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Studies the inhibition of bacterial sulphate-reduction in presence of short chain fatty acids. First evidence of the occurrence of hydrogen sulphide in the course of methane fermentation of cellulose by impure enrichments cultures of anaerobic bacteria; Study methods.

The present paper describes the effect of (+)-biotin on the metabolism of a freshly isolated strain of Desulphovibrio desulphuricans. In proliferating pure cultures of this Zürich strain on a synthetic substrate with ammonium chloride, lactate and sulphate an oxido-reduction process takes place according to the stoichiometric relation established by Baars (1930). In the medium mentioned (+)-biotin was shown to have favourable action when added in comparatively small amounts, whereas in presence of greater amounts of the vitamin a marked inhibition was observed. The maximum stimulation is induced at a concentration of 25 jig. of biotin per litre, while a pronounced inhibition sets in when the vitamin concentration is increased from 100 to 250 μg. per litre. It is proposed that the beneficial effect of biotin might be related to the action of the vitamin in the synthesis of aspartic acid and other amino acids from pyruvic acid, carbon dioxide and ammonia through Wood-Werkman condensation, amination and transamination. [ABSTRACT FROM AUTHOR]

The present paper reports the results obtained in examining 191 freshly isolated saccharolytic Clostridium strains for growth under anaerobic conditions in a synthetic nutrient solution with or without addition of (+) -biotin and p-aminobenzoic acid. Further, the pH of the substrates was determined electrometrically after completed fermentation. The strains were isolated from soil, sewage, green plants, silage, potato-, corn-, rye- and chestnut-mash, spoiled Emmentaler and process cheese, faeces of cow and sheep, etc. The pure cultures were obtained from the pasteurized material directly by means of smear-cultures on glucose-meat infusion-agar, glucose-yeast water-agar, etc. or after enrichment on skim milk, glucose-skim milk, corn- and pea-broth, glucose-meat-peptone-broth, Winogradsky's solution, etc. The pH measurements and analyses of the fermented substrates showed that out of the 191 strains thus isolated 88 (46 per cent) were true butyric acid bacteria producing great amounts of butyric and acetic acids, along with traces of neutral compounds, whereas 22 strains (11,5 per cent) were butanol-isopropanol or butanol-acetone bacteria capable of forming large quantities of neutral products, together with only small amounts of fatty acids. 81 strains (42,5 per cent) were found to be intermediate types. The synthetic medium used contained 20 amino acids in addition to glucose, ammonium acetate and mineral salts. (+) -biotin and p-aminobenzoic acid were supplied in amounts of 0.001 μg and 0.05 μg, respectively, per ml of substrate. In order to check the quality of the pasteurized spore suspensions used for inoculation parallel cultures were grown in a modified Karnicki-Dorner medium. It was demonstrated conclusively that 178 strains (93 per cent) were heterotrophic for (+) -biotin, whereas 6 strains (3 per cent) showed auxo-autotrophic tendencies, and 7 strains (3-4 per cent) required (+)-biotin or p-aminobenzoic acid for normal growth in the synthetic substrate mentioned. The end products of fermentation found in the synthetic medium supplied with (+) -biotin are, qualitatively and quantitatively, the same as those observed in parallel cultures on a glucose-yeast extract substrate. As far as selection and genic mutations involving changes from an autotrophic to a heterotrophic growth-factor habit do not occur in the media employed for isolating the strains and growing the subcultures used in preparing the spore suspensions, we may conclude that the natural populations of butyric acid as well as butanol-isopropanol and butanol-acetone bacteria of the genus Clostridium contain a very great number of strains requiring an exogenous supply of (+) -biotin for normal growth even in media containing most of the amino acids obtained on hydrolysis of bacterial proteins. The number of strains with auxo-autotrophic tendencies is obviously very small. In some strains a replacement of (+) -biotin by p-aminobenzoic acid seems possible. [ABSTRACT FROM AUTHOR]

