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PubMedDate not supplied

A method for the determination of bacterial spore DNA content based on isotopic labelling, spore germination and diphenylamine assay; ploidy of spores of several Bacillus species.

A reliable method for measuring the spore DNA content, based on radioactive DNA labelling, spore germination in absence of DNA replication and diphenylamine assay, was developed. The accuracy of the method, within 10-15%, is adequate for determining the number of chromosomes per spore, provided that the genome size is known. B subtilis spores were shown to be invariably monogenomic, while those of larger bacilli Bacillus megaterium, Bacillus cereus and Bacillus thuringiensis, often, if not invariably, contain two genomes. Attempts to modify the spore DNA content of B subtilis by altering the richness of the sporulation medium, the sporulation conditions (liquid or solid medium), or by mutation, were apparently unsuccessful. An increase of spore size with medium richness, not accompanied by an increase in DNA content, was observed. The implication of the apparently species-specific spore ploidy and the influence of the sporulation conditions on spore size and shape are discussed.

Bacillus↗
PubMed1984

Hypochlorite effects on spores and spore forms of Bacillus subtilis and on a spore lytic enzyme.

Spores of Bacillus subtilis NCTC 10073 were converted to ion-exchange (Ca, H) forms and coat-defective (urea-mercaptoethanol, urea-dithiothreitol-sodium lauryl sulphate) forms. The resistance of these to sodium hypochlorite (1000 parts/10(6) free chlorine) was compared and related to uptake from which the assumed monolayer capacities were calculated. Hypochlorite effects on spore protoplasts and cortical fragments were also examined in relation to DPA and hexosamine release. A spore lytic enzyme was extracted and examined in respect of hypochlorite activity. The results are discussed in terms of the mechanism and site of action of hypochlorite on the bacterial spore.

Bacillus subtilis↗
PubMed1977

Bacteriophage conversion of spore-negative mutants to spore-positive in Bacillus pumilus.

A pseudolysogenic phage, PMB1, was isolated from soil on the basis of its ability to increase the sporulation frequency of the oligosporogenic Bacillus pumilus strain NRS 576 (sporulation frequency, less than 1%). Several spore-negative mutants (sporulation frequency, less than 10-8) derived from strain NRS 576, which were converted to spore positive by infection with PMB1, were subsequently identified. PMB1 repeatedly grown on a given spore-negative mutant (e.g., GW2) converted GW2 cells to spore positive. Each plaque-forming unit initiated the conversion of a spore-positive clone in semisolid agar overlays. GW2 cells remained spore positive as long as they maintained PMB1. Return of PMB1-converted cells to the orginal spore-negative phenotype correlated with loss of PMB1. In liquid media, PMB1 infection increased the sporulation frequency of mutant GW2 over 106-fold. More than half of the spore-negative mutants we isolated from strain NRS 576 were converted to spore positive by PMB1 infection. PMB1-induced spores of the spore-negative mutant GW2 were somewhat more heat sensitive than uninfected or PMB1-infected spores of the spore positive parent of GW2. PMB1-induced spores of GW2 do not differ from wild-type spores in morphology by phase-contrast microscopy, dipicolinic acid content, or rate of sedimentation through Renografin gradients.

Bacillus↗
PubMed1973

Glutamic acid decarboxylase in spores of Bacillus megaterium and its possible involvement in spore germination.

Spores of Bacillus megaterium were examined for glutamic acid decarboxylase (GAD). Although dormant spores showed no GAD activity, spores given sonic treatment and heat-activated spores had high activities when assayed for this enzyme. Several parameters of GAD in heat-activated spores were examined. The effects of KCN, NaN(3), 2,4-dinitrophenol, and KF on GAD activity were examined. Only KCN was an effective inhibitor of GAD activity in heated spores and was also shown to be the only effective inhibitor of GAD activity in vegetative bacteria. Similar patterns of inhibition were obtained with GAD activity and with spore germination, KCN being the only effective inhibitor of both, although at different concentrations. Spore GAD activity in heat-activated spores showed a loss with storage at 4 C; on the other hand, storage at 25 C was not accompanied by a loss, but, to the contrary, showed an increase in GAD activity of about 30%. A comparison of GAD activity at different times during germination, growth, and sporulation showed it to be highest in freshly germinated spores. Although vegetative cells contained GAD activity, the level in log-phase cells was approximately one-half the level obtained with freshly germinated spores. Heat-activated mutant spores with a requirement of gamma-aminobutyric acid for germination gave no GAD activity. GAD activity appeared in mutant spores after germination and increased to levels comparable to parent spores after 9 min of germination.

