[Lipids of a paraffin-oxidizing strain of Pseudomonas aeruginosa]

The qualitative and quantitative composition of lipids was studied in a paraffin-oxidizing Pseudomonas aeruginosa P-20 strain. The content of free lipids was 7% of the dry biomass weight in a medium with hexadecane and 6.7% in a medium with glucose. The content of bound lipids was 6.7 and 5.6%, respectively. Phospholipids and free fatty acids are main components of lipids in the both cases. Phospholipids are represented by diphosphatidyl glycerol, phosphatidyl ethanolamine, phosphatidyl glycerol, and phosphatidyl choline. The fatty acids of free lipids consist by 72% of even acids with an unbranched carbon chain, among which palmitic and octadecenic acids prevail no matter what is the composition of a medium. 'Uneven' acids are represented mainly by nonadecenic acid: 17.8% in the medium with hexadecane and 15.9% in the medium with glucose. The content of unsaturated acids is 55.95% in 'hexadecane' cells and 44.89% in 'glucose' cells; octadecenic and nonadecenic acids predominate among unsaturated acids. Fatty acids covalently bound to cellular proteins and polysaccharides contain much less unsaturated compounds (particularly in cells grown in the medium with hexadecane) and more branched acids; C18:1, C16:0 and C17:0-branched acids predominate among them.

Disappearance of calcium and other electrolytes from microvolume samples

Studies involving micropuncture and microperfusion of single nephrons require the handling of very small fluid samples. To facilitate handling, the tubule fluids are normally manipulated under paraffin oil. Calcium and, to a lesser extent, magnesium and phosphate concentrations may change significantly when placed in hydrated paraffin oil. Fluids of alkaline pH (about 7.4), either intrinsic or because of loss of CO2, may very quickly lose calcium in paraffin oil. Evidence suggests that this is due to a reversible binding of calcium and perhaps magnesium to the aqueous-oil interface that is dependent on the pH of the sample. It is recommended that tubule fluid samples be kept acidic to prevent calcium loss. A convenient method is by equilibrating the paraffin oil, prior to placement of aqueous samples, with a CO2 tension sufficient to lower the sample pH to below 7.0.

[Theoretical determination of the energy efficiency of microbial carbon substrate conversion and comparison with experimental values in phase cultures]

The phenomenological description of microbial substrate conversion is possible by connecting energy and material balance equations. The change of free enthalpy of microbial substrate conversion was determined on the basis of exact material balance equations. A simultaneous determination of heat production allowed to calculate the energetic efficiency of microbial growth processes. In addition to this the change of free enthalpy by microbial substrate conversion was standardized by the free standard formation enthalpy of biomass. Both quantities were used for comparing microbial combustion of several substrates into biomass. Comparable with the concept of substrate combustion enthalpy standardized by the combustion enthalpy of biomass an optimal strategy of mixing different substrates can be deduced from energy and material balance equations on the basis of theoretic consumption coefficients. Besides the energetic efficiency the binding state of the substrate is important in the search for optimal substrate mixing ratios. This could be shown by experimental work. Thus, the fermentation systems sucrose/yeast, paraffin/yeast, and sucrose/paraffin/yeast were studied using synchronous populations produced by the method of phased cultures. The investigations of real fermentation systems confirm the theoretical predictions on special conditions.

[Growth of obligate-thermophilic bacteria on a medium with paraffin]

The obligate thermophilic bacteria Bacillus stearothermophilus (the optimal growth temperature 55-73 degrees C) and Thermus ruber (the optimal growth temperature 60 degrees C) were isolated from hot water springs of the Kunashir Island for the first time in a liquid mineral medium with paraffin. Some of the bacteria belonging to Bac. stearothermophilus grew at a high rate in a liquid medium with paraffin (strain 16); other strains (12a, 12b) were capable of growing only together with Thermus ruber; some strains could grow only on a solid medium with paraffin (strains 14a, 14b).

[Paraffin oxidizing system of the yeast Candida guilliermondii]

It has been demonstrated that the enzyme system of Candida guilliermondii responsible for hydrocarbon oxidation involves NADPH-cytochrome c-reductase (EC 1623) and cytochrome P-450. The system is located in the microsomal fraction. Cytochrome P-450 synthesis is induced by hexadecane occurring in the medium. The cellular content of cytochrome P-450 varies in the course of the culture growth. There is a correlation between the cellular content of cytochrome P-450 and the synthesis of primary products of hexadecane oxidation.

[Cultivation of feed yeasts on media with carbohydrates]

The different culture of yeasts oxidizing hydrocarbons and the accompanying microflora are, under certain physico-chemical conditions, in metabiotic relationships which provide stability of the system. These relationships were studied with yeast cultures belonging to the Candida genus and oxidizing hydrocarbons. The relationships between the hydrocarbon oxidizing yeast Candida guilliermondii and other species of the genus Candida were determined by a combination of active and passive antogonism, as the result of which strains of this species completely dominated in the cenosis of fermenters.

