Relationship between intracellular pH and antibiotic biosynthesis in Fusidium coccineum

A correlation between the value of the intracellular pH and the biosynthesis of fusidic acid was studied by ³¹P-NMR spectroscopy in two strains of the fungus Fusidium coccineum. One of the strains was highly active and the other strain had low activity with respect to the antibiotic production. The position of the orthophosphate resonance in the ³¹P-NMR spectra was considered as a measure of the intracellular pH. In the cells of the highly active strain pH was in the range 7.0–7.5 in the cytoplasm and 6.1–6.25 in the vacuoles. In the cells of the strain with low activity was in the range 7.3–7.9 in the cytoplasm and 6.0–6.2 in the vacuoles. During high antibiotic productivity, the intracellular pH in the highly active strain full sharply, while in the less active strain it effectively did not change. This suggested that the change in the intracellular pH was responsible for the action of the enzymes in the cells and could be a factor defining the function of the cyanide-resistant respiration pathway and consequently the synthesis of fusidic acid in F. coccineum. *** DIRECT SUPPORT *** AG903062 00009     

Characteristics of fucidin biosynthesis by a Fusidium coccineum 257 A strain

The physiological features of Fusidium coccineum, strain 257 A, an organism producing fusidin were studied. It was found that increased concentrations of the carbon sources in the medium stimulated production of fusidin, while an increase in the content of various forms of nitrogen differently affected the level of the antibiotic viosynthesis: high concentrations of the amino acid-peptide form of nitrogen of corn-steep liquor decreased, while the protein form of nitrogen was associated with consumption of the significant part of carbon in the medium for formation of the fungus mycelium. Therefore, the concentration of the easily mobilizing forms of nitrogen may be considered as a regulator of the growth process of F. coccineum 257 A and production of fusidin by it.     

Energy metabolism study of Fusidium coccineum strains with varying levels of antibiotic formation

Energy parameters of the two strains of the inperfect fungus Fusidium coccineum with different levels of antibiotic production were studied comparatively. It was shown that the respiration activity of the both strains was almost completely suppressed by KCN+ salycyl hydroxomate. It provided a supposition that the respiration activity was almost selectively connected with the mitochondria. The analysis of the energy parameters and especially the efficiency of the substrate consumption indicated that the system of oxidative phospholiration was dominant in the energy supply in both the strains. The differences between the strains were observed in the growth rate and the level of KCN-stable respiration. A change in the respiration of the active strain to the alternative KCN-stable path was observed by the end of the 6-8 day fermentation process when significant amounts of fusidin accumulated in the fermentation broth. Correlation between the level of KCN-stability and the antibiotic production was found.     

Characteristic features of protoplast formation and regeneration in Fusidium coccineum

The methods for preparation and regeneration of protoplasts were tested with respect to the strains of F. coccineum markedly differing in their capacity for antibiotic production, sporulation and the growth rate. It was found that the substrate used for the culture growth had a significant effect on the cell wall and sensitivity of the mycelium to lytic enzymes. An enzyme from Hellix pomatia and its combination with lysozyme were used for lysing the culture. The cytological investigation of the time course of the culture lysis revealed a stage-by-stage pattern of protoplast formation by means of fragmentation of the hyphal contents till a ball was formed. Two to 4 protoplasts differing in their size and structure were formed within a cell. The pH value and osmotically stabilizing component had some effect on the rate of protoplast formation. Highly productive strains were characterized by formation of protoplasts heterogenous in their size and by decreased frequency of regenerations. The enzyme-free protoplasts preserved their viability and capacity for germination in osmotically stabilizing media for 72-96 hours of storage at 4 degrees C. On solid media the regeneration frequency reached 38 per cent. The regenerated cells formed colonies morphologically similar to those of the intact culture.     

Morphofunctional characteristics of the development of strains of Fusidium coccineum differing in antibiotic activity in stab cultivation

The object of the work was to study the morphological and functional characteristics of Fusidium coccineum strains producing fusidic acid and differing in the antibiotic activity. The high metabolic activity of the culture is accompanied by the following morphological characteristics: the cells are rich in ribosomes and mitochondria, they have early vacuolisation, are filled with lipid granules, and then the mycelium undergoes autolysis. As strains with a high activity grow, the structure of the cells changes, the number of ribosomes and mitochondria falls down, and the latter are destroyed. For a long time, the cells contain electron-dense granular structures limited with the membrane and capable of transformation into lipid granules and membranous structures. As was shown by cytochemical studies, the structures have not merely proteins and lipids, but also phosphorus compounds. Their functional role in the fungal metabolism is discussed. As soon as super-synthesis of fusidic acid commences, the cells of the highly active strains are filled with lipid granules associated possibly with the steroid antibiotic. These formations are released from the cell during local lysis of the cell wall and the cytoplasmic membrane.     

Carbohydrate and pyruvic acid degradation pathways in Fusidium coccineum strains with varying levels of antibiotic synthesis]

A number of enzymes and reactions of glycolysis, pentose-phosphate cycle and degradation of pyruvic acid in strains of F. coccineum with various levels of antibiotic production was studied comparatively. The experiments showed that highly productive strains were characterized by higher activity of the NADP-deficient enzymes of the pentoze-phosphate cycle as compared to the low active strains. The activity levels of glycolytic enzymes, such as fructose-diphosphate-aldolase and 3-phosphoglycerolaldehydehydrogenase did not practically differ. Significant differences were found in the reactions of puryvic acid degradation: the activity of cytoplasmic pyruvatedecarboxylase in the mutant with high antibiotic production level was lower than that in the low productive strain, while oxidation of the pyruvate of the mitochondrial fraction was on the contrary more intensive than in the highly productive strain. Therefore, metabilism in the strains studied was characterized by ever-increasing biochemical changes with an increase in their antibiotic productivity. Lowering of the growth rate of the mutants as their capacity for antibiotic supersynthesis increased and subsequently the anabolic processes became more intensive was accompanied by increasing derepression of the key enzymes of carbohydrate metabolism and in particular NADR-deficient dehydrogenase of the pentose cycle and pyruvatedehydrogenase, significant for fusidin biosynthesis and providing production of the antibiotic of steroid nature by cofactor NADP-H and acetyl-KoA, the primary precursor.     

Bimodal karyotype in Cynomorium coccineum L. and its systematic implications

The presence of a bimodal karyotype in Cynomorium coccineum (2n = 28) is used to support its separation from Balanophoraceae and the maintenance of Cynomoriaceae as a separate family.     

Morphology,systematic position,and distribution of Bothriocidaroid echinoids

This is a brief review of conceptions of morphology, distribution and systematic position of the most ancient echinoid group—order Bothriocidaroida. It comprises 3 genera: Bothriocidaris, Neobothriocidaris, and Unibothriocidaris. More than 20 species of these genera are distributed from Upper Ordovician (Caradocian) to Lower Silurian (Llandoveri) in North Western Europe and North America. The question of whether this group belongs to the class Echinoidea or not has been the subject to discussions several times, particularly based on cladistic methodology. In my opinion the peculiarities of bothriocidaroids are quite typical of archetype definition of this class, however, so-called unique modalities of its merons are actually prone to variation both inside the group and among other echinoid groups. For example, Bothriocidaris maquoketensis has a structure transitional from uniserial to biserial interambulacra, however uniserial interambulacra are found in Paleozoic family Cravenechinidae and in some Cretaceous holasteroids and Cenozoic clypeasteroids. Unfortunately, such an important feature as the apical system is found only in one genus Bothriocidaris.     

Catabolite regulation of antibiotic biosynthesis

Conclusion In view of the possible mediation of carbon catabolite repression of antibiotic biosynthesis by phosphorylated substances, the concept of the role of phosphorus in the regulation of secondary metabolism should be re-evaluated. Many conclusions are based on an analogy with the effect of phosphorus in animal or plant cells (for review cf. Martin 1977). However, in contrast with plant and animal physiology, the production physiology of actinomycetes, typical soil microorganisms, was studied under nonphysiological conditions of nutrient over-supply in a submerged culture. This is analogous e.g. to space biology which studies the physiology of organisms in the state of weightlessness. Both disciplines have an extremely high significance but the elucidation of basic biological regularities is to be carried out back on Earth. In conclusion we may state that a critical evaluation of our contemporary knowledge seem to support the hypothesis that the antibiotic biosynthesis in actinomycetes, as well as the spore formation in bacilli — both regulated by the mechanism of catabolite repression — has its ecological significance, i.e. makes it possible for the organism to survive under conditions when vegetative growth is limited. For this reason this aotivity was preserved in the course of evolution as a protective mechanism of microbial populations and remained a part of the genome of many species.     

Floral ontogeny and systematic position of the Didiereaceae

Floral ontogenetical data from all four genera of the Didiereaceae (s.str.) are presented for the first time. All Didiereaceae s.str. are dioecious, having unisexual flowers with organ rudiments of the opposite sex. Two median bracts followed by a tetramerous perianth (two alternating dimerous ``whorls'), a slightly complex androecium with 6–12 stamens in a single row (on a common ring primordium), four of which mostly alternating with the perianth members, and one basal ovule connecting three free septa at their very base are flower characters in Didiereaceae, supporting phylogenetic analyses based on nucleotide sequence data. Closest relatives are the (formerly) portulacaceous genera Portulacaria (5 stamens alternating with the perianth), Ceraria (5 stamens alternating with the perianth), and Calyptrotheca (many stamens), all with pentamerous perianths, from which the tetramerous perianth in Didiereaceae can be derived. Applequist and Wallace (2003) included these three genera in an expanded family Didiereaceae (with three subfamilies).     

Reevaluation of the systematic position of Scenella

Specimens originally illustrated from Lower Cambrian rocks of the Sierra Morena in Badajoz and Sevilla Provinces, southwestern Spain are supplemented by new material from another locality and are described as Scenella morenensis n. sp. Although Scenella was originally considered to be a patelliform gastropod, for three decades now the genus has been classified as a monoplacophoran. The type species of Scenella, S. reticulata Billings, does not show any paired muscles scars, nor does this new species; such scars are indicative of the Monoplacophora. This new species of Scenella does exhibit features which suggest assignment to the chondrophorine coelenterates. If so, Scenella cannot represent the ancestral form of mollusk.     

Floral anatomy and systematic position ofVivianiaceae

The floral anatomy of four species ofViviania has been studied. In the basic floral plan and essential floral anatomical featuresViviana closely resembles theGeraniaceae. Evidence from vegetative and floral anatomy, ultrastructural studies on phloem as well as phytochemistry supports geranialean affinity ofViviania; the placement within thePittosporales sensuHutchinson being unnatural.