Photodamage to spores of Fusarium fungi sensitized by protoporphyrin IX

The photodynamic effect on the state of hydrated spores of micopathogen genus Fusarium and germination of conidia on a nutrient medium was studied using protoporphyrin IX as a sensitizer. It was shown that micromolar concentrations of protoporphyrin IX sensitize photooxidation of proteins and lipids in hydrated spores of Fusarium poae and Fusarium culmorum fungi under illumination of their suspensions at doses of 50–200 kJ/m². Photosensitized oxidation of cell components leads to damage the permeability of membranes and suppress spore germination during their further cultivation on the nutrient medium.     

The microbiology of cut-away peat

Summary Fungi occurring commonly in cut-away peat were selected for autecological study, being chosen to represent both cosmopolitan and indigenous elements of the peat flora. A fungus alien to peat,Fusarium culmorum, was also included in the study. The germination in peat of the spores of these species and their ability to grow and colonise organic material added to peat were examined. It was concluded that the cosmopolitan element was composed of efficient saprophytes but that the ability of their spores to germinate in unamended peat was limited. Although Fusarium spores germinated, the germ tubes subsequently formed chlamydospores. Only spores of the indigenous peat fungi germinated well in peat but their growth habit was not suited to the colonisation and utilisation of organic matter, added to peat, in competition with the cosmopolitan flora. The concept of ‘source potential’ is introduced to explain the variance in fungal growth from different substrate bases.     

Dry mass of Fusarium roseum spores before and after germination

The total dry mass of Fusarium roseum spores and contained lipid bodies were determined before and after spores germinated using quantitative interference microscopy. The mean for spore dry mass before germination was about 57 pg. Lipid bodies accounted for about 61% of that. Areas of lipid bodies in spores before and after germination were about 23 % but the contents of the lipid bodies accounted for only 10% of the spore dry mass after germination. The total dry mass of the spore and germ tube(s) greatly exceeded that of the spore before germination. We infer that nutrients for germ tube growth are derived from within the germinating spore and from the medium which must contain nutrients leached from non-germinating spores.     

唾液乳杆菌抑制镰孢霉的研究

目的 研究唾液乳杆菌抑制产毒镰孢霉的生物学性能,初步探索抑菌机制.方法 以禾谷镰孢霉和尖孢镰孢霉2种典型霉菌为指示菌,唾液乳杆菌为测试对象,对霉菌孢子萌芽、孢子生长和菌丝体生长3个生理阶段进行抑制效应观察.结果 10%的唾液乳杆菌耗尽上清就能抑制83%的禾谷镰孢霉孢子和50%尖孢镰孢霉孢子萌芽;耗尽上清24 h内能显著抑制镰孢霉孢子的生长;96 h内孢霉菌丝体的生长.结论 唾液乳杆菌产生的有机酸对禾谷镰孢霉和尖孢镰孢霉生长起主要抑制作用.     

Conidial germination in the filamentous fungus Fusarium graminearum

The ascomycetous fungus Fusarium graminearum is an important plant pathogen causing Fusarium head blight disease of wheat and barley. To understand early developmental stages of this organism, we followed the germination of macroconidia microscopically to understand the timing of key events. These events, recorded after suspension of spores in liquid germination medium, included spore swelling at 2h, germination tube emergence and elongation from conidia at 8h and hyphal branching at 24h. To understand changes in gene expression during these developmental changes, RNA was isolated from spores and used to interrogate the F. graminearum Affymetrix GeneChip. RNAs corresponding to 5813 genes were detected in fresh spores and 5146, 5249 and 5993, respectively, in spores incubated in germination medium after 2, 8 or 24h (P<0.001). Gene expression data were used to predict the cellular and physiological state of each developmental stage for known processes. Predictions were confirmed microscopically for several previously unreported developmental events such as manifestation of peroxisomes in fresh spores and nuclear division resulting in binuclear cells within macroconidia prior to spore germination. Knowledge of stage-specific gene expression and changes in gene expression levels between developmental stages are an important first step to understanding the molecular mechanisms responsible for spore germination and development.     

