Role of carbon substrates of culture media on Mycobacterium smegmatis susceptibility to antitubercular agents

Influence of medium composition on Mycobacterium smegmatis growth and susceptibility to antituberculosis drugs (ATD)--isoniazid and rifabutin--was studied. It was shown that addition of phospholipids (PL) in form of liposomes to meat peptone broth resulted in activation of M. smegmatis growth and decrease of its susceptibility to ATD. Growth characteristics of M. smegmatis and its susceptibility to ATD were studied using variants of modified on source of carbon synthetic medium Sauton as growth substrate. It was revealed that presence of acetate or PL in growth medium results in significant decrease of M. smegmatis susceptibility to isoniazid and rifabutin. It was suggested that this phenomenon is determined by activation of glyoxylate cycle by PL and fatty acids, which, in its turn, can stimulate expression of a number of proteins, including cell membrane pumps excreting antibiotics out of microbial cell.     

Determination of new derivatives of genistein in culture media by liquid chromatography

Methods for determination of genistein and its four new analogues in culture media have been developed to support studies on their potential anticancer activities. The investigated compounds were extracted from the media using liquid-liquid extraction with appropriate solvent. After evaporation of organic solvents each of the dry extracts was reconstituted in appropriate mobile phase. Reversed-phase HPLC was applied to quantitative determining of tested compounds. The methods are specific, sensitive and technically simple. They were used to evaluate concentration level of investigated compounds in experiments with human promyelocytic leukemia cells (HL-60 cell line).     

A closed system for the filtration of Mycobacterium bovis liquid cultures using disposable capsule filters

A filtration system was designed to sterilize large volumes of Mycobacterium bovis BCG Tokyo culture safely, needed to purify protein antigens for immunodiagnosis of bovine tuberculosis. A closed system consists of culture bottles connected to three disposable filter capsules of decreasing pore size in series : a depth prefilter over a 1·2 μm filter ; a 0·8 μm prefilter over a 0·45 μm filter ; and a 0·2 μm sterile filter. Low air pressure (3 psi) forces liquid from below the bacillary pellicle. The system features a stainless steel clamp to hold rubber stoppers on the culture bottles, pleated filters to exclude bacillary clumps, a quick disconnector to minimize aerosols, and a closed system with plastic disposable filters that can be autoclaved as a unit without dismantling.     

Growth and sporulation of Entomophthora virulenta on semidefined media in liquid culture

Entomophthora virulenta was tested for growth and sporulation under various nutritional conditions in shake cultures containing combinations of dextrose and protein hydrolysates. Darkness, a temperature of 25°C, and a pH near 6.5 induced the formation of the greatest number of zygospores when the carbon and nitrogen sources were held constant. The influence of the total concentration of nutrients and of the ratio of the carbon and nitrogen sources depended on the nitrogen source used: The highest amount of spores under these conditions was produced with yeast extract as nitrogen source, a carbon/nitrogen source ratio of 2, and a 15% total nutrient concentration. The influence of the preinoculum and inoculum on sporulation is discussed.     

A method for estimating oxygen availability of stationary plant cell cultures in liquid media

A method for estimating the oxygen availability in plant cell cultures grown in stationary liquid media (e.g. many protoplast cultures) was developed. The method is based on short-term measurements of respiration rate versus oxygen concentration on a sample of cells, suspended in liquid media. From such data it is possible to estimate the oxygen concentration at the bottom of a stagnant liquid culture, by calculating the amount of oxygen reaching the cells by diffusion. As an example, rape (Brassica napus L. cv. Omega) hypocotyl protoplasts were grown with different oxygen concentrations at the site of the cells, obtained by varying the cell density, the height of the liquid layer and the oxygen content of the gas phase. The number of surviving calli was positively correlated with the estimated oxygen availability in the range between 60 and 350 M O₂, below 60 M all cells died. This indicates that oxygen availability can be a limiting factor in the range usually encountered in protoplast cultures, and that the method can be useful when designing optimal growth conditions for stationary cultures of plant cells.Abbreviations C₁ bulk oxygen concentration in agitated medium - C_o oxygen concentration in medium at the gas-liquid interface, in equilibrium with the gas - C_x oxygen concentration at cell level - D diffusion constant of oxygen in water - K_La oxygen transfer rate - l height of liquid above cells - n number of cells per ml - R_x respiration rate per cell     

Effect of ultrasonic waves on the growth intensity of Mycobacterium leprae in liquid nutrient media

Ultrasound-treated M. leprae grow in liquid culture media at a greater rate than untreated ones. Ultrasound-treated M. leprae retain their capacity for intensive growth after their passage in mice.