植烟土壤硫化细菌与反硫化细菌分布特点研究

利用选择性培养基,采用最大或然数法对其计数,对云南大理州主要植烟区土壤硫化细菌及反硫化细菌进行分离,以了解硫化细菌和反硫化细菌在烟草不同生长时期的动态变化。结果表明,剑川甸南、下庄、程官和弥渡4个烤烟主产区硫化细菌和反硫化细菌根际土细菌数大于田间土,硫化细菌根际与田间土之比为R:S=6～10:1,反硫化细菌的根土比约R:S=2.5～3.5:1,弥渡烤烟区细菌数量要明显大于其他3个烤烟区。永平和南涧地区田间土硫化细菌数比根际要高。土壤pH与土壤细菌含量呈负相关性,对反硫化细菌的影响要远远大于硫化细菌;根际硫化细菌与田间土硫化细菌呈显著正相关性r=1.00,根际与田间土反硫化细菌呈显著正相关性r=0.879。硫化细菌在成熟期含量较高,反硫化细菌数在团棵期含量较高。     

控制细菌生物膜感染的可替代策略-噬菌体疗法

在自然界中,细菌常以细菌生物膜的形式存在,其形成给公共卫生、食品安全、环境等诸多领域带来了不利影响。复杂的细菌生物膜结构为生理多样化的细菌细胞提供了保护屏障,细菌生物膜的形成是细菌感染及细菌抗药耐药性问题出现的主要驱动因素。噬菌体是细菌的天敌,细菌与噬菌体之间的共同进化迫使噬菌体开发特定的策略来克服生物膜防御屏障并杀死细菌。本文总结了细菌生物膜的组成、结构、形成过程及噬菌体对细菌生物膜的感染机制;综述了基于噬菌体及其衍生物对抗生物膜和耐药细菌感染的最新研究进展;最后,针对目前噬菌体疗法存在的问题进行了讨论,以期发现和更好地利用噬菌体的天然抗菌潜力,促进新型、高效的细菌生物膜检测及控制技术进一步发展。     

绢纺腐化液中细菌除油效果的研究

对同一绢纺厂不同腐化缸的腐化液所含除油细菌进行分离,并对不同细菌的除油效果进行比较。结果表明不同腐化缸中所含除油细菌的种类和数量不同,细菌的除油效果也不同;除油细菌能产生脂肪酶促进油脂分解;三丁酸甘油酯双层平板法可以用于除油细菌的初步筛选,而细菌除油效果则需通过残油率判断。     

乳酸菌细菌素纯化技术的检测及研究进展

细菌素可以抑制大量的食品源腐败菌和致病菌,因此,近年来受到国内外广大学者的关注,其中乳酸菌细菌素因其安全性尤为受到关注。然而要使细菌素更好地应用到生物技术领域,揭示乳酸菌细菌素的生物化学结构和作用位点就显得尤为重要,而这又是建立在乳酸菌细菌素的纯化基础上。文章结合乳酸菌细菌素纯化技术及检测的最新研究进展,讨论乳酸菌细菌素在食品和医疗领域的发展潜力。     

乳酸菌细菌素抑菌特性及在食品中的应用研究进展

乳酸菌细菌素是细菌在核糖体上合成的具有抗菌活性的多肽类物质,这些细菌素能杀灭或抑制引起食品腐败的细菌的繁殖,可作为天然的食品防腐剂在食品中应用。该文综述了乳酸菌细菌素的分类、国内外研究现状、抑菌特性及应用等方面的最新研究进展,并对乳酸菌细菌素未来研究趋势进行简要分析,对乳酸菌细菌素在食品中的应用有一定参考价值。     

傅里叶变换红外光谱技术用于细菌检测的影响因素

应用傅里叶变换红外光谱(FT-IR)技术,结合化学计量学分析方法,以大肠杆菌为例,探讨细菌浓度、培养时间、加热灭活等对FT-IR用于细菌检测的影响。结果表明,FT-IR技术可以分别将不同浓度、不同培养时间、活体与加热灭活的细菌进行有效区分,说明细菌浓度、培养时间及加热灭活会影响细菌的光谱特征并干扰FT-IR的细菌检测结果。表明,统一的样品前处理是决定FT-IR检测细菌成功的关键技术之一。     

单核细胞增生性李斯特菌自溶素研究进展

自溶素是由细菌产生的可以降解细菌细胞壁的肽聚糖水解酶,参与细菌的分裂、细胞壁更新、细菌自溶等生理过程。自溶素也是细菌的重要毒力因子之一,参与细菌的黏附与侵袭,与细菌的致病性密切相关。本文对单核细胞增生性李斯特菌的胞壁水解酶p60、酰胺酶Ami、自溶素IspC、自溶素Auto与胞壁水解酶MurA等自溶素的蛋白结构、生理功能及致病性进行了简要介绍。     

