Macromolecular Synthesis During Microcycle Sporogenesis of Bacillus cereus T

Microcycle sporogenesis induced in Bacillus cereus T by phosphate limitation occurs over a narrow range of phosphate to spore inoculum ratios. Sufficient phosphate is required to satisfy the demands for a twofold increase in deoxyribonucleic acid; net ribonucleic acid synthesis is not required. The total ribonucleic acid content of the culture was variable, and deoxyribonucleic acid synthesis was restricted to a twofold increase. Developmental changes during outgrowth occurred synchronously, whereas enzyme synthesis was periodic. The timing of the synthesis of tricarboxylic cycle enzymes, extracellular protease, arginase, histidase, and alkaline phosphatase was measured. Histidase could be induced after 2.5 hr throughout microcycle sporogenesis. Several other features of macromolecular synthesis during microcycle sporogenesis are described. Differences between this pattern and those observed during outgrowth leading to cell division are discussed. A technique for accurately estimating the levels and time of synthesis of incompletely extractable, labile enzymes is also presented.     

Biochemical changes occurring during microcycle sporogenesis of Bacillus cereus T.

The biochemical changes occurring during microcycle sporogenesis of $\text{B. cereus}$ T in glucose enriched Mackechnie and Hanson medium(1) was studied by using alpha picolinic acid and ethyl picolinate. Alpha picolinic acid inhibited microcycle sporogenesis by chelating with some metal essential for the transition of a vegetative cell to a sporulating cell probably by suppressing aconitase. The mode of action of ethyl picolinate did not seem to be metal chelation as its effects could not be reversed by zinc sulphate.     

Microcycle sporogenesis in some streptomycetes without shift down treatment

Conditions for microcycle sporogenesis in two streptomycete strains without shifting the culture were found. The sporulation in Streptomyces granaticolor took place after 24 h of cultivation. The dry mass was increasing till 32 h probably due to production of a hydrophobic substance resembling fibrous sheath of aerial hyphae and spores. Ultrathin section of microcycle spores are presented.     

Microcycle conidiation — A review

Microcycle conidiation is defined as the germination of spores by the direct formation of conidia without the intervention of mycelial growth, as occurs in most normal life cycles. It is a method of asexual spore formation in which the normal life cycle of the fungus is bypassed. Spores formed through sexual reproduction and species with unicellular thalli are not included in microcycle conidiation. The term secondary conidium or secondary spore is usually, but not always, synonymous with microcycle conidiation. In the laboratory various factors, but especially temperature, can induce the microcycle condition in such fungi asAspergillus niger, Penicillium andNeurospora crassa, providing a useful tool for research. Microcycle conidiation has also been reported in a broad range of species in nature, and comprises a normal part of the life cycle in several groups, including the Entomophthorales, Taphrinales, Clavicipitales, Uredinales, Ustilaginales, Tremellales and Exobasidiales. The presence of a microcycle in such fungi undoubtedly provides a survival mechanisn for spores that encounter unfavorable conditions.     

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.     

Microcycle Sporogenesis of Bacillus cereus in a Chemically Defined Medium

A chemically defined medium which allowed germination, outgrowth, and subsequent resporulation of Bacillus cereus T spores, without intervening cell division (microcycle sporogenesis), is described. No medium replacement was required. The second-stage spores were heat-stable and had similar germination characteristics and dipicolinic acid content to primary spores. Deoxyribonucleic acid (DNA) replication began soon after germination and there was a doubling in the DNA content of the cells within 2 hr.     

Induction of microcycle sporulation in Bacillus brevis spp. AG4 by amethopterin

Addition of amethopterin to medium before inoculation inhibited DNA synthesis and induced microcycle sporogenesis in Bacillus brevis spp. AG4. Synthesis of RNA and proteins occurred at a considerably reduced rate.Abbreviations TVC total viable counts - HSC heat stable counts - CDGS chemically defined medium for growth and sporulation - TCA trichloro acetic acid     

Achievement of complete Bacillus subtilis microcycle sporulation by the addition of S-adenosylmethionine and phospholipids.

In an attempt to find factors that may be responsible for the initiation of sporulation, a system in which the germination and outgrowth phases were separate was applied to Bacillus subtilis. Outgrowth of the germinated spores to only the primary singlet cells was followed in chemically defined medium. Addition of specific metabolites induced the primary singlet cells to sporulate via microcycle sporulation. Experiments are described that led to complete sporulation by the addition of diaminopimelic acid, S-adenosyl-L-methionine and phosphatidylethanolamine.     

