Carbon Concentration and Carbon-to-Nitrogen Ratio Influence Submerged-Culture Conidiation by the Potential Bioherbicide Colletotrichum truncatum NRRL 13737

We assessed the influence of various carbon concentrations and carbon-to-nitrogen (C:N) ratios on Colletotrichum truncatum NRRL 13737 conidium formation in submerged cultures grown in a basal salts medium containing various amounts of glucose and Casamino Acids. Under the nutritional conditions tested, the highest conidium concentrations were produced in media with carbon concentrations of 4.0 to 15.3 g/liter. High carbon concentrations (20.4 to 40.8 g/liter) inhibited sporulation and enhanced the formation of microsclerotiumlike hyphal masses. At all the carbon concentrations tested, a culture grown in a medium with a C:N ratio of 15:1 produced more conidia than cultures grown in media with C:N ratios of 40:1 or 5:1. While glucose exhaustion was often coincident with conidium formation, cultures containing residual glucose sporulated and those with high carbon concentrations (>25 g/liter) exhausted glucose without sporulation. Nitrogen source studies showed that the levels of C. truncatum NRRL 13737 conidiation were similar for all protein hydrolysates tested. Reduced conidiation occurred when amino acid and inorganic nitrogen sources were used. Of the nine carbon sources evaluated, acetate as the sole carbon source resulted in the lowest level of sporulation.     

Sporulation of Streptomyces antibioticus ETHZ 7451 in submerged culture.

Streptomyces antibioticus ETHZ 7451 formed spores in cultures grown in a liquid medium from either a spore or a mycelium inoculum. The spores formed were similar to those formed on surface-grown cultures, except for reduced heat resistance. Both types of spores were sensitive to lysozyme, which is unusual for Streptomyces spores. Glucose and other carbon sources, which promoted different growth rates, did not affect sporulation efficiency. Nitrogen sources, such as casamino acids, that allowed high growth rates suppressed the sporulation. A remarkable repression was also observed in media with some nitrogen sources that promoted noticeably lower growth rates. In permissive media, with nitrogen sources that permitted relatively high growth rates, sporulation was conditioned to the consumption of ammonium in the medium, but not to that of other nitrogen sources, such as asparagine. Phosphate did not show a repressive effect on sporulation in the assayed conditions.     

Descriptive Physiology and Biochemistry of the Abnormally Ripening Tomato Fruit (Lycopersicon esculentum) cv. Snowball

Aspergillus tamarii Kita grew and sporulated best at 30°C. The best pH for growth and sporulation were 5.5 and 6.5, respectively. Among the carbon sources employed, glucose supported the highest growth and sporulation. Best growth was obtained with sodium nitrate as nitrogen source and best sporulation with ammonium tar-tarate. When glucose was used as carbon source, the carbohydrates found in the mycelium included myoinositol. dulcitol, fructose, arabinose and ribose.     

Global metabolic response of Escherichia coli to gnd or zwf gene-knockout, based on 13C-labeling experiments and the measurement of enzyme activities

An integrated study on cell growth, enzyme activities and carbon flux redistribution was made to investigate how the central metabolism of Escherichia coli changes with the knockout of genes in the oxidative pentose phosphate pathway (PPP). Mutants deficient in glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase were constructed by disrupting the zwf and gnd genes and were grown in minimal media with two different carbon sources, such as glucose or pyruvate. It was shown that the knockout of either gnd or zwf gene did not affect the cell growth rate significantly, but the cellular metabolism was changed. While the specific substrate uptake rate and the specific carbon dioxide evolution rate for either mutant grown on glucose were higher than those obtained for the parent strain, these two rates were markedly decreased in mutants grown on pyruvate. The measurement of enzyme activities implied a significant change in metabolism, when alternative pathways such as the Entner–Doudoroff pathway (EDP) and the malic enzyme pathway were activated in the gnd mutant grown on glucose. As compared with the parent strain, the activities of phosphoglucose isomerase were increased in mutants grown on glucose but decreased in mutants grown on pyruvate. The metabolic flux redistribution obtained based on ¹³C-labeling experiments further indicated that the direction of the flux through the non-oxidative PPP was reversed in response to the gene knockout. Moreover, the knockout of genes caused an increased flux through the tricarboxlic acid cycle in mutants grown on glucose but caused a decrease in the case of using pyruvate. There was also a negative correlation between the fluxes through malic enzyme and isocitrate dehydrogenase in the mutants; and a positive correlation was found between the fluxes through malic enzyme and phosphoenolpyruvate carboxylase.Electronic Supplementary Material Supplementary material is available in the online version of this article at     