基于高通量测序技术巴彦淖尔市酸粥中细菌多样性分析

采用Illumina MiSeq高通量测序技术对采集自内蒙古自治区巴彦淖尔市的10份酸粥样品中的细菌多样性进行解析,同时基于细菌属水平对其进行围绕中心点的划分（PAM）,并基于PICRUSt和BugBase软件对细菌的基因功能及表型进行预测。结果表明,所有酸粥样品中的细菌隶属于9个细菌门的55个属,样品间细菌多样性和丰度存在明显差异,但优势细菌门均为硬壁菌门（Firmicutes）和变形菌门（Proteobacteria）,优势细菌属均为乳杆菌属（Lactobacillus）和醋杆菌属（Acetobacter）。所有酸粥样品可分为两个聚类,聚类I以醋杆菌属（Acetobacter ）为主,聚类II以乳杆菌属（Lactobacillus）为主;两个聚类中细菌对于碳水化合物的利用和细菌的生长繁殖等存在显著差异（P＜0.05）,隶属于聚类I的酸粥样品中,其细菌的代谢和繁殖更加迅速。     

糙米发芽过程中优势细菌分离鉴定

研究糙米在发芽过程中细菌总数变化,分离、纯化、鉴定发芽糙米中优势细菌;以营养琼脂为培养基,采用十倍稀释法分离、纯化发芽糙米中优势细菌,并采用16S rDNA测序与基因比对方法鉴定发芽糙米优势细菌。发芽过程中,细菌总数先减少再增加,在发芽完成时,细菌总数达7.08×108 cfu/g;分离到1株优势细菌,该细菌菌株与蜡样芽孢杆菌(Bacillus cereus)16S rDNA序列相似性为99.5%;所以,发芽糙米存在食品安全隐患,必须控制糙米发芽过程中微生物。     

淋浇发酵法生产细菌纤维素的结构与性质研究

主要对淋浇发酵生产的细菌纤维素的外观形态、微观结构、化学结构、纯度、持水性、孔隙度和热重特性进行了研究,将其与静态和摇瓶培养方式得到的细菌纤维素进行了比较。结果表明,培养方式不同,细菌纤维素的外观形态、合成模式和微观结构都不相同;淋浇发酵法得到的细菌纤维素的-OH缔合度、聚合度、纯度、持水性、孔隙度、热稳定性均高于静态发酵细菌纤维素和摇瓶发酵细菌纤维素,但结晶度和晶体粒度小于静态发酵细菌纤维素,大于摇瓶发酵细菌纤维素。     

从泡菜水中分离抗生物质产生菌的筛选方法

报道了一种用1.5mL Ep管培养菌液,用滤纸片法筛选抗生物质产生菌的新型初筛方法。与传统方法相比具有工作量小,检测手段灵敏,特别适用于微好氧菌及兼性厌氧菌的筛选等特点。使用此法一天时间可以制备4000～5000个滤纸片样品,每个EP管至少可以检测对十种以上致病菌的抑菌效果,这些是传统的琼脂块法无法比拟的。使用此种筛选方法从泡菜水中检出抗生物质产生茵的比率高达71.3％。     

致病性尖孢镰刀拮抗菌的筛选与鉴定

该研究从清香型白酒大曲中筛选出一株对致病性尖孢镰刀菌（Fusarium oxysporum）拮抗效果最好的拮抗菌株,采用形态观 察、生理生化试验和16S rRNA序列分析对其进行鉴定,并绘制该菌株生长曲线、考察其培养液中的蛋白类及脂肽类物质的抑菌效 果。 结果表明,从清香型白酒大曲中筛选出一株对致病性尖孢镰刀菌拮抗效果最好的拮抗菌株,编号为P9,其抑菌圈直径达到20 mm 左右。 经鉴定,拮抗菌P9为贝莱斯芽孢杆菌（Bacillus velezensis）;生长曲线结果表明,拮抗菌P9在第9小时生长速率达到最大;抑菌物 质提取实验表明,拮抗菌P9能分泌具有抑菌作用的蛋白类物质及脂肽类物质。     

Characterization of a new keratin-degrading bacterium isolated from deer fur

A keratin-degrading bacterium was isolated from soil containing deer fur. An axenic culture of the keratin-degrading bacterium was obtained in liquid culture using a keratin enrichment technique. The isolated bacterium was gram negative and catalase- and oxidase-positive. Transmission electron microscopic observations showed that the bacterium was rod-shaped, 1.0-1.3 microm long and 0.7 microm in diameter. Phylogenetic analysis of 16S rDNA revealed that the new isolate has only 90.6% homology with Stenotrophomonas nitritireducens. Hence, this new bacterium was designated as Stenotrophomonas sp. D-1. The optimum temperature was determined to be 20 degrees C for maximum growth and keratinolytic enzyme production. Amino acid data, obtained after treating keratin powder with the supernatant culture, suggest that the major free amino acids resulting from keratin degradation are phenylalanine, tyrosine and valine. In addition, native chicken feather was degraded completely at 20 degrees C in 2.5 d by this bacterium.     

