Effect of the composition of the medium and magnesium and calcium ions on the germination of spores of Thermoactinomyces vulgaris]

The germination of the spores of Thermoactinomyces vulgaris formed on a complex medium is stimulated by suspending them in solutions containing Mg2+ and Ca2+ ions. The stimulation is not the result of the initiation of the spores in the presence of the ions since the experiments were carried out at a temperature of 20 degrees C at which the initiation did not virtually take place. The ions of Na+ and K+ have almost no effect on the germination of the spores. The fraction of the resting spores of Thermoactinomyces vulgaris depends on the composition of the growth medium, especially on its amino acid composition. The addition of Mg2+ and Ca2+ ions to a minimal synthetic growth medium stimulates the growth of the cultures and decreases the dormancy of the spores. The spores formed on the synthetic medium are less thermostable than the spores formed on the complex medium. Thermostability of the spores increases upon the addition of Mg2+ to the synthetic medium. Spore suspensions obtained on the synthetic medium with Mg2+ or Ca2+ are initiated more completely than spore suspensions obtained on the complex medium.     

氮、硅限制对赤潮藻扁面角毛藻休眠孢子形成的影响

休眠孢子的形成对于赤潮藻种群的保存、延续以及分布扩散等均具有重要的意义。通过单因子营养限制研究氮、硅对赤潮藻扁面角毛藻（Chaetoceros compressus）休眠孢子形成的影响,结果表明：培养基中氮的初始浓度对休眠孢子的出现时间有一定影响。氮的初始浓度越低,休眠孢子出现的时间越早：反之,氮的初始浓度越高,休眠孢子出现的时间越晚。氮缺乏是硅藻形成休眠孢子的必需条件之一,当培养基中氮含量低于10μmol·L^-1时,扁面角毛藻可以形成休眠孢子。氮缺乏诱发的休眠孢子的形成需要大量的硅,当培养基中硅含量低于23μmol·L^-1时,即使氮缺乏,扁面角毛藻也几乎不再继续形成休眠孢子。这说明硅藻休眠孢子的形成不仅受氮浓度的影响,还与硅浓度有关。     

Properties of Bacillus anthracis spores prepared under various environmental conditions

Bacillus anthracis makes highly stable, heat-resistant spores which remain viable for decades. Effect of various stress conditions on sporulation in B. anthracis was studied in nutrient-deprived and sporulation medium adjusted to various pH and temperatures. The results revealed that sporulation efficiency was dependent on conditions prevailing during sporulation. Sporulation occurred earlier in culture sporulating at alkaline pH or in PBS than control. Spores formed in PBS were highly sensitive towards spore denaturants whereas, those formed at 45°C were highly resistant. The decimal reduction time (D-10 time) of the spores formed at 45°C by wet heat, 2 M HCl, 2 M NaOH and 2 M H₂O₂ was higher than the respective D-10 time for the spores formed in PBS. The dipicolinic acid (DPA) content and germination efficiency was highest in spores formed at 45°C. Since DPA is related to spore sensitivity towards heat and chemicals, the increased DPA content of spores prepared at 45°C may be responsible for increased resistance to wet heat and other denaturants. The size of spores formed at 45°C was smallest amongst all. The study reveals that temperature, pH and nutrient availability during sporulation affect properties of B. anthracis spores.     

Alteration in timing of cell differentiation resulting from cell interactions during development of the cellular slime mold, Dictyostelium discoideum

The effect of cell interactions on the timing of cell differentiation of Dictyostelium discoideum was studied by monitoring spore differentiation in chimeric aggregates composed of two cell populations, one of which was cycloheximide resistant.Chimeras were constructed with cells of a rapidly developing strain, FR-1, and cells of a normally developing cycloheximide resistant strain, CR-2. CR-2 cells formed spores 4 to 5 hr prematurely while spore formation by FS-1 cells was delayed by 1 hr. The two cell populations formed spores 3 hr apart from each other. FS-1 spores were localized to the enlarged bases of the fruiting bodies, whereas CR-2 spores were found in the apical structures.Chimeras were also constructed with cells of two normally developing strains, CR-2 and A3, one population of which had been dissociated at 8.5 hr and the other at 19 hr of development. The 19-hr cells formed spores 2 hr late and 8.5-hr cells 2 to 4 hr prematurely. The two cell populations formed spores within 1 hr of each other although they were asynchronous by 10.5 hr at the time of mixing. These chimeras formed normal fruiting bodies. The results indicate that the timing of cell differentiation is altered by the presence of cells developing at a different rate.     

