Showing papers on "Growth medium published in 2002"

Structure and function in rhodopsin: a tetracycline-inducible system in stable mammalian cell lines for high-level expression of opsin mutants.

Abstract: Tetracycline-inducible HEK293S stable cell lines have been prepared that express high levels (up to 10 mg/liter) of WT opsin and its mutants only in response to the addition of tetracycline and sodium butyrate The cell lines were prepared by stable transfection of HEK293S-TetR cells with expression plasmids that contained the opsin gene downstream of a cytomegalovirus promoter containing tetO sequences as well as the neomycin resistance gene under control of the weak H2Ld promoter The inducible system is particularly suited for overcoming problems with toxicity either due to the addition of toxic compounds, for example, tunicamycin, to the growth medium or due to the expressed protein products By optimization of cell growth conditions in a bioreactor, WT opsin, a constitutively active opsin mutant, E113Q/E134Q/M257Y, presumed to be toxic to the cells, and nonglycosylated WT opsin obtained by growth in the presence of tunicamycin have been prepared in amounts of several milligrams per liter of culture medium

Biosorption of cadmium ions by different yeast species.

Abstract: Toxicity and accumulation of Cd2+ in yeasts were studied in eight different yeast species. The adaptation to toxic concentration of this metal was dependent on the production of extracellular yeast glycoproteins. The highest concentration of Cd2+ ions in the growth medium was tolerated by a Hansenula anomala, strain while the lowest tolerance was found by the strain of species Saccharomyces cerevisiae. Extracellular glycoproteins of Hansenula anomala absorbed nearly 90% of the total content of Cd2+ ions bound by yeast cells, while extracellular glycoproteins of Saccharomyces cerevisiae bound only 6% of the total amount of cadmium. This difference is caused by the variable composition of the saccharide moiety in the extracellular glycoproteins. The composition of extracellular glycoproteins changed during the adaptation of the yeast cells to the presence of Cd2+ ions.

HXT5 expression is determined by growth rates in Saccharomyces cerevisiae.

Abstract: In the yeast Saccharomyces cerevisiae, hexose transporter (Hxt) proteins transport glucose across the plasma membrane. The Hxt proteins are encoded by a multigene family with 20 members, of which Hxt1-4p and Hxt6-7p are the major hexose transporters. The remaining Hxt proteins have other or unknown functions. In this study, expression of HXT5 under different experimental set-ups is determined. In glucose-grown batch cultures, HXT5 is expressed prior to glucose depletion. Independent of the carbon source used in batch cultures, HXT5 is expressed after 24 h of growth and during growth on ethanol or glycerol, which indicates that growth on glucose is not necessary for expression of HXT5. Increasing the temperature or osmolarity of the growth medium also induces expression of HXT5. In fed-batch cultures, expression of HXT5 is only observed at low glucose consumption rates, independent of the extracellular glucose concentration. The only common parameter in these experiments is that an increase of HXT5 expression is accompanied by a decrease of the growth rate of cells. To determine whether HXT5 expression is determined by the growth rate, cells were grown in a nitrogen-limited continuous culture, which enables modulation of only the growth rate of cells. Indeed, HXT5 is expressed only at low dilution rates. Therefore, our results indicate that expression of HXT5 is regulated by growth rates of cells, rather than by extracellular glucose concentrations, as is the case for the major HXTs. A possible function for Hxt5p and factors responsible for increased expression of HXT5 upon low growth rates is discussed.

