A dried nutrient medium for the isolation of Vibrio cholerae

A dried differential nutrient medium for the isolation of V. cholerae has been developed. The medium is sufficiently sensitive, has pronounced differentiating properties and greatly inhibits the appearance of microbial associations. During the cultivation of V. cholerae with the use of this medium the cultural, morphological and agglutination properties of the initial strains are retained.     

A new dried nutrient medium for the isolation of Corynebacterium diphtheriae (its development and experimental study)

A new dried diagnostic medium for the isolation of C. diphtheriae has been developed on the basis of aminopeptide. This new aminopeptide-based medium compares favorably with Buchin's medium in its growth and inhibitory properties.     

Dried nutrient media for the cultivation of pneumococcus and meningococcus

Dried synthetic nutrient medium for the cultivation of meningococci and the accumulation of their biomass has been developed. The kinetics of the culture growth, changes in pH and in the content of dissolved oxygen in the medium during prolonged controlled processes of the cultivation of meningococci in a bioreactor with the use of this medium have been studied. The stable physico-chemical properties and composition of the polysaccharide-protein complex isolated from the biomass of meningococci grown in the above-mentioned medium have made it possible to use it for the preparation of the samples of group B meningococcal vaccine. In addition, dried semi-synthetic nutrient medium for the accumulation of pneumococci without the necessity of introducing blood or serum into the medium has been developed. As regards its biological properties, this newly developed medium make it not inferior to meat media, containing blood or serum, and ensures good yield of biomass.     

Evaluation of the efficiency of a new dried nutrient medium for isolating Corynebacterium diphtheriae

Tellurite blood media prepared on a new dried base with amino peptide have been found to have advantages, when used for the bacteriological diagnosis of C. diphtheriae infection, over Buchin's selective quinosol medium with respect to the rate and time of the isolation of C. diphtheriae; besides, these new media have been found to possess pronounced differentiating properties with respect to the concomitant microflora.     

Development and experimental study of a dried nutrient medium for the microbiological diagnosis of streptococcal infections

The comparative study of different protein bases has shown that the combined base containing animal blood hydrolysate (amino peptide) and acidic casein hydrolysate, moderately cleaved, in the proportion 1:1 is a good source of nitrogen and ensures the intensive growth of streptococci. As determined by the study of the physiological parameters and growth of streptococci, the presence of fodder yeast extract, glutamine, glucose and phosphates in media containing blood hydrolysate and casein hydrolysate has been found to render a stimulating effect on the growth and multiplication of these organisms. The data thus obtained have been used as the basis for developing the formula of a dried culture medium, capable of ensuring the growth of streptococci without blood or serum added and not inferior in its quality to Todd-Hewitt Broth manufactured by Oxoid Ltd. (Great Britain) and Difco Laboratories (USA). The physico-chemical and physiological characteristics of the proposed medium have been determined. The use of the new dried culture medium in medical practice will make it possible to improve the microbiological diagnosis of streptococcal infections.     

The determination of Escherichia virulence on nutrient media]

The virulence of 250 pathogenic Escherichia strains secreted from humans and from various environmental objects has been studied on nutrient media with stains, ram erythrocytes and in hemagglutination reactions. The highest percentage of strain virulence is revealed when using crystal violet and in the blood agar (44.0 and 27.2%, respectively), evidently, due to nonspecific reactions. The medium with congo red showed a positive result in 20.3 + 3.1%, and the d-mannose-resistant hemagglutination reaction--in 16.5 + 2.3% cases. In practice it is recommended to use several methods which enable estimating correctly the risk to infect humans and to conduct timely preventive measures.     

Diagnostic effectiveness of nutrient media for the bacteriological detection of enterobacteria

The effectiveness of new nutrient media intended for the differential isolation of pathogenic and opportunistic enterobacteria (SS agar), as well as for the preliminary identification of enterobacteria, was determined on a wide range the strains of the family Enterobacteriaceae. The comparative evaluation of SS agar and Ploskirev's bactoagar was carried out. The newly developed medium was shown to have advantage in its differentiating and inhibiting properties. The clinical trials of the media, carried out in this study, revealed high detection rate and exceedingly exact differentiation of lactose-negative lactose-positive enterobacteria, as well as 100% coincidence of the results obtained on the nutrient medium for the preliminary identification of enterobacteria and on laboratory-made control media.     

