噬菌蛭弧菌生物特性研究进展

本文介绍了噬菌蛭弧菌的培养特性,温度对噬菌蛭弧菌的影响,噬菌蛭弧菌的生化特征,感染宿主的机制,在死的宿主菌中生长的特性,宿主的特异性以及噬菌蛭弧菌对致病菌的生物净化作用等生物特性的研究进展。研究认为,噬菌蛭弧菌是自然环境(水、土壤)中致病微生物的生物拮抗体,且极有可能利用它的寄生和溶解宿主菌细胞的特殊性,对环境水体的生物净化。     

噬菌蛭弧菌的分离及初步鉴定

采用双层平板法,以滤膜过滤的方法来收集噬菌蛭弧菌,以嗜水气单胞菌(Aeromonas hudrophila)、荧光假单胞菌(Pseudomonas fluorescent)和绿脓杆菌(Pseudomonas aeruginosa)为宿主菌,进行噬菌蛭弧菌的分离研究;并在此基础上,通过接触酶检测和寄生性确认对噬菌蛭弧菌(Bdellovibrio bacteriovorus)进行了初步的鉴定.结果表明未使用滤膜过滤,采用自来水琼脂双层平板法分离噬菌蛭弧菌的效果较好;并经过接触酶和寄生性检测初步鉴定此BD-SPOI菌株为噬菌蛭弧菌.     

细菌寄生菌——噬菌蛭弧菌

细菌的寄生菌—噬菌蛭弧菌的研究,国外是60年代中期开始的。我国1982年首次报道这类菌的发现。本文介绍了噬菌蛭弧菌的培养特性、形态特片、生物学特性、生态学及在自然水体中对某些肠道致病菌的净化作用以及对宿主细胞的侵入、感染和宿主范围等方面的研究情况。研究认为,噬菌蛭弧菌是环境水体中某些致病菌的自然净化的重要生物因子这一。并为利用噬菌蛭弧菌改善水源,减少或控制疾病的发生,保护人群的健康提供了极为可靠的依据和途径。     

鱼病蛭弧菌的微生态学初步研究

本次以鲫鱼出血性腹水病病原菌点状产气单胞菌（Ａｅｒｏｍｏｎａｓ Ｐｕｎｃｔａｔａ）为宿主菌。从自然界分离获得６株噬菌蛭弧菌菌株,它们具有噬菌蛭弧菌的生物学特性。研究表明,这６株蛭弧菌的最适培养条件为温度２５￣２８℃,ｐＨ７．２,有溶菌性,能裂解多种鱼类病原菌。其中对蛭弧菌Ｂｄｓ－４菌株在实验条件下对病原菌的自然净化作用等方面进行了研究。说明蛭弧菌是精养鱼糖水体中某些致病菌的自然净化的重要生物因素之     

人粪便中分离的噬菌蛭弧菌生物学特性的研究

本文研究了人粪便中分离的噬菌蛭弧菌的生物学特性,测定了它们的生长曲线,并利用微孔滤膜过滤和机械振荡的方法,研究了它们的吸附和穿入动力学,发现链霉素、庆大霉素和卡那霉素能抑制蛭弧菌的吸附;青霉素不影响蛭弧菌的吸附和穿入,但抑制蛭弧菌在宿主内的生长过程。从人粪中分出的噬菌蛭弧菌不仅能裂解大部分需氧的革兰氏阴性菌,而且在微氧条件下也能裂解厌氧菌中的二株脆弱拟杆菌。我们发现一株人粪便中分出的噬菌蛭弧菌能形成蛭弧菌囊体——它的休眠态,它对高热、紫外线照射和真空干燥的耐受力较相应的繁殖体强,看来它是蛭弧菌保持生命期限的一种方式。     

噬菌蛭弧菌对嗜水气单胞菌裂解作用的研究

本文报道了8株噬菌蛭弧菌对河水中分离的9株嗜水气单胞菌的裂解作用。结果发现,噬菌蛭弧菌Bd32的裂解率为77.78％;Bd83、Bd98的裂解率为88.89％,其余5株噬菌蛭弧菌对9株嗜水气单胞菌全部裂解。     

鱼类致病菌的蛭弧菌研究

噬菌蛭弧菌(Bdellovibrio bacteriovors)是一类有寄生性的细菌。Stolp及Stzold(1962年)曾首次报导,我国司稚东、秦生巨等(1982年)在国内亦首次报导了这类细菌的发现。本文介绍了以鲫鱼出血病病原菌点状产气单胞菌(Aeromonas punctata)为宿主菌,经分离得到的噬菌蛭弧菌Bd3—2菌株的培养特征、细菌形态、细菌生理生化特征、感染宿主机制及在实验室条件下水体中对宿主菌净化作用等方面的研究内容。说明噬菌蛭弧菌是精养鱼塘水体中某些致病菌的自然净化的重要生物因子之一,并为利用蛭弧菌来减少或控制鱼塘细菌性病害的发生,开展生物防治新技术提供了较好的依据和途径。     