Growth-dependent stable carbon isotope fractionation by basidiomycete fungi: δ13C pattern and physiological process

Abstract: We grew 11 basidiomycetes in axenic culture to characterize their physiological capacities to fractionate stable C isotopes. Generally, delta(13)C values of the fungal biomass were (i) enriched in (13)C relative to the growth medium, (ii) variable among the isolates, and (iii) dependent on the growth rate and growth stage of the fungi. We found a multiphasic dynamic of fractionation for Cryptoporus volvatus and Marasmius androsaceus during various growth stages. The first phase, P1, corresponded to the exponential growth stage and was characterized by an increasing enrichment in (13)C content of the fungal biomass relative to the growth medium ranging between 4.6 and 6.9 per thousand. The second phase, P2, exhibited a continual depletion in (13)C of the fungal biomass, with the delta(13)C values of the fungal biomass asymptotically returning to the delta(13)C value of the growth medium at inoculation. The expression of the various fractionation phases was dependent on the amount of low-concentration micronutrients and growth factors added to the growth medium. The onset of P2 occurred at reduced concentrations of these elements. All of the sugars in the growth medium (sucrose, maltose, and glucose) were utilized for growth, indicating that the observed fractionation was not an artifact derived from the preferential use of (13)C-rich maltose, which was found at low concentrations in the growth medium. In this study, we establish a framework with which to explore the impact of physiological fractionations by fungal interfaces on natural distributions of stable C isotopes.

Effect of transport enrichment medium, transport time, and growth medium on the detection of Campylobacter fetus subsp. venerealis.

Abstract: The combination of medium and growth conditions, including transport enrichment medium (TEM), transport time, TEM incubation time, and growth medium, that best support Campylobacter fetus subsp. venerealis while inhibiting contaminants was studied. The 3 TEMs evaluated, Weybridge, Cary-Blair, and 0.85% saline solution, were inoculated with preputial smegma spiked with C. fetus subsp. venerealis and held in the laboratory for 4 or 24 hours before inoculation onto growth medium. The effect of overnight incubation at 37 C of the TEM was also evaluated. Median scores of C. fetus subsp. venerealis growth and microbial contaminant inhibition were compared within TEM, transport time, overnight incubation, and growth medium groups using the Mann-Whitney U-test and the Kruskal-Wallis test. The proportion of samples with any growth or contamination within each group was also compared using the chi-square test. Results suggest that the growth of C. fetus subsp. venerealis was influenced by 3 of the 4 criteria evaluated. Weybridge TEM more effectively maintained the organism than did either Cary-Blair or 0.85% saline solution (P < 0.001). Transport time of 4 hours rather than 24 hours (P < 0.001) and avoiding overnight incubation of TEM at 37 C (P < 0.001) were associated with improved growth. Significant differences were not identified among growth media; however, Skirrow Campylobacter agar appeared to yield slightly better growth than did either blood agar or Greenbriar Plus agar. Contaminant growth was also influenced by 3 of the 4 variables. Weybridge TEM inhibited contaminant growth more effectively than did either Cary-Blair or 0.85% saline solution (P < 0.001). Transport time was not associated with contaminant growth. Eliminating overnight incubation of TEM reduced contamination (P < 0.01). Skirrow agar was preferred to both blood agar and Greenbriar Plus agar for suppression of contaminants on solid medium (P < 0.001). These results suggest that the detection of C. fetus subsp. venerealis is enhanced when preputial smegma samples arrive at the diagnostic laboratory within 4 hours after inoculation into Weybridge TEM and are transferred to Skirrow agar the same day they arrive in the laboratory.

In vitro uptake of minerals by Gypsophila paniculata and hybrid eucalypts, and relevance to media mineral formulation