Aminobutyrates↗
PubMed1986

Essential role of small, acid-soluble spore proteins in resistance of Bacillus subtilis spores to UV light.

Bacillus subtilis strains containing deletions in the genes coding for one or two of the major small, acid-soluble spore proteins (SASP; termed SASP-alpha and SASP-beta) were constructed. These mutants sporulated normally, but the spores lacked either SASP-alpha, SASP-beta, or both proteins. The level of minor SASP did not increase in these mutants, but the level of SASP-alpha increased about twofold in the SASP-beta- mutant, and the level of SASP-beta increased about twofold in the SASP-alpha- mutant. The growth rates of the deletion strains were identical to that of the wild-type strain in rich or poor growth media, as was the initiation of spore germination. However, outgrowth of spores of the SASP-alpha(-)-beta- strain was significantly slower than that of wild-type spores in all media tested. The heat resistance of SASP-beta- spores was identical to that of wild-type spores but slightly greater than that of SASP-alpha- and SASP-alpha(-)-beta- spores. However, the SASP-alpha- and SASP-alpha(-)-beta- spores were much more heat resistant than vegetative cells. The UV light resistances of SASP-beta- and wild-type spores were also identical. However, SASP-alpha(-)-beta- spores were slightly more sensitive to UV light than were log-phase cells of the wild-type or SASP-alpha(-)-beta- strain (the latter have identical UV light resistances); SASP-alpha- spores were slightly more UV light resistant than SASP-alpha(-)-beta- spores. These data strongly implicate SASP, in particular SASP-alpha, in the UV light resistance of B. subtilis spores.

Bacillus subtilis↗
PubMed1981

Mutual relationship between antibiotics and resting spores of Bacillus subtilis: morphological changes and macromolecular synthesis after germination of spores treated with cyclic polypeptide and aminoglycoside antibiotics.

Morphological changes and synthesis of DNA, RNA, protein, and cell wall were investigated during germination of resting spores of Bacillus subtilis exposed transiently to the cyclic polypeptide antibiotics, polymyxin B and gramicidin S, and the aminoglycoside antibiotics, streptomycin, kanamycin, and gentamicin. Normal germinated spores showed breaks of the spore coat, a diminution in size and a fibrillar appearance of the cortex, a swelling core, a cell wall as thick as that of vegetable cells, some mesosomes and DNA fibrils. On the other hand, no breaks of the spore coat, a spore core with a slight swelling and irregular form, a thin cell wall, no demonstration of the nuclear material and no granularity in the cytoplasm were characteristic of the germinated spores derived from polymyxin B- and gramicidin S-treated resting spores. With gramicidin S-treated germinated spores a few vacuoles were formed in the cytoplasm. Both polymyxin B- and gramicidin S-treated germinated spores showed little or no synthesis of DNA, RNA, and protein. The vegetative cells derived from streptomycin-treated resting spores demonstrated several finely granular regions in the cytoplasm and a disorder of the fibrillar nucleoid, and their autolysis occurred early. Their DNA and RNA synthesis was normal, whereas protein synthesis was low. In spite of no occurrence of cell division and very low protein synthesis, the most striking characteristics of the outgrowing cells derived from kanamycin-treated resting spores were a markedly thickened cell wall and a continuous incorporation of labeled D-alanine suggesting cell wall synthesis; RNA synthesis was slightly lower and DNA synthesis was almost normal. The outgrowing cells from gentamicin-treated resting spores also revealed relatively thick cell walls and a very slight incorporation of labeled D-alanine. Their DNA and RNA synthesis was fairly low and protein synthesis was almost completely inhibited. These results coincide with the growth curves of individual antibiotic-treated resting spores.

Aminoglycosides↗
PubMed1987

Changes in the hydrophobic characteristics of Clostridium perfringens spores and spore coats by heat.

The hydrophobic characteristics of Clostridium perfringens NCTC 8679 spores were demonstrated by adherence to toluene in a toluene-aqueous partition system. Spores and spore coat preparations were hydrophobic. Vegetative cells and spores extracted with a dithiothreitol-sodium dodecyl sulfate treatment known to remove spore coats were not hydrophobic. A heat activation treatment (75 degrees C for 20 min) which promotes more rapid spore germination increased the hydrophobicity of intact spores and decreased that of isolated spore coats. The hydrophobic changes were reversed by washing and stabilized by 0.5% glutaraldehyde. Heat-induced hydrophobic changes were observed in spore coats prepared from spores that were preheated and washed before rupturing in a buffer containing glutaraldehyde. These results suggest the occurrence of a heat-induced change in the spore coat (possibly in the conformation of a macromolecule) which was stable only within the architectural confines of the intact spore.

Bacterial Adhesion↗
PubMed1987

Thymine-containing dimers as well as spore photoproducts are found in ultraviolet-irradiated Bacillus subtilis spores that lack small acid-soluble proteins.

Dormant spores of a Bacillus subtilis mutant that lacks two major small, acid-soluble spore proteins are very sensitive to UV irradiation, which in spores generates about half the amount of thymine-containing dimers formed by comparable irradiation of vegetative cells. Irradiation of mutant spores also produces spore photoproducts, but again only about one-half the amount formed in comparably irradiated wild-type spores. These findings suggest that the high UV sensitivity of the mutant spores is due to the production of pyrimidine dimers, which are not found in UV-irradiated wild-type spores, and that the high level of small, acid-soluble proteins found in wild-type spores is directly involved in spore UV resistance by facilitating a conformational change in spore DNA, preventing pyrimidine dimer formation.

Bacillus subtilis↗
PubMed1987

Involvement of the spore coat in germination of Bacillus cereus T spores.

Bacillus cereus T spores were prepared on fortified nutrient agar, and the spore coat and outer membrane were extracted by 0.5% sodium dodecyl sulfate-100 mM dithiothreitol in 0.1 M sodium chloride (SDS-DTT) at pH 10.5 (coat-defective spores). Coat-defective spores in L-alanine plus adenosine germinated slowly and to a lesser extent than spores not treated with SDS-DTT, as determined by decrease in absorbance and release of dipicolinic acid and Ca2+. Spores germinated in calcium dipicolinate only after treatment with SDS-DTT. Biphasic and triphasic germination kinetics were observed with normal and coat-defective spores, respectively, in an environment with temperature increasing from 20 to 65 degrees C at a rate of 1 degree C/min. Therefore, the physical and biochemical processes involved in germination are modified by coat removal. The data suggest that a portion of the germination apparatus located interior to the coat may be protected by the coat and outer membrane or that the coat and outer membrane otherwise enhance germination in L-alanine plus adenosine. When coat-defective spores were heat activated with the dialyzed (12,000-Mr cutoff) components extracted from the spores, germination of the SDS-DTT-treated spores was enhanced; thus, one or more components located in the spore coat or outer membrane with a molecular weight greater than 12,000 were essential for fast germination.

Alkanes↗
PubMed1976

Dry-heat inactivation of Bacillus subtilis var. niger spores with special reference to spore density.

The dry-heat inactivation kinetics of Bacillus subtilis var. niger (ATCC9372) spores has been studied in the temperature range of 120-190 degrees C. The spores were applied to glass plates of a standardized area (3.24 cm2). Spore preparations of five different spore densities were used (8.3 X 10(4), 7.4 X 10(6), 6.3 X 10(7), and 6.6 X 10(8) spores per sample, respectively). The heat resistance of the spore was dependent on the number of spores per surface unit. Maximum resistance was observed when the concentration was 7.4 X 10(5) spores per sample. The D-values obtained at 160 degrees C from these samples were about twice as high as the D-values obtained from samples with a concentration of 6.3 X 10(7) or 6.6 X 10(8) spores per sample. The z-value was found to be independent of spore density. Thus, for the two concentrations 7.4 X 10(5) and 6.3 X 10(7) spores per sample, the z-value was found to be 22 degrees C and constant over the temperature range investigated.

Bacillus subtilis↗
PubMed1991

Ultraviolet irradiation of DNA complexed with alpha/beta-type small, acid-soluble proteins from spores of Bacillus or Clostridium species makes spore photoproduct but not thymine dimers.

UV irradiation of complexes of DNA and an alpha/beta-type small, acid-soluble protein (SASP) from Bacillus subtilis spores gave decreasing amounts of pyrimidine dimers and increasing amounts of spore photoproduct as the SASP/DNA ratio was increased. The yields of pyrimidine dimers and spore photoproduct were less than 0.2% and 8% of total thymine, respectively, when DNA saturated with SASP was irradiated at 254 nm with 30 kJ/m2; in the absence of SASP the yields were reversed-4.5% and 0.3%, respectively. Complexes of DNA with alpha/beta-type SASP from Bacillus cereus, Bacillus megaterium, or Clostridium bifermentans spores also gave spore photoproduct upon UV irradiation. However, incubation of these SASPs with DNA under conditions preventing complex formation or use of mutant SASPs that do not form complexes did not affect the photoproducts formed in vitro. These results suggest that the UV photochemistry of bacterial spore DNA in vivo is due to the binding of alpha/beta-type SASP, a binding that is known to cause a change in DNA conformation in vitro from the B form to the A form. The yields of spore photoproduct in vitro were significantly lower than in vivo, perhaps because of the presence of substances other than SASP in spores. It is suggested that as these factors diffuse out in the first minutes of spore germination, spore photoproduct yields become similar to those observed for irradiation of SASP/DNA complexes in vitro.

Bacillus↗
PubMed1991

Expression of meiotic drive elements Spore killer-2 and Spore killer-3 in asci of Neurospora tetrasperma.

It was shown previously that when a chromosomal Spore killer factor is heterozygous in Neurospora species with eight-spored asci, the four sensitive ascospores in each ascus die and the four survivors are all killers. Sk-2K and Sk-3K are nonrecombining haplotypes that segregate with the centromere of linkage group III. No killing occurs when either one of these killers is homozygous, but each is sensitive to killing by the other in crosses of Sk-2K x Sk-3K. In the present study, Sk-2K and Sk-3K were transferred by recurrent backcrosses from the eight-spored species Neurospora crassa into Neurospora tetrasperma, a pseudohomothallic species which normally makes asci with four large spores, each heterokaryotic for mating type and for any other centromere-linked genes that are heterozygous in the cross. The action of Sk-2K and Sk-3K in N. tetrasperma is that predicted from their behavior in eight-spored species. A sensitive nucleus is protected from killing if it is enclosed in the same ascospore with a killer nucleus. Crosses of Sk-2K x Sk-2S, Sk-3K x Sk-3S, and Sk-sK x Sk-3K all produce four-spored asci that are wild type in appearance, with the ascospores heterokaryotic and viable. The Eight-spore gene E, which shows variable penetrance, was used to obtain N. tetrasperma asci in which two to eight spores are small and homokaryotic. When killer and sensitive alleles are segregating in the presence of E, only those ascospores that contain a killer allele survive. Half of the small ascospores are killed. In crosses of Sk-2K x Sk-3K (with E heterozygous), effectively all small ascospores are killed. The ability of N. tetrasperma to carry killer elements in cryptic condition suggests a possible role for Spore killers in the origin of pseudohomothallism, with adoption of the four-spored mode restoring ascospore viability of crosses in which killing would otherwise occur.

Crosses, Genetic↗
PubMed1981

Extraction of spore-lytic enzyme from Clostridium perfringens spores.

Various chemical reagents known to extract spore coat protein were used to extract spore-lytic enzyme (SLE) from intact and germinated spores of Clostridium perfringens. Of the reagents tested, 7.2 M-urea plus 10% (v/v) mercaptoethanol, pH 2.85, solubilized the most SLE activity per mg spores. The quantity of SLE extracted was dependent on the initial pH of the reagent, with a maximum between pH 2.7 and 3.0. Germinated spores yielded more SLE than non-germinated spores upon urea/mercaptoethanol extraction. SLE release during spore germination probably utilizes a trigger mechanism not satisfied by germination alone. Significant amounts of SLE were released during germination when spores were suspended in potassium chloride or a complex germinant mixture containing brain-heart infusion, yeast extract and chloramphenicol, but not during germination with sodium nitrite, which non-enzymically lysed the cortical peptidoglycan. Greater solubilization of SLE activity was obtained by urea/mercaptoethanol extraction of spores germinated with nitrite than of spores germinated with either potassium chloride or the complex germinant.

Clostridium perfringens↗
PubMed1977

Mitochondrial biogenesis during fungal spore germination: respiratory cytochromes of dormant and germinating spores of Botryodiplodia.

The mitochondrial respiratory cytochrome contents of dormant and germinating conidia of Botryodiplodia theobromae were examined. Oxidized versus reduced difference spectra at 77 degrees K of whole mitochondria from physiologically mature germinated spores showed a typical a-band pattern for cytochromes c, b, and a, with absorption maxima at 549, 554 + 559, and 604 nm, respectively, whereas the difference spectrum of the counterpart mitochondrial fraction from dormant spores showed no cytochrome a bands. However, a fraction prepared from dormant spore mitochondria by detergent extraction and (NH4)2SO4 fractionation contained readily detectable quantities of cytochromes c and b (as shown by the a and Soret absorption bands), but it did not contain the a or Soret bands of cytochrome a observed in a counterpart preparation from germinated spores. The pyridine hemochromogen preparation from the dormant spore mitochondria contained no material that is spectroscopically characteristic of a-type heme and protoheme. These results suggest that cytochrome a is not present as a functional molecule in dormant spores. The first spectroscopically detectable cytochromes were observed in whole mitochondria at 210 min of spore germination, and the amount of each of the cytochromes increased with cell growth. A precursor of the heme porphyrin, delta-[4-14C]aminolevulinic acid, was first incorporated (at accelerating rates) into acid-insoluble spore material at 180 min of germination, which appears to be the approximate time of organization of new mitochondria in these spores.

Aminolevulinic Acid↗
PubMed1968

Correlation between spore structure and spore properties in Bacillus megaterium.

The spores of six strains of Bacillus megaterium were divided into two distinct groups on the basis of germination. Three of the strains germinated in a mixture of l-alanine and inosine (AL type spores), and three strains germinated in a mixture of glucose and potassium nitrate (GN type spores); recriprocal germination in the respective solutions did not occur. The AL spores and the GN spores were morphologically distinct. Other differences between the two spore groups included germination inhibition characteristics, dipicolinic acid content, hexosamine content, phosphorus and magnesium content, spore coat features, ion exchange properties, and heat resistance. A correlation appears to exist between spore morphology and certain other spore properties in strains of B. megaterium.

Bacillus megaterium↗
PubMed1983

High calcium content in Streptomyces spores and its release as an early event during spore germination.

The metal ion content of spores of five Streptomyces species was studied. A general feature of this study was the finding of a very high calcium content (1.1 to 2.1% of the dry weight). Accumulation of calcium occurred preferentially during the sporulation process. Spore calcium was located in the integument fraction, and more than 95% of the calcium was removed from intact spores by ethylene glycol-bis(beta-aminoethyl ether)-N,N-tetraacetic acid. Several divalent cations (Mg2+, Mn2+, Zn2+, and Fe2+) which induced darkening of spores and loss of heat resistance also caused the release of calcium from spores. In addition, darkening of spores was blocked by metabolic inhibitors, whereas calcium excretion was not affected. Two different categories of events in the initiation of germination may be differentiated; first, calcium release from spores which is not energy dependent and is a consequence of triggering of germination by some divalent cations, and second, some other events including loss of heat resistance, loss of spore refractility, and a decrease in absorbance, with at least one energy-dependent step.

Calcium↗
PubMed1991

Structural and germination defects of Bacillus subtilis spores with altered contents of a spore coat protein.

The start sites for transcription and translation of a Bacillus subtilis spore coat protein gene, cotT, were determined. The CotT protein was synthesized as a 10.1-kDa precursor which was processed to a coat polypeptide of 7.8 kDa. Insertional inactivation of the cotT gene resulted in spores with an altered appearance of the inner coat layers and slow germination in response to a germination solution containing fructose, glucose, and asparagine. Rates of germination in L-alanine and in Penassay broth were the same as that of the wild type. A strain containing the cotT gene on a low-copy-number plasmid produced spores with an excess of CotT precursor and a thickening of the striated inner coat. These spores responded poorly to all of the germinants mentioned above. A site-directed mutation of the codon at the processing site of CotT resulted in the accumulation of the precursor in sporulating cells and on the spores, but there was no effect on the germination rates or solvent resistance of these spores. Both the lack and the overproduction of CotT led to subtle alterations in the structure of the inner spore coat and in the capacity of spores to respond to particular germinants.

Amino Acid Sequence↗