Factors influencing odour production by actinomycetes

Odour production by actinomycete (Streptomyces spp.) strains isolated from hypereutrophic natural waters in which muddy odours in fish have occurred, were studied by the ISP (International Streptomyces Project) carbon utilization method. The streptomycete strains were isolated from water, bottom mud and aquatic plants. Nine different carbon sources were used. Odour character was determined by sniffing the cultures. Odour production varied depending on the strain and the carbon source used. Some of the strains produced similar odours in all media regardless of the carbon source. In other strains, the odour varied depending on the carbohydrate used. The total colony counts of actinomycetes may not necessarily indicate the role of actinomycetes in odour problems in the aquatic environment because the odour production by actinomycetes depends on environmental factors.     

Experiment to study some suspension media for the lyophilization of actinomycetes]

Viability and cultural properties of 59 actinomycetes and 17 bacteria lyophilized in polyvinylpyrrolidone (PVP), sodium glutamate, their combinations and horse serum were studied after storage for 2 years at a temperature of 4-10 degrees. A 5 per cent solution of sodium glutamate had a high protective effect on viability of the above organisms. The solution containing 3 per cent of sodium glutamate and 3 per cent of PVP was somewhat less effective. The cultures lyophilized in 5 per cent solution of sodium glutamate had the same viability levels as those lyophilized in horse serum, while the latter had better growth rates on their plating out on nutrient media. A 5 per cent solution of PVP had no advantages over sodium glutamate or horse serum with respect to preservation of the organism viability. No significant differences in the cultural properties: colour of the aerial and substrate mycelium and pigment production were noted in the actinomycetes lyophilized in various protective media and the analogous control cultures maintained by means of passages on fresh nutrient media.     

Development of media for growth ofDioscorea Deltoidea cells andin vitro diosgenin production: Influence of media constituents and nutrient stress

Summary Callus culture ofDioscorea deltoidea produced diosgenin and sterols during stationary phase. Ammonium nitrate (420 mg Nitrogen/l) as sole nitrogen source supported better growth than a combination of ammonium nitrate and potassium nitrate (totally equivalent to 840 mg Nitrogen/l). The production of diosgenin increased under low phosphate concentration (100 mg/l) whereas high phosphate concentration (240 mg/l) promoted growth. Micronutrients, when used at 1 1/2 strength, enhanced growth and diosgenin production. Depletion of nitrogen increased the diosgenin synthesis by a factor of 2. Adoption of a two stage culture method enhanced the diosgenin production in cultured cells by eight-fold.     

黄孢原毛平革菌产絮凝剂营养条件优化

微生物絮凝剂与传统化学絮凝剂相比,安全无毒、无二次污染,具有开发潜力.黄孢原毛平革菌(Phanerochaete chrysosporium)能产生微生物絮凝剂,但目前缺少对其产絮凝剂营养条件的优化.使用高岭土并利用单因素法研究碳源、氮源、碳氮比、接种量对Phanerochaete chrysosporium产絮凝剂的...     

Improving production of bioactive secondary metabolites in actinomycetes by metabolic engineering

Production of secondary metabolites is a process influenced by several physico-chemical factors including nutrient supply, oxygenation, temperature and pH. These factors have been traditionally controlled and optimized in industrial fermentations in order to enhance metabolite production. In addition, traditional mutagenesis programs have been used by the pharmaceutical industry for strain and production yield improvement. In the last years, the development of recombinant DNA technology has provided new tools for approaching yields improvement by means of genetic manipulation of biosynthetic pathways. These efforts are usually focused in redirecting precursor metabolic fluxes, deregulation of biosynthetic pathways and overexpression of specific enzymes involved in metabolic bottlenecks. In addition, efforts have been made for the heterologous expression of biosynthetic gene clusters in other organisms, looking not only for an increase of production levels but also to speed the process by using rapidly growing and easy to manipulate organisms compared to the producing organism. In this review, we will focus on these genetic approaches as applied to bioactive secondary metabolites produced by actinomycetes.     

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.     

Trial of different nutrient media for the production of an intracellular thermolabile enterotoxin by Escherichia coli strains H74-114 and 86

The conditions of cultivation, ensuring the maximum accumulation of intracellular thermolabile enterotoxin in the cultures of two E. coli strains of different origin, have been studied. Culture media manufactured in the USSR have been selected and the conditions of cultivation, necessary for obtaining intracellular thermolabile enterotoxin in preparative amounts, have been established. Under these conditions the yield of thermolabile enterotoxin in 1.4 mg per 1 liter of culture medium for strain H74-114 and 1.0 mg per 1 liter of culture medium for strain 86.     

Optimal conditions for the production of exopolysaccharide by marine microorganismHahella chejuensis

A marine microorganism, strain 96CJ10356 produced exopolysaccharide, designated as EPS-R. To optimize culture conditions for the production of EPS-R, carbon and nitrogen sources, mineral salts, temperature, and pH were examined. From this study, STN medium for the production of EPS-R was suggested as follows; sucrose 20 g, tryptone 10 g, NaCl 10 g, MgSO₄ 5 g, CaCl₂ 1 g, KH₂PO₄ 76 mg, K₂HPO₄ 83 mg, FeCl₂ 5 mg, MnCl₂ 1 mg, NaMoO₄ 1 mg, and ZnCl₂ 1 mg per liter at pH 7.0. About 9.23 g/L of EPS-R was obtained from STN medium after cultivation for 120 h at 25°C in a 5-liter jar fermentor with an aeration rate of 0.17 vvm. Apparent viscosity and flocculation activity of the culture broth were increased with the production of EPS-R and the maximal values were 415 cP and 1400 unit/mL against 0.5% activated carbon, respectively.