Anthrenus sp. The paraffin block eater bug

Review of several years-old, paraffin-embedded specimens showed unusual damage, especially of the sectioned surface of hyperkeratotic lesions. The larva of Anthrenus sp., feeding on the embedded material, was identified as the causative agent. Normally found in birds' nests, this species prefers keratin for nutrition, and can therefore damage histopathology collections.

Chlorinated paraffins: formation of sulphur-containing metabolites of polychlorohexadecane in rats

A uniformly 14C-labelled polychlorinated hexadecane (14C-PCHD; 65% chlorine by wt) was injected into the portal vein in bile duct-cannulated rats (5-6 mg/kg) and the bile was collected for two or three days. Less than 3% of the total amount of radioactivity excreted in the bile was due to unchanged 14C-PCHD. The radioactivity was separated by ion-exchange chromatography into two major fractions: one acidic, the other amphoteric. Comparison with a similar fractionation of propachlor metabolites indicates that the fractions contain 14C-PCHD conjugates of N-acetylcysteine (mercapturic acid) and glutathione, respectively. The tentative 14C-PCHD-mercapturic acid on t.l.c. had an RF value similar to that of a synthetic PCHD-mercapturic acid, and chlorine and divalent sulphur were shown to be present.

[Bacterial interaction in a culture containing Pseudomonas and Mycobacterium in relation to hydrocarbon oxidation]

An experimental association of Pseudomonas and Mycobacterium was employed for a more complete oxidation of a hydrocarbon substrate. The maximum effect of combined cultivation (74% vs. 50 and 47% in the pure cultures of Mycobacterium and Pseudomonas, respectively) was obtained under steady-state conditions. The result is attributed to the processes of co-oxidation and the physiological properties of the microorganisms.

[Joint utilization of glucose and n-alkanes in citric acid synthesis by Saccharomycopsis lipolytica]

Fermentations for the overproduction of citrate and isocitrate with S. lipolytica in media containing both glucose and n-alkanes as mixed C-source have been performed. Biomass and product yields strongly depend on the C-source of the inoculation culture. If the inoculation culture had been taken from media containing glucose as sole C-source both glucose and n-alkanes were utilized for cell growth in the main culture whereas only glucose was utilized if the inoculation medium contained only n-alkanes. For idiophasic citrate and isocitrate production both glucose and n-alkanes were consumed independently of the C-source of the inoculum but that C-source was preferentially utilized which has been the C-source of the inoculation culture. These findings are reflected by the activities of the isocitrate lyase and the pyruvate carboxylase, respectively. In S. lipolytica both anaplerotic pathways are coexisting but the C-source of the inoculation culture determines the level of the specific activities even if the ratio of the cell-mass of the inoculum to the cell mass of the main culture at the end of the growth phase is about 1:35.

[Chemotactic reactions of a paraffin-oxidizing strain of Pseudomonas aeruginosa]

The reactions of chemotaxis were studied in a paraffin-oxidizing Pseudomonas aeruginosa strain using the method of migration in viscous media. Diesel fuel and paraffin become attractants only if they are contaminated with hydrocarbon-oxidizing mycobacteria. A suspension of mycobacterial cells as well as their lipids (peptidoglycolipids, wax, triglycerides, methyl esters of mycolic acids) are attractants, too. A mycobacterial biomass containing no lipids does not cause chemotaxis of P. aeruginosa cells.

[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).