苏云金芽孢杆菌gerA操纵子在芽孢萌发中的作用

芽孢萌发的营养诱导剂通过与特异的萌发受体结合激活下游的萌发过程,从而使芽孢经过一系列的遗传变化及生化反应恢复营养生长.从苏云金芽孢杆菌(Bacillus thuringiensis)中克隆到一个与枯草芽孢杆菌(Bacillus subtilis)gerA操纵子和蜡状芽孢杆菌(Bacillus cereus)gerR操纵子同源的gerA操纵子.苏云金芽孢杆菌gerA操纵子含有3个开放读码框:gerAA、gerAC和gerAB,该操纵子在产孢起始3个小时后开始转录.gerA的破坏阻断了L-丙氨酸诱导的芽孢萌发并且延迟了肌苷诱导的萌发.在L-丙氨酸诱导芽孢萌发的过程中D-环丝氨酸能够提高芽孢的萌发率.     

一株抗真菌内生多粘芽孢杆菌的分离鉴定及对水稻恶苗病菌的抑制作用

目的：从番茄叶片中筛选具广谱抑真菌活性的拮抗内生细菌,研究其对水稻恶苗病菌的抑制作用。方法：采用对峙培养法筛选拮抗内生细菌,根据菌株形态、生理生化特性结合16S rRNA基因序列分析鉴定菌株;采用硫酸铵沉淀法提取抗菌粗蛋白,研究其对水稻恶苗病菌菌丝生长和孢子萌发的影响。结果：从番茄叶片中筛选到一株抗真菌内生多粘芽孢杆菌（Paenibacillus polymyxa）SD-6,该菌株具有广谱抑菌活性,对供试的13种植物病原真菌均具较强的抑制作用;该菌株产生的抗菌粗蛋白能够显著抑制水稻恶苗病菌菌丝生长和孢子萌发,并能导致萌发孢子畸形和破裂。结论：从番茄叶片中分离到一株能产生抗真菌蛋白并具有广谱高效抑真菌作用的内生多粘芽孢杆菌,该菌株及其抗菌蛋白具有防治水稻恶苗病的潜力。     

革兰氏阳性菌群体感应系统研究进展

细菌利用群体感应系统进行细菌间以及细菌与宿主间的交流,革兰氏阳性与阴性菌的群体感应系统差异显著,阳性菌的群体感应系统主要由寡肽类信号分子和受体蛋白组成,对细菌致病性等相关生理特性具有重要作用。就常见的革兰氏阳性菌：蜡样芽孢杆菌、枯草芽孢杆菌、金黄色葡萄球菌和肺炎链球菌的群体感应系统的基因组成、信号分子及其调控机制特点的研究进行了总结,对群体感应系统在细菌营养吸收、生物膜形成、毒力因子和孢子产生等重要生理活动的调节机制进行了重点阐述,为革兰氏阳性菌群体感应的相关研究提供了有益参考。     

EPA高产菌的繁殖体诱导条件初探

研究了诱导介质、处理时间及温度等因素对高产EPA、AA等多不饱和脂肪酸的菌株－－轮梗霉（Diasporangium sp.）产游动孢子能力的影响。结果表明：胡萝卜片介质上、25℃诱导6d,要得到最大数量的孢子。同一条件下游动孢子量则在第8d达到最高。进一步探讨孢子的萌发条件发现：25℃、营养琼脂上孢子的萌发率最高。     

生防枯草芽孢杆菌B29菌株抗菌物质的初步研究

通过检测生防枯草芽孢杆菌除菌上清液对黄瓜枯萎病菌Fusarium oxysporium f．cumerinum菌丝生长和分生孢子萌发的抑制作用,初步研究了生防枯草芽孢杆菌B29菌株抗菌物质的活性。结果表明,枯草芽孢杆菌B29菌株分泌的抗菌物质不仅抑制病原菌的生长;并可抑制尖孢镰刀菌孢子的萌发,使分生孢子萌发畸形。研究确定了该菌株抗菌物质产生的最佳条件：培养温度30℃;培养基初始pH值7.5;装液量为250ml三角瓶装液75ml培养基;培养时间120h。经30%~70%硫酸铵沉淀获得的抗菌粗提物对60℃处理具有稳定性（活性达97.8%）;对蛋白酶K具有部分耐受性,对胰蛋白酶和胃蛋白酶较敏感。     

