Identification of Bacillus cereus Group Species Associated with Food Poisoning Outbreaks in British Columbia, Canada

Food poisoning laboratories identify Bacillus cereus using routine methods that may not differentiate all Bacillus cereus group species. We recharacterized Bacillus food-poisoning strains from 39 outbreaks and identified B. cereus in 23 outbreaks, B. thuringiensis in 4, B. mycoides in 1, and mixed strains of Bacillus in 11 outbreaks.     

Antifungal activity and enhancement of plant growth by Bacillus cereus grown on shellfish chitin wastes

Bacillus cereus QQ308 produced antifungal hydrolytic enzymes, comprising chitinase, chitosanase and protease, when grown in a medium containing shrimp and crab shell powder (SCSP) produced from marine waste. The growth of the plant-pathogenic fungi Fusarium oxysporum, Fusarium solani, and Pythium ultimum were considerably affected by the presence of the QQ308 culture supernatant. The supernatant inhibited spore germination and germ tube elongation of F. oxysporum, F. solani, and P. ultimum. The increase in the growth time of the fungal culture was associated with a gradual decrease in inhibition. Besides antifungal activity, QQ308 enhanced growth of Chinese cabbage. These characteristics were unique among known strains of B. cereus. To our knowledge, this is the first report on the antifungal and Chinese cabbage growth enhancing compounds produced by B. cereus.     

高产蛋白酶菌株Bacillus cereus KM-4的产酶实时动态研究

从昆明豆豉样品分离得到一株蛋白酶活性较高的菌株,其酶活达14.58 U/mL.采用SDS-gelatin-PAGE蛋白电泳及Zymography染色,结合茚三酮法测定其蛋白酶活性,对KM-4菌株分泌的蛋白酶进行酶谱分析.结果表明,培养pH6.0有利于该菌株分泌分子量约为116 kD的蛋白酶,经明胶诱导培养后,其酶活明显提高,推测其所分泌的蛋白酶可能需要蛋白质诱导.     

Ultrastructural Changes Associated with Activation and Germination of Bacillus cereus T Spores

The ultrastructural changes occurring during defined stages of the transition of dormant Bacillus cereus T spores into heat-sensitive forms were investigated. The coat of the heat-activated spores displayed conspicuous striations across its middle layer. Electron microscopy of thin sections of heat-activated spores revealed the presence in the spore of a layer consisting of hexagonally oriented subunits. It was demonstrated that the subcoat region, but not the cortex, disappears rapidly during germination of B. cereus T spores. The fibrous structures apparently associated with the spore coat remain virtually unchanged during the entire course of activation and germination.     

Perspectives on the Behavior of Entomopathogenic Nematodes from Dispersal to Reproduction: Traits Contributing to Nematode Fitness and Biocontrol Efficacy

The entomopathogenic nematodes (EPN) Heterorhabditis and Steinernema are widely used for the biological control of insect pests and are gaining importance as model organisms for studying parasitism and symbiosis. In this paper recent advances in the understanding of EPN behavior are reviewed. The “foraging strategy” paradigm (distinction between species with ambush and cruise strategies) as applied to EPN is being challenged and alternative paradigms proposed. Infection decisions are based on condition of the potential host, and it is becoming clear that already-infected and even long-dead hosts may be invaded, as well as healthy live hosts. The state of the infective juvenile (IJ) also influences infection, and evidence for a phased increase in infectivity of EPN species is mounting. The possibility of social behavior - adaptive interactions between IJs outside the host - is discussed. EPNs’ symbiotic bacteria (Photorhabdus and Xenorhabdus) are important for killing the host and rendering it suitable for nematode reproduction, but may reduce survival of IJs, resulting in a trade-off between survival and reproduction. The symbiont also contributes to defence of the cadaver by affecting food-choice decisions of insect and avian scavengers. I review EPN reproductive behavior (including sperm competition, copulation and evidence for attractive and organizational effects of pheromones), and consider the role of endotokia matricida as parental behavior exploited by the symbiont for transmission.     

