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Z Zakowska

Publications and source records attributed to Z Zakowska.

9 recordsLinked to original sources
PubMed1999

Effect of Spumol K on the ultrastructure of Aspergillus niger strains sensitive or resistant to toxic compounds of beet molasses.

Aspergillus niger strains sensitive and resistant to toxic compounds of beet molasses grown in the presence of Spumol K were the object of the present studies. The antifoamer used diminished the number of mitochondria in both groups of strains and caused the reduction of their cristae in the sensitive ones. The disturbances in the ultrastructure of nucleus and mitochondria appeared mostly in sensitive strains. On the other hand, Spumol K presence in resistant strains not only increased the number of deposits of electron dense material in mitochondria, vacuoles, cytoplasm and in nuclear envelope but also was responsible for multivesicular body formation. The differences also existed in the ultrastructure of the cell wall: in the sensitive strains treated with Spumol K, the cell wall was completely deprived of fibrillar component, only granular component was present. In the resistant strains, granular component dominated, although fibrillar one was still visible. The present studies suggest that antifoamer in resistant strains becomes inactivated in different cell compartments, therefore its toxicity is lower than in sensitive strains where defence mechanism, inactivating toxic substances, is weaker and toxicity stronger.

Antifoaming Agents↗
PubMed1997

Cell wall analysis in Aspergillus niger strains characterized by different tolerance to toxic compounds of beet molasses.

Aspergillus niger strains, sensitive or resistant to toxic compounds of beet molasses, were the object of the present studies. Between the studied strains differences existed in the cell wall dry mass and wall components content, chitin synthesis, activity of enzymes involved in cell wall synthesis, and in the wall ultrastructure. Higher content of proteins and lipids but lower of glucan and chitin; less or lack of fibrillar components, thinner cell wall as well as lower level of glucanase and chitinase, diminished [3H] glucosamine incorporation into cytoplasm and cell wall characterized the sensitive strains of A. niger.

Aspergillus niger↗
PubMed1997

Effect of Spumol K on cell wall of Aspergillus niger strains characterized by different tolerance to toxic compounds of beet molasses.

Cell walls in the mycelium of Aspergillus niger strains sensitive or resistant to toxic molasses compounds growing in the presence of Spumol K were the object of the present studies. Although the inhibitory effect of Spumol K on the cell wall was noticed in studied mycelia the sensitive strains reacted more strongly. In sensitive strains in Spumol K presence lower content of cell wall was accomplished by higher amount of proteins but lower of lipids as well as structural polymers i.e. of glucans and chitin in this wall. A weaker synthesis of chitin and lower level of cell wall enzymes, especially chitinase, were observed in these strains. The described changes seem to be responsible for the growth inhibition and mycelium sinking in sensitive strains of A. niger.

Antifoaming Agents↗
PubMed1993

Changes in dehydrogenases activity, number and ultrastructure of mitochondria in Aspergillus niger mycelium growing on molasses media.

Effects of toxic molasses compounds and of the antifoamer (Spumol BJ) on dehydrogenases activity, on the number and ultrastructure of mitochondria in A. niger mycelium of two strains characterized by different tolerance to toxic agents, were observed. In spite of significantly higher dehydrogenases activity in the intolerant strain (R-16) mycelia developing both on productive molasses in the presence of the defoamer and on non-productive molasses are characterized by marked reduction in the activity of these enzymes. Changes in respiratory enzymes activity are partly correlated with the number of mitochondria but mostly with abnormalities in their ultrastructure.

Aspergillus niger↗
PubMed1991

Changes in development and ultrastructure of Aspergillus niger mycelium in the presence of toxic substances from molasses in citric acid fermentation medium.

Effects of a surface-active agent (Spumol BJ) and toxic molasses compounds on development and ultrastructure of Aspergillus niger strain R-16 mycelium producing citric acid in surface fermentation on molasses medium with 80% yield are presented. Microscopic observations showed that Spumol BJ in concentration of 5 microliters/100 cm3 as well as toxic molasses compounds stimulated the process of swelling and germinating of conidia. Giant conidia unable to germinate, appeared along with typical ones. Delicate mycelium outgrowing from germinating conidia however, sank after 20-24 h culture. Observations of hyphae in electron microscope showed changes in the ultrastructure and dimensions of mitochondria followed by successive degeneration of protoplast. The data obtained indicate that one of the reasons disqualifying raw molasses for biotechnological processes might be the excessive amount of surface-active antifoaming additives.

Aspergillus niger↗
PubMed1991

Changes in development and ultrastructure of Aspergillus niger mycelium, strain with increased tolerance to toxic substances from beet molasses.

Effects of a defoamer and toxic molasses compounds on development and ultrastructure of A. niger mycelium, strain Z, characterized by high tolerance to these substances and producing citric acid in surface fermentation on proper molasses media with 70% yield were presented. Spumol BJ in concentration of 5 microliters/100 cm3 as well as toxic molasses compounds stimulated the process of swelling and germinating of conidia. Moreover, giant conidia, unable to germinate, appeared. Developing mycelium with dispersed hyphae became mucilaginous after 17-20 h culture, which indicated the process of sinking but after 24 h some part of the mycelium developed normally. Electron microscopic observations of mycelium developing in the presence of the toxic substances showed along with electron-transparent cytoplasm in a consequence of decrease in ribosome number, changes in ultrastructure of mitochondria. It may be assumed that one of the reasons of the above described abnormalities in development and ultrastructure of mycelium was a disturbance of respiration processes. The appearance of deposits of electron-dense material in mitochondria suggested the existence of a defence mechanism, eliminating toxic substances.

Aspergillus niger↗