Glyoxylate metabolism in growth and sporulation of Bacillus cereus

Megraw, Robert E. (Iowa State University, Ames), and Russell J. Beers. Glyoxylate metabolism in growth and sporulation of Bacillus cereus. J. Bacteriol. 87:1087-1093. 1964.-Isocitrate lyase and malate synthetase were found in cell-free extracts of Bacillus cereus T. The patterns of synthesis of enzymes of the glyoxylic acid cycle were dependent upon the medium in which the organism was grown. Cells grown in acetate or in an acetate precursor, such as glucose, produced enzymes of the glyoxylic acid cycle in greatly diminished quantities, as compared with cells grown in media containing glutamate or yeast extract as principal carbon sources. Glutamate-grown cells had high isocitrate lyase activity but very low malate synthetase activity. Glyoxylate produced in this situation is metabolized by alternate pathways: conversion to tartronic semialdehyde and the latter to glyceric acid, thus providing evidence for a glycerate pathway; and reduction to glycolate (the reverse of this reaction was present at a low rate). Enzymatic activity of the glyoxylic acid cycle declines at the point where sporogenesis begins, indicating a metabolic shift for the synthesis of spore material.     

灰绒泡菌生活史及其子实体发育过程的显微观察

为明确灰绒泡菌Physarum cinereum的个体发育特征,本研究在实验室条件下完成了该菌的生活史,并对其子实体发育过程进行显微观察。灰绒泡菌P. cinereum孢子萌发方式为裂式,显型原质团水白色;子实体形态建成可分为孢囊形成期和孢囊成熟期,孢囊成熟期幼孢囊颜色随着孢子的形成呈现白色-红棕色-黑褐色逐渐加深的变化;子实体在发育过程中孢丝形成后原生质割裂形成孢子。     

Germination of Aspergillus fumigatus conidia in the lungs of normal and cortisone-treated mice.

Inhaled conidia of Aspergillus fumigatus germinated in the lungs of mice at a low rate but both germinated and ungerminated spores were cleared. Spores germinated at a high rate in the lungs of cortisone-treated mice.     

Growth of Nosema algerae in Pig Kidney Cell Cultures*

SYNOPSIS. Nosema algerae, a microsporidan parasite of mosquitoes, can infect pig kidney cell cultures. Spores germinated in the culture medium, infected the cells within 30 min of germination, multiplied, and produced spores. The early developmental stages in the N. algerae life cycle are described.     

Oxidation of leucine by Leishmania donovani.

The metabolism of leucine by Leishmania donovani was investigated. Washed promastigotes were incubated with [1-14C]- or [U-14C]leucine or [1-14C]alpha-ketoisocaproate (KIC) and 14CO2 release was measured. The amount of KIC-derived acetyl-CoA oxidized in the citric acid cycle was computed. Promastigotes from mid-stationary phase cultures oxidized each of these labeled substrates less rapidly than cells from late log phase cultures, and significantly less acetyl-CoA derived from KIC oxidation was oxidized in the citric acid cycle. Glucose was a stronger inhibitor than was acetate of CO2 formation in the citric acid cycle in log phase promastigotes, but the reverse was observed in cells from mid-stationary phase. Alanine also inhibited leucine catabolism, but glutamate had little effect. Acute hypo-osmotic stress did not affect leucine catabolism, but hyper-osmotic stress caused appreciable inhibition of leucine oxidation. Cells grown under hypo- or hyper-osmotic conditions showed no changes in the effects of hypo- or hyper-osmotic stress on leucine catabolism, i.e. L. donovani is not an osmoconformer with respect to leucine metabolism. Leucine utilization in L. donovani was insensitive to a number of drugs that affect leucine metabolism in mammalian cells, indicating that the leucine pathway in L. donovani is not regulated in the same manner as in mammalian cells.     

The effects of white fluorescent light,far-red light,darkness, and moisture on spore germination of Lygodium heterodoxum (Schizaeaceae)

Spores of Lygodium heterodoxum Kunze were stored in dry and fully water-imbibed conditions in darkness at 23–25 C. Spores stored in dry conditions lose viability faster than those stored fully water-imbibed. After 1 year, less than 1% of the spores stored in dry condition germinated, while about 40% of the stored water-imbibed spores still germinated. The spores do not germinate in darkness, but they do germinate under white and far-red light.     

