Constitution of the metabolic type of streptomycetes during the first hours of cultivation

Using the examples of biosynthesis of streptomycin, bialaphos, actinorhodin, oligoketides and autoregulators during the first hours of streptomycete cultivation, it is stressed that the external environment in cooperation with the internal metabolic abilities of the cell determines the metabolic type that would develop during the life cycle of the producing streptomycetes. If we accept that a certain metabolic type (from the point of view of the production of secondary metabolites) was determined already during the first hours of cultivation of the microorganisms, we must also admit that the availability of primary metabolites in the so-called production phase of growth (stationary phase, idiophase,etc.) is to a certain extent determined by the very early stages of strain development. The work of J.J. was supported byIGA grant no. A5011501.     

Media for cultivation of animal cells: an overview

The increasing interest in products from animal cells has caused an extensive research effort towards development of media for cell cultivation.The basic components in the media used for cultivation of animal cells vary depending upon the characters of the cells and the cultivation method. Basic components consist of an energy source, nitrogen source, vitamins, fats and fatty soluble components, inorganic salts, nucleic acid precursors, antibiotics, oxygen, pH buffering systems, hormones, growth factors and serum. Extensive efforts are directed towards developing serum-free or chemically defined media. Among the serum substitutes is a long list of hormones and growth factors.     

Engineering solutions for open microalgae mass cultivation and realistic indoor simulation of outdoor environments

Microalgae could become an important renewable source for chemicals, food, and energy if process costs can be reduced. In the past 60 years, relevant factors in open outdoor mass cultivation of microalgae were identified and elaborate solutions regarding bioprocesses and bioreactors were developed. An overview of these solutions is presented. Since the cost of most microalgal products from current mass cultivation systems is still prohibitively high, further development is required. The application of complex computational techniques for cost-effective process and reactor development will become more important if experimental validation of simulation results can easily be achieved. Due to difficulties inherent to outdoor experimentation, it can be useful to conduct validation experiments indoors. Considerations and approaches for realistic indoor reproduction of the most important environmental conditions in microalgae cultivation experiments—light, temperature, and substance concentrations, are discussed.     

Method for isolating cyanobacteria-lysing streptomycetes from soil

A new technique is described for the isolation and enumeration of cyanobacteria-lysing Streptomyces spp from soil or water. Two cyanobacteria, Anabaena cylindrica (ACTT 27899) and Tolypothrix tenuis (ATCC 27914) were used as the test organisms. Ten-day-old cyanobacterial cultures were vacuum-filtered to form a lawn on a 7 cm Whatman No. 1 filter paper which was then supported on Allen's agar. When the lawn was inoculated with dilutions of a heavy clay prairie soil and incubated at 27 PT 1dEC under constant illumination, white or grey colonies of streptomycetes grew. These colonies were surrounded by zones where a yellowing and lysis of the algal cells occurred. Streptomyces achromogenes was identified as a major lytic species within a population of 5 times 10₃ plaque-producing streptomycetes/g (dry weight) soil.     

Rapid biochemical tests for the characterisation of streptomycetes

Eighty-eight streptomycetes representing numerically circumscribed species-groups were examined for their ability to use a range of 4-methyl-umbelliferone-linked substrates. The test strains produced acid and alkaline phosphatases, acyl-hydrolase (C₇) but the discontinuous distribution of the remaining enzymes provided information of taxonomic value. Fluorogenic probes prepared from 4-methylumbelliferone provide a rapid and simple means of detecting enzymes in small amounts of whole streptomycetes.     

Protein secretion in streptomycetes

Some aspects of the current knowledge on protein secretion in streptomycetes are presented, including recent data on the identification of genes involved in the general secretory pathway, on the importance of the signal peptide structure and on the number of ribosome-binding sites inside signal peptides which can influence the production level of a gene product.     

Biosynthesis of antibiotics in streptomycetes

Meeting announcements     

Outdoor and indoor cultivation of Spirulina platensis in the extreme south of Brazil

Water supplemented with 10% or 20% (v/v) of Zarrouk medium was used to cultivate Spirulina platensis in closed and open bioreactors under controlled conditions (30 degrees C, 32.5 micromol m(-2) s(-1), 12 h light/dark photoperiod) and in a greenhouse (9.4 to 46 degrees C, up to 2800 micromol m(-2) s(-1), variable day length photoperiod) using different initial biomass concentrations (X0) in the extreme south of Brazil (32.05 degrees S, 52.11 degrees W). Under controlled conditions the maximum specific growth rate (micromax) was 0.102 d(-1), the biomass doubling time (t(d)) was 6.8 d, the maximum dry biomass concentration (Xmax) was 1.94 g L(-1) and the maximum productivity (Pmax) was 0.059 g L(-)1 d(-1), while the corresponding values in the greenhouse experiments were micromax = 0.322 d(-1), t(d) = 2.2 d, Xmax = 1.73 g L(-1) and Pmax = 0.112 g L(-1) d(-1). Under controlled conditions the highest values for these parameters occurred when X0 = 0.15 g L(-1), while in the greenhouse X0 = 0.4 g L(-1) produced the highest values. These results show that the cultivation of S. platensis in greenhouses in the extreme south of Brazil is technically viable and that the S. platensis inoculum and the concentration of Zarrouk medium can be combined in such a way as to obtain growth and productivity parameters comparable, or superior, to those occurring in bioreactors under controlled conditions of temperature, illuminance and photoperiod.     