Abstract: Despite the importance of mineral nutrition for plantlet growth in vitro, there have been few studies on mineral uptake from growth media or on optimising the media used in tissue culture. As plants in vitro experience abnormal growth conditions and may not possess roots, they may use different mechanisms of mineral uptake than plants growing ex vitro. To examine this possibility, plantlets of Gypsophila paniculata were grown on media in which the K or Ca concentration was varied. Mineral analysis showed a linear relationship between concentrations of K or Ca in the growth medium and plantlet tissues, suggesting uptake is by passive diffusion. However, interactions occurred between K, Ca and Mg uptake; therefore, other mechanisms are also likely to be involved in regulating mineral concentrations in tissue. The study also demonstrated that critical mineral concentrations could be estimated by using tissue-culture systems, as the concentration ranges of K and Ca in vitro correlated well with data for a related species ex vitro. This knowledge of critical concentrations, in conjunction with tissue analysis and ion speciation modelling, can be used to optimise in vitro mineral formulations through cycles of culture, tissue analysis and medium reformulation. To test this proposal, plantlets of Eucalyptus europhylla × grandis were grown on a proprietary medium formulation (SEM) and one modified as a result of tissue analysis (MEM). Plantlets cultured on SEM had chlorotic leaves and serious mineral imbalances. In contrast, plantlets cultured on MEM were not chlorotic, had more uniform growth and a more balanced mineral content. However, modification of mineral concentrations in the culture medium did not always result in similar changes in plant tissues. These differences in the proportions of minerals in the medium and those in the plant indicate that there are interactions between minerals in the medium and/or between minerals and the agar matrix that influence mineral availability and uptake.

Growing of potato microplants in the presence of alginate-silverthiosulfate capsules reduces ethylene-induced culture abnormalities during minimal growth conservation in vitro

Abstract: Alginate capsules containing anionic complex silverthiosulfate (STS) [Ag(S2O3)2 3-] were placed in the culture tubes over minimal growth media for studying whether STS could be used at higher concentrations to sustain ethylene-inhibiting effect during conservation of microplants in six potato (Solanum tuberosum L.) genotypes in vitro. Different concentrations of STS (0.1, 0.5, 1.0, 2.0, 3.0 and 4.0 mM) were incorporated into the alginate capsules, and 12 alginate-STS capsules were tested in semisolid (7 g l−1 agar) minimal growth medium containing 20 g l−1 mannitol and 40 g l−1 sucrose. This indirect supplementation of STS through alginate capsules rendered reduced total availability of STS in the minimal growth medium as compared to when it was directly supplemented in the medium at a given concentration. Growing of microplants in the presence of alginate-STS capsules improved the microplant growth and reduced the culture abnormalities over a period of 16 months under minimal growth conditions. Most significant improvement in microplant growth was in terms of green leaf production and leaf senescence. Vitrification, flaccidity and other growth abnormalities, viz., leaf loss, abnormal stem swelling and necrosis were not observed when the microplants were conserved in the presence of alginate-STS capsules. To foster optimum microplant growth and reduce culture abnormalities, potato microplants could favourably be maintained in the presence of 0.5–1.0 mM alginate-STS capsules during minimal growth conservation. Higher concentrations of alginate-STS capsules (>1.0 mM) were in general detrimental to potato microplant growth and survival during prolonged storage in vitro. Release kinetics of STS from the alginate-STS capsules, its distribution in the medium and accumulation of silver in potato microplants were studied using 110mAg. The release rate of STS from the capsules was found to be directly proportional to the concentrations of alginate-STS capsules. A distinct concentration gradient of 110mAg in the medium with increasing depth from top to bottom, and its accumulation in the potato microplants may be attributed to the improved anti-ethylene action of STS at higher concentrations through alginate capsules.

Effect of a lipopolysaccharide from E. coli on the proliferation of fibroblasts and keratinocytes in vitro

Abstract: Studies previously conducted in our laboratory have shown that an extract from the leaves of Chromo-laena odorata is mitogenic for human skin fibroblasts and keratinocytes. However, lipopolysaccharides, sometimes present in plant extracts, can also play a role in cell growth and might have been responsible for or contributed to the mitogenic activity observed. The present study aimed to investigate whether a lipopolysaccharide would have any effect on the proliferation of human fibroblasts and keratinocytes. Cells were seeded in 96-well plates and concentrations from 0.0 to 5.0 microg/mL of lipopolysaccharide in basal or growth medium were added. Cell growth was determined over a period of 10 days using a colorimetric assay. Lipopolysaccharide at concentrations between 0.05 microg/mL and 0.5 microg/mL in the growth medium significantly stimulated fibroblast proliferation after incubation for more than 6 days. In basal medium, more than 8 days of incubation was needed for significant stimulation of growth. Lipopolysaccharide stimulation of keratinocytes was evident at 0.5 microg/mL by day 3 in basal medium and by day 5 in growth medium. Although the lipopolysaccharide did stimulate cell growth it did so only at higher concentrations than were present in our plant extracts and to a lesser degree.