Sporulation of Streptomyces antibioticus ETHZ 7451 in submerged culture.

Streptomyces antibioticus ETHZ 7451 formed spores in cultures grown in a liquid medium from either a spore or a mycelium inoculum. The spores formed were similar to those formed on surface-grown cultures, except for reduced heat resistance. Both types of spores were sensitive to lysozyme, which is unusual for Streptomyces spores. Glucose and other carbon sources, which promoted different growth rates, did not affect sporulation efficiency. Nitrogen sources, such as casamino acids, that allowed high growth rates suppressed the sporulation. A remarkable repression was also observed in media with some nitrogen sources that promoted noticeably lower growth rates. In permissive media, with nitrogen sources that permitted relatively high growth rates, sporulation was conditioned to the consumption of ammonium in the medium, but not to that of other nitrogen sources, such as asparagine. Phosphate did not show a repressive effect on sporulation in the assayed conditions.     

Influence of cellular differentiation on ultraviolet induced DNA damage and its repair mechanisms in B. cereus

Susceptibility to UV irradiation of B. cereus BIS-59 spores undergoing germination at various stages-dormant spores to vegetative cell stage and their ability to recover from radiation damage were studied. For a given dose of radiation, the number of spore photoproducts (SPP) formed in the DNA of dormant spores was about 5-times greater than that of thymine dimers (TT) formed in the DNA of vegetative cells. At intermediate stages of the germination cycle, there was a rapid decline in the UV radiation-induced SPP formed in DNA with a concomitant increase in the UV radiation-induced TT formed in DNA. Bacterial spores undergoing germination (up to 3 hr) in the low nutrient medium (0.3% yeast extract) displayed much higher resistance to UV radiation than those germinating in the rich nutrient medium, even though there was no discernible difference under the two incubation conditions in respect of the extent of germination and the time at which the outgrowth stage appeared (3 hr). This was due to the formation TT in the DNA of spores germinating in the low nutrient as compared to that of spores germinating in the rich-nutrient medium. In UV-irradiated dormant spores, SPP formed in the spore DNA did not disappear even after prolonged incubation in the non-germinating medium. However, when the UV-irradiated dormant spores were germinated in low or rich nutrient medium, a significant proportion of SPP in DNA was eliminated. The dormant spores incubated in either of the germinating media for 15 min and then UV-irradiated were capable of eliminating SPP (presumably by monomerization) even by incubation in a non-germinating medium and in the complete absence of protein synthesis (buffer holding recovery), thereby implying that spore-repair enzymes were activated in response to initial's germination. The acquisition of photo-reactivation ability appeared in spores subjected to germination only in the rich-nutrient medium at the outgrowth stage and required de novo synthesis of the required enzymes.     

The effect of acid shock on sporulating Bacillus subtilis cells

AIMS: To study the effect of acid shock in sporulation on the production of acid-shock proteins, and on the heat resistance and germination characteristics of the spores formed subsequently. METHODS AND RESULTS: Bacillus subtilis wild-type (SASP-alpha+beta+) and mutant (SASP-alpha-beta-) cells in 2 x SG medium at 30 degrees C were acid-shocked with HCl (pH 4, 4.3, 5 and 6 against a control pH of 6.2) for 30 min, 1 h into sporulation. The D85-value of B. subtilis wild-type (but not mutant) spores formed from sporulating cells acid-shocked at pH 5 increased from 46.5 min to 78.8 min, and there was also an increase in the resistance of wild-type acid-shocked spores at both 90 degrees C and 95 degrees C. ALA- or AGFK-initiated germination of pH 5-shocked spores was the same as that of non-acid-shocked spores. Two-dimensional gel electrophoresis showed only one novel acid-shock protein, identified as a vegetative catalase 1 (KatA), which appeared 30 min after acid shock but was lost later in sporulation. CONCLUSIONS: Acid shock at pH 5 increased the heat resistance of spores subsequently formed in B. subtilis wild type. The catalase, KatA, was induced by acid shock early in sporulation, but since it was degraded later in sporulation, it appears to act to increase heat resistance by altering spore structure. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first proteomic study of acid shock in sporulating B. subtilis cells. The increasing spore heat resistance produced by acid shock may have significance for the heat resistance of spores formed in the food industry.     

