Role of endogenous tryptophan during submerged fermentation of ergot alkaloids

Shake flask cultures ofClaviceps paspali (Stev. et Hall) andClaviceps purpurea (Fr.) Tul. on simple synthetic medium have been studied. Both strains grown in the absence of added tryptophan accumulate extra endogenous tryptophan. A certain concentration of cell-pool tryptophan is needed to promote alkaloid synthesis. Alkaloid production commences while tryptophan synthetase activity is increasing. In the alkloid-producing phase cell-pool tryptophan shows a single minimum while the change in level of cell-protein tryptophan is negligible. Alkaloid formation is suggested to reflect a regulatory device to keep endogenous tryptophan balanced. By adding amitrole the alkaloid spectrum is changed. The tryptophan-histidine cross-pathway probably serves a useful function inthe biosynthesis of ergot alkaloids.     

Turnover of mucopeptide during the life cycle ofBacillus megaterium

Sporogenic and asporogenicBacillus megaterium strains, as well asBacillus cereus degraded the murein component of the cell wall labelled with¹⁴C-diaminopimelic acid to TCA-soluble compounds during growth. The rate of murein turnover was about 15% during one generation in all three cases. The addition of chloramphenicol instantaneously markedly decreased the degradation rate, whereas in the presence of penicillin the degradation proceeded at the beginning at a rate comparable with that in the control and decreased only after a certain time interval. The cell wall degradation was considerably or completely stopped during the stationary phase of growth. In sporogenic strains ofBacillus megaterium andBacillus cereus the release of mature spores was associated with a new wave of the wall degradation, during which the wall of the sporangial cell was completely digested to TCA-soluble fragments. Free spores contained practically no mucopeptide component (cortex or spore wall) originating from the wall of the vegetative cell. A possible existence of a stable fraction of the cell wall not subject to turnover was investigated by measuring the³H/¹⁴C ratio in cells labelled simultaneously with³H (or¹⁴C)-diaminopimelic acid and¹⁴C (or³H)-leucine. The ratio changed during five generations, remaining constant later. This indicates that a certain portion of murein could be stable. The murein degradation during growth was not associated with secretion or release of a significant quantity of autolytic enzymes into the medium. The wall was apparently attacked from the inside. On the other hand, the release of the spore was accompanied by an increasing autolytic activity in the medium. This latter activity reached values corresponding to 3–8 μg lysozyme/ml. The results published here were presented at the 2nd Harden Conference “Cell walls and cell membranes”, Wye, Kent, England in September 1970.     

Unterschiede in der Pflanzendecke extremer Standorte von verschiedener petrographischer Beschaffenheit in Bosnien und der Herzegowina

Ohne Zusammenfassung     

Light regime effect on the growth rate variability ofScenedesmus quadricauda (Turp.) Bréb. Clones originating from cells treated by a mutagen when grown on the surface of a solid medium

The light regime effect on the growth rate variability of clones of one chlorococcal alga strain growing on the surface of a solid medium was studied from the point of view of the clone selections manifesting the desired grade of this complex character. Several combinations of light regimes used for the cultivation of coenobia treated by UV-light and untreated control on two types of solid media proved the significance of manifestation degree changes of this character due to the given light conditions. The sizes of the alga colonies after a certain growth time on the surface of solid medium were evaluated statistically and the values obtained indicated the degree of growth rate manifested by the clones of a given population. The \(\bar x\) and s_x values of their growth rate variability were considered as the indicators facilitating the choice of selec-tion type and screening level. This paper is a partial contribution to the solution of the problems concerning the primary selection of alga clones on the surface of solid media.     

Interaction of cucumber mosaic virus and potato virus y with tobacco mosaic virus

A study was performed on the interaction of cucumber mosaic virus (CMV) of potato virus Y (PVY) with tobacco mosaic virus (TMV). Interference was evaluated using tobacco plantsNicotiana tabacum cv. Java responding to CMV and PVY with a systemic infection and to TMV with local necrotic lesions. The decrease in TMV — induced lesion number gave evidence of a decrease in susceptibility caused by the previous infection with CMV or PVY, the decrease of lesion enlargement demonstrated a decreased TMV reproduction in the plants previously infected with CMV or PVY. The interference concerned was incomplete, as evaluated from reproduction of the challenging TMV and from the decrease in susceptibility of the host to TMV brought about by the first infection with CMV or PVY.     

The history of flora and vegetation on the Bláto mire in southeastern Bohemia,Czechoslovakia (Palaeoecological study)

The paper summarizes the results of the palaeoecological study of one profile of the Bláto mire, situated in southeastern Bohemia (Czechoslovakia). The authors evaluate their finds and endeavour to present a phytocenological picture of the composition and succession of peatforming communities from the Alleröd Period onwards.     

Influence of ionic strength on the stability of phage t2r to osmotic shock

The authors assume that an increase in the ionic strength of the medium results in dissociation of the DNA-polyamine complex in the phage head. The released polyamines and internal protein molecules are unable to permeate into the external environment. Their thermal movement causes constant pressure within the phage; this contributes to rupture of the head by osmotic shock and probably plays a decisive role in injection of the phage DNA into the bacterium. Study of osmotic shock by glycerol in media of different ionic strengths showed that, as the ionic strength increases, the bacteriophage is at first destabihized by the action of the released polyamines and that only when the ionic strength is raised still further, it is restabilized by the influence of the ionic strength on the resistance of the membrane. The osmotic prossures required to rupture the phage head are practically the same for NaCl and KCl solutions, while for shock by glycerol solutions, considerably lower values were measured in media of low ionic strengths. The authors attribute these differences to differences in the rate of permeation of the shocking substance across the phage membrane. The equilibrium for NaCl and KCl is established in less than one minute and for glycerol in 5–10 min.     

Chlorella pyrenoidosa 7-11-05 in batch and in homogeneous continuous culture under autotrophic conditions

The growth ofChlorella pyrenoidosa 7-11-05 in batch and in continuous culture using two types of cultivation vessels was compared. The high values of specific growth rate obtained in batch deep stirred tank culture containing small amount of inoculum are not easily attainable in continuous culture with regard to the high number of autospores formed throughout the ontogenetic cycle ofChlorella. The obtained surface and volume productivities prove that in both types of cultivation vessels a high growth intensity can be achieved. The deep tank perfectly mixed cultivation may become of significance in the future.     

Note on study of the sporulation of fungi: endotrophic sporulation in the genusPenicillium

Conidiophore formation and sporulation can be induced inPenicillium sp. strain P 17 by an environmental factor—carbohydrate (carbon) starvation. Both surface and submerged mycelium, when transferred from synthetic medium to glucose-free salt solution, form conidiophores and sporulate, while in the control cultures on complete medium, vegetative growth continues. The time required for the formation of conidiophores, i.e. the induction interval, is 7–14 h and its length increases with the age of both surface and submerged mycelia. During the induction phase the mycelium undergoes autolysis, associated with degradation of energy motabolism involving the comsumption of reserve substances, a rapid drop in endogenous respiration and the endogenous reducing activity of the mycelium, a decrease in the labile phosphate concentration, proteolysis, an increase in the ammonia and orthopsphate concentration and exhaustion of readily oxidized amino acids from the pool. A transient increase in respiration occurs before differentiation of the conidiophores starts. During the second half of the induction phase, polyphenol substances and polyphenol oxidase appear in the mycelium.The enzyme is not induced by exogenous phenols. Its possible role in the sporulation of fungi is considered.     

The mutagenic effect of hydroxylamine onMycobacterium phlei strain PA

The mutagenic effect of 0.05m and 1m HA onMycobacterium phlei PA was investigated. To establish the mutagenic effect the inactivating effect was studied under the same experimental conditions. Hydroxylamine at a higher concentration (1m) exhibited relatively high mutagenic effect. This was indicated by about 100-fold and 10-fold higher frequency of INH^r and STM^r mutants, respectively (as compared with spontaneous mutations) and induction of auxotrophic mutants. On the other hand, the mutagenic effect of 0.05m hydroxylamine was low under the same experimental conditions. The inactivating effect of a higher HA concentration (1m under given experimental conditions) was considerably higher when using the given model microorganism than that of the lower one (0.05m under the same experimental conditions). This finding does not agree with literature data obtained in other experimental models.