Streptomyces viridochromogenes spore germination initiated by calcium ions

Abstract

Initiation of germination of heat-activated Streptomyces viridochromogenes spores occurs in media containing only calcium ions and organic buffer. The calcium-induced initiation of germination was accompanied by a decrease in absorbance of the spore suspension, an increased rate of endogenous metabolism, the loss of spore carbon, and the loss of heat resistance. Calcium amounts to 0.28% of the dry weight of freshly harvested spores. The amount of calcium remained the same after incubation of spores in water and after heat activation. The spore content of calcium doubled after incubation in 0.5 mM CaCl2 for 5 min at 4°C and during calcium-induced germination. Nearly all of the calcium appears to be bound to sites external to the spore membrane, since the chelating agents (ethylenedinitrilo)tetraacetic acid and arsenazo III removed virtually all of the calcium ions. The calcium ions must be present during the entire initiation of germination period. Germination ceases after an (ethylenedinitrilo)tetraacetic acid wash and begins again immediately after addition of calcium ions. Spores of Streptomyces viridochromogenesgerminate when incubated in a defined medium (DGM) comprised of alanine, glutamic acid, adenosine, MgSO4, and CaCl2 (4). The early events in germination, to be referred to as initiation of germination in this paper, involve loss of refractility of the spores accompanied by a decrease in optical density, excretion of spore carbon, increased respiratory activity and ATP content, and release of a germination inhibitor compound (4, 6). Germination is dependent on a continual supply of CO2 which serves to replenish tricarboxylic acid intermediates through anaplerotic fixation reactions (2).The data to be presented establish that the physiological events associated with germination of the spores can be initiated by calcium ions alone. Initiation of germination is dependent on the capacity for production of energy. As mentioned above, germination is accompanied by increased respiratory activity and ATP production. In addition, chemicals that affect energy production, such as cyanide, carbonyl cyanidem-chlorophenylhydrazone, arsenate, dicumarol, and phenazine methosulfate, completely inhibit the initiation process, and the germination inhibitor molecule (6) was recently found to be a specific sodium-potassium ATPase inhibitor (unpublished observations). Germination of S. antibioticus spores is also dependent on energy production (3). Initiation of germination of streptomyces spores appears to be quite a differt Present address: U. S. Department of Agriculture, Forest Service, Forest Products Laboratory, Madison, WI 53705. ent process than that of Bacillus megaterium endospores, where production of energy is not involved (1,8). Germination of fungal spores requires a continuous supply of energy (9, 10).We report in this paper the results of an investigation of the mechanism by which calcium ions initiate germination of S. viridochromogenes spores.MATERIALS AND METHODS Organisms and growth conditions. The organis...

Effects of Metals on Streptomyces coelicolor Growth and Actinorhodin Production

“…The studies of Salas et al (13) showed that there was a high calcium content in spores of Streptomyces spp. and that for some species it was an essential triggering factor of spore germination (6,13). Examination of Fig.…”

Pre-sporulation stages ofStreptomycesdifferentiation: state-of-the-art and future perspectives

“…Darkening only required exogenous divalent cations (Ca 2+ , Mg 2+ or Fe 2+ ) and spore energy reserves. Calcium was reported to accumulate in the spore covers and be released during germination (Eaton & Ensign, 1980;Salas et al, 1983). Wang et al (2008) demonstrated that calcium regulation could be mediated, at least in part, by cabC, a gene encoding an EF-hand calciumbinding protein.…”

Pathways of glucose catabolism during germination of Streptomyces spores

“…When glucose is metabolized by the EMP pathway with the operation of the tricarboxylic acid cycle, C-1 and C-6 are equivalent and produce equal amounts of CO2; the difference between the percentages of respiratory CO 2 in these carbons will indicate the actual participation of the PP pathway. Therefore, the comparison of the ratio [C-1]-[C-6]/[C- 3,4] along the different developmental stages will give us information about the changes occurring in the participation of both pathways in glucose catabolism. A comparison of these values ( Table 2) showed that this ratio continuously increased during germination, indicating that the participation of the PP pathway in glucose catabolism continuously increased during the germination process.…”

“…">INTRODUCTIONIn the early stages of germination (i.e., the darkening process), Streptomyces spores require the presence of individual divalent cations and no exogenous energy source is needed [1,2]. However, this is an energy-dependent process which is blocked by inhibitors of energy-producing metabolism [1,3], although a very early event such as calcium release is not affected by these inhibitors [4]. It is therefore assumed that, during initiation of germination, the spore must mobilize endogenous energetic reserves [1].…”