A SELECTIVE MEDIUM FOR BACILLUS CEREUS IN MILK

SUMMARY: A medium is described by means of which cells of Bacillus cereus in milk may be estimated without the prior use of a heat treatment. Into a nutrient agar are incorporated: egg yolk, to demonstrate production of the characteristic opacity; citrate, to render the inoculated medium more transparent; lithium chloride and polymyxin, to reduce the growth of other bacteria. A cover of water agar limits the development of certain spreading organisms. The medium has proved of value in a survey of samples of raw milk, providing information additional to that obtained by plating after a heat treatment.     

蜡质芽孢杆菌超氧化物歧化酶的理化性质研究

本文对从蜡质芽孢杆菌发酵菌体中纯化的Ｆｅ－ＳＯＤ进行了理化性质研究,测定结果表明：在２７℃,ｐＨ６８,光照强度为４０００Ｌｕｘ条件下,光照２０分钟为酶活性测定的最佳条件;经ＳＤＳ－聚丙烯酰胺凝胶电泳分析得其亚基分子量为１７,７８３道尔顿;等电聚焦电泳表明：Ｆｅ－ＳＯＤ的等电点（ＰＩ）大约为６５左右;经ＤＮＳ法分析Ｎ－末端氨基酸为谷氨酸（Ｇｌｕ）;其氨基酸的组成中酸性氨基酸的含量大于碱性氨基酸的含量,表明此酶为酸性蛋白。     

对金龟子具有杀虫专一性的苏云金芽孢杆菌综述(英文)

自从 190 1年Ishiwata首次报导猝倒菌以来 ,已有数千篇有关苏云金芽孢杆菌的论文相继发表。在苏云金芽孢杆菌 (Bt)的害虫生物防治领域中首次发现对鳞翅目昆虫有杀虫专一性的Bt菌株以后 ,又有了划时代的进展。Goldberg和Margalit发现了杀双翅目幼虫的以色列亚种 (subsp .isrealensis) ,以及Kreig等人发现了对某些鞘翅目幼虫有毒的拟步行甲亚种 (sbusp .tenebrionis)。 1992年 ,Ohba等分离到了日本亚种(subsp .japonensis)对金龟子有专一性杀虫作用的菌株Buibui。该菌株及与之有关的研究进展即是本文讨论的重点。这些发现不仅丰富了苏云金芽孢杆菌科学 ,也丰富了生物防治的应用策略。另一方面 ,在毒素蛋白结构及其杀虫机制的分子生物学和生物化学领域也已获巨大进展。但对杀虫机制尚未完全明了。例如 ,对杀虫蛋白与中肠上皮细胞原生质膜上的受体蛋白的相互作用就知之甚少。这一领域在某种程度上还是众说纷纭。展论这些令人兴奋而又难解的课题将最终促成二十一世纪可持续农业的建立。     

抗真菌多肽APS—1的分离纯化与特性

蜡状芽孢杆菌（Ｂａｃｉｌｕｓｃｅｒｅｕｓ）Ｓ１菌株对多种作物真菌性病害有良好的防效。本文报道了Ｓ１菌株产生的抗真菌物质的纯化及其部分特性。该菌株的发酵液经过酸沉淀和有机溶剂抽提、ＳｅｐｈａｄｅｘＧ１００与ＤＥＡＥ５２柱层析等步骤后,抗真菌物质得到纯化,硅胶薄层层析显色为单点。该物质在２７５ｎｍ处有吸收峰,对蛋白酶有一定耐受性,茚三酮反应呈阴性,但酸水解后,茚三酮反应呈阳性,双缩脲反应也呈阳性。氨基酸组分分析结果表明,该物质由谷氨酸、天门冬氨酸、酪氨酸、丝氨酸、苏氨酸、脯氨酸、亮氨酸、异亮氨酸、缬氨酸和一种异常氨基酸组成。推测该物质为一种环状多肽,命名为ＡＰＳ１。紫外光照射和高压灭菌处理后,ＡＰＳ１的抗真菌活性损失不大。平板抑菌试验结果表明,ＡＰＳ１对９种供试真菌的孢子萌发有抑制作用,其完全抑制浓度因真菌种类不同而有差异     

