The effect of changes in pH on phosphate and potassium uptake by Monascus rubiginosus ATCC 16367 in submerged shaken culture.

Monascus rubiginosus ATCC 16367 was cultivated aerobically in media containing ammonium and nitrate as nitrogen source. The pH of the medium was adjusted at different times, the pH of the nitrate medium being lowered to the pH of the ammonium medium and the pH of the ammonium medium raised to that of the nitrate. More phosphate was taken up on the nitrate medium, but potassium uptake did not start until 24h. On the ammonium medium, both were taken up in parallel from the beginning, but the amount of phosphate taken up never reached the same level as on nitrate medium. When the pH was adjusted, the uptakes changed, especially on the ammonium medium where a great increase in phosphate uptake was observed. More conidia were formed on the nitrate medium and more pigment on the ammonium medium. When the pH of either media was adjusted, the development of conidia and pigment production changed to that of the other control medium where the pH evolved normally in the direction of the change, regardless of the source of nitrogen. The reasons for the development of conidia on nitrate medium or where the pH is high, and the production of pigment on ammonium medium or at low pH is discussed.     

The effect of different nitrogen sources on pigment production and sporulation of Monascus species in submerged, shaken culture.

Thirty-nine strains from the genus Monascus were cultivated aerobically to study the relation between nitrogen nutrition and sporulation and pigment production. The effects of yeast extract, nitrate, ammonium, and ammonium nitrate have been compared. During cultivation the pHs of the different media are not the same, resulting in the formation of different coloured pigments. When the source of nitrogen is yeast extract or nitrate the pH is around 6.5 and red pigments are formed, whereas with ammonium or ammonium nitrate the pH is around 2.5 and the pigments are orange. It is proposed that only the orange pigments, monascorubrin and rubropunctatin, are produced biosynthetically and that the other pigments are formed from these by chemical transformations depending on the cultural conditions. The presence of organic nitrogen is optimal for growth and unfavourable for pigment production. Reduced growth and best pigment formation occurs with the three other nitrogen sources. Nitrate stimulates conidiation and sexual reproduction, while ammonium is inhibitory. Pigment production is better when conidiation is reduced. A mechanism is proposed for the control of sporulation and pigment production.     

Sexal reproductive cycle of Monascus in submerged shaken culture.

A strain of Monascus was grown in submerged, shaken culture using a glucose-salts mediumn. The formation of ascospores was studied by microscopic examination of samples taken at regular intervals for 6 days. All the stages of sexual reproduction previously described for Monascus were observed. The unusual feature of the strain studied was that it produced sexual structures and cliestothecia of greatly varying sizes.     

A new process for red pigment production by submerged culture of Monascus purpureus

Formation of red pigment by Monascus purpureus via diauxic growth on glucose and ethanol in submerged culture was optimized based on inoculum preparation and culture medium. A vegetative inoculum was prepared from spores grown on ethanol. The optimized culture medium was low in phosphates, and had an initial pH?of 5.5. The characteristics of Monascus purpureus grown on glucose and on ethanol were compared: the specific consumption rate of glucose (q_G) was higher than the specific consumption rate of ethanol (q_E), whereas the specific growth rate was greatest with ethanol. The specific production rate of red pigment (p_OD) and pigment yield (Y_OD/s) with glucose was twice that with ethanol. A novel fermentation process was developed with M. purpureus initially grown with controlled ethanol formation, and consumption of the latter during pigment formation.     

Secretory enzyme production and conidiation of Aspergillus oryzae in submerged liquid culture

Summary The production of - and -galactosidases, proteinase and -amylase and also conidiation of Aspergillus oryzae were examined in liquid soybean meal culture. In a culture of soybean meal only, conidiation of the fungus was not induced and the production of the enzymes was not significant, although fungal growth was abundant. When phosphate was added to the medium at concentrations above 0.2 M, enzyme production was significantly increased and the cells formed conidiophores after enzyme production had attained maximum level. Increase in production of galactosidases was the most marked.K- or Na-salts other than phosphate were not effective stimulants for enzyme production, while conidiation was not induced under these growth conditions. Conidiation and production of enzymes were repressed by the addition of glucose or casamino acids to the soybean meal medium containing KH₂PO₄.Conidiation and enzyme production were also studied in modified Czapek media in which sucrose was replaced by other carbon sources. Lactose, lactulose, melibiose and polysaccharides composed of galactosyl linkage such as arabinogalactan induced both conidiation and production of the enzymes.     