Bacillus anthracis, Bacillus cereus, and Bacillus thuringiensis—One Species on the Basis of Genetic Evidence

Bacillus anthracis, Bacillus cereus, and Bacillus thuringiensis are members of the Bacillus cereus group of bacteria, demonstrating widely different phenotypes and pathological effects. B. anthracis causes the acute fatal disease anthrax and is a potential biological weapon due to its high toxicity. B. thuringiensis produces intracellular protein crystals toxic to a wide number of insect larvae and is the most commonly used biological pesticide worldwide. B. cereus is a probably ubiquitous soil bacterium and an opportunistic pathogen that is a common cause of food poisoning. In contrast to the differences in phenotypes, we show by multilocus enzyme electrophoresis and by sequence analysis of nine chromosomal genes that B. anthracis should be considered a lineage of B. cereus. This determination is not only a formal matter of taxonomy but may also have consequences with respect to virulence and the potential of horizontal gene transfer within the B. cereus group.     

Electron Transport System Associated with Membranes of Bacillus cereus During Vegetative Growth and Sporulation

Membranes isolated from Bacillus cereus ATCC 4342 during vegetative growth and during sporulation contained cytochromes b, c and a + a(3) as well as flavoprotein as determined from reduced-minus-oxidized difference spectra. Although there appeared to be no qualitative change in the cytochromes, there was a significant increase in the amount of cytochromes associated with membranes isolated from sporulating cells. Succinate and nicotinamide adenine dinucleotide (reduced form) (NADH) reduced the same cytochromes indicating similar pathways of electron transport. The electron transport inhibitors-cyanide, azide, 2-heptyl-4-hydroxyquinoline-N-oxide, dicumarol and atebrine-were examined for their effect on succinate oxidase (succinate: [O(2)] oxidoreductase) and NADH oxidase (NADH: [O(2)] oxidoreductase). NADH oxidase associated with vegetative cell membranes was less sensitive to certain inhibitors than was succinate oxidase, suggesting a branched electron transport pathway for NADH oxidation. In addition to electrons being passed to O(2) through a quinone-cytochrome chain, it appears that these intermediate carriers can be bypassed such that O(2) is reduced by electrons mediated by NADH dehydrogenase. Both oxidases associated with sporulating cell membranes were inhibited to a lesser degree than were the oxidases associated with vegetative cell membranes.     

利用ERIC-PCR对苏云金芽胞杆菌与蜡状芽胞杆菌进行鉴定的研究

为了探索ERIC-PCR技术在苏云金芽胞杆菌和蜡状芽胞杆菌的鉴定及分型中的应用价值,本研究采用PCR方法初步检测苏云金芽胞杆菌杀虫晶体蛋白基因的组成,并对苏云金芽胞杆菌和蜡状芽胞杆菌的总DNA进行ERIC-PCR扩增,分析ERIC-PCR指纹图谱的特点并采用NTSYS2.10软件对其进行聚类。结果显示,各菌株的ERIC指纹图谱表现出不同程度的多态性,但图谱与菌株所含cry基因的类型存在一定的相关性。聚类分析结果显示,含有相同或相近cry基因类型的Bt菌株在进化树上趋向聚为一类,而不含cry基因的蜡状芽胞杆菌趋向于与不含cry基因的Bt菌株聚为一类或单独聚类。若在多种模式菌株的参考下,该方法可用于苏云金芽胞杆菌的初步鉴定和分型。     

利用PCR技术检测致病性腊样芽孢杆菌的研究

目的：利用PCR技术对致病性蜡样芽孢杆菌（Bacillus cereus）进行检测。方法：对致病性蜡样芽孢杆菌溶血素HBLa基因序列进行分析设计一对特异引物,通过优化PCR反应条件,来实现对致病蜡样芽孢杆菌的快速检测,结果：该方法具有较强的灵敏性及特异性,能够对肠毒素型腊样芽孢杆菌进行有效的检测,其最低检出限可达9CFU／ml,用PCR技术对食物样品中致病性蜡样芽孢杆菌的检测取得与普通生化检测方法一致的结果。结论：利用PCR技术对食品中蜡样芽孢杆菌的检测较常规的生化检测方法具有省时省力的特点且灵敏性较高,具有较强的实际应用价值。     

A Note on the Occurrence of Bacillus cereus and Other Species of Bacillus in Indian Spices of Export Quality

Four unprocessed Indian spices sampled at the point of export were shown to be highly contaminated with bacteria. Bacillus cereus was detected in more samples of these spices than any other spore-forming aerobe.     