Conidial germination in the filamentous fungus Fusarium graminearum.

The ascomycetous fungus Fusarium graminearum is an important plant pathogen causing Fusarium head blight disease of wheat and barley. To understand early developmental stages of this organism, we followed the germination of macroconidia microscopically to understand the timing of key events. These events, recorded after suspension of spores in liquid germination medium, included spore swelling at 2h, germination tube emergence and elongation from conidia at 8h and hyphal branching at 24h. To understand changes in gene expression during these developmental changes, RNA was isolated from spores and used to interrogate the F. graminearum Affymetrix GeneChip. RNAs corresponding to 5813 genes were detected in fresh spores and 5146, 5249 and 5993, respectively, in spores incubated in germination medium after 2, 8 or 24h (P<0.001). Gene expression data were used to predict the cellular and physiological state of each developmental stage for known processes. Predictions were confirmed microscopically for several previously unreported developmental events such as manifestation of peroxisomes in fresh spores and nuclear division resulting in binuclear cells within macroconidia prior to spore germination. Knowledge of stage-specific gene expression and changes in gene expression levels between developmental stages are an important first step to understanding the molecular mechanisms responsible for spore germination and development.     

Effects of temperatures above the maximum for germination on the endospore of Bacillus cereus

Knaysi, Georges (Cornell University, Ithaca, N.Y.). Effects of temperatures above the maximum for germination on the endospore of Bacillus cereus. J. Bacteriol. 87:1129-1136. 1964.-This is chiefly a study of heat activation and of the instability observed in spores of Bacillus cereus exposed to high temperatures. Temperatures up to 80 C for periods up to 6 hr were used. The spores were in colonies grown on collodion films, and were observed with the phase microscope, in dark contrast, for any evidence of change in their optical properties, the structure of their spodograms, and any other evidence of germination or growth. Exposure of the endospores to 80 C for 4 hr or more, whether in distilled water or in glucose broth, entirely eliminated stage II (i.e. the germcell stage, when the germinating spore begins to grow), and also tended to render the spores unstable and to produce uniformly dark spodograms. This instability involves some destructive processes and is not equivalent to normal entry into stage I (the initial stage). True heat-activation seemed to take place at a stage prior to the one which yielded uniformly dark spodograms. It was shown to consist of two factors: accumulation of germination-promoting components of the medium and activation of some spore components involved in germination. Activation of the medium components by preheating did not stimulate the spores of the strain employed. Unstable or activated spores can not be instantaneously stabilized, deactivated, or their changes arrested by exposure to acid buffers. It is concluded that the optimal temperature for activation, without danger of injury to the spore, in a given strain, is just above the maximum for stage I in that strain.     

Effect of volatile and gaseous metabolites of germinating pea seeds on micromycetes

Differences in the effect of volatile and gaseous metabolites of germinating pea seeds on the germination of spores of Mucor racemosus and macroconidia of Fusarium oxysporum are described. Germination of spores of M. racemosus was inhibited by seed metabolites whereas germination of macroconidia of F. oxysporum was stimulated during the first two days and inhibition occurred only after further two days of germination of the seeds. A pronounced inhibition of germination of spores of both micromycetes took place due to absorption of CO2 from volatile and gaseous metabolites. Absorption of some components of seed metabolites in a KMnO4 solution led to a decrease of the inhibitory effect on germination of spores of M. racemosus and stimulatory effect on germination of macroconidia of F. oxysporum.     