Growth under alkaline conditions of the salt-tolerant yeast Debaryomyces hansenii IFO10939.

Abstract: A salt-tolerant yeast Debaryomyces hansenii IFO 10939, which is able to grow at pH 10.0, was isolated and characterized. IFO 10939 had the ability of maintaining intracellular pH. The in vivo activation of plasma membrane ATPase was observed in cells grown at pH 6.2 during conditioning in buffer at pH 9.0. Alkalification of growth medium exhibited a significant increase in acetate and propionate production. The results suggested that the regulation of intracellular pH was involved in plasma membrane ATPase pumping protons out of the cells and weak acid formation for the source of the protons in cells growing at high pH.

The Role of Morphology during Growth of Mortierella alpina in Arachidonic Acid Production

Abstract: The filamentous fungus Mortierella alpina was incubated aerobically at 20 °C for two weeks with shaking in a flask containing liquid medium composed of urea, dextrose, and various minerals including KH2PO4, MgSO4·7H2O and CaCl2·2H2O. Urea was found to be as good a source of nitrogen as potato protein only when certain minerals were present in the growth medium. The potassium, phosphorus, and magnesium minerals particularly affected the growth of the fungus. The cell mass yielded was proportional to the amount of KH2PO4 present in the growth medium while only a small amount of MgSO4·7H2O was critical for the growth, although additional amounts of MgSO4·7H2O did not increase the cell mass accordingly. Under mild agitation conditions the fungus grew in pulpy form, however, magnesium sulfate pelleted the fungus in the urea medium when potassium dihydrogenphosphate was present in a KH2PO4/MgSO4·7H2O weight ratio below 1. Lipid-free cells of the uniform pellets remarkably weighed more than the pulpy form and the arachidonic acid content in fatty acids of the pellet was greater, even though the overall level of fatty acids was lower. The results suggested that the lipid-free uniform pellets consumed much glucose leaving a small amount for lipid synthesis and that in the final stage of the incubation starvation of the fungus accelerated the fatty acid conversion to produce arachidonic acid.

Production of fungal extracellular immune stimulating compounds

Abstract: A process is described for the production of an immunostimulant by submerged cultivation of Lentinus edodes in which mycelium from agar plates or a fermentation broth is added to a liquid medium in a shake flask or a bioreactor containing nutrients such as malt extract, yeast extract, peptone and glucose having access to air or to which air is added, and which is kept in constant movement at approx. 28 °C. At the proper conditions, there will be an increase in the production of extracellular lentinan, which is shown to be a better immunostimulant than intracellular lentinan. The extracellular product is precipitated from the growth medium by means of methods for the precipitation of microbial polysaccharide.

Simple method of Arabidopsis thaliana cultivation in liquid nutrient medium

Abstract: Simple method of Arabidopsis thaliana w.t. cv. Columbia (L.) Heynh. cultivation in liquid nutrient medium is presented. After 5 weeks of growth in soil, the plants were transferred to modified Hoagland nutrient medium. This allowed us to cultivate Arabidopsis in conditions comparable to all other hydroponically grown higher plants used in plant physiology and plant stress physiology experiments. Absence of agar in growth medium and free access to whole root system makes this method useful also in experiments concerning root physiology.