我国若干地区蜡样芽孢杆菌723株噬菌体分型的初步报告

四年来,作者由水中获取蜡样芽孢杆菌噬菌体13株,旨在试作噬菌体分型。待检菌株共723株,由国内16个地区提供(其中食物中毒株121株;食品株602株)。分型结果显示:C29、C30、C24、C27、C19和A_4等型别占优势。中毒株     

'BITTY' CREAM: THE OCCURRENCE AND SIGNIFICANCE OF BACILLUS CEREUS SPORES IN RAW MILK SUPPLIES

SUMMARY: Methods for determining the Bacillus cereus content of milks and of rinses of dairy equipment are described and their limitations discussed. Milk samples from various sources were examined throughout the year for 'bittiness' as well as for B. cereus. The organism was not detected in all samples showing bittiness. There was a marked seasonal variation in the B. cereus index of raw milk supplies; maximum numbers were obtained from July to September and minimum numbers in April and May. Rinses of farm dairy equipment yielded few B. cereus spores but milk cans not uncommonly contained large numbers, especially in the summer months, when 10·5% of cans showed more than 5 × 10³/can. Preliminary observations on other sources of B. cereus are described and some of the problems of the control of this organism in raw milk supplies are discussed.     

RAPID DETECTION OF GERMINATING BACILLUS CEREUS CELLS USING FLUORESCENT IN SITU HYBRIDIZATION

Methods for the specific detection of Bacillus spores are needed in many situations such as the recognition of food poisoning. This study presents an experimental design in order to find the best combination of germination conditions leading to a rapid and detectable fluorescent in situ hybridization (FISH) signal from Bacillus cereus spores present in pure cultures and milk samples.
B. cereus ATCC 14579 and HER 1414 were incubated in 20 different growth media by using a combination of various germinants such as sugars, amino acids and dipicolinic acid. Also, three different germination factors were tested: incubation temperature, inoculum concentration and a heat shock treatment. Permeabilization procedure and hybridization time were optimized on the best germination condition found. B. cereus -specific FISH probes were validated under the optimized condition and in detection of spiked B. cereus spores in 1% ultra heat-treated milk samples. FISH-labeled cells were detected by using flow cytometry, and the results were confirmed by fluorescence microscopy. The optimal condition allows the detection of B. cereus spores in less than 2 h. Overall, a ninefold reduction in total time for detection was achieved when comparing with previous works. Therefore, the permeabilization and hybridization optimizations mentioned in this study are major improvements for the detection time of B. cereus spores.

PRACTICAL APPLICATIONS

By using the optimized conditions of germination/outgrowth, permeabilization and hybridization, the detection of 10³ cfu/mL of Bacillus cereus spores using fluorescent in situ hybridization is possible within 2 h in milk sample.     

对双歧杆菌DM9227株的实验研究 Ⅲ.双歧杆菌DM9227株与蜡样芽胞杆菌DM423株共生关系的初步研究

本文对厌氧的双歧杆菌DM9227株与需氧的蜡样芽胞杆菌DM423株的共生关系进行了初步研究。将DM9227株与DM423株分别单独及按一定比例等量混合接种于BS肉汤内进行培养,间隔一定时间检测两菌在培养基内菌数的消长情况。结果表明DM423株与DM9227株之间呈偏生关系,即DM423株对DM9227株有促进作用,且在两菌比例适宜(1:100)情况下促进作用更明显,而DM9227株对DM423株有抑制作用。进一步将接种DM423株的Nb琼脂平板与接种DM9227株的BS琼脂平板在普通环境下一起密闭培养,可见厌氧的DM9227株生长良好,提示DM423株可能是通过消耗氧气,降低培养基的Eh,从而促进DM9227株生长的。