枯草芽孢杆菌JA脂肽类及挥发性物质抑菌效应的研究

枯草芽孢杆菌JA产生的脂肽类抗生素对植物病原真菌有广谱抗性。将发酵液经过酸沉淀、甲醇抽提以及反相高效液相色谱等步骤, 分离得到脂肽类抗生素的纯品。经IC50实验和抗菌谱测定, 考察了脂肽类抗生素对多种植物病原菌的作用, 确定了脂肽类抗生素的抗菌谱。深入研究表明, 枯草芽孢杆菌JA还产生未知成分的挥发性抑菌物质, 能够抑制灰霉病菌孢子的萌发和菌丝的生长。脂肽类抗生素和挥发性抑菌物质的协同作用, 有助于提高枯草芽孢杆菌的生物防治效果。     

枯草芽孢杆菌JA脂肽类及挥发性物质抑菌效应的研究

枯草芽孢杆菌JA产生的脂肽类抗生素对植物病原真菌有广谱抗性.将发酵液经过酸沉淀、甲醇抽提以及反相高效液相色谱等步骤,分离得到脂肽类抗生素的纯品.经IC50实验和抗菌谱测定,考察了脂肽类抗生素对多种植物病原菌的作用,确定了脂肽类抗生素的抗菌谱.深入研究表明,枯草芽孢杆菌JA还产生未知成分的挥发性抑菌物质,能够抑制灰霉病菌孢子的萌发和菌丝的生长.脂肽类抗生素和挥发性抑菌物质的协同作用,有助于提高枯草芽孢杆菌的生物防治效果.     

EPA高产菌的繁殖体诱导条件初探*

研究了诱导介质、处理时间及温度等因素对高产EPA、AA等多不饱和脂肪酸的菌株———轮梗霉 (Diasporangiumsp.)产游动孢子能力的影响。结果表明 :胡萝卜片介质上、2 5℃诱导 6d ,可得到最大数量的孢子 ,同一条件下游动孢子量则在第 8d达到最高。进一步探讨孢子的萌发条件发现 :2 5℃、营养琼脂上孢子的萌发率最高。     

枯草芽孢杆菌感受态细胞的制备及质粒转化方法研究

为便于枯草芽孢杆菌工业化生产应用,对Spizizen创立的枯草芽孢杆菌DNA转化方法进行改进.用GMI和GMII溶液处理枯草芽孢杆菌野生型菌株BS501a、营养缺陷型突变株DBl342和非营养缺陷型突变株WB800,用改进的方法制备感受态细胞,用7.5kb质粒pSBPTQ进行转化,并研究RNA、酵母粉、水解酪蛋白、培养方法对枯草芽孢杆菌质粒转化的影响.结果表明,该方法适用于不同基因型枯草芽孢杆菌的质粒转化,营养缺陷型突变株DBl342的转化率为750 CFU/μg/DNA,非营养缺陷型突变株WB800转化率为1 070 CFU/xg DNA,野生型菌株BS501a转化率为270 CFU/μg/DNA.根据影响转化效率的因素,推测在该方法中,枯草芽孢杆菌质粒转化原理:一定生物量的枯草芽孢杆菌在外界营养条件和钙、镁离子作用下,细胞壁和细胞膜形成缺陷,使外源DNA转入枯草芽孢杆菌细胞内.     

三种微生物杀虫油烟剂成烟后菌体活性的测定

本研究通过电子显微镜扫描和菌体活性测定三种微生物杀虫油烟剂成烟后菌体的活性,结果表明：使用烟雾机分别施放白僵菌、苏云金杆菌和松毛虫质型多角体病毒三种微生物杀虫油烟剂,其成烟后,三种菌体能保持原来的形态和活性,白僵菌孢子能正常萌发,苏云金杆菌芽孢在营养琼脂上能形成晶体,松毛虫质型多角体病毒能有效地感染松毛虫,为进一步研究常规和应急防治松毛虫的简单易行、高效的使用方法提供技术依据。     

The influence of gramicidin S on hydrophobicity of germinating Bacillus brevis spores

Gramicidin S is known to prolong the outgrowth stage of spore germination in the producing culture. Bacillus brevis strain Nagano and its gramicidin S-negative mutant, BI-7, were compared with respect to cell-surface hydrophobicity and germination of their spores. Parental spores were hydrophobic as determined by adhesion to hexadecane, whereas mutant spores showed no affinity to hexadecane. Addition of gramicidin S to mutant spores resulted in a high cell surface hydrophobicity and a delay in germination outgrowth. The hydrophobicity of parental spores was retained throughout most of the germination period. Hydrophobicity was lost as outgrowing spores entered into the stage of vegetative growth. The data indicate that gramicidin S is responsible for the hydrophobicity of B. brevis spores. It is suggested that in making spores hydrophobic, the antibiotic plays a role in concentrating the spores at interfaces where there is a higher probability of finding nutrients for germination and growth.Abbreviation GS Gramicidin S     

