REVERSIBLE ACTIVATION FOR GERMINATION AND SUBSEQUENT CHANGES IN BACTERIAL SPORES

Modification of GerQ reveals a functional relationship between Tgl and YabG in the coat of Bacillus subtilis spores

Here we describe the functional relationship between YabG and transglutaminase (Tgl), enzymes that modify the spore coat proteins of Bacillus subtilis. In wild-type spores at 37 degrees C, Tgl mediates the crosslinking of GerQ into higher molecular mass forms; however, some GerQ multimers are found in tgl mutant spores, indicating that Tgl is not essential. Immunoblotting showed that spores isolated from a yabG mutant after sporulation at 37 degrees C contain only very low levels of GerQ multimers. Heat treatment for 20 min at 60 degrees C, which maximally activates the enzymatic activity of Tgl, caused crosslinking of GerQ in isolated yabG spores but not in tgl/yabG double-mutant spores. In addition, the germination frequency of the tgl/yabG spores in the presence of l-alanine with or without heat activation at 60 degrees C was lower than that of wild-type spores. These findings suggest that Tgl cooperates with YabG to mediate the temperature-dependent modification of the coat proteins, a process associated with spore germination in B. subtilis.

ACTIVATION OF BACTERIAL ENDOSPORES

A. Keynan (Israel Institute of Biological Research, Ness Ziona, Israel), Z. Evenchik, H. O. Halvorson, and J. W. Hastings. Studies on the activation of bacterial endospores. J. Bacteriol. 88:313-318. 1964.-Heat activation of bacterial endospores was imitated by suspending spores in reducing agents (mercaptoethanol or thioglycolate) or in a pH less than 4.5. Urea (6 m) had no effect on spores. In addition to the well-known activation at 65 C for 45 min, spores were also activated by exposure to 34 C for 48 hr. The activation by heat and by reducing agents was reversible; the reverse reaction was temperature-dependent. No reversion occurred at -20 C, whereas at 28 C the spores reversed to their original dormant state within 72 hr. It is suggested that the heat-activation phenomenon could be explained by assuming that heat or reducing agents change the tertiary structure of a protein responsible for the maintenance of the dormant state by reducing the disulfide linkages which stabilize the protein in a specific configuration. The partial denaturation of this protein is reversible by reoxidation of the reduced disulfide bonds.

[Ethylene oxide sterilization. I. Influence of the sporulation medium on the resistance of spores of Bacillus subtilis var. niger]

Some elements influencing the resistance of spores used in ethylene oxide sterilization process control are standardized. Spores of Bacillus subtilis var. niger were produced in chemically defined liquid and solid sporulation media to a total of 12 lots; after standardization of the number of spores, they were challenged by sub-lethal cycles, followed by a lethality study. According to the statistical model applied, there were no differences between the resistance of spores produced in chemically defined liquid and those produced in solid sporulation media. The advantage of the solid sporulation media consists in the larger production of spores.

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.

Study of Bacillus subtilis Endospores in Soil by Use of a Modified Endospore Stain

The Schaeffer-Fulton endospore stain was modified so that it would stain Bacillus subtilis endospores in soil smears. The modified stain differentiated among dormant spores, spores undergoing activation, and spores which had germinated but had not yet shown outgrowth. These differentiations were seen for spores in soil and for pure spore preparations in the laboratory. This stain was used to show reversible B. subtilis spore activation promoted by an Ensifer adhaerens -like indigenous bacterium in soil and by pure cultures of E. adhaerens added to spores in the laboratory. Under the specific conditions in the laboratory, spore germination did not proceed beyond the activation stage, and relatively little change occurred in the numbers of both E. adhaerens and B. subtilis. This was also true in soil, although some germination with destruction of spores and vegetative cells did occur if the soil had been nutritionally enriched by preincubation with incorporated ground alfalfa.

Factors influencing the resistance of biological monitors to ethylene oxide

The resistance of bacterial spore monitors is markedly influenced by the environmental conditions existing during development of spores and, subsequently, in the preparation and evaluation of the monitor. Sporulation medium, suspending medium, pasteurization and storage conditions influence resistance of spores of Bacillus subtilis var. niger to ethylene oxide, but incubation temperature and age of sporulating culture appear to be unimportant. The conditions under which the spore suspension is dried on the supporting medium of the monitor exerts a major influence on resistance. Spores exposed to ethylene oxide are abnormally susceptible to damage by shaking with Ballotini, a method frequently used to recover spores from monitors. Nutritional conditions, pH and temperature of incubation influence the ability of survivors to form colonies on solidified media.

Effects of added germination agents on loss of optical density in electron-irradiated spores

Spores of Bacillus megaterium ATCC 14581, subjected to partial-cell iradiation, were exposed to either lysozyme, H2O2, or glucose in an attempt to reduce or eliminate the nonmonotonic behavior in curves of percentage of germination versus energy, obtained when such spores were resuspended in phosphate buffer alone. Except at the lower doses. H2O2 effectively eliminated this anomalous dip in these curves, whereas lysozyme amplified it greatly. Glucose was generally ineffective. Coinciding with the increases in optical density when lysozyme was present was the formation of an occluding product.