Porphyrin Accumulation and Export by Isolated Barley (Hordeum vulgare) Plastids (Effect of Diphenyl Ether Herbicides)

We have investigated the formation of porphyrin intermediates by isolated barley (Hordeum vulgare) plastids incubated for 40 min with the porphyrin precursor 5-aminolevulinate and in the presence and absence of a diphenylether herbicide that blocks protoporphyrinogen oxidase, the enzyme in chlorophyll and heme synthesis that oxidizes protoporphyrinogen IX to protoporphyrin IX. In the absence of herbicide, about 50% of the protoporphyrin IX formed was found in the extraplastidic medium, which was separated from intact plastids by centrifugation at the end of the incubation period. In contrast, uroporphyrinogen, an earlier intermediate, and magnesium protoporphyrin IX, a later intermediate, were located mainly within the plastid. When the incubation was carried out in the presence of a herbicide that inhibits protoporphyrinogen oxidase, protoporphyrin IX formation by the plastids was completely abolished, but large amounts of protoporphyrinogen accumulated in the extraplastidic medium. To detect extraplastidic protoporphyrinogen, it was necessary to first oxidize it to protoporphyrin IX with the use of a herbicide-resistant protoporphyrinogen oxidase enzyme present in Escherichia coli membranes. Protoporphyrinogen is not detected by some commonly used methods for porphyrin analysis unless it is first oxidized to protoporphyrin IX. Protoporphyrin IX and protoporphyrinogen found outside the plastid did not arise from plastid lysis, because the percentage of plastid lysis, measured with a stromal marker enzyme, was far less than the percentage of these porphyrins in the extraplastidic fraction. These findings suggest that of the tetrapyrrolic intermediates synthesized by the plastids, protoporphyrinogen and protoporphyrin IX, are the most likely to be exported from the plastid to the cytoplasm. These results help explain the extraplastidic accumulation of protoporphyrin IX in plants treated with photobleaching herbicides. In addition, these findings suggest that plastids may export protoporphyrinogen or protoporphyrin IX for mitochondrial heme synthesis.     

Properties of the germination inhibitor of Streptomyces viridochromogenes spores

Germinating spores of Streptomyces viridochromogenes excreted a substance into the surrounding medium which inhibited germination of another sample of the spores. The germination inhibitor (GI) was produced during submerged culture after exponential growth had ceased. The GI was purified 51-fold following extraction from growth liquor with chloroform. It was soluble in alcohol and water and had a molecular weight of less than 1000. The GI blocked growth and respiration of some Gram-positive bacteria and was an inhibitor of the membrane bound, but not solubilized, calcium-dependent ATPase of germinated spores and mycelia of the producing organism. Several sodium-potassium activated ATPases were also inhibited. All four activities (respiration, growth, germination inhibition, ATPase) co-purified during column and thin-layer chromatography. The GI activities released during germination and produced during growth were identical. A role for the GI antibiotic in regulation of dormancy of spores of the producing organism is discussed.     

韭菜对香蕉枯萎病菌生长及香蕉枯萎病发生的抑制作用

结合实验室抑菌试验和大棚人工接菌盆栽试验,研究韭菜对香蕉枯萎病菌4号生理小种(Foc4)的拮抗作用及其对香蕉枯萎病发生的防控效果.结果显示:离体条件下,韭菜粗提取液显著抑制Foc4菌丝的生长,造成菌丝变形、细胞的解体;也能显著抑制孢子的萌发并导致孢子失去活性.大棚盆栽试验中,韭菜处理的巴西香蕉苗枯萎病发病率降低70%,病情指数降低86.9%;韭菜处理的广粉1号粉蕉苗枯萎病的发病率降低76.7%,病情指数降低93.4%.研究表明,韭菜对Foc4有很高拮抗效果,而且对香蕉枯萎病有很高的防控作用.     

The effect of volatile and gaseous metabolites of swelling seeds on germination of fungal spores

Effects of volatile and gaseous metabolites of swelling seeds of pea, bean, wheat, corn, cucumber, tomato, lentil, carrot, red pepper and lettuce on germination of spores of five genera of fungi were found to depend rather on the fungal than on the plant genus. Germination of spores ofBotrytis cinerea, Mucor racemosus andTrichoderma viride was most severely inhibited. Spores ofVerticillium dahliae were less sensitive and germination of spores ofFusarium oxysporum was inhibited only in two cases. On the other hand, exudates of pea and bean stimulated germination of spores ofFusarium oxysporum. Also spores ofTrichoderma viride germinated better in an atmosphere enriched with exuded metabolites of swelling lettuce seeds. When carbon dioxide produced by the swelling seeds was absorbed in potassium hydroxide, spores ofTrichoderma viride andVerticillium dahliae did not germinate at all, the inhibitory effects of volatile and gaseous exudates on germination of spores ofMucor racemosus were accentuated, and also the percentage of germinated spores ofFusarium oxysporum decreased. Germination of spores ofBotrytis cinerea was not influenced. Absorption of volatile and gaseous metabolites in a solution of potassium permanganate decreased in most cases their inhibitory effects, particularly inBotrytis cinerea.     