乳酸菌在发酵香肠中的研究现状

本文综述了乳酸菌在发酵香肠中的研究现状,主要介绍了发酵香肠中常用的乳酸菌种类及作用,乳酸菌的作用机制,国内外研究现状,最后对其发展趋势进行了展望。     

Origin and spoilage potential of the microbiota dominating genus Psychrobacter in sterile rehydrated salt-cured and dried salt-cured cod (Gadus morhua)

Salt-cured and dried salt-cured cod rehydrated using sterile water and equipment have a short shelf life at 4 degrees C due to high bacterial counts. The microbiota develops off-odours which partly can be described as musty, causing sensory rejection within 7-10 days of chilled storage. The microbiota composition was studied in a total of 38 samples obtained from 10 different, both commercial and laboratory produced, salt-cured and dried salt-cured cod products. The dominating bacterium, representing at least 90% of the total viable count in all products studied, was identified as belonging to the genus Psychrobacter; a Gram-negative, oxidase- and catalase-positive, nonpigmented, halotolerant, psychrotolerant, facultative aerobe and nonmotile bacterium. The morphology of the bacterium resembles coccobacilli and the cells occur most often in pairs. The bacterium was able to hydrolyze lipids, but not proteins. It did not produce H(2)S or TMA and the spoilage in rehydrated salt-cured and dried salt-cured cod is therefor different from what is observed in fresh cod. However, samples inoculated with Psychrobacter immobilis gave the same musty odour as spoiled control samples but earlier in the storage period and of a stronger intensity. In a field experiment, carried out to investigate the origin of the dominating bacterium, it was found that the microbiota in both sterile rehydrated commercially produced and laboratory (aseptically) produced salt-cured cod was dominated by this same bacterium. The bacterium was also isolated from cod skin mucus immediately after capture. The bacterium survived NaCl concentrations up to 25% (w/v) NaCl, stating its ability to survive during the salt-curing process. The dominating bacterium in rehydrated salt-cured and dried salt-cured cod seems to mainly originate from the fresh fish itself and not from contamination during processing.     

多菌混合发酵制草莓醋的研究

为了提高草莓的附加值,研究多菌混合发酵酿造草莓果醋的工艺,主要考察原料糖度、温度和菌种量对草莓果醋产量和品质的影响,确定最佳的酿造工艺条件。结果表明,多菌混合发酵法酿造苹果醋的最佳工艺条件:原料糖度为18%,接菌种量为原料质量的10%,发酵温度为30℃,发酵周期16～18 d。证明多菌混合发酵法简化了工艺,是一种值得推广的果醋生产技术。     

苎麻微生物-化学联合脱胶--菌种的分离与纯化

从沤麻水中,分离出多种菌株,经初筛、复筛获得4种好氧菌。用革兰氏染色后镜鉴,R-M26是黑曲酶;R-X80为芽孢杆菌;R—S76、R-S136都是链球状,革兰氏染色呈紫色。对选出的4种菌分别进行单菌和混菌脱胶,发现4种菌混合脱胶效果好,且脱胶效果提高了10％。     

响应面法优化馒头的抑菌配方

微生物(主要是腐败菌)的生长繁殖是引起馒头腐败变质的主要原因,控制馒头的水分活度、pH值和添加防腐剂有利于抑制细菌。利用响应曲面设计,以木糖醇、丙酸钙、柠檬酸为因素,细菌生长对数为响应值建立响应曲面模型,以确定最佳的馒头抑菌配方。优化结果表明:在木糖醇3.252%(质量分数),丙酸钙0.134%(质量分数),柠檬酸0.234%(质量分数)时,培养48h后,馒头中的细菌生长对数为2.591,抑制细菌的效果最佳,且该配方下的实验结果与模型拟合程度较好。     

己酸菌、液体窖泥的发酵罐混合培养及应用的进一步研究

对己酸菌、液体窖泥的混合培养进行了工艺调整以及应用的研究，其结果表明了：采用优质老窖泥一次性获得大量液体窖泥菌种的工艺调整是可行的；采用己酸菌、液体窖泥混合培养液进行窖泥养护的用量是有一定限制的；采用己酸菌、液体窖泥混合培养液进行退化窖泥的养护具有一定的效果，但要彻底改善退化窖泥有一定的难度。     

Hollow PET fibers containing silver particles as antibacterial materials

Silver ions can effectively kill bacteria due to their adsorption onto the negatively charged bacterial cell wall, thus deactivating cellular enzymes, disrupting membrane permeability, and ultimately leading to cell lysis and death. In this study, silver particles incorporated into hollow polyethylene terephthalate (PET) fibers are utilized as an antibacterial composition against the bacterium, Staphylococcus aureus. Also, a silver ion–bacterium model similar to the predator–prey model is established to analyze the inhibitory effect of silver ions on S. aureus. In contact with an aqueous solution, silver ions are released from hollow PET fibers into the solution. When a silver ion in an active medium is absorbed by a bacterium, the bacterium dies and the concentration of silver ions lowers in the medium. To keep the concentration of silver ions in the medium constant, another silver ion is released from the hollow fiber, making the silver ion–bacterium model much simpler to be solved analytically. This study shows that there is an optimal concentration of silver ions at which minimal cytotoxicity and maximal antibacterial efficacy can be achieved. To support this, experimental verification is also carried out in this study.