Results of testing a new method of using antibiotics in nutrient media for the isolation of Shigella: the 2-streak method]

A new variant of media with antibiotics for isolation of Shigella, i.e. a method of 2 streaks each containing different antibiotics was tested in analysis of excrements from patients with acute dysentery. It was found that the new method is more effective than the well known method of gradient plates (isolation of Shigella in one series of the experiments amounted to 85.2 and 64.7 per cent respectively, and in the other series of the experiments the respective figures were 95.4 and 89.3 per cent). Its efficiency was lower as compared to the procedure of inoculation onto 2 plates, i.e. onto the media with and without an antibiotic (isolation of Shigella was 67.5 and 77.4 per cent respectively). The new method provided a higher frequency of Shigella isolation as compared to inoculation onto the media without an antibiotic, as well as onto any of the media used with one antibiotic. The method of 2 streaks offers wider possibilities for choosing the antibiotics for adding to the nutrient medium, as well as estimation of the antibioticograms and species structures of Shigella distributed in a concrete area.     

Variation in nutrient content of samples of dried bakery product

Samples of dried bakery product (DBP) were obtained from a blending facility. Sixty-six samples taken over a 198-day period were assayed for moisture, protein, ether extract, and salt. The samples averaged 6.05% moisture and 9.78% ether extract, 11.94% protein and 2.52% salt (dry matter basis). The results of the study indicate that DBP samples should be constantly monitored by the feed industry to determine nutrient values to be used in feed formulation.     

Use of dried algae as a food source for zooplankton growth and nutrient release experiments

Zooplankton growth and nutrient recycling are key processes in the operation of pelagic food webs. Most studies investigating these processes rely on complex methods and often require extensive laboratory facilities. Here we introduce a technique for preserving algae by rapid drying for later use in laboratory- or field-based growth and nutrient recycling experiments. Chemostat-grown Scenedesmus acutus was rapidly dried for later experiments evaluating its nutritional composition, suitability for animal growth and potential for use in nutrient release experiments. Reconstituted dried algae had slightly lower nitrogen (N), Phosphorus (P) and protein content (% dry weight) than fresh algae, but lipid content did not differ and elemental ratios were in the range considered to indicate favorable food quality. These elemental and biochemical differences did not appear functionally important, as Daphnia magna grew identically on fresh and dried food. Freeze-dried S.acutus did not work as an alternative to oven drying as it resulted in 100% mortality. NH4 and PO4 concentrations did not change over 24 h when dried algae were resuspended in normal media or boiled lake water. However, concentrations of PO4 decreased over 24 h, suggesting chemical adsorption of PO4 to the dried algae and reinforcing the need for animal-free controls in nutrient release experiments using this approach. N and P release rates for D.magna and natural zooplankton communities were estimated using dried algae, and values were comparable to published ones. Thus, dried algae may be a useful, simple technique for studying food quality and nutrient release in environments where maintaining active algal cultures may not be practical and a constant supply of consistent quality food is needed.      

Determination of the bacterial contamination of nutrient media for the biosynthesis of antibiotics

Contamination of separate components of nutrient media used in biosynthesis of antibiotics was tested. It was shown that corn steep liquor, corn and soybean meals were the most contaminated components. The results provided determination of the nutrient media contamination levels by the additive factor with respect to the percentage of the components. The safe period of 2-3 hours for the storage of the nutrient media was determined. After that period the media contamination levels markedly increased.     

Choice of nutrient media for the laboratory diagnosis of Streptococcus group B

The comparative study of a large assortment of liquid and solid culture media used for the cultivation of streptococci in laboratory practice in the USSR and abroad was carried out with the aim of selecting the optimal media for the laboratory diagnosis of group B. streptococci. Liquid media were tested with the use of 7 streptococcal reference strains, and some of these media, found to yield the best results, were selected for tests on clinical material. The use of liquid accumulation media was shown to permit the isolation of group B. streptococcal strains which could not be detected by the direct inoculation of clinical material into dishes with blood agar. The character of hemolysis induced by group B. streptococci in solid media with 5% of blood added was found to depend on the composition of the medium and the conditions of cultivation.