Sporulation Synchrony of Saccharomyces cerevisiae Grown in Various Carbon Sources

Sporulation of several strains of Saccharomyces cerevisiae grown in a variety of carbon sources that do not repress the tricarboxylic acid cycle enzymes was more synchronous than the sporulation of cells grown in medium containing dextrose which does repress those enzymes. Dextrose-grown cells showed optimal sporulation synchrony when inoculated into sporulation medium from early stationary phase when the dextrose in the medium is exhausted. Logarithmic-phase cells grown in either non-fermentable carbon sources (acetate and glycerol) or a fermentable carbon source that does not repress tricarboxylic acid cycle enzymes (galactose) sporulated more synchronously than the early stationary-phase dextrose cells. Attempts were made to sporulate cells taken from both complex and semidefined media. The semidefined acetate medium failed to support the growth of a number of strains. However, cells grown in the complex acetate medium, as well as both complex and semidefined glycerol and galactose media, sporulated with better synchrony than did the dextrose-grown cells.     

Microplate Assay for Colletotrichum Spore Production

A simple microplate method was devised to assay spore production by Colletotrichum gloeosporioides by growing the fungus on 1 ml of solid media in the wells of tissue culture plates. Growth and sporulation on microplates were compared at days 4 and 8 with growth and sporulation in 100-ml liquid batch cultures that involved 11 common media. Spore production per unit volume of medium was the same for solid and liquid forms of the media. Qualitative assessment of mycelial growth measured on microplates agreed with that of growth measured in liquid cultures. The microplate assay indicated that V8 juice was the best medium and that an organic content of about 6 mg/ml was optimal for high sporulation and low mycelium production. The assay provides a convenient, rapid, and inexpensive means of screening media for the production of fungal conidia in large numbers, to be used, for example, in biological control programs.     

Utilization of Carbohydrates by Rhynchosporium secalis. I. Growth and Sporulation on Glucose, Galactose, and Galacturonic acid

The fungus Rhynchosporium secalis (Oud.) Davis grew and speculated in liquid nutrient media that contained glucose, galactose or galacturonic acid, or a pair of those substances, as the sole carbon source. Sporulation was inhibited by high concentrations of glucose and galacturonic acid. Growth and sporulation were greatest on glucose, and least on galactose. Growth was increased when glucose and galacturonic acid were mixed. Nitrogen concentration affected sporulation but not growth.     

Growth and β-galactosidase synthesis in aerobic chemostat cultures of Kluyveromyces lactis

Growth and β-galactosidase (β-gal) expression were characterized in the yeast Kluyveromyces lactis strain NRRL Y-1118 growing in aerobic chemostat cultures under carbon, nitrogen or phosphate limitation. In lactose or galactose-limited cultures, β-gal accumulated in amounts equivalent to 10–12% of the total cell protein. The induced β-gal expression was repressed when cells were grown under N- or P-limitation. In lactose medium, enzyme levels were 4–8 times lower than those expressed in C-limited cultures. A similar response was observed when galactose was the carbon source. These results suggest that a galactose-dependent signal (in addition to glucose) may have limited induction when cells were grown in carbon-sufficient cultures. Constitutive β-gal expression was highest in lactate-limited and lowest in glucose-limited media and was also repressed in glucose-sufficient cultures. Other K. lactis strains (NRRL Y-1140 and CBS 2360) also showed glucose repression (although with different sensitivity) under non-inducing conditions. We infer that these strains share a common mechanism of glucose repression independent of the induction pathway. The kinetics of β-gal induction observed in C-limited cultures confirms that β-gal induction is a short-term enzyme adaptation process. Applying a lactose pulse to a lactose-limited chemostat culture resulted in ‘substrate-accelerated death’. Immediately after the pulse, growth was arrested and β-gal was progressively inactivated. Yeast metabolism in C-limited cultures was typically oxidative with the substrate being metabolized solely to biomass and CO₂. Cells grown under P- or N-limitation, either with glucose or lactose, exhibited higher rates of sugar consumption than C-limited cells, accumulated intracellular reserve carbohydrates and secreted metabolic products derived from the glycolytic pathway, mainly glycerol and ethanol. Received 16 October 1997/ Accepted in revised form 17 April 1998     

Regulation of spindle pole function by an intermediary metabolite

Spore formation in the yeast Saccharomyces cerevisiae depends on a modification of spindle pole bodies (SPBs) at the onset of meiosis II that allows them to promote de novo membrane formation. Depletion of the environmental carbon source during sporulation results in modification of only one SPB from each meiosis II spindle and formation of a two-spored ascus, called a nonsister dyad (NSD). We have found that mutants impaired in the glyoxylate pathway, which is required for the conversion of acetate to glucose, make NSDs when acetate is the primary carbon source. Wild-type cells make NSDs when the carbon source is glycerol, which is converted to glucose independently of the glyoxylate pathway. During NSD formation in glycerol, only the two SPBs created at the meiosis I/II transition ("daughters") are modified. In these conditions, the SPB components Mpc70p and Spo74p are not recruited to mother SPBs. Moreover, cooverexpression of Mpc70p and Spo74p suppresses NSD formation in glycerol. Our findings indicate that flux through the glyoxylate pathway during sporulation regulates modification of mother SPBs via recruitment of Mpc70p and Spo74p. These results define a cellular response in which the accumulation of an intermediary metabolite serves as a measure of biosynthetic capacity to regulate the number of daughter cells formed.     

Growth of Pseudomonas C on C1 compounds: enzyme activites in extracts of Pseudomonas C cells grown on methanol, formaldehyde, and formate as sole carbon sources.

Pseudomonas C can grow on methanol, formaldehyde, or formate as sole carbon source. It is proposed that the assimilation of carbon by Pseudomonas C grown on different C1 growth substrates proceeds via one of two metabolic pathways, the serine pathway or the allulose pathway (the ribose phosphate cycle of formaldehyde fixation). This contention is based on the distribution of two key enzymes, each of which appears to be specifically involved in one of the assimilation pathways, glycerate dehydrogenase (serine pathway) and hexose phosphate synthetase (allulose pathway). The assimilation of methanol in Pseudomonas C cells appears to occur via the allulose pathway, whereas the utilization of formaldehyde or formate in cells grown on formaldehyde or formate as sole carbon sources appears by the serine pathway. When methanol is present together with formaldehyde or formate in the growth medium, the formaldehyde or formate is utilized by the allulose pathway.     

Sporulation of Streptomyces venezuelae in submerged cultures

Shaken cultures of Streptomyces venezuelae ISP5230 in minimal medium with galactose and ammonium sulphate as carbon and nitrogen sources, respectively, showed extensive sporulation after 72 h incubation at 37 degrees C. The spores formed in these cultures resembled aerial spores in their characteristics. The ability of the spores to withstand lysozyme treatment was used to monitor the progress of sporulation in cultures and to determine the physiological requirements for sporulation. In media containing ammonium sulphate as the nitrogen source, galactose was the best of six carbon sources tested. With galactose S. venezuelae ISP5230 sporulated when supplied with any of several nitrogen sources; however, an excess of nitrogen source was inhibitory. In cultures containing galactose and ammonium sulphate, sporulation was suppressed by a peptone supplement. The onset of sporulation was accompanied by a drop in intracellular GTP content. When decoyinine, an inhibitor of GMP synthase, was added to a medium containing starch and ammonium sulphate, a slight increase in sporulation was seen after 2 d. The suppression of sporulation by peptone in liquid or agar cultures was not reversed by addition of decoyinine. A hypersporulating mutant of S. venezuelae ISP5230 was altered in its ability to assimilate sugars. In cultures containing glucose the mutant sporulated more profusely than did the wild-type and did not acidify the medium to the same extent. However, the suppressive effect of glucose on sporulation was not merely a secondary result of acid accumulation.     

Gleevec (STI571) influences metabolic enzyme activities and glucose carbon flow toward nucleic acid and fatty acid synthesis in myeloid tumor cells

Chronic myeloid leukemia cells contain a constitutively active Bcr-Abl tyrosine kinase, the target protein of Gleevec (STI571) phenylaminopyrimidine class protein kinase inhibitor. Here we provide evidence for metabolic phenotypic changes in cultured K562 human myeloid blast cells after treatment with increasing doses of STI571 using [1,2-13C2]glucose as the single tracer and biological mass spectrometry. In response to 0.68 and 6.8 microm STI571, proliferation of Bcr-Abl-positive K562 cells showed a 57% and 74% decrease, respectively, whereas glucose label incorporation into RNA decreased by 13.4% and 30.1%, respectively, through direct glucose oxidation, as indicated by the decrease in the m1/Sigma(m)n ratio in RNA. Based on the in vitro proliferation data, the IC50 of STI571 in K562 cultures is 0.56 microm. The decrease in 13C label incorporation into RNA ribose was accompanied by a significant fall in hexokinase and glucose-6-phosphate 1-dehydrogenase activities. The activity of transketolase, the enzyme responsible for nonoxidative ribose synthesis in the pentose cycle, was less affected, and there was a relative increase in glucose carbon incorporation into RNA through nonoxidative synthesis as indicated by the increase in the m2/Sigma(m)n ratio in RNA. The restricted use of glucose carbons for de novo nucleic acid and fatty acid synthesis by altering metabolic enzyme activities and pathway carbon flux of the pentose cycle constitutes the underlying mechanism by which STI571 inhibits leukemia cell glucose substrate utilization and growth. The administration of specific hexokinase/glucose-6-phosphate 1-dehydrogenase inhibitor anti-metabolite substrates or competitive enzyme inhibitor compounds, alone or in combination, should be explored for the treatment of STI571-resistant advanced leukemias as well as that of Bcr-Abl-negative human malignancies.     

Analysis of Sporulation Mutants I. Response of Uracil Incorporation to Carbon Sources, and Other Mutant Properties

Mutants deficient in sporulation were isolated and characterized with respect to antibiotic and protease activity, transformability, growth, and sporulation. All but two mutants could grow on minimal medium containing glucose. The inability of most mutants to incorporate uracil into trichloroacetic acid-precipitable material (ribonucleic acid) during the developmental period, and their response to a number of carbon sources, were used to characterize their biochemical blocks. Reproducible measurements of these responses were possible when the pH of the culture, which changed during growth and greatly influenced the rate of uracil uptake, was adjusted to 6.5. By their response to ribose and glutamate, the sporulation mutants could then be divided into four groups. All mutants of the first three groups produced antibiotic activity against Staphylococcus aureus, whereas all mutants, except one, of the fourth group produced none or very little of this activity. Mutants which did not respond to glutamate belonged to the first three groups; they also grew slowly or not at all on glutamate as sole carbon source. One of these mutants lacked succinic dehydrogenase activity. The results indicate that most of our sporulation mutants are unable to produce or utilize a natural carbon precursor, which is normally used as a slowly available carbon and energy source via the Krebs cycle when other carbon sources are used up. It enters the Krebs cycle as a precursor of alpha-ketoglutarate, probably via acetylcoenzyme A. All mutants of group four are blocked in this pathway before alpha-ketoglutarate.     

Polysaccharide That May Serve as a Carbon and Energy Storage Compound for Sporulation in Bacillus cereus

An intracellular, glucose-containing polysaccharide accumulates in Bacillus cereus early in sporulation and is degraded at the time of spore maturation. This pattern of accumulation and degradation occurred when growth was limited by glucose or a component of yeast extract. These data suggest that the polysaccharide may be serving as a carbon and energy storage compound for sporulation. A somewhat similar pattern of accumulation and degradation of poly-beta-hydroxybutyric acid (PHB) was shown earlier by Kominek and Halvorson (1965) to occur in Bacillus cereus. When cells were grown in a medium buffered strongly at pH 7.4, however, very little accumulation of PHB occurred. We have found that polysaccharide accumulates in cells grown in both the strong and weakly buffered media. Perhaps polysaccharide is the major carbon and energy storage compound when cells are grown under conditions preventing significant accumulation of PHB. The lack of polysaccharide accumulation during the exponential phase of growth may be an indication that the needed biosynthetic enzymes are controlled by catabolite repression during growth. The polysaccharide was purified and found to consist of glucose. The iodine absorption spectrum suggests a degree of branching between that of glycogen and amylopectin.     

Oxidation of glucose, ribose, alanine, and glutamate by Leishmania braziliensis panamensis

The metabolism of [1-14C]- and [6-14C]glucose, [1-14C]ribose, [1-14C]- and [U-14C]alanine, and [1-14C]- and [5-14C]glutamate by the promastigotes of Leishmania braziliensis panamensis was investigated in cells resuspended in Hanks' balanced salt solution supplemented with ribose, alanine, or glutamate. The ratio of 14CO2 produced from [1-14C]glucose to that from [6-14C]glucose ranged from about two to six, indicating appreciable carbon flow through the pentose phosphate pathway. A functional pentose phosphate pathway was further demonstrated by the production of 14CO2 from [1-14C]ribose although the rate of ribose oxidation was much lower than the rate of glucose oxidation. The rate of 14CO2 production from [1-14C]glucose was almost linear with time of incubation, whereas that of [6-14C]glucose accelerated, consistent with an increasing rate of flux through the Embden-Meyerhof pathway during incubation. Increasing the assay temperature from 26 degrees C to 34 degrees C had no appreciable effect on the rates or time courses of oxidation of either [1-14C]- or [6-14C]glucose or of [1-14C]ribose. Both alanine and glutamate were oxidized by L. b. panamensis, and at rates comparable to or appreciably greater than the rate of oxidation of glucose. The ratios of 14CO2 produced from [1-14C]- to [U-14C]alanine and from [1-14C]- to [5-14C]glutamate indicated that these compounds were metabolized via a functioning tricarboxylic acid cycle and that most of the label that entered the tricarboxylic acid cycle was oxidized to carbon dioxide.(ABSTRACT TRUNCATED AT 250 WORDS)     

An analysis of the growth of Gluconobacter oxydans in chemostat cultures

Gluconobacter oxydans was grown successively in glucose and nitrogen-limited chemostat cultures. Construction of mass balances of organisms growing at increasing dilution rates in glucose-limited cultures, at pH 5.5, revealed a major shift from extensive glucose metabolism via the pentose phosphate pathway to the direct pathway of glucose oxidation yielding gluconic acid. Thus, whereas carbon dioxide production from glucose accounted for 49.4% of the carbon input at a dilution rate (D)=0.05 h^-1, it accounted for only 1.3% at D=0.26 h^-1. This decline in pentose phosphate pathway activity resulted in decreasing molar growth yields on glucose. At dilution rates of 0.05 h^-1 and 0.26 h^-1 molar growth yields of 19.5 g/mol and 3.2 g/mol, respectively, were obtained. Increase of the steady state glucose concentration in nitrogen-limited chemostat cultures maintained at a constant dilution rate also resulted in a decreased flow of carbon through the pentose phosphate pathway. Above a threshold value of 15–20 mM glucose in the culture, pentose phosphate pathway activity almost completely inhibited. In G. oxydans the coupling between energy generation and growth was very inefficient; yield values obtained at various dilution rates varied between 0.8–3.4 g/cells synthesized per 0.5 mol of oxygen consumed.     

Biosynthesis of d-arabinose in Mycobacterium smegmatis: specific labeling from d-glucose

d-Arabinose is a major sugar in the cell wall polysaccharides of Mycobacterium tuberculosis and other mycobacterial species. The reactions involved in the biosynthesis and activation of d-arabinose represent excellent potential sites for drug intervention since d-arabinose is not found in mammalian cells, and the cell wall arabinomannan and/or arabinogalactan appear to be essential for cell survival. Since the pathway involved in conversion of d-glucose to d-arabinose is unknown, we incubated cells of Mycobacterium smegmatis individually with [1-(14)C]glucose, [3,4-(14)C]glucose, and [6-(14)C]glucose and compared the specific activities of the cell wall-bound arabinose. Although the specific activity of the arabinose was about 25% lower with [6-(14)C]glucose than with other labels, there did not appear to be selective loss of either carbon 1 or carbon 6, suggesting that arabinose was not formed by loss of carbon 1 of glucose via the oxidative step of the pentose phosphate pathway, or by loss of carbon 6 in the uronic acid pathway. Similar labeling patterns were observed with ribose isolated from the nucleic acid fraction. Since these results suggested an unusual pathway of pentose formation, labeling studies were also done with [1-(13)C]glucose, [2-(13)C]glucose, and [6-(13)C]glucose and the cell wall arabinose was examined by NMR analysis. This method allows one to determine the relative (13)C content in each carbon of the arabinose. The labeling patterns suggested that the most likely pathway was condensation of carbons 1 and 2 of fructose 6-phosphate produced by the transaldolase reaction with carbons 4, 5, and 6 (i.e., glyceraldehyde 3-phosphate) formed by fructose-1,6 bisphosphate aldolase. Cell-free enzyme extracts of M. smegmatis were incubated with ribose 5-phosphate, xylulose 5-phosphate, and d-arabinose 5-phosphate under a variety of experimental conditions. Although the ribose 5-phosphate and xylulose 5-phosphate were converted to other pentoses and hexoses, no arabinose 5-phosphate (or free arabinose) was detected in any of these reactions. In addition, these enzyme extracts did not convert arabinose 5-phosphate to any other pentose or hexose. In addition, incubation of [(14)C]glucose 6-phosphate and various nucleoside triphosphates (ATP, CTP, GTP, TTP, and UTP) with cytosolic or membrane fractions from the mycobacterial cells did not result in formation of a nucleotide form of arabinose, although other radioactive sugars including rhamnose and galactose were found in the nucleotide fraction. Furthermore, no radioactive arabinose was found in the nucleotide fraction isolated from M. smegmatis cells grown in [(3)H]glucose, nor was arabinose detected in a large-scale extraction of the sugar nucleotide fraction from 300 g of cells. The logical conclusion from these studies is that d-arabinose is probably produced from d-ribose by epimerization of carbon 2 of the ribose moiety of polyprenylphosphate-ribose to form polyprenylphosphate-arabinose, which is then used as the precursor for formation of arabinosyl polymers.     

Secretion of pectic isoenzymes by Sclerotinia sclerotiorum

Abstract Cultures of Sclerotinia sclerotiorum grown on different pectin-related polysaccharides (citrus pectin, apple pectin, sodium polygalacturonate), carboxymethylcellulose (CMC) or glucose as the only carbon source were examined daily for polygalacturonase and pectinase activities. Electrophoretic forms of polygalacturonase and pectin methylesterase activities were revealed using analytical IEF and sodium polygalacturonate and citrus pectin as substrates in overlay gels. A sequence in the production of pectic enzymes and isoenzyme synthesis was found in pectic-polymer cultures corresponding to the induction of several isoenzymes. Enzyme activities in glucose media were associated with three polygalacturonase and two pectinmethylesterase isoforms which were produced constitutively. Sodium-dodecyl-sulphate polyacrylamide-gel electrophoresis followed by immunoblotting with polyclonal antibodies against an exo-polymethylgalacturonase and an exo-polygalacturonase revealed that these exo-enzymes were secreted from the beginning of cultivation in the different culture media showing characteristics of constitutive enzymes.     

FACTORS CONTROLLING THE SPORULATION OF YEASTS. I. THE PRESPORULATION PHASE

SUMMARY: Yeasts tend to dissociate into mixtures of cell types with different powers of sporulation; hence single cell isolates are recommended for sporulation studies. The ability of yeasts to produce 4-spored asci can be improved by single cell selection. Cells from actively fermenting cultures sporulate much better than those grown under aerobic conditions. Sporulating ability depends on fermentation 'age', reaching a maximum when 85–90% of the CO₂ has been evolved. Carbon dioxide assimilation in the presporulation phase appears essential for maximal sporulation, but complete anaerobiosis in this phase is detrimental to sporulating ability. Malt wort cultures of a baker's yeast have given remarkably constant figures, in successive tests, for sporulation; but some batches of wort have an adverse effect on sporulating ability. The same yeast, grown on Lodder-Rij's synthetic medium containing 4 or 8% (w/v) of glucose, is capable of 80% sporulation (proportion of cells forming asci) on sodium acetate agar, comparable to that obtainable with malt wort cultures. Sporulation is depressed by excess storage of fat, while storage of glycogen does not affect sporulating ability.     

Shigella dysenteriae 60R strain adheres to and invades tissue culture cells in the absence of virulence plasmid

The influence of various carbon and nitrogen sources on fusarin C synthesis was examined in submerged cultures of Fusarium moniliforme NRRL 13616. Using a zinc-deficient, synthetic medium, highest levels of fusarin C were produced by cultures grown with urea or ammonium sulfate as the nitrogen source and fructose, sucrose, or glucose as the carbon source. In media supplemented with various concentrations of glucose and ammonium sulfate, glucose concentrations which provided excess carbohydrate significantly increased fusarin C synthesis, regardless of the ammonium sulfate concentration.