THE PORPHYRIN REQUIREMENTS OF HAEMOPHILUS INFLUENZAE AND SOME FUNCTIONS OF THE VINYL AND PROPIONIC ACID SIDE CHAINS OF HEME

1. Iron protoporphyrin IX was required for the growth of H. influenzae. It could be replaced by protoporphyrin IX. When grown on protoporphyrin evidence was obtained for the presence of Fe porphyrin in the organism. It was concluded that the organism could insert iron into the protoporphyrin ring. 2. In the smooth strains, other porphyrins containing no iron such as deutero-, hemato-, meso-, and coproporphyrins could not replace protoporphyrin for growth. Since protoporphyrin has two vinyl groups which other porphyrins lack, it was concluded that the two vinyl groups were essential for growth. 3. When porphyrins lacking vinyl groups were converted chemically into iron porphyrins and then supplied to the organisms it was found that these iron porphyrins supported growth. It was concluded that the "smooth" organisms were able to insert iron only into the porphyrin containing the vinyl groups; i.e., protoporphyrin. One function of the vinyl groups then was to permit iron to be inserted biologically into the porphyrin ring. 4. An anomalous behavior in the rough Turner strain was observed and discussed. This organism was able to insert iron into mesoporphyrin at low concentrations but was inhibited by this compound at higher concentrations. In all other reactions with the porphyrins this rough strain behaved in the same was as did the smooth strains. 5. All strains which were grown on iron porphyrins lacking vinyl groups could not reduce nitrate to nitrite. When grown on protoporphyrin or Fe protoporphyrin reduction of nitrate occurred. It was concluded that the nitrate-reducing mechanism required the presence of the vinyl groups either for its formation or function. 6. The porphyrins lacking iron and lacking vinyl groups inhibited the growth of H. influenzae on Fe protoporphyrin. The inhibition between a porphyrin and Fe protoporphyrin was a competitive one. It was suggested that the porphyrin inhibited the growth-promoting properties of Fe protoporphyrin by attaching on to a particular apoprotein, thus preventing the formation of a heme catalyst. Likewise, competition between two growth-promoting Fe porphyrins for apoenzymes could be shown to occur. 7. Protoporphyrin and Fe protoporphyrin supported growth. When their propionic acid side chains were esterified they no longer supported growth. It was suggested that the esterified carboxyl groups could not attach to the specific apoproteins to form the heme enzymes and so could not act to support growth. For the same reason the inhibitory action of porphyrins lacking vinyl groups could be prevented by esterifying their propionic acid groups.     

青霉TS67菌株活性产物的抗真菌作用

本文初步探讨了青霉TS67(Penicillum sp.)的发酵活性产物对植物病原真菌的抑制作用机理,实验结果表明,用其50%的发酵液分别处理玉蜀黍平脐蠕孢菌(Bipolarismaydis)和大豆尖孢镰刀菌(Fusarium oxysporum)120 h后,菌丝生长的抑制率分别为77.78%和70.30%,对孢子产生的抑制率分别达58.8%和73.5%:同时发现用50%发酵液处理病原茵的无性繁殖孢子12 h后,孢子萌发抑制率分别达78.3%和62.O%.经显微镜观察抗菌活性物质处理后的菌丝体,发现菌丝体表面瘤状畸形、菌丝生长顶端不规则膨胀、内部发生原生质浓缩,初步推测青霉TS67主要通过影响植物病原真菌的细胞壁而实现抑制作用.     

The influence of sucrose and wheat root exudates on the germination and growth of conidia ofFusarium culmorum (W.G.S.M.) Sacc

Summary It is shown in these studies that the germination of the conidia ofFusarium culmorum (W.G.Sm.) Sacc. is influenced by both constitutive and exogenous factors. In a dense suspension, selfinhibited spores are induced to germinate by dilution with distilled water and by suspending in either sucrose solution or wheat root exudates. The exudates not only stimulate conidial germination but also promote subsequent growth of the fungus. The significance of this in pathogenesis is discussed.     

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 Estimation of Coproporphyrin III and Protoporphyrin IX from Their Mixture by Spectrofluorometry

For quantitative estimation of coproporphyrin III and protoporphyrin IX from their mixture, a sensitive spectrofluorometric method was developed. At room temperature, coproporphyrin III fluoresces in neutral or alkaline pH at 622 nm having substantial fluorescence at 632 nm where protoporphyrin IX also fluoresces maximally. Similarly, protoporphyrin IX also has substantial fluorescence at 622 nm. Therefore, while estimating protoporphyrin IX (E400 F632) or coproporphyrin III (E400 F622) concentratton, it is essential to correct for the fluorescence due to coproporphyrin III at 632 nm and protoporphyrin IX at 622 nm. This was done by formulating equations from appropriate constants derived from pure samples of coproporphyrin III and protoporphyrin IX. As law as 1 pmole of coproporphyrin III or protoporphyrin IX could be estimated from their mixture by using the spectrofluorometric method.     

Characterization of spore germination of a thermoacidophilic spore-forming bacterium, Alicyclobacillus acidoterrestris

The germination behaviors of spores of Alicyclobacillus acidoterrestris, which has been considered to be a causative microorganism of flat sour type spoilage in acidic beverages, were investigated. The spores of A. acidoterrestris showed efficient germination and outgrowth after heat activation (80 degrees C, 20 min) in Potato dextrose medium (pH 4.0). Further, the spores treated with heat activation germinated in McIlvaine buffer (pH 4.0) in the presence of a germinative substance (L-alanine) and commercial fruit juices, although not in phosphate buffer (pH 7.0). Heat activation was necessary for germination. The spores of A. acidoterrestris, which easily survived the heat treatment in acidic conditions, lost their resistance to heat during germination. Our results suggest that the models obtained from spore germination of A. acidoterrestris might be beneficial to determine adequate thermal process in preventing the growth of potential spoilage bacteria in acidic beverages.     

Effects of nutrient medium composition and temperature on the germination of conidia and the entomopathogenic activity of the fungi

The effects of nutrient medium composition and temperature on the germination of conidia of the fungi Beauveria bassiana (strain AlG) and Metarhizium anisopliae (strain M-99) and their entomopathogenic activity have been studied. It was demonstrated that the presence of carbohydrates alone was sufficient for the spores of M. anisopliae M-99 to germinate, whereas the germination of B. bassiana AlG spores was inhibited by carbohydrates. Addition of KJ, ZnSO4, or KBr into the Czapek medium increased the entomopathogenic activity of B. bassiana. The optimum temperature for spore germination was 20-35 degrees C in both fungal species.     

Germination of spores of Bacillales and Clostridiales species: mechanisms and proteins involved

Under conditions that are not conducive to growth, such as nutrient depletion, many members of the orders Bacillales and Clostridiales can sporulate, generating dormant and resistant spores that can survive in the absence of nutrients for years under harsh conditions. However, when nutrients are again present, these spores can return to active growth through the process of germination. Many of the components of the spore germination machinery are conserved between spore forming members of the Bacillales and Clostridiales orders. However, recent studies have revealed significant differences between the germination of spores of Clostridium perfringens and that of spores of a number of Bacillus species, both in the proteins and in the signal transduction pathways involved. In this review, the roles of components of the spore germination machinery of C. perfringens and several Bacillus species and the bioinformatic analysis of germination proteins in the Bacillales and Clostridiales orders are discussed and models for the germination of spores of these two orders are proposed.