秆的最佳发酵条件。试验结果表明:秸秆的含水量为65%、温度为37℃、接种量为0.125 g/kg秸秆时发酵12 d最优。     

共轭亚油酸（CLA）负突变植物乳杆菌p8中转录因子rpoD基因序列的变化研究

对离子束诱变所产生的共轭亚油酸（CLA）下调的植物乳杆菌p8中,转录因子rpoD基因序列的变化进行分析。通过PCR扩增获得野生型和几株突变型菌株的rpoD基因,构建到pMD-19T载体上,转化大肠杆菌DH5α,经菌落PCR和测序分析筛选与鉴定阳性克隆子,并对野生型和突变型菌株的rpoD基因序列预测编码的氨基酸进行差异比较。结果表明,突变菌株的rpoD基因并未发生突变, CLA产量下调并不是由转录因子rpoD突变所引起。     

利用乳酸菌生产传统发酵食品研究进展

传统发酵食品种类丰富,风味独特,是食品工业重要组成部分,乳酸菌是应用于传统食品发酵的重要菌株。通过对乳酸菌的基本特征及其在传统发酵食品生产中的应用进行分析,旨在为实现传统发酵食品工业化生产提供参考。     

固体联合发酵对棉粕发酵产物富肽蛋白产量及脱毒效果的影响

利用枯草芽孢菌（Bacillus subtilis NDX6）和植物乳杆菌（Lactobacillus plantarum BLLP）对棉粕、豆粕不同比例混合样品进行有氧和无氧联合发酵试验,并用纯棉粕进行联合发酵生长曲线研究,探讨固体联合发酵对棉粕发酵产物中富肽蛋白含量及脱毒效果的影响.结果表明,6个配方中纯棉粕发酵降解有毒物质游离棉酚含量最高约81％,游离氨基酸及小肽的含量提高约6.5倍（P＜0.05）,饲料pH由原来的6.20以上降低到5.12以下,有益菌活菌数提高约10倍;纯棉籽粕有氧发酵时间为38 h,无氧发酵时间60～66 h,游离氨基酸含量提高约7.54倍,游离棉酚降低约89％.用棉粕固体联合发酵可以脱毒,降解蛋白提高饲料吸收利用率.     

阿鲁科尔沁牧区牛乳中乳酸菌生物学特性的研究——第一报:乳杆菌属的鉴定

本项研究从科尔沁草原的阿鲁科尔沁牧区南北 4个苏木 16个牧户中采集 43个乳样。从 43个乳样中分离到 6 4株乳酸菌 ,对其中的 47株进行了鉴定 ,结果分离到 2 9株乳杆菌属的细菌。对其中 10株进行了种的鉴定 ,结果 4株为犊牛乳杆菌 (L actobacillus vitulinus)、 2株德氏乳杆菌 (L .delbrueckii )、 2株植物乳杆菌 (L .plantarum )、1株瘤胃乳杆菌 (L .ruminis)、1株清酒乳杆菌 (L .sake )共为 5个种。本项研究发现 ,该牧区自然发酵酸乳中主要菌株是乳杆菌属细菌和肠球菌属细菌的乳酸菌菌株 ,这些菌均属于中温发酵性菌株 ,经对其生物学特性的鉴定基本符合乳杆菌属、种的鉴定标准。     

Administration of L. salivarius expressing 3D8 scFv as a feed additive improved the growth performance,immune homeostasis,and gut microbiota of chickens

Probiotics have been defined as live microorganisms that are administered in an appropriate amount to provide health benefits to the host animal. In this study, we investigated the effect of L. salivarius DJ‐sa‐01 secreting the 3D8 single‐chain variable fragment (3D8 scFv) on the growth performance, cytokine secretion, and intestinal microbial flora of chickens. The experiment was divided into the control group and L. salivarius expressing 3D8 scFv experimental group. Chicken was fed 10⁹ colony‐forming units (CFUs) of wild‐type (WT) L. salivarius or 3D8 scFv‐secreting L. salivarius daily for 35 days. The administration of L. salivarius expressing 3D8 scFv significantly improved the body weight of chickens compared with the administration of WT L. salivarius. A 16S ribosomal RNA metagenomic analysis showed that Firmicutes, Proteobacteria, Actinobacteria, and Bacteroidetes were the dominant phyla in both experimental groups. At the genus level, Lactobacillus was more abundant (22.82%) in the L. salivarius/3D8 group compared with the WT L. salivarius group. The serum levels of cytokines, such as IL‐8, TNF‐α, IL‐1β, IFN‐γ, IL‐4, and IGF1, were significantly reduced in the L. salivarius/3D8‐treated chickens. In summary, our results suggest that L. salivarius expressing 3D8 scFv could be considered a feed additive for improving the growth performance, immune function, and disease resistance of poultry.     

Lactobacillus rhamnosus GG promotes M1 polarization in murine bone marrow‐derived macrophages by activating TLR2/MyD88/MAPK signaling pathway

Lactobacillus rhamnosus GG (LGG) is increasingly applied in functional food products and acts as a probiotic model in nutritious and clinical studies. Increasing evidences have revealed the immune modulation of LGG on macrophages. The aim of this study is to investigate the effect of LGG on macrophage polarization of murine bone marrow‐derived macrophages (BMDMs). BMDMs were treated with 10⁸ colony‐forming units (CFU)/ml LGG for 1.5, 3, and 6 hr. Results showed that LGG obviously upregulated the mRNA expression of M1‐associated cytokines (p < .05), including interleukin‐1 beta (IL‐1β), IL‐6, tumor necrosis factor‐alpha (TNF‐α), and inducible nitric oxide synthase (iNOS), whereas had no effect on the expression of M2‐associated markers (p > .05), including arginase 1 (Arg1), mannose receptor, and chitinase‐like protein 3 (YM1). Furthermore, LGG markedly increased the expression of pro‐inflammatory cytokines (IL‐12p40, cyclooxygenase‐2 [COX‐2], and interferon‐γ [IFN‐γ]) (p < .05) and anti‐inflammatory cytokines (IL‐10, IL‐4, and transforming growth factor‐β [TGF‐β]) (p < .05). In addition, we also found that TLR2/MyD88/MAPK signaling pathway was required for LGG‐induced M1 macrophage polarization and M1‐related cytokines expression. Together, these findings demonstrate that probiotic LGG facilitates M1 polarization of BMDMs, suggesting that LGG may have an immunotherapeutic potential in regulating the host defense against pathogen invasion.