Role of acetate in sporogenesis of Bacillus cereus

Nakata, H. M. (Washington State University, Pullman). Role of acetate in sporogenesis of Bacillus cereus. J. Bacteriol. 91:784-788. 1966.-The distribution of radioactivity associated initially with acetate-2-C(14) was followed during sporogenesis of Bacillus cereus strain T. This was accomplished by replacing cells committed to sporulation into a chemically defined sporulation medium. It was observed that 65 to 70% of the initial radioactivity was incorporated into poly-beta-hydroxybutyrate, whereas 20 to 25% was found in other cellular constituents. Virtually no radioactivity was lost as C(14)O(2) during the first 5 to 6 hr after replacement. Then, a gradual evolution of C(14)O(2) coincident with poly-beta-hydroxybutyrate degradation, was observed until about the ninth hour. By this time, the polymer was essentially depleted, and the first spore structures were observed in stained preparations. The total amount of radioactivity lost as C(14)O(2) was 20 to 25%. The major portion of products derived from poly-beta-hydroxybutyrate was incorporated into the spores. As much as 17% of the radioactivity associated with the spores was found in dipicolinic acid. More than 50% was located in spore proteins, 20 to 25% in the hot 5% trichloroacetic acid-soluble fraction, 4 to 5% in the lipid fraction, and 15 to 20% in the cold 5% trichloroacetic acid-soluble fraction. These data, accounting for 70 to 75% of the initial radioactivity, confirmed the hypothesis that the major role of acetate, and subsequently of poly-beta-hydroxybutyrate, in sporulation of B. cereus T is to provide carbon precursors and energy for sporogenesis.     

The Effect of Oxidation-Reduction Potential on Spore Germination,Outgrowth, and Vegetative Growth of Clostridium tetani,Clostridium butyricum,and Bacillus subtilis

Spores of Clostridium tetani germinated in liver broth with +580 mV as the starting Eh value, and those of Clostridium butyricum germinated in liver broth with an initial Eh of +400 mV regardless of the presence or absence of a liquid paraffin covering. Spores of Bacillus subtilis germinated in liver broth with ?100 mV as the starting Eh value. Also, it was found that there are two ranges of starting Eh values for germination and vegetative growth of Cl. tetani, Cl. butyricum, and B. subtilis. In the first range these spores germinated and grew, but in the second range they only germinated and then died without outgrowth.     

Metabolism and the triggering of germination of Bacillus megaterium. Use of L-[3H]alanine and tritiated water to detect metabolism.

L-[2,3-3H]Alanine was used to probe for metabolism of alanine during triggering of germination of spores of Bacillus megaterium KM. No detectable incorporation of label into any compound, including water, was found, indicating that any metabolism involving the alanine germinant must be at a very low rate and also that alanine racemase is absent from spores of this strain. Spores were germinated in 3H2O to find if any of the many metabolic reactions causing irreversible incorporation of 3H into reaction products took place during triggering of germination. No incorporation was detected until 2-3 min after addition of germinants. It is therefore concluded that a wide variety of metabolic routes, including glycolysis, the tricarboxylic acid cycle, the pentose phosphate pathway and amino acid metabolism are either not involved in the reactions causing the triggering of germination or operate at an extremely low rate during this process.     

Factors affecting the germination of spores of Bacillus anthracis

Spores of Bacillus anthracis germinated poorly at high cell densities unless the alanine racemase inhibitor O-carbamyl-D-serine was added to the germination medium. Spores derived from a variety of strains of B. anthracis germinated optimally at 22°C. No correlation was found between rate of spore germination and virulence or between susceptibility of animal species to anthrax and spore germination rate using sera from those animals as the germination medium.     

Factors affecting the germination of spores of Bacillus anthracis

Spores of Bacillus anthracis germinated poorly at high cell densities unless the alanine racemase inhibitor O-carbamyl-D-serine was added to the germination medium. Spores derived from a variety of strains of B. anthracis germinated optimally at 22 degrees C. No correlation was found between rate of spore germination and virulence or between susceptibility of animal species to anthrax and spore germination rate using sera from those animals as the germination medium.     

Mechanisms of sorbate inhibition of Bacillus cereus T and Clostridium botulinum 62A spore germination.

The mechanism by which potassium sorbate inhibits Bacillus cereus T and Clostridium botulinum 62A spore germination was investigated. Spores of B. cereus T were germinated at 35 degrees C in 0.08 M sodium-potassium phosphate buffers (pH 5.7 and 6.7) containing various germinants (L-alanine, L-alpha-NH2-n-butyric acid, and inosine) and potassium sorbate. Spores of C. botulinum 62A were germinated in the same buffers but with 10 mM L-lactic acid, 20 mM sodium bicarbonate, L-alanine or L-cysteine, and potassium sorbate. Spore germination was monitored by optical density measurements at 600 nm and phase-contrast microscopy. Inhibition of B. cereus T spore germination was observed when 3,900 micrograms of potassium sorbate per ml was added at various time intervals during the first 2 min of spore exposure to the pH 5.7 germination medium. C. botulinum 62A spore germination was inhibited when 5,200 micrograms of potassium sorbate per ml was added during the first 30 min of spore exposure to the pH 5.7 medium. Potassium sorbate inhibition of germination was reversible for both B. cereus T and C. botulinum 62A spores. Potassium sorbate inhibition of B. cereus T spore germination induced by L-alanine and L-alpha-NH2-n-butyric acid was shown to be competitive in nature. Potassium sorbate was also a competitive inhibitor of L-alanine- and L-cysteine-induced germination of C. botulinum 62A spores.