Morphological Variation in Spores of Pyricularia oryzae Cavara

Two mutant isolates of Pyricularia oryzae formed abnormal, longer, cylindrical spores with more septa than those of normal, obpyriform spores of wild isolates. These isolates also produced normal spores, although their number was less than that of the abnormal spores. When normal and abnormal spores were single-spore-isolated from the lesions caused by the mutant isolates and inoculated to an agar medium, each colony produced both types of spores, regardless of the type of single spores usedfor inoculation.     

Influence of transition metals added during sporulation on heat resistance of Clostridium botulinum 113B spores.

Sporulation of Clostridium botulinum 113B in a complex medium supplemented with certain transition metals (Fe, Mn, Cu, or Zn) at 0.01 to 1.0 mM gave spores that were increased two to sevenfold in their contents of the added metals. The contents of calcium, magnesium, and other metals in the purified spores were relatively unchanged. Inclusion of sodium citrate (3 g/liter) in the medium enhanced metal accumulation and gave consistency in the transition metal contents of independent spore crops. In citrate-supplemented media, C. botulinum formed spores with very high contents of Zn (approximately 1% of the dry weight). Spores containing an increased content of Fe (0.1 to 0.2%) were more susceptible to thermal killing than were native spores or spores containing increased Zn or Mn. The spores formed with added Fe or Cu also appeared less able to repair heat-induced injuries than the spores with added Mn or Zn. Fe-increased spores appeared to germinate and outgrow at a higher frequency than did native and Mn-increased spores. This study shows that C. botulinum spores can be sensitized to increased thermal destruction by incorporation of Fe in the spores.     

Influence of transition metals added during sporulation on heat resistance of Clostridium botulinum 113B spores

Sporulation of Clostridium botulinum 113B in a complex medium supplemented with certain transition metals (Fe, Mn, Cu, or Zn) at 0.01 to 1.0 mM gave spores that were increased two to sevenfold in their contents of the added metals. The contents of calcium, magnesium, and other metals in the purified spores were relatively unchanged. Inclusion of sodium citrate (3 g/liter) in the medium enhanced metal accumulation and gave consistency in the transition metal contents of independent spore crops. In citrate-supplemented media, C. botulinum formed spores with very high contents of Zn (approximately 1% of the dry weight). Spores containing an increased content of Fe (0.1 to 0.2%) were more susceptible to thermal killing than were native spores or spores containing increased Zn or Mn. The spores formed with added Fe or Cu also appeared less able to repair heat-induced injuries than the spores with added Mn or Zn. Fe-increased spores appeared to germinate and outgrow at a higher frequency than did native and Mn-increased spores. This study shows that C. botulinum spores can be sensitized to increased thermal destruction by incorporation of Fe in the spores.     

Morphological Variation in Spores of Pyricularia oryzae Cavara

Two mutant isolates of Pyricularia oryzae formed abnormal, longer, cylindrical spores with more septa than those of normal, obpyriform spores of wild isolates. These isolates also produced normal spores, although their number was less than that of the abnormal spores. When normal and abnormal spores were single-spore-isolated from the lesions caused by the mutant isolates and inoculated to an agar medium, each colony produced both types of spores, regardless of the type of single spores used for inoculation.     

中国蕨类植物孢子形态的研究 Ⅱ. 中国蕨科

利用扫描电镜对国产中国蕨科Sinopteridaceae植物9属61种6变种的孢子进行了观察。结果表明,该科植物的孢子可分为3种类型：(1)孢子球形,三裂缝;周壁较厚,疏松地包在孢子之外;外壁光滑,表面纹饰由周壁形成,呈网状、嵴状、刺状或皱状。除金粉蕨属Onychium和珠蕨属Cryptogramma外,该科其他属的植物都具此类型孢子。(2)孢子钝三角形,三裂缝;周壁较薄,由周壁和外壁共同形成表面轮廓,表面具疣状或颗粒状纹饰。具此类型孢子的只有珠蕨属。(3)孢子钝三角形,三裂缝,沿裂缝两侧各有一脊状隆起或瘤状纹饰;周壁薄,由外壁形成表面纹饰的基本轮廓;具赤道环、近极脊和远极脊。具此类型孢子的只有金粉蕨属。另外,从孢粉学的角度对该科的分类和系统演化进行了探讨。     

A new genus of microsporidans Cristulospora gen. n. (Amblyospiridae) with 3 new species from blood-sucking mosquitoes in Uzbekistan

Three new species of microsporidans of the new genus Cristulospora are described from mosquitoes of the genera Culex and Aedes (floodlands of the Syr Darya, Syrdarya Province, Bukharski? oasis). In mosquitoes microsporidans have sporogony of two types that is characteristic of the family Amblyosporidae. The development in larvae ends in the formation of 8 uninucleate spores in pansporoblasts. In females single binucleate spores are formed. The new genus differs from other amblyosporids in the presence of appendages in shape of magnificent plumes on both poles of octospores, which are distinct without staining. C. sherbani sp. n. from Culex modestus forms spores measuring 5.0-8.1 X 4.3-5.6 microns in larvae. During the fixation the poles become flattened, plumes are equal, most of them having wide bases. In genital ducts of females oval cylindrical thin-walled spores of 6.3-8.7 X 2.5-3.7 microns are formed. C. cadyrovi sp. n. from Culex pipiens forms spores of 5.6-6.8 X 3.7-5.0 microns in larvae. After the fixation the poles do not become flattened, plumes are equal, with narrow base. The second type of spores has not been discovered. C. aedis sp. n. from Aedes caspius has spores of 6.2-7.5 X 4.3-5.6 microns in larvae. Plumes with narrow base, the anterior and posterior ones are different in shape. In genital ducts of females thin-walled spores of 8.7-11.8 X 3.7-5.0 microns are formed.     

Use of a lacZ gene fusion to determine the dependence pattern and the spore compartment expression of sporulation operon spoVA in spo mutants of Bacillus subtilis

A spoVAA::lacZ gene fusion has been used to study expression of the spoVA operon during sporulation in Bacillus subtilis. beta-Galactosidase activity, encoded by the fusion gene, begins to be produced about 2.5 h after the induction of sporulation, well before the phenotypic consequences of spoVA mutations are manifested. spoVA expression is dependent on all of the known spo0 and spoII loci and on some of the 'early' spoIII loci, but not on 'later' loci. Several lines of evidence suggest that spoVA expression occurs only in the spore compartment. The implications of this observation for models of the overall regulation of gene expression during sporulation are discussed.     

Spores of microorganisms

The spores ofBacillus cereus formed during endotrophic sporulation in the presence of β 2-thienylalanine differ by the curve of heat-inactivation from the spores produced in distilled water containing calcium or in bactopeptone medium: the initial lag phase observed on heat inactivation is missing. The content of dipicolinic acid is comparable with that of control spores. Their UV resistance remains practically unchanged.     

氮、硅限制对赤潮藻扁面角毛藻休眠孢子形成的影响

休眠孢子的形成对于赤潮藻种群的保存、延续以及分布扩散等均具有重要的意义。通过单因子营养限制研究氮、硅对赤潮藻扁面角毛藻 (Chaetoceros compressus )休眠孢子形成的影响, 结果表明: 培养基中氮的初始浓度对休眠孢子的出现时间有一定影响。氮的初始浓度越低, 休眠孢子出现的时间越早; 反之, 氮的初始浓度越高, 休眠孢子出现的时间越晚。氮缺乏是硅藻形成休眠孢子的必需条件之一, 当培养基中氮含量低于10 mmol.L^-1时, 扁面角毛藻可以形成休眠孢子。氮缺乏诱发的休眠孢子的形成需要大量的硅, 当培养基中硅含量低于23 mmol.L^-1时, 即使氮缺乏, 扁面角毛藻也几乎不再继续形成休眠孢子。这说明硅藻休眠孢子的形成不仅受氮浓度的影响, 还与硅浓度有关。     

Regulation of trehalose metabolism by Streptomyces griseus spores.

Spores of Streptomyces griseus contain trehalose and trehalase, but trehalose is not readily hydrolyzed until spore germination is initiated. Trehalase in crude extracts of spores, germinated spores, and mycelia of S. griseus had a pH optimum of approximately 6.2, had a Km value for trehalose of approximately 11 mM, and was most active in buffers having ionic strengths of 50 to 200 mM. Inhibitors or activators or trehalase activity were not detected in extracts of spores or mycelia. Several lines of evidence indicated that trehalose and trehalase are both located in the spore cytoplasm. Spores retained their trehalose and most of their trehalase activity following brief exposure to dilute acid. Protoplasts formed by enzymatic removal of the spore walls in buffer containing high concentrations of solutes also retained their trehalose and trehalase activity. Protoplasts formed in buffer containing lower levels of solutes contained low levels of trehalose. The mechanism by which trehalose metabolism is regulated in S. griseus spores is unresolved. A low level of hydration of the cytoplasm of the dormant spores and an increased level of hydration during germination may account for the apparent inactivity of trehalase in dormant spores and the rapid hydrolysis of trehalose upon initiation of germination.     

Spore Appendages and Taxonomy of Clostridium sordellii

Twenty-five strains of Clostridium sordellii were divided into two groups on the basis of spore fine structure. Sixteen strains formed spores with smooth tubular appendages, and nine strains formed spores which lacked appendages. The other properties of the 25 strains were relatively constant. Since the minor strain variability which was encountered did not correlate with spore appendage status, fragmentation of this species on the basis of spore appendage status is not advocated.     

Spore morphology of pteridophytes from China Ⅰ. Lygodiaceae

This paper is the first report of an investigation on the spore morphology of Chinese ferns. Spore morphology of 20 species (10 species from China and 10 species from other countries) in the genus Lygodium (Lygodiaceae) was investigated under scanning electron microscope (SEM) and transmission electron microscope (TEM). The spores are tetrahedral-globose, trilete, rarely monolete. The surface ornamentation of the spores can be divided into four main types: In type I , the surface of spores is tuberculate or spheroid-tuberculate. Most of the species of the genus have this type of surface ornamentation of spores. In type II , the surface of spores is smooth. L. palmatum, L . subareolatum , L . yunnanense and L . volubile have this type of surface ornamentation of spores. In type III, both the distal and equatorial areas of spores are coarsely verrucate, while the proximal area is smooth. L. dimorphum, L. digitatum and L. kingii have this type of surface ornamentation of spores. In type IV, the surface of spores is coarsely reticulate. L. scandens and L. reticulatum have this type of surface ornamentation of spores. The surface contours of the reticulate type (type IV) are formed by the exospore, while that of the other types (types I, II, III) are formed by the perispore. The surface ornamentation of spores seems to be stable within species and thus is of important value in the taxonomy of the genus Lygodium.     

The effect of the pH of the sporulation environment on the heat resistance ofClostridium perfringens spores

The inactivation ofClostridium perfringens NCTC 8239 spores at 95° and 105° C, as determined by colony formation on an agar base containing lysozyme (BASE + lysozyme), was influenced by the initial pH of the sporulation medium. In the pH range of 7.0–8.5, established by the addition of each of several biological buffers or carbonate buffer to Duncan-Strong (DS) medium, increased pH resulted in formation of spores with greater resistance to inactivation at elevated temperatures. An increase of pH from 8.5 to 9.0 resulted in increased resistance of spores formed in DS-carbonate but not DS-TAPS (N-tris[hydroxymethyl]methyl-3-aminopropanesulfonic acid) medium. Resistance to spore injury, as determined by reduced recovery on BASE compared with BASE + lysozyme, was not increased for spores formed in media with higher pH's. As the pH of the medium increased, cell growth and number of spores formed were decreased, but the percentage of sporulation was apparently not affected.