Biocontrol of aflatoxin in corn by inoculation with non-aflatoxigenic Aspergillus flavus isolates

The ability of two non-aflatoxigenic Aspergillus flavus Link isolates (CT3 and K49) to reduce aflatoxin contamination of corn was assessed in a 4-year field study (2001–2004). Soil was treated with six wheat inoculant treatments: aflatoxigenic isolate F3W4; two non-aflatoxigenic isolates (CT3 and K49); two mixtures of CT3 or K49 with F3W4; and an autoclaved wheat control, applied at 20 kg ha^?1. In 2001, inoculation with the aflatoxigenic isolate increased corn grain aflatoxin levels by 188% compared to the non-inoculated control, while CT3 and K49 inoculation reduced aflatoxin levels in corn grain by 86 and 60%, respectively. In 2002, the non-toxigenic CT3 and K49 reduced aflatoxin levels by 61 and 76% compared to non-inoculated controls, respectively. In 2001, mixtures of aflatoxigenic and non-aflatoxigenic isolates had little effect on aflatoxin levels, but in 2002, inoculation with mixtures of K49 and CT3 reduced aflatoxin levels 68 and 37% compared to non-inoculated controls, respectively. In 2003 and 2004, a low level of natural aflatoxin contamination was observed (8 ng g^?1). However, inoculation with mixtures of K49?+?F3W4 and CT3?+?F3W4, reduced levels of aflatoxin 65–94% compared to the aflatoxigenic strain alone. Compared to the non-sclerotia producing CT3, strain K49 produces large sclerotia, has more rapid in vitro radial growth, and a greater ability to colonize corn when artificially inoculated, perhaps indicating greater ecological competence. Results indicate that non-aflatoxigenic, indigenous A. flavus isolates, such as strain K49, have potential use for biocontrol of aflatoxin contamination in southern US corn.     

Production of an Emetic Toxin,Cereulide, Is Associated with a Specific Class of Bacillus cereus

The emetic toxin (cereulide) of Bacillus cereus was quantified in several isolates of B. cereus and in various food sources. When the emetic toxin was produced, vomiting-type food poisoning was observed in humans. We also found that the H-1 serovar phenotype was strongly associated with the production of cereulide and that none of the isolates that hydrolyzed starch or expressed diarrheal enterotoxin activity produced cereulide. Received: 4 December 1995 / Accepted: 30 January 1996     

生防用枯草芽孢杆菌固态发酵工艺的研究

目的:提高一株生防用枯草芽孢杆菌固体发酵生产过程中的芽孢产量。方法:研究通过优化固体发酵培养基及发酵生产工艺条件等方法提高了固体发酵枯草芽孢杆菌的芽孢产量。结果:固体发酵过程中,豆饼粉作用显著,能显著提高固体发酵枯草芽孢杆菌的芽孢数,可达到7.1×1010CFU/g。结论:该枯草芽孢杆菌的最优培养基为:麸皮84.4%、稻壳粉10%、豆饼粉5%、硫酸铵0.5%、硫酸镁0.1%、硫酸锰0.05%。生产工艺为料水比为1:1.2,发酵温度为37℃,发酵培养时间为52 h。     

Biocontrol of Rhizoctonia Damping-off of Tomato by Bacillus subtilis Combined with Burkholderia cepacia

Bacillus subtilis strain RB14‐C and Burkholderia cepacia strain BY were used in combination to control damping‐off of tomato plants caused by Rhizoctonia solani. Microcosm tests showed complete inhibition of R. solani growth on filter disks buried in soil added with the mixture of both bacteria. Single BY inhibited the fungus, but not completely, and RB14‐C had only slight inhibitory effect on pathogen growth. The efficacy of this combining treatment was checked in pot experiments, where bacteria were applied to the soil in several combinations: RB14‐C and BY together 4 days before seed planting, RB14‐C 4 days and BY 2 days before seed planting, RB14‐C 4 days and BY immediately before seeds. The effect of these treatments on population of R. solani in soil and infection of plants was compared with the activity of single application of each agent. All bacterial treatments significantly decreased damping‐off of tomato plants. The best control was obtained when BY was added 2 days after RB14‐C. In this treatment plant protection was significantly higher than that obtained in other combined applications and obtained by single strains, except BY added to the soil 4 days before seed planting. The lowest suppression indicated BY introduced to the soil before seed planting. RB14‐C only slightly decreased number of R. solani in the soil. In contrast, BY drastically reduced population of the pathogen. However, there was not a clear relation between decrease of pathogen density in soil and the rate of plant infection. The results show that combination of B. subtilis RB14‐C with B. cepacia BY can lead to greater damping‐off suppression than biocontrol exhibited by these strains used separately, but the effect of combining bacterial agents was clearly related to the order in which both agents were introduced.     

Screening of Antifungal Protein Producing Strain TG26 of Bacillus spp. and Studies on Its Cultrual Conditions

An antagonistic strain, Bacillus spp. TG26 isolated from roots of a towel gourd (Luffa cylindrica (L.) Roem.), secretes large amount of antifungal proteins with strong inhibiting activity against Gibberella zeae, Fusarium oxysporum f. vasinfectum and niveum, ,4hernarict longipes, Trichoderma viride as well as bacterial pathogens of Xanthomonas campestris pv. oryzae and Psendomonas solanaceanum. Crude proteins obtained by precipitation of the cellfree culture of TG26 strain with ammonium sulphate at 70% saturation are over 130 mg/L. The optimal culture conditions of TG26 strain are as following: BPY medium, initial pH 7.0, temperature 30 ℃ and cultivation time 36 hours.     

离子注入选育高效植物病原真菌拮抗菌JA

Bacillus subtitles JA能够对多种植物病原菌如小麦赤霉菌、西瓜枯萎病菌、黄瓜黑星、油菜菌核、小麦白粉等有良好的抑制效果,本文利用离子注入诱变筛选高效植物病原真菌拮抗菌并且对JA菌株的发酵特性作了进一步的研究,获得了两株高效拮抗菌。其发酵水平的抑菌圈直径从16.62mm提高到21.23mm,经传代实验表明,其遗传性较为稳定。     

Production of Diarrheal Enterotoxins and Other Potential Virulence Factors by Veterinary Isolates of Bacillus Species Associated with Nongastrointestinal Infections

With the exceptions of Bacillus cereus and Bacillus anthracis, Bacillus species are generally perceived to be inconsequential. However, the relevance of other Bacillus species as food poisoning organisms and etiological agents in nongastrointestinal infections is being increasingly recognized. Eleven Bacillus species isolated from veterinary samples associated with severe nongastrointestinal infections were assessed for the presence and expression of diarrheagenic enterotoxins and other potential virulence factors. PCR studies revealed the presence of DNA sequences encoding hemolysin BL (HBL) enterotoxin complex and B. cereus enterotoxin T (BceT) in five B. cereus strains and in Bacillus coagulans NB11. Enterotoxin HBL was also harbored by Bacillus polymyxa NB6. After 18 h of growth in brain heart infusion broth, all seven Bacillus isolates carrying genes encoding enterotoxin HBL produced this toxin. Cell-free supernatant fluids from all 11 Bacillus isolates demonstrated cytotoxicity toward human HEp-2 cells; only one Bacillus licheniformis strain adhered to this test cell line, and none of the Bacillus isolates were invasive. This study constitutes the first demonstration that Bacillus spp. associated with serious nongastrointestinal infections in animals may harbor and express diarrheagenic enterotoxins traditionally linked to toxigenic B. cereus.