The oxygen uptake of two strains of Mycelium Radicis atrovirens was measured volumetrically in the respirometer apparatus of von Euler, Myrbäck and Nilsson. The vessels employed were 100 cm Erlenmeyer flasks with center cup containing the solution of potassium hydroxide used for absorption of carbon dioxide. The mycelium was grown in a submerged state in shaking cultures according to the method of Wikén and Somm. The oxygen consumption of the growing young mycelium in a glucose-ammonium tartrate medium amounted to about 2 × 10 cm per milligram of dry weight per hour. The respiratory activity of the washed mycelium in distilled water or phosphate buffer was equal to that shown by the intact mycelium in its actual culture medium. The high autorespiration (endogenous respiration) thus observed was reduced appreciably by starvation for 48 hours in phosphate buffer under aerated conditions. The autorespiration of the starved mycelium amounted to 0.1−0.3×10 cm per milligram of dry weight per hour, whereas its oxygen uptake in solutions of glucose, succinate, fumarate, and citrate was equal to 0.6−1.7×10 cm. [ABSTRACT FROM AUTHOR]

In investigations on fungi incapable of producing spores, conidia, or oidia under laboratory conditions the liquid media used for growth experiments are, according to the ordinary technique, inoculated with mycelium bits cut from colonies of the fungi grown on solid agar media in tubes or Petri dishes. The difficulties and disadvantages met with in employing this method are discussed. A new method is described using mycelial suspensions for inoculation of liquid substrates. The suspensions are prepared by shaking bits of mycelial mats with glass beads, about 6 mm in diameter, and distilled water or 'physiological' salt solution under sterile conditions. The large mycelial particles are allowed to settle. The supernatant suspension is pipetted into a sterile flask and diluted to the propervolume. The suspended particles may be washed by sedimenting in a centrifuge, resuspending in distilled water or salt solution, and recentrifuging under sterile conditions. Of course the method may be modified in different ways. The new method is now used on a routine scale in this institute in investigations on mycorrhiza-forming and litter-decomposing fungi. [ABSTRACT FROM AUTHOR]

Three strains of Mycelium Radicis atrovirens were grown in a submerged state with aeration brought about by continual shaking of the cultures (100 ml Erlenmeyer flasks containing 20 ml of substrate; shaking speed = 50-60 cycles per minute; amplitude =15 cm). The shake cultures showed a marked acceleration in growth as compared with the corresponding stationary cultures, maximum dry weight of mycelium being attained after incubation for 7 to 10 days in the former and after 13 to 20 days, respectively, in the latter cultures. The submerged mycelium produced in the shake cultures was successfully used in experiments on respiration of the fungus. [ABSTRACT FROM AUTHOR]

In an aqueous extract of fruit bodies of Coprinus comatus 3-octanone, 3-octanol, 1-octen-3-ol, 1-octanol, 2-methyl-2-penten-4-olide, 1-dodecanol and caprylic acid were identified conclusively and n-butyric and isobutyric acids preliminarily. Amino-acids, nucleotides and sugars were also determined. A mixture of 37 compounds found in the extract had a stronger flavour than the natural extract. 3-Octanol, 1-octen-3-ol, 1-octanol and 2-methyl-2-penten-4-olide were the volatiles with the strongest flavour. Mass and IR spectra of 2-methyl-2-penten-4-olide are presented.

The flavour of Agaricus bisporus was studied by comparing the results obtained in chemical and organoleptic analysis of the same extract. The natural (-)-form of 1-octen-3-ol had a stronger flavour than the (+)-form and was the most important aroma component. Nucleotides, amino-acids and carbohydrates also contributed significantly. Benzaldehyde, benzyl alcohol, 1-octen-3-one, n-butyric and isovaleric acids as well as low-boiling volatiles contributed less to the flavour. A synergistic effect of nucleotides, carbohydrates and (-1-octen-3-ol on the flavour was not observed.