噬菌蛭弧菌对致病性大肠杆菌感染小鼠保护性作用的研究

实验建立了致病性大肠杆菌Ｅ０１１１ 感染昆明小鼠动物模型,用噬菌蛭弧菌进行保护试验。致病性大肠杆菌Ｅ０１１１ 攻击前３ 天,用噬菌蛭弧菌预先保护,小鼠生存时间与对照组比较明显延长,存活率高（Ｐ＜ ０．０５） 。致病性大肠杆菌Ｅ０１１１ 攻击后１ 小时,用噬菌蛭弧菌保护与对照组比较生存时间,存活率无差异（Ｐ＞ ０．０５） 。并证明噬菌蛭弧菌８ ×１０５ＣＦＵ／ｍｌ 小鼠腹腔注射０．０２ｍｌ／ｇ 对小鼠无毒性反应。     

蛭弧菌的分离及其生长条件和裂解能力的研究

噬菌蛭弧菌具有裂解病原菌、净化水体的功效,从海洋环境中分离到4株Bh04系列蛭弧菌,对其生长条件进行了测定,同时研究了它们对61株菌株的裂解能力。结果表明,在1%～3%的盐度范围内,蛭弧菌均可生长,最适盐度为3%;在15～30℃温度条件下蛭弧菌也可生长,但最适培养温度为20-25℃;只有在使用活的宿主菌的培养条件下,蛭弧菌才能生长。4株蛭弧菌分别可裂解21、24、40、43株菌,各占总试验菌数(61)的34.4%、39.3%、65.6%和70.5%。4株蛭弧菌一起,则可裂解55菌株,占总试验菌株的90.2%。研究结果揭示了蛭弧菌在消除海洋环境中有害细菌方面的潜在应用价值。     

海洋蛭弧菌的分离鉴定及其对副溶血弧菌的作用

蛭弧菌广泛存在于自然水体, 具有噬菌的特性, 对水体中细菌数量控制具调节作用。以副溶血弧菌为宿主菌, 利用双层琼脂法, 从海洋水体中分离出15株具有噬菌作用的细菌, 对形成噬菌斑能力最强的1株菌株进行特异性16S rDNA扩增, 确认为蛭弧菌, 命名为Bd-M1。Bd-M1对大多数海水养殖动物病原菌有裂解作用, 裂解率在90%(20/22)以上, 模拟水环境实验发现, 蛭弧菌对副溶血弧菌有较强的裂解和净化作用, 102 h内能使副溶血弧菌从3.0′108 CFU/mL下降到8.7×103 CFU/mL。动物实验表明蛭弧菌能有效预防对虾弧菌病的发生, 表明蛭弧菌有望成为水产动物疾病防治的一种有效的生物制剂。     

细胞对纳米材料的胞吞及其胞内定位相关机制的研究进展

纳米材料具有独特的理化性质,其在纳米生物医药技术中得到广泛的研究,有着良好的应用前景。纳米材料的尺寸分布在纳米级。使其入胞途径和转运方式与一般尺寸的物质略有不同。细胞可通过网格蛋白介导胞吞、陷窝小泡介导胞吞、吞噬作用和巨胞饮等胞吞方式摄取纳米颗粒。吞噬的方式及后续的转运和定位受细胞的类型、状态,以及纳米颗粒的理化性质如元素组成、尺寸、形状、电荷、表面修饰等多种因素共同影响。     

Shadowing the actions of a predator: backlit fluorescent microscopy reveals synchronous nonbinary septation of predatory Bdellovibrio inside prey and exit through discrete bdelloplast pores

The Bdellovibrio are miniature "living antibiotic" predatory bacteria which invade, reseal, and digest other larger Gram-negative bacteria, including pathogens. Nutrients for the replication of Bdellovibrio bacteria come entirely from the digestion of the single invaded bacterium, now called a bdelloplast, which is bound by the original prey outer membrane. Bdellovibrio bacteria are efficient digesters of prey cells, yielding on average 4 to 6 progeny from digestion of a single prey cell of a genome size similar to that of the Bdellovibrio cell itself. The developmental intrabacterial cycle of Bdellovibrio is largely unknown and has never been visualized "live." Using the latest motorized xy stage with a very defined z-axis control and engineered periplasmically fluorescent prey allows, for the first time, accurate return and visualization without prey bleaching of developing Bdellovibrio cells using solely the inner resources of a prey cell over several hours. We show that Bdellovibrio bacteria do not follow the familiar pattern of bacterial cell division by binary fission. Instead, they septate synchronously to produce both odd and even numbers of progeny, even when two separate Bdellovibrio cells have invaded and develop within a single prey bacterium, producing two different amounts of progeny. Evolution of this novel septation pattern, allowing odd progeny yields, allows optimal use of the finite prey cell resources to produce maximal replicated, predatory bacteria. When replication is complete, Bdellovibrio cells exit the exhausted prey and are seen leaving via discrete pores rather than by breakdown of the entire outer membrane of the prey.     

