Assessment of the safety and applications of bacteriocinogenic Enterococcus faecium Y31 as an adjunct culture in North-eastern Chinese traditional fermentation paocai

Enterococcus faecium Y31 is a class IIa bacteriocin producer found in traditional Chinese fermented foods. The bacteriocin produced by Y31 (bacteriocin Y31) has a broad inhibitory spectrum. Here, we investigated the safety and behaviours of E. faecium Y31 in North-eastern Chinese traditional fermentation paocai (NCTFP) to assess its suitability as an adjunct culture. E. faecium Y31 showed interesting features, such as the absence of virulence determinants (aggregation substance [agg], enterococcal surface protein [esp], endocarditis antigen [efaAfm], gelatinase [gelE], hemolysin [cylA, cylB, cylM], sex pheromone [cpd, cob, ccf], adhesion of collagen [ace], and hyaluronidase [hyl] genes), sensitivity to various antibiotics, lack of haemolytic compounds, and lack of biogenic amine production. E. faecium Y31 could propagate in raw Chinese cabbage and produce bacteriocin Y31. To evaluate its performance as an adjunct culture for NCTFP, changes in the overall quality of control (noninoculated) and experimental NCTFP (inoculated with E. faecium Y31 under previously optimised fermentation conditions) were determined in duplicate fermentations of Chinese cabbage using chemical, microbiological, texture, and sensory evaluations. In the presence of E. faecium Y31, faster fermentation and higher bacteriocin Y31 production were observed than in the control. Additionally, the nitrite concentration of the fermentation solution decreased more rapidly, the total viability of the culture increased, and the lactic acid bacterium population was higher than those in NCTFP produced by spontaneous fermentation. No yeasts and moulds were detected in NCTFP produced by inoculation fermentation or spontaneous fermentation, and the textural properties of these two products were similar. Sensory evaluation results for NCTFP produced by inoculation fermentation were superior to those produced by spontaneous fermentation. Therefore, E. faecium Y31 was sufficient as an adjunct culture to enhance both the hygienic and sensory attributes of NCTFP and its use may help to address the issues inherent in commercial production of NCTFP.     

彩色图像数字水印新算法的研究

为了解决电子产品印刷盗版的问题,提出了基于LAB色彩空间和DWT的彩色图像数字水印算法,算法将水印置乱后嵌入到LAB色彩空间的亮度L分量的小波分解系数,实验证明,所提出的算法对常用的图像处理如JPEG压缩、加噪、剪切和滤波等攻击具有较好的鲁棒性、不可见性和安全性.     

Antibacterial activity and mechanism of bifidocin A against Listeria monocytogenes

Bifidocin A, produced by Bifidobacterium animalis BB04, is a novel bacteriocin with antimicrobial activity against a wide range of gram-positive and gram-negative foodborne bacteria. The objective of this study was to investigate the antibacterial activity and mechanism of action of bifidocin A against Listeria monocytogenes, one of the most susceptible bacteria to this bacteriocin. The minimum inhibitory concentration (MIC) of bifidocin A for L. monocytogenes 35152 was 0.029 mg/mL. Time-kill assays showed that bifidocin A effectively inhibited the growth of L. monocytogenes in a time-and concentration-dependent manner. The mechanism of action of bifidocin A was studied by analyzing its effects at a MIC on the cell morphology, intracellular organization, membrane permeability, membrane integrity, and membrane proton motive force (PMF) of L. monocytogenes. Scanning and transmission electron microscopy analyses showed that bifidocin A induced alterations in the morphology and intracellular organization of L. monocytogenes cells. Confocal laser scanning microscopy images showed that L. monocytogenes cells treated with bifidocin A took up propidium iodide. Bifidocin A treatment also induced the leakage of K⁺ and inorganic phosphate, the hydrolysis and release of ATP, and a collapse of the transmembrane electrical potential and pH gradient in L. monocytogenes cells. These results suggested that bifidocin A exerted its anti-Listeria monocytogenes effect through the dissipation of the cytoplasmic membrane PMF, increased membrane permeability, cell membrane pore formation, destruction of membrane integrity, and ultimately complete disintegration of the cells.     

影响乳酸菌胞外多糖合成的因素

乳酸菌胞外多糖能够明显提高乳制品感官特性研究日益深入。但如何从合成条件出发提高其产量是首要解决的问题，其中包括从自身遗传角度、培养基的类型、培养时间、温度、pH值等合成因素对对胞外多糖产量的影响。     

烷基苯装置脱烷烃塔塔效降低原因分析及解决方法

分析了金陵石化公司烷基苯厂烷基苯装置的脱烷烃塔分离效果下降的技术原因,提出了一系列有效的改造措施,并在工业装置中实施,取得了良好的效果。     

烷基化反应中苯烯比的工艺改造

苯烯比是烷基化反应中重要的调节参数,其值直接影响产品的质量与收率。从原理上分析了高苯烯比的必要性,并经生产实践将苯烯比定为8：1。在此基础上,根据影响苯烯比的主要因素,对生产工艺进行了改造,将实际苯烯比调整到合适值。改造达到了工业生产要求,取得了较好的经济效益。     

直链烷基苯磺酸钠的发展及现状分析

介绍了直链烷基苯磺酸钠（LAS）的生产工艺流程和商品形式由单体过渡到磺酸的原由。概述了国内三氧化硫连续磺化技术从引进到国产化的演变过程。对国内LAB、LAS的生产现状进行了分析和总结,并对磺酸装置产能的过剩提出了警告。     

基于LAB颜色空间的图像阴影检测与去除方法

为实现单幅图像快速去阴影处理,提出基于LAB颜色空间的图像阴影检测与去除方法。首先,将RGB图像转换成LAB图像,再对阴影图像进行边缘检测。然后,通过对不同颜色通道进行分析、计算及重新整合,得到阴影区域与非阴影区域平均色度值相匹配的图像。最后,对图像进行色度校正和边缘校正,实现单幅图像去阴影处理。为验证本文方法的可行性和有效性,分别采用峰值信噪比（PSNR）和结构相似度（SSIM）这2种性能指标,来客观评价图像的去阴影结果,并与2种典型的图像去阴影方法进行比较。结果表明,本文方法的各性能指标最高,如：在3组实验中,PSNR分别达到17.4721、17.6206、17.3048,SSIM分别达到0.8192、0.8344、0.8027。而且去阴影后图像特征信息清晰,保留的结构信息更接近于真实无阴影场景图像,整体取得了很好的去阴影效果。     

灵芝、低聚果糖、乳酸菌营养液保藏实验研究

通过检测灵芝菌球、低聚果糖和乳酸菌制各7种剂型营养液在不同温度贮藏过程中乳酸菌数量、干物质、pH值的变化,探讨7种剂型营养液的保藏温度和时间.结果表明,以3种乳酸菌为菌种发酵生产灵芝低聚果糖保健营养液,在室温和37℃保藏时干物质、pH值的变化较小,Ⅳ、Ⅴ、Ⅵ剂型的乳酸菌数量初始为6.5x108个/mL左右,经室温保藏270d为4×108个/mL,高温(37℃)保藏150d后减少为2×108个/mL左右.根据酸度对产品口感的影响确定营养液的储存时间为室温270d,37℃为90d.