Nitroalkane oxidation by streptomycetes.

Crude cell-free extracts of nine strains of Streptomyces tested for nitroalkane-oxidizing activity showed production of nitrous acid from 2-nitropropane, 1-nitropropane, nitroethane, nitromethane, and 3-nitropropionic acid. These substrates were utilized in most strains but to a decreasing extent in the order given, and different strains varied in their relative efficiency of oxidation. p-Nitrobenzoic acid, p-aminobenzoic acid, enteromycin, and omega-nitro-l-arginine were not attacked. d-Amino acid oxidase, glucose oxidase, glutathione S-transferase, and xanthine oxidase, enzymes potentially responsible for the observed oxidations in crude cellfree extracts, were present at concentrations too low to play any significant role. A nitroalkane-oxidizing enzyme from streptozotocin-producing Streptomyces achromogenes subsp. streptozoticus was partially purified and characterized. It catalyzes the oxidative denitrification of 2-nitropropane as follows: 2CH(3)CH(NO(2))CH(3) + O(2) --> 2CH(3)COCH(3) + 2HNO(2). At the optimum pH of 7.5 of the enzyme, 2-nitropropane was as good a substrate as its sodium salt; t-nitrobutane was not a substrate. Whereas Tiron, oxine, and nitroxyl radical acted as potent inhibitors of this enzyme, superoxide dismutase was essentially without effect. Sodium peroxide abolished a lag phase in the progress curve of the enzyme and afforded stimulation, whereas sodium superoxide did not affect the reaction. Reducing agents, such as glutathione, reduced nicotinamide adenine dinucleotide, and nicotinamide adenine dinucleotide phosphate, reduced form, as well as thiol compounds, were strongly inhibitory, but cyanide had no effect. The S. achromogenes enzyme at the present stage of purification is similar in many respects to the enzyme 2-nitropropane dioxygenase from Hansenula mrakii. The possible involvement of the nitroalkane-oxidizing enzyme in the biosynthesis of antibiotics that contain a nitrogen-nitrogen bond is discussed.     

Protein tyrosine phosphorylation in streptomycetes

Using phosphotyrosine-specific antibodies, we demonstrate that in several Streptomyces spp. a variety of proteins are phosphorylated on tyrosine residues. Tyrosine phosphorylation was found in a number of Streptomyces species including Streptomyces lividans, Streptomyces hygroscopicus and Streptomyces lavendulae. Each species exhibited a unique pattern of protein tyrosine phosphorylation. Moreover, the patterns of tyrosine phosphorylation varied during the growth phase and were also influenced by culture conditions. We suggest that metabolic shifts during the complex growth cycle of these filamentous bacteria, and possibly secondary metabolic pathways, may be controlled by the action of protein tyrosine kinases and phosphatases, as has been demonstrated in signal transduction pathways in eukaryotic organisms.     

链霉菌看家基因引物的设计与验证

看家基因的扩增与测序是进行多基因系统进化分析首先需要解决的问题。针对链霉菌这一群高(G C)mol%革兰氏阳性细菌,选定4个看家基因:atpD、recA、rpoB和trpB,利用NCBI数据库中已有的2个链霉菌和3个分枝杆菌的全基因组序列,以及另两个链霉菌的recA基因序列,通过软件分析设计了各基因的扩增和测序引物,并优化了扩增反应条件。从所试验的55株链霉菌中,均特异地扩增出了上述4个基因的片段,并成功进行了序列测定,验证了所设计引物的实用性。所归纳的引物设计方法可用于高(G C)mol%革兰氏阳性细菌的其它看家基因,以促进多基因系统进化研究的开展。     

Morphological subtype of the smooth-spored streptomycetes

Tresner, H. D. (Lederle Laboratories, American Cyanamid Co., Pearl River, N.Y.), M. C. Davies, and M. E. Englert. Morphological subtype of the smoothspored streptomycetes. J. Bacteriol. 91:1998-2005. 1966.-Electron microscopy reveals that certain Streptomyces species produce chains of smooth-surfaced, contiguous, cylindrical spores that resemble the phalanges. Although spore shape itself has not, heretofore, provided an especially important aid in the taxonomy of the streptomycetes, the "phalangiform" spore character promises to be helpful in the identification of species possessing it.