Effect of pH and nitrogen source on pigment production by Monascus purpureus

The effect of pH and nitrogen source on pigment production by Monascus purpureus 192F using glucose as the carbon and energy source, was studied in pH-controlled, batch fermentor cultures using HPLC analysis to determine individual pigment concentrations. A maximum of four pigments were detected in fungal extracts. These were the yellow pigments monascin and ankaflavin, the orange rubropunctatin and the red pigment monascorubramine. Monascorubramine was present as the major product in all instances. Fungal growth and ankaflavin synthesis were favoured at low pH (pH 4.0), whereas production of the other pigments was relatively independent of pH. The nature of the nitrogen source affected fungal growth and pigment production, independent of pH. Ammonium and peptone as nitrogen sources gave superior growth and pigment concentrations compared to nitrate. Ankaflavin was not detected in nitrate cultures. The highest red pigment production was obtained using a glucose-peptone medium at pH 6.5, due to the secretion of red pigments into the medium under these conditions. Correspondence to: M. R. Johns     

Enhancement of monascus pigment production by the culture of Monascus sp. J101 at low temperature

In general, high broth viscosity is a key factor to be considered in a submerged fermentation of filamentous fungi. High broth viscosity was also observed in a batch fermentation of Monascus sp. J101 at 30 degrees C. In a batch culture at 30 degrees C, most cell growth was accomplished within 48 h, which induced highly entangled clumps. The resultant high viscosity induced heterogeneity inside the fermentor, poor oxygen transfer, and low pigment yield. However, these problems could be overcome by reducing fungal growth rate through culture at low temperature (25 degrees C). Cell growth was moderate and continued for 120 h, and low viscosity was maintained. The DO levels remained at 50% or higher with good mixing. As a result, the pigment yield at 25 degrees C was 10 times greater than at 30 degrees C.     

The effect of AmtR on growth and amino acids production in Corynebacterium glutamicum

AmtR, the master regulator of nitrogen control in Corynebacterium glutamicum, plays important roles in nitrogen metabolism. To investigate the influence of AmtR on amino acids production in C. glutamicum ATCC 13032, the amtR deletion strain C. glutamicum Q1 was constructed and cultured in modified CGXII minimal medium for 60 h. The ammonium consumption rates as well as amino acids production of both strains cultured in modified CGXII minimal medium were determined. The amtR deletion in C. glutamicum caused an obvious growth defect in the exponential growth phase, but both strains had the same biomass in the stationary phases. Maybe the less alpha-oxoglutarate was used for the tricarboxylic acid cycle to influence the growth of strains. During 12 h, the rate of ammonium consumption and the concentration of Glu, Pro, Arg and Ser were higher but Asp, Gly, Ile, Leu, Lys were lower in the mutation strain. During 48 h, the Q1 had higher levels of Asp, Lys, Pro, Ala and Val,and lower levels of Glu, Arg, Leu and Ile, compared to the wild. The more Glu was synthesized by the activated GS/GOGAT pathway in Q1, and then the accumulation of relative amino acids (Pro, Arg and Ser) were up-regulated within 12 h growth. After 48 h growth, the amtR deletion obviously influenced accumulation of Ala, Asp and Pro. The amtR deletion could influence the growth and amino acids production, which could be useful to the production of amino acids.     

The effect of citric acid concentration and pH on the submerged production of lysergic acid derivatives

Summary Succinic acid can just as well be replaced by citric acid in submerged fermentation of lysergic acid derivatives by a strain of Claviceps paspali. The highest alkaloid yields were obtained with a 1% citric acid concentration in the medium at a constant pH of 5.2. When the optimal pH was not maintained, growth was inhibited and all aspects of metabolic activity of the fungus were depressed.     

The modulating effect of amino acids on an organotypic culture of lymphoid tissue

The effect of 20 essential and nonessential L-amino acids on the dynamics of development of spleen explants from 1- and 21-day-old rats on an organotypic tissue culture was studied. The hydrophilic amino acids with a higher molecular mass (asparagine, lysine, arginine, and glutamic acid) induced an inhibitory effect on the growth zone of explants of immature tissue from 1-day-old animals and an opposite, stimulating effect on the mature spleen tissue of 21-day-old rats. An immunohistochemical analysis revealed a reciprocal correlation between the expression of the proapoptotic protein p53 and the cell proliferation upon the action of lysine, asparagine, and glutamic acid. The role of polar amino acids in the modulation of cell proliferation and apoptosis in dependence on the period of ontogenesis was determined. The English version of the paper: Russian Journal of Bioorganic Chemistry, 2006, vol. 32, no. 3; see also http://www.maik.ru.     

The modulating effect of amino acids on an organotypic culture of lymphoid tissue

The effect of 20 essential and nonessential L-amino acids on the dynamics of development of spleen explants from 1-and 21-day-old rats on an organotypic tissue culture was studied. The hydrophilic amino acids with a higher molecular mass (asparagine, lysine, arginine, and glutamic acid) induced an inhibitory effect on the growth zone of explants of immature tissue from 1-day-old animals and an opposite, stimulating effect on the mature spleen tissue of 21-day-old rats. An immunohistochemical analysis revealed a reciprocal correlation between the expression of the proapoptotic protein p53 and the cell proliferation upon the action of lysine, asparagine, and glutamic acid. The role of polar amino acids in the modulation of cell proliferation and apoptosis in dependence on the period of ontogenesis was determined.     

The complete Corynebacterium glutamicum ATCC 13032 genome sequence and its impact on the production of L-aspartate-derived amino acids and vitamins

The complete genomic sequence of Corynebacterium glutamicum ATCC 13032, well-known in industry for the production of amino acids, e.g. of L-glutamate and L-lysine was determined. The C. glutamicum genome was found to consist of a single circular chromosome comprising 3282708 base pairs. Several DNA regions of unusual composition were identified that were potentially acquired by horizontal gene transfer, e.g. a segment of DNA from C. diphtheriae and a prophage-containing region. After automated and manual annotation, 3002 protein-coding genes have been identified, and to 2489 of these, functions were assigned by homologies to known proteins. These analyses confirm the taxonomic position of C. glutamicum as related to Mycobacteria and show a broad metabolic diversity as expected for a bacterium living in the soil. As an example for biotechnological application the complete genome sequence was used to reconstruct the metabolic flow of carbon into a number of industrially important products derived from the amino acid L-aspartate.     

Influence of pH on the morphology ofTrichoderma reeseiqm 9414 in submerged culture.

The influence of pH on the germination characteristics and the microscopic morphology ofTrichoderma reesei QM 9414 has been investigated. The parameters of a kinetic model were estimated by fitting model simulations to morphological measurements during submerged cultures at different pH values. Both the tip extension rate and the branching frequency varied with the pH and had maximum values around pH 4.5. The time of spore germination was dependent on the pH, but within the used pH-range (2.2–7.6), no significant effect of pH on the fraction of viable spores was observed.     

The effect of the coded amino acids on meso- and ectodermal tissue development in organotypic culture

The effect of L-amino acids was investigated in organotypic tissue culture ofmesodermal tissue (spleen, myocardium) and ectodermal tissue (brain cortex) in mature rats. The low hydrophobic amino acids: asparagine, hystidine, serine, lysine, arginine and glutamine acid, induced the proliferation stimulation. The high hydrophobic amino acids had both the apoptose effect (spleen) and no effect at all (myocardium). The proliferation stimulation occurred in the ectodermal tissue under the effect of the high hydrophobic amino acids (asparagines acid, valine, threonine, methionine, leucine, isoleucine), whereas the low hydrophobic amino acids had no effect on the nervous tissue development. The combination of two amino acids one of which stimulated and another one inhibited the explant growth zone (or was not active in myocardium) lead to an increase of the stimulatory effect in meso- and ectodermal tissue. The amino acid modulated properties can be taken in consideration in synthesis of new regulatory peptides.     

The effect of amino acids on the production of ochratoxin A in chemically defined media

The specific ability ofl-glutamic acid and ofl-proline to induce the formation of ochratoxin by a strain of the fungusAspergillus ochraceus in chemically defined media has been further confirmed. This induction was inhibited by 22 other amino acids as well as by analogues and antagonists of glutamic acid and proline. The inhibition could be reversed by increasing the concentrations of glutamic acid or proline and by adding lactic acid in low concentrations.