Three-Membered Parasitic System: a Bacteriophage, Bdellovibrio bacteriovorus, and Escherichia coli

Two bacteriophages for Bdellovibrio bacteriovorus were isolated. One of the phages (VL-1) was isolated on a host-independent Bdellovibrio strain, and the other (VL-2) was isolated on a host-dependent strain. Both phages grew on host-dependent as well as on host-independent Bdellovibrio strains. The development of the phages in host-dependent bdellovibrios occurred only when the phage-infected bdellovibrios parasitized cells of other bacteria. In the absence of other bacteria, the phages adsorbed to the bdellovibrios and killed them and in the process lost their own plaque-forming ability.     

Predatory Bdellovibrio bacteria use gliding motility to scout for prey on surfaces

Bdellovibrio bacteriovorus is a famously fast, flagellate predatory bacterium, preying upon Gram-negative bacteria in liquids; how it interacts with prey on surfaces such as in medical biofilms is unknown. Here we report that Bdellovibrio bacteria "scout" for prey bacteria on solid surfaces, using slow gliding motility that is present in flagellum-negative and pilus-negative strains.     

A novel assay to monitor predator-prey interactions for Bdellovibrio bacteriovorus 109 J reveals a role for methyl-accepting chemotaxis proteins in predation

Bdellovibrio bacteriovorus are Gram-negative bacteria that prey upon other Gram-negative bacteria, including some pathogens, in a wide variety of habitats including soil, sewage, marine and estuarine environments. In order to facilitate studies on predation by this organism, we have developed a method that assays killing of luminescent Escherichia coli by B. bacteriovorus. Moreover, we have used this assay to compare predation of cells by derivatives of B. bacteriovorus containing targeted mutations in genes we have identified. Two genes are described; one, mcp2, encoding a methyl-accepting chemotaxis protein (MCP) and the other, an mviN homologue. Bdellovibrio bacteriovorus mcp2::aphII were less efficient predators on luminescent E. coli than B. bacteriovorus containing a randomly inserted aphII gene via TnphoA transposition. These and other chemotaxis experiments implicated at least a minor role for chemotaxis in predation by B. bacteriovorus. They also open the way for further studies on Bdellovibrio ecology, genomics and predator-prey interactions. The results further confirm that Bdellovibrio uses a chemotaxis system in order to sense, and respond to, changes in its environment, including prey.     

Predation in the presence of decoys: an inhibitory factor on pathogen control by bacteriophages or bdellovibrios in dense and diverse ecosystems

Several attempts have been made at the removal of specific pathogens from the intestinal microflora using either bacteriophages or "predatory" bacteria such as Bdellovibrio spp. To date these attempts have had mixed success. A mechanism explaining these findings based on competitive hindrance by non-prey, or decoy species is put forward. It is shown that this hindrance tends to damp out predator-prey oscillations, and therefore reduces the probability of prey extinction. Possible experiments to verify this theory are discussed. The decoy effect may play a role in any system with high densities of bacteria or other particulate matter, such as activated sludge or biofilms.     

Effects of orally administered Bdellovibrio bacteriovorus on the well-being and Salmonella colonization of young chicks

Bdellovibrio bacteriovorus is a bacterium which preys upon and kills Gram-negative bacteria, including the zoonotic pathogens Escherichia coli and Salmonella. Bdellovibrio has potential as a biocontrol agent, but no reports of it being tested in living animals have been published, and no data on whether Bdellovibrio might spread between animals are available. In this study, we tried to fill this knowledge gap, using B. bacteriovorus HD100 doses in poultry with a normal gut microbiota or predosed with a colonizing Salmonella strain. In both cases, Bdellovibrio was dosed orally along with antacids. After dosing non-Salmonella-infected birds with Bdellovibrio, we measured the health and well-being of the birds and any changes in their gut pathology and culturable microbiota, finding that although a Bdellovibrio dose at 2 days of age altered the overall diversity of the natural gut microbiota in 28-day-old birds, there were no adverse effects on their growth and well-being. Drinking water and fecal matter from the pens in which the birds were housed as groups showed no contamination by Bdellovibrio after dosing. Predatory Bdellovibrio orally administered to birds that had been predosed with a gut-colonizing Salmonella enterica serovar Enteritidis phage type 4 strain (an important zoonotic pathogen) significantly reduced Salmonella numbers in bird gut cecal contents and reduced abnormal cecal morphology, indicating reduced cecal inflammation, compared to the ceca of the untreated controls or a nonpredatory ΔpilA strain, suggesting that these effects were due to predatory action. This work is a first step to applying Bdellovibrio therapeutically for other animal, and possibly human, infections.     

The dual probiotic and antibiotic nature of Bdellovibrio bacteriovorus

Bdellovibrio bacteriovorus is a predatory bacterium which attacks and consumes other bacterial strains, including the well known pathogens E. coli O157 : H7, Salmonella typhimurium and Helicobacter pylori. This remarkable activity has been the focus of research for nearly five decades, with exciting practical applications to medical, agriculture and farming practices recently being published. This article reviews many of the exciting steps research into this bacterium, and similar bacteria, has taken, focusing primarily on their use as both an antibiotic to remove harmful and pathogenic bacteria and as a probiotic to help curb and control the bacterial populations within the intestinal tract. Owing to the unique and dual nature of this bacterium, this review proposes the use of "amphibiotic" to describe these bacteria and their activities.