A nutrient medium for the isolation and cultivation of Campylobacter

Campylobacter agar, nutrient medium intended for the isolation of bacteria of the genus Campylobacter from clinical material, has been developed. The composition of the medium includes sprat hydrolysate, aerotolerant additive (ferric sulfate--oxide, sodium pyruvate, sodium pyrosulfite), sodium glutaminate, agar. The selective properties of the medium are ensured by introducing the mixture of antibiotics consisting of polymyxin B, rifampicin, amphotericin B, ristomycin. The balanced composition of Campylobacter agar ensures the aerotolerance of Campylobacter organisms and gives the optimal conditions for their growth when the inoculated material is cultivated in the atmosphere made up of the mixture of three gases (5% of oxygen, 10% of carbon dioxide, 85% of nitrogen), as well as under the conditions of a "candle vessel". The medium suppresses the development of the associative microflora diluted 10(-1). As shown in the trial of the quality of Campylobacter agar by the inoculation of material taken from patients with acute enteric infections, agricultural animals and monkeys, the medium has pronounced selective, properties with regard to extraneous microflora, while ensuring the isolation of Campylobacter on the level of the control medium.     

Viability of escherichia coli cells under long-term cultivation in a rich nutrient medium

We investigated the viability of Escherichia coli cells during long-term cultivation in Brain Heart Infusion (BHI) medium and observed that the number of viable cells increased, then decreased, and increased again, in this medium, and finally the cells died out within about 10 days. This cell death may result from an increase in the pH of the medium. After repeated cultivation in BHI, bacterial cells that did not die out even under conditions of further cultivation were obtainable from cultures showing a stabilized viable count. We propose that long-term cultivation in BHI medium is a good system for studying growth phase-specific events in E. coli cells, because the total life-cycle of a population of E. coli, including exponential growth, stationary phase, and extinction, can be seen during a period of only about 10 days. Also, this system clearly allows detection of a phenotype that may not be detectable in other commonly used media. Moreover, in this report, we show that mutants displaying the GASP (growth advantage in stationary phase) phenotype appear at high frequency under long-term cultivation conditions.     

Dynamics of growth of Haemophilus influenzae serotype B and synthesis of capsular polysaccharide in the process of cultivation in a synthetic nutrient medium

The dynamics of H. influenzae, serotype b, growth and synthesis of their capsular polysaccharide in the synthetic nutrient medium, proposed by Herriot for noncapsular strains, was studied using 6 strains. The growth rate of H. influenzae, serotype b, and the amount of capsular polysaccharide, synthesized in the above mentioned medium, practically were not different from those in heart-brain broth (Difco). The possibility of minimizing the composition of Herriot's medium without any adverse effect on the amount of synthesized capsular polysaccharide was shown. As the result of these studies, the expediency of the cultivation of H. influenzae, serotype b, in the synthetic medium, intended for obtaining the preparations of capsular polysaccharide, was proved.     

Inclusion of geothermal water in composition of nutrient medium for mycobacteria cultivation

New effective nutrient medium for isolation and cultivation of mycobacteria was developed. Time of their growth on the developed medium decreased by 3 to 11 days compared with control media (Finn II, Levenstein-Jensen). Rate of mycobacteria isolation increased by 20 to 40% compared with control media.     

Efficient cellulase production by Trichoderma reesei in continuous cultivation on lactose medium with a computer-controlled feeding strategy

A low-foaming hydrophobin II deletant of the Trichoderma reesei strain Rut-C30 was used for production of cellulases by continuous cultivation on lactose medium in a laboratory fermenter. The control paradigm of the addition of new medium to the continuous process was based on the growth dynamics of the fungus. A decrease in the rate of base addition to the cultivation for pH-minimum control was used as an indicator of imminent exhaustion of carbon source for growth and enzyme induction. When the amount of base added per 5 min computation cycle decreased below a given value, new medium was added to the fermenter. When base addition for pH control thereafter increased above the criterion value, due to increased growth, the medium feed was discontinued or decreased. The medium feeding protocol employed was successful in locking the fungus in the stage of imminent, but not actual, exhaustion of carbon source. According to the results of a batch cultivation of the same strain on the same medium, this is the phase of maximal enzyme productivity. The medium addition protocol used in this work resulted in a very stable continuous process, in which cellulase productivity was maintained for several hundred hours at the maximum level observed in a batch cultivation for only about 10 h. Despite a major technical disturbance after about 420 h, the process was restored to stability. When the cultivation was terminated after 650 h, the level of enzyme production was still maximal, with no signs of instability of the process.     

An improved synthetic medium for continuous cultivation of Zymomonas mobilis

Summary A synthetic medium for continuous cultivation of Zymomonas mobilis was developed using the chemostat pulse technique in appropriate experimental designs. Yeast extract could be replaced by a mixture of six mineral salts, Ca-pantothenate, l-as-partate, and l-serine. Kinetic data from continuous cultivations of strains ATCC 10988 and ZM4 are presented and compared with published data.     

Cultivation of yeasts on hydrolysate nutrient medium obtained from the production of microcrystalline cellulose

Studies of the biomass production during a continuous cultivation of yeasts on a nutrient medium, prepared from a hydrolysate from the production of microcrystalline cellulose, have been carried out. A new strain of yeasts has been used. Its cultivation has been achieved without addition of biostimulators to the nutrient medium in spite of their absence in the initial hydrolysate. Practically a complete assimilation of sugars has been achieved at high dilution rates (D = 0.25 to 0.50 h⁺¹). The yield of biomass achieved is above 50% compared to the initial sugars and it contains 48.89% true protein. The results obtained offer the possibility of a complex utilization of the products of cellulose hydrolysis in the production of microcrystalline cellulose with a realization of a waste free technology.     

Plasmodium falciparum: continuous cultivation of erythrocyte stages in plasma-free culture medium

Continuous in vitro cultivation of the malaria parasite, Plasmodium falciparum, was performed in plasma-free medium. The medium used was standard RPMI 1640 supplemented with adenosine, unsaturated C-18 fatty acids, and fatty acid-free bovine serum albumin. The medium was changed daily and the cultures were diluted with washed erythrocytes twice weekly. Growth was routinely maintained for 1 month at which time the experiments were usually terminated. Although the overall growth rates were consistently lower than in control cultures with plasma, continuous growth occurred in the absence of plasma in cultures containing cis-vaccenic, oleic, and linoleic acids.     

Effect of different pH values on the medium on the synthesis of antibiotics in the joint cultivation of Actinomyces levoris with yeasts]

Changes in the pH level of the fermentation medium used for preliminary cultivation of C. tropicalis were studied with respect to its initial aciditv or alkalinitv. When C. tropicalis was grown on the medium used for levorin fermentation with ph 5.1--10.3, the yeast changed it in 24 hours to the level of 6.2--7.9. As dependent on the initial pH values for cultivation of C. trophicalis, production of levorin on subsequent inoculation of Act. levoris changed. The antibiotic activity increased and ranged within 120--178% of the control. Synthesis of levoristatin, a non-polyenic antibiotic equally increased under such conditions and ranged within 153--163% of the control. The pH values of 9.4--10.3 of the initial fermentation medium were optimal for mixed cultivation of Act levoris and C. tropicalis and maxium production of levorin and levoristatin.