Screening of thermotolerant yeast for use as microbial feed additive

Abstract: With the objective of identifying the commercial potential of new direct-fed microbials, several temperature-tolerant strains were isolated from cane molasses at 39°C and tested for their tolerance to pH, bile salts, and a mixture of volatile fatty acids (acetic acid:propionic acid:butyric acid=6.5:2.0:1.5). It was found that the isolated strain DY 252 grew very well up to pH 2.0 and was resistant to relatively high concentrations of bile salts. Among the strains tested, DY 252 was least inhibited by the addition of volatile fatty acids to the growth medium at 39°C. Accordingly, it would appear that strain DY 252, identified as yeast Issatchenkia orientalis, may be a potential candidate for use as a microbial feed additive.

The simultaneous biosynthesis and uptake of amino acids by Lactococcus lactis studied by 13C‐labeling experiments

Abstract: Uniformly 13 C labeled glucose was fed to a lactic acid bacterium growing on a defined medium supplemented with all proteinogenic amino acids except glutamate. Aspartate stemming from the protein pool and from the extracellular medium was enriched with 13 C disclosing a substantial de novo biosynthesis of this amino acid simultaneous to its uptake from the growth medium and a rapid exchange flux of aspartate over the cellular membrane. Phenylalanine, alanine, and threonine were also synthesized de novo in spite of their presence in the growth medium.

[The role of low-molecular-weight nitrogen compounds in the osmotolerance of Rhodococcus erythropolis and Arthrobacter globiformis].

Abstract: Investigations showed that Rhodococcus erythropolis E-15 and Arthrobacter globiformis 2F cells respond to osmotic shock by increasing the synthesis of free amino acids, primarily glutamic acid (80% of the intracellular free amino acid pool) The osmoprotective role of glutamic acid follows from its beneficial effect on the growth of bacteria in high-salinity media It was found that the addition of this amino acid to the growth medium at a concentration of 2 mM shortened the lag phase and increased the growth rate and biomass yield of either of the two bacteria The addition of another osmoprotectant, trehalose, to the high-salinity growth medium of R erythropolis E-15 at the same concentration (2 mM), restored the growth parameters of this bacterium to the control values

Stimulation and inhibition of Escherichia coli cell growth during cultivation in the catholyte and anolyte of culture medium

Abstract: The effect of pretreatment of growth medium M-9 with direct electric current in the cathode and the anode compartments of a diaphragm electrolyzer on the growth of Escherichia coli cells was studied. The cells were cultured separately in the catholyte and the anolyte of the growth medium. The cell growth was registered as a change in optical density of the culture suspension by the method of turbidimetry. It was found that cells grown in the catholyte at a temperature of 37 degrees C yielded a 20-30% increase in amount as compared to the control. No cell growth was observed in the anolyte, and a part of the initial cells were lysed. Possible mechanisms of stimulation and inhibition of cell growth and the reasons of discrepancies in the earlier published data are discussed.

Method of testing for the presence of microorganisms in a gaseous environment comprising hydrogen peroxide

Abstract: The invention relates to a method of testing for the presence of microorganisms in a gaseous environment comprising hydrogen peroxide, comprising the following steps: (i) bringing the gaseous environment comprising the hydrogen peroxide into contact with an agar growth medium, comprising a salt of pyruvic acid. (ii) placing the growth medium in an environment favoring the development of colonies of microorganisms; (iii) determining the presence of colonies of microorganisms which may have developed during step (ii). The invention also relates to a cassette containing an agar growth medium comprising a salt of pyruvic acid.