Spores of microorganisms. XXVI. Synthetic activities of germinating spores of Bacillus cereus prevented from outgrowth

Spores of Bacillus cereus were germinated in a germination limited medium (GL-medium) which facilitates only germination but not the postgerminative development of spores. Under these conditions a limited protein synthesis occurs. However, this protein synthesis is stopped after a short time interval. The rate of synthesis of new proteins, as well as their total amount, is influenced by the length of the activation heat shock. Synthesis of the wall material continues for several hours and thick-walled cells with a changed ultrastructure are formed. Synthesis of the diaminopimelic acid (dap) containing material of the cell wall is sensitive to actinomycin D and relatively resistant to chloramphenicol. Similarly, protein synthesis is relatively chlorapmhenicol-resistant but is fully inhibited by azauracil or spiramycin. Whereas RNA formed in the control culture is partially decomposed after 30 min of incubation, chloramphenicol accelerates its synthesis and prevents its decay. Exudate components apparently stimulate synthesis of ribonucleic acid, proteins and the wall material. The 14-C-dap containing material released by prelabelled spores in the form of the exudate during the germination is not re-utilized by the spores germinated in the GL-medium. The results are discussed with respect to the atypical primary synthetic activities of spores under conditions when the postgerminative development is prevented and from the point of view of participation of the germination exudate during these syntheses.

Ultrahigh-temperature activation of a low-temperature Bacillus subtilis spore germination system

Exposure of Bacillus subtilis A spores to 115 to 125 C for several seconds activated a low-temperature germination system that remained dormant after a heat treatment that activated the normal l-alanine- and glucose-stimulated germination systems. The low-temperature germination system was characterized by an optimum temperature lower than that of the l-alanine or glucose germination systems (30 C versus 45 C), germination in the absence of exogenous germination stimulants, and the capacity for heat-induced deactivation and subsequent reactivation. The rates of activation at 115 to 125 C were exponential and were not influenced by a previous heat treatment that activated the l-alanine- or glucose-stimulated germination systems. Although activation of the low-temperature germination system was accompanied by suppression of l-alanine-stimulated germination, it did not appear to be a modification of the l-alanine germination system.

Biochemical studies of bacterial sporulation and germination. XVII. Sulfhydryl and disulfide levels in dormancy and germination

A fourfold increase in sulfhydryl content upon germination of Bacillus megaterium spores was observed by the standard fluorescein mercuric acetate assay as reported by others. However, assay of ruptured dormant spores or the use of N-ethylmaleimide and a denaturing agent on intact spores showed a constant sulfhydryl level in dormancy and in germination. The apparent increase in sulfhydryl groups observed on germination was shown to be due to inaccessibility of most sulfhydryl groups in the dormant spore to sulfhydryl reagents. The disulfide content of dormant spores showed no change on germination, nor was any evidence found for production of low-molecular-weight sulfhydryl or disulfide compounds during germination.

Initiation of germination and inactivation of Bacillus pumilus spores by hydrostatic pressure

The effect of hydrostatic pressures as high as 1,700 atm at 25 C on the heat and radiation resistance of Bacillus pumilus spores was studied. Phosphate-buffered spores were more sensitive to compression than spores suspended in distilled water. Measurements of the turbidity of suspensions, the viability, refractility, stainability, dry weight, and respiratory activity of spores, and calcium and dipicolinic acid release were made for different pressures and times. Initiation of germination occurred at pressures exceeding 500 atm and was the prerequisite for inactivation by compression. The rate of initiation increased with increasing pressure at constant temperature. This result is interpreted as a net decrease in the volume of the system during initiation as a result of increased solvation of the spore components.

Water vapor, aqueous ethyl alcohol, and heat activation of Bacillus megaterium spore germination

Dormant spores of Bacillus megaterium were activated for germination on glucose by heating them in aqueous suspension (but not if heated dry), by treating them with aqueous ethyl alcohol at 30 C, or by exposing them to water vapor at room temperature. The degree of water vapor activation depended upon the relative humidity, the time, and the temperature of exposure. Activation increased the extent and rate of glucose-induced germination and decreased the average microlag. Extended water vapor treatment also activated spores for germination induced by KI and by l-alanine. Spores activated by any of the three treatments were deactivated by treatment at 66 C, either for 18 hr in 100% ethyl alcohol or for 40 hr over P(2)O(5). Deactivated spores were reactivated by heat, by 5 m ethyl alcohol, or by water vapor. It is postulated that heating and ethyl alcohol may change the structure of liquid water, so that it is more like water vapor and can more readily penetrate to and hydrate a critical (enzymatic?) spore site, leading to activation.

Direct Transition of Outgrowing Bacterial Spores to New Sporangia Without Intermediate Cell Division

Vinter, Vladimir (Syracuse University, Syracuse, N.Y.), and Ralph A. Slepecky . Direct transition of outgrowing bacterial spores to new sporangia without intermediate cell division. J. Bacteriol. 90: 803–807. 1965.—A direct transition was observed of the primary cell developed after germination of Bacillus cereus spores into new sporangia without intermediate division stages. Two simple methods were used for replacement of outgrowing spores into diluted medium or saline. Elongated primary cells prevented from division by limitation of nutrients in the suspending medium were able to form new forespores in 8 hr and sporangia in 12 hr. These new sporangia were still marked by attached envelopes of the original spore. Under the same conditions, cells replaced during the first divisions quickly lysed. Spores formed in the elongated primary cell during “microcycle sporogenesis” possessed normal heat resistance and refractility and were later released from sporangia.