[Effect of carbon source and cultivation temperature on growth limitation of Candida tropicalis by biotin]

The effect of biotin on the specific growth rate of Candida tropicalis was studied on media with various sources of carbon nutrition at temperatures of 29 and 39degreesC. The yeast was found to require 3--5 times less biotin on the medium with paraffin than on the medium with glucose and hexodecane, and 3--4 times more biotin on the same substrate with an increase in temperature. The growth rate increased by 36--40% on liquid paraffins containing 0.5 mcg/litre of biotin at 29degreesC and 1.5--2.0 mcg/litre of biotin at 39degreesC. The saturation constant of biotin increased from 0.033 to 0.063 mcg/litre on the medium with paraffin, and more by an order on the medium with glucose and hexadecane, at a rise of growth temperature from 29 to 39degreesC.

[Increased flavinogenesis in 1 of the strains of Candida tropicalis]

Candida tropicalis IBFM 303 is capable of the active production and liberation of flavins during the oxidation of solid paraffins with the carbon chain consisting of 20 carbon atoms and more. Unlike other known strains, this strain does not accumulate considerable amounts of the vitamin neither on media containing liquid n-paraffins not on media with glucose, even under the conditions of iron deficiency.

[Structure of Candida tropicalis K-41 thermotolerant yeasts at various growing temperatures on a mineral medium with hydrocarbons]

In the C. tropicalis K-41 cells fixed by glutaraldehyde and osmium most membranes consisted of two electron-transparent and one electron-dense layer. Morphologo-structural peculiarities of the cell fraction grown at 39 degrees testify to a certain disconnection of energetic and constructive metabolism, inhibition of synthetic processes. Cell division was more active at 29 degrees.

[Activity of certain dehydrogenases in accumulation and continuous-flow culture of paraffin-oxidizing yeast of the genus Candida]

Lability of NADP- and NAD-dependent glutamate dehydrogenases and malate dehydrogenases has been demonstrated during a change of the physiological activity of yeast Candida guilliermondii in the exponential phase of growth. Variations in the isoenzyme spectrum of the enzymes and total dehydrogenase activity of the yeast has been found during their transition from the accumulative to the continuous cultivation. Changes in the physiological state of yeast during their growth are accompanied by a rearrangement of the isoenzyme spectrum of malate dehydrogenase and glutamate dehydrogenases.

[Cytochromes of paraffin oxidizing yeast Candida guillermondii K-5]

The cytochrome group of the enzymes-electron carriers in the terminal site of the respiratory chain of paraffin-oxidizing yeast C. guilliermondii K-5 has been identified. Spectral peaks of their reduced form correspond to the following wave lengths: c-412, a1-510 and a2-546nm. Variations in the content of cytochrome C of the accumulative culture have been studied. Reduced forms are predominant in the lag-phase and in the phase of exponential growth. This predominance disappears in the phase with negative acceleration and the dying culturt contains a greater number of oxidized forms.

[The effect of prolonged injestion of paraffin oil in pigs: selective retention and interference with cholesterol metabolism]

Hydrocarbons administered to the pig as paraffin oil fix preferentially in the liver, and the existence of a selective filtration mechanism can be supposed. Moreover a significant increase of the level of squalene is observed in adipose tissue and liver; it could correspond to an inhibition of the cholesterol synthesis following vitamin A deficiency due to perturbation of intestinal absorption.

[Changes in the activity of glyoxylate cycle enzymes of yeast during hydrocarbon nutrition]

Six strains of Candida guillermondii of different productivity showed a higher isocitrate lyase and malate dehydrogenase activity of cell-free extracts when grown on paraffin than when grown on glucose. In most cases isocitrate dehydrogenase activity was higher on glucose than on paraffin. A positive correlation between isocitrate activity and growth rate was found from studies of the strains of varying growth rate and the cultures cultivated under different conditions (nitrogen content and the presence or absence of biotin or autolysate in the medium).

Numerical taxonomy of Nocardia

One hundred and seventeen features each for 157 strains belonging to the species Nocardia asteroides, N. brasiliensis, N. caviae, N. madurae, N. pelletieri, and N. dassonvillei and Streptomyces somaliensis were studied. The data were subjected to computer analysis, which included calculating S-value matrix, link sort and clustering, feature frequency sort, and median organism calculation. Of the 157 strains studied, 96 strains formed seven distinct groups, whereas the other strains remained unclustered or presented irregular groupings. The seven groups represented N. asteroides (four groups), N. caviae, N. brasiliensis, and N. madurae. Group II of N. asteroides corresponds to N. farcinica group of Tsukamura. The results are discussed and compared with those of other workers.