The Enzymes of Carbon Metabolism in the Thermotolerant Bacillar Strain K1

Abstract: To determine enzymatic activities in the thermotolerant strain K1 (formerly “Sulfobacillus thermosulfidooxidans subsp thermotolerans”), it was grown in a mineral medium with (1) thiosulfate and Fe2+ or pyrite (autotrophic conditions), (2) Fe2+, thiosulfate, and yeast extract or glucose (mixotrophic conditions), and (3) yeast extract (heterotrophic conditions) Cells grown mixo-, hetero-, and autotrophically were found to contain enzymes of the tricarboxylic acid (TCA) cycle, as well as malate synthase, an enzyme of the glyoxylate cycle Cells grown organotrophically in a medium with yeast extract exhibited the activity of the key enzymes of the Embden–Meyerhof–Parnas and Entner–Doudoroff pathways The increased content of carbon dioxide (up to 5 vol %) in the auto- and mixotrophic media enhanced the activity of the enzymes involved in the terminal reactions of the TCA cycle and the enzymes of the pentose phosphate pathway Carbon dioxide is fixed in the Calvin cycle The highest activity of ribulose bisphosphate carboxylase was detected in cells grown autotrophically at the atmospheric content of CO2 in the air used for aeration of the growth medium The activities of pyruvate carboxylase, phosphoenolpyruvate carboxylase, phosphoenolpyruvate carboxykinase, and phospho-enolpyruvate carboxytransphosphorylase decreased with increasing content of CO2 in the medium

The effect of vanadate on Pichia pastoris growth, protein kinase A activity and ribosomal protein phosphorylation.

Abstract: It was found that wild type yeast Pichia pastoris can tolerate vanadate concentration as high as 25 mM in the growth medium. Moreover, four vanadate-resistant P. pastoris strains designated JC100/1, JC100/3, JC100/9 and JC100/15 exhibiting tolerance up to 150 mM vanadate were selected. Growth of P. pastoris was correlated with vanadate to vanadyl reduction and its accumulation in the growth medium. In two selected strains, JC100/9 and JC100/15, protein kinase A activity was much higher in comparison to the wild type strain even without vanadate addition to the growth medium. Moreover, in the presence of vanadate, protein kinase A activity was significantly increased in the wild type and the vanadate-resistant JC100/1 and JC100/3 strains. It was also found that phosphorylation of a 40 kDa protein associated with ribosomes occured in all vanadate-resistant strains from the logarithmic, while in the wild type strain from the stationary growth phase. From the presented results it can be concluded that a protein kinase A signalling pathway(s) might be involved in the mechanism of P. pastoris vanadate resistance. The results also indicate a possible role of the 40 kDa protein in protection of P. pastoris against vanadate toxicity.

Analysis of the Effects of Hyperosmotic Stress on the Derepression of Invertase Activities and the Growth of Different Baker's Yeast Strains

Abstract: The growth of baker's yeast Saccharomyces cerevisiae in medium containing sucrose requires a high level of extracellular invertase enzyme activity. However, the expression of invertase is under the strict control of glucose repression in S. cerevisiae. In addition, invertase enzyme activity is also affected by physiological stress conditions that baker's yeast is exposed to during the various stages of industrial level production and downstream processing. We analyzed the effect of hyperosmotic stress on the derepression of invertase activities of a haploid laboratory yeast strain and three different industrial baker's yeast strains. Our results indicated that hyperosmotic stress interferes with the derepression of invertase activity in the yeast. The invertase activities of the yeast strains remained essentially at a repressed level in the presence of 1M NaCl or 1M KCl in the growth medium. However, the presence of low amounts of NaCl in the growth medium (0.2M) increased the invertase activities of yeast strains up to 40-50%. We also found that industrial yeast strains are more sensitive to hyperosmotic stress than the laboratory strains of S. cerevisiae used in this study.

The enzyme of carbon metabolism in the thermotolerant sulfobacillus strain K1

Abstract: To determine enzymatic activities in the thermotolerant strain K1 (formerly "Sulfobacillus thermosulfidooxidans subsp. thermotolerans"), it was grown in a mineral medium with (1) thiosulfate and Fe2+ or pyrite (autotrophic conditions), (2) Fe2+, thiosulfate, and yeast extract or glucose (mixotrophic conditions), and (3) yeast extract (heterotrophic conditions). Cells grