J. Panoš

Studies on methanol-oxidizing yeast

The yeast strain 11Bh was studied from the aspect of qualitative and qunatitative composition of lipids formed in cells during growth on methanol, synthetic ethanol and glucose. The strain was found to form some 3% free fatty acids toward the end of the growth phase. More esterified fatty acids are formed on ethanol and glucose (2.75 and 2.86%, respectively) than on methanol (1.6%). The composition of lipids and representation of the various fatty acids in the lipids is similar on all three substrates. The cell lipids contain over 40 rel.% oleic and about 16 rel.% each of palmitoleic, palmitio and linolenic acid. Odd-numbered fatty acids are present after growth on any of the three substrates, amounting to at most 4 rel.%. Of the extracellular fatty acids formed toward the end of growth of cells on methanol, propionic and acetic acid occurred in largest amounts in the medium.

Effect of cultivation conditions on the activity of the beromycin producerStreptomyces glomeratus 3980 and its spontaneous variants

Optimal conditions for the submerged cultivation ofStreptomyces glomeratus 3980, producer of the anthracycline antibiotics beromycins, and its variants were sought in media with glucose, soybean meal and salts differing in the content of ammonium sulphate. As compared with the original activity of the strain the antibiotic titre of some variants increased about 12 times on increasing the glucose concentration from 3 to 5 %, or on omitting CaCO3 from the medium (i.e. under conditions leading to an increased production of propionic acid and suppression of production of the melanin-like pigment). In melanin-less variants accumulating propionate even under standard conditions the activity increased about 18–40 times in the medium with 3 % glucose and 0.2 % CaCO3 under conditions of more intensive aeration (i.e. under conditions when no propionic acid accumulated). Individual strains also differed in the requirement for (NH4)2SO4 in the medium, their response to changes of volume of the vegetative inoculum and sensitivity to MgSO4.7H2O. The biosyiithetic activity of all strains was inhibited by the addition of ZnSO4.7H2O or CaCl2 and substitution of glucose with starch, lactose or sucrose.

Batch kinetics and oxygen consumption ofCandida lipolytica 4-1 onn-alkanes

Detailed batch kinetics ofCandida lipolytica 4-1 onn-hexadecane for varying dispersed phase volume from 0.5 to 5% v/v is presented. All batch growth curves exhibited a linear growth region, indicating a substrate uptake limit. System productivities derived from the linear region were correlated to the dispersed phase volume. The correlation coefficient was identical with that obtained on gas oil. This implies that a correlation coefficient of interfacial area to the dispersed phase volume is identical for both systems. Dissolved oxygen profile and uptake of oxygen from gas phase were also measured. The oxygen uptake rate, volumetric oxygen transfer rate and oxygen demand (requirement) were calculated by means of the balance method. Under limiting dissolved oxygen concentration the maximal oxygen transfer of the fermenter was assessed.

Ethanol-Induced Death and Lipid Composition of Saccharomyces cerevisiae: A Comparative Study of the Role of Sterols

Ethanol tolerance of fourSaccharomyces cerevisiae strains characterized by different amounts of Δ5,7-sterols was tested. The individual tolerances did not correlate with the strains sterol levels. The highly and medium-accumulating strains exhibited the highest and lowest ethanol tolerances, respectively.

Spontaneous variability ofStreptomyces glomeratus, a producer of the anthracycline antibiotics beromycins

Spontaneous variants of the beromycin-producing strainStreptomyces glomeratus 3980 were divided into five groups (A-E) according to increasing antibiotic activity. The most active variants (group E) differed from the other types and the wild strain by a suppressed ability to produce aerial mycelium and melanoid pigment and by an increased production of propionic acid. Strains with a 12-fold higher antibiotic production capacity (with respect to strain 3980) were obtained by selection of superior segregants from submerged cultures of the E type.

Isolation of Acetonitrile-Utilizing Bacteria

Corynebacterium sp. 3 B and three unidentified bacterial strains, all utilizing acetonitrile as a sole carbon and nitrogen source, were isolated from soil by the enrichment culture technique.Agrobacterium radiobacter 8/4/1, also capable of growing on acetonitrile as a sole C and N source, was obtained from a bromoxynil-metabolizing strainA. radiobacter 8/4 using the same method. Resting cells of strains BSA 1 and 3 B produced acetamide and acetic acid during incubation with acetonitrile, whileA. radiobacter 8/4/1 produced acetic acid only.

Effect of growth rate on ethanol tolerance of Saccharomyces cerevisiae

AbstractΔ5,7Saccharomyces cerevisiae cells growing in chemostat at a specific growth rate of 0.075/h exhibited higher ethanol tolerance measured as ethanol-induced death and anaerobic growth inhibition than the cells growing at 0.2/h, the difference being dependent on the carbon-to-nitrogen molar proportion in the medium. The observed difference in sensitivity to ethanol of anaerobic growth between the slowly and rapidly-growing cells was completely reversed as a result of a block in sterol synthesis causing a negligible synthesis of Δ5,7. Two physiological parameters, budding frequency and membrane composition, evidently affected ethanol tolerance. Differences between the Δ5,7 and deficient strains documented a profound effect of the quality of the sterol present on the physiological state of the cell.

Growth ofCandida tropicalis 2838 cells on straw hydrolyzates

Improved strain ofCandida tropicalis 2838 grows on nonseparated straw hydrolyzates with no addition of vitamins and trace elements at a specific growth rate μ = 0.34 and 44 % yield coefficient (referred to reducing substances). The reducing substances in hydrolyzates contain predominantly monosaccharides (xylose, glucose, arabinose, mannose). Cells grown in this way are rich in proteins (62 %) and essential amino acids (lysine, phenylalanine, leucine, threonine and valine). The product obtained under industrial conditions by fermentation of the nonseparated hydrolyzates contains 8 – 9 % of proteins and it is a suitable supplement of fodder mixtures for monogastric domestic animals. Nutrition tests on rats and pigs indicated that this product can substitute the hay-flour, and, partially, blood-flour barley, and that the strain used is nonpathogenic.

Production of ethanol by the yeastCandida utilis under autoanaerobic conditions

Candida utilis CCY 29-38-65 converts glucose to ethanol under autoanaerobic conditions. On aeration switch-on the produced ethanol is utilized as carbon source and the specific rate of biomass production increases.

A lipopolysaccharide fromAspergillus flavus conidia

A lipopolysaccharide was isolated by extraction ofAspergillus flavus conidia with 45 % phenol at 68–70 °C. Quantitative analysis revealed 7 % nucleic acids, 5.5 % proteins, 46 % polysaccharides and 49 % lipids, of which 12 % were covalently bound. Glucose, mannose, galactose and fucose were detected as monosaccharide components of the polysaccharide moiety by gas chromatography; palmitic acid, stearic acid, oleic acid, linoleic acid and myristic acid were mainly present in the lipidic fraction. This material differs from the bacterial lipopolysaccharides, both in composition of the polysaccharide moiety and representation of fatty acids in the lipidic fraction.