Quantitative analysis of spatial-temporal correlations during germination of spores of Bacillus Species

Bacteria of Bacillus species sporulate upon starvation, and the resultant dormant spores germinate when the environment appears likely to allow the resumption of vegetative growth. Normally, the rates of germination of individual spores in populations are very heterogeneous, and the current work has investigated whether spore-to-spore communication enhances the synchronicity of germination. In order to do this work, time-lapse optical images of thousands of individual spores were captured during germination, and an image analysis algorithm was developed to do the following: (i) measure the positions and germination rates of many thousands of individual spores and (ii) compute pairwise correlations of their germination. This analysis showed that an individual spore''s germination rate was dependent on its distance from other spores, especially at short distances. Thus, spores that were within a few micrometers exhibited an increased synchronicity in germination, suggesting that there is a mechanism for short-range communication between such spores during germination. However, two molecules known to be germinants that are released during germination, l-alanine and the 1:1 chelate of Ca²⁺ and dipicolinic acid, did not mediate spore-to-spore communication during germination.     

Effects of moderately high pressure plus heat on the germination and inactivation of Bacillus cereus spores lacking proteins involved in germination

Aims:  To determine the germination and inactivation of Bacillus cereus spores lacking various germination proteins using moderately high pressure (MHP) and heat.
Methods:  The inactivation and germination of wild-type B. cereus spores in buffer by MHP (150 MPa) at various temperatures, as well as the MHP inactivation and germination of B. cereus spores lacking individual germinant receptors and monovalent cation antiporters, was determined.
Results:  Loss of individual germinant receptors had no large effects on spore inactivation or germination, although germination of receptor-deficient spores was generally slightly decreased. Loss of the GerN in particular the GerN and GerT antiporters also decreased spore germination by MHP, especially at 40 and 50°C.
Conclusions:  Both inactivation and germination of B. cereus spores by MHP increased with rise of temperature; however, mutant strains lacking individual germinant receptor had similar levels of germination as compared to wild-type spores. To evaluate the role of germinant receptors in MHP, a strain lacking a large number of germinant receptors is needed.
Significance and Impact of the Study:  The results of this work may lead to a better understanding of how MHP causes germination of spores of B. cereus .     

Analysis of the Loss in Heat and Acid Resistance during Germination of Spores of Bacillus Species

A major event in the nutrient germination of spores of Bacillus species is release of the spores'' large depot of dipicolinic acid (DPA). This event is preceded by both commitment, in which spores continue through germination even if germinants are removed, and loss of spore heat resistance. The latter event is puzzling, since spore heat resistance is due largely to core water content, which does not change until DPA is released during germination. We now find that for spores of two Bacillus species, the early loss in heat resistance during germination is most likely due to release of committed spores'' DPA at temperatures not lethal for dormant spores. Loss in spore acid resistance during germination also paralleled commitment and was also associated with the release of DPA from committed spores at acid concentrations not lethal for dormant spores. These observations plus previous findings that DPA release during germination is preceded by a significant release of spore core cations suggest that there is a significant change in spore inner membrane permeability at commitment. Presumably, this altered membrane cannot retain DPA during heat or acid treatments innocuous for dormant spores, resulting in DPA-less spores that are rapidly killed.     

Blue Light Interference in the Phytochrome-controlled Germination of the Spores of Cheilanthes farinosa

Short exposure of the spores of Cheilanthes farinosa to low intensity red light promotes their germination, which is not reversed by a subsequent exposure to far red light. Germination is, however, inhibited by blue light administered before or after red light. Inhibition of germination by blue light is annulled by exposure to a higher intensity of red light, and germination of the repromoted spores is inhibited by far red light. Mutual photoreversibility of germination is also observed in repromoted spores irradiated successively with far red and red light. Although germination appears to be basically under phytochrome control, it is postulated that the presence of a blue light-absorbing pigment interferes with phytochrome transformations in the spores.     

Biochemistry of L-proline-triggered germination of Bacillus megaterium spores.

The mechanism by which L-proline triggers germination in Bacillus megaterium QM B1551 spores was investigated. First, brief exposure of spores to L-proline, followed by dilution, was sufficient to trigger germination. Once germination was triggered, the spores continued initiation of germination and did not require high concentrations of L-proline. Triggering of germination was pH and temperature dependent. Second, enzymes for L-proline catabolism were absent in spores, and several non-metabolizable analogs of L-proline were effective trigger compounds. Third, triggering of germination occurred in the presence of inhibitors of proton motive force production, oxygen uptake, and metabolism. Fourth, uptake of L-proline occurred after the triggering of germination. These results argue that neither uptake nor metabolism of L-proline was necessary to trigger germination. Instead, L-proline probably causes a biophysical alteration in the spores that triggers the biochemical changes in germination.     

Germination of spores of Bacillus subtilis with dodecylamine

AIMS: To determine the properties of Bacillus subtilis spores germinated with the alkylamine dodecylamine, and the mechanism of dodecylamine-induced spore germination. METHODS AND RESULTS: Spores of B. subtilis prepared in liquid medium were germinated efficiently by dodecylamine, while spores prepared on solid medium germinated more poorly with this agent. Dodecylamine germination of spores was accompanied by release of almost all spore dipicolinic acid (DPA), degradation of the spore's peptidoglycan cortex, release of the spore's pool of free adenine nucleotides and the killing of the spores. The dodecylamine-germinated spores did not initiate metabolism, did not degrade their pool of small, acid-soluble spore proteins efficiently and had a significantly lower level of core water than did spores germinated by nutrients. As measured by DPA release, dodecylamine readily induced germination of B. subtilis spores that: (a) were decoated, (b) lacked all the receptors for nutrient germinants, (c) lacked both the lytic enzymes either of which is essential for cortex degradation, or (d) had a cortex that could not be attacked by the spore's cortex-lytic enzymes. The DNA in dodecylamine-germinated wild-type spores was readily stained, while the DNA in dodecylamine-germinated spores of strains that were incapable of spore cortex degradation was not. These latter germinated spores also did not release their pool of free adenine nucleotides. CONCLUSIONS: These results indicate that: (a) the spore preparation method is very important in determining the rate of spore germination with dodecylamine, (b) wild-type spores germinated by dodecylamine progress only part way through the germination process, (c) dodecylamine may trigger spore germination by a novel mechanism involving the activation of neither the spore's nutrient germinant receptors nor the cortex-lytic enzymes, and (d) dodecylamine may trigger spore germination by directly or indirectly activating release of DPA from the spore core, through the opening of channels for DPA in the spore's inner membrane. SIGNIFICANCE AND IMPACT OF THE STUDY: These results provide new insight into the mechanism of spore germination with the cationic surfactant dodecylamine, and also into the mechanism of spore germination in general. New knowledge of mechanisms to stimulate spore germination may have applied utility, as germinated spores are much more sensitive to processing treatments than are dormant spores.     

REVERSIBLE ACTIVATION FOR GERMINATION AND SUBSEQUENT CHANGES IN BACTERIAL SPORES

Lee, W. H. (University of Illinois, Urbana) and Z. John Ordal. Reversible activation for germination and subsequent changes in bacterial spores. J. Bacteriol. 85:207-217. 1963.-It was possible to isolate refractile spores of Bacillus megaterium, from a calcium dipicolinate germination solution, that were activated and would germinate spontaneously in distilled water. Some of the characteristics of the initial phases of bacterial spore germination were determined by studying these unstable activated spores. Activated spores of B. megaterium were resistant to stains and possessed a heat resistance intermediate between that of dormant and of germinated spores. The spontaneous germination of activated spores was inhibited by copper, iron, silver, or mercury salts, saturated o-phenanthroline, or solutions having a low pH value, but not by many common inhibitors. These inhibitions could be partially or completely reversed by the addition of sodium dipicolinate. The activated spores could be deactivated and made similar to dormant spores by treatment with acid. Analyses of the exudates from the variously treated spore suspensions revealed that whatever inhibited the germination of activated spores also inhibited the release of spore material. The composition of the germination exudates was different than that of extracts of dormant spores. Although heavy suspensions of activated spores gradually became swollen and dark when suspended in solutions of o-phenanthroline or at pH 4, the materials released resembled those found in extracts of dormant spores rather than those of normal germination exudates.     

Spore pool glutamic acid as a metabolite in germination

Spore glutamic acid pools were examined in dormant and germinating spores using colorimetric and (14)C analytical procedures. Germination of spores of Bacillus megaterium (parent strain), initiated by d-glucose, was accompanied by a rapid drop in the level of spore pool glutamate, from 12.0 mug/mg of dry spores to 7.7 mug/mg of dry spores after 30 sec of germination. Similar decreases in extractable spore pool glutamate were observed with l-alanine-initiated germination of B. licheniformis spores. On the other hand, glutamate pools of mutant spores of B. megaterium, with a requirement of gamma-aminobutyric acid for spore germination, remained unchanged for 9 min of germination, at which time more than 50% of the spore population had germinated. Evidence for conversion of spore pool glutamate to gamma-aminobutyric acid during germination of spores of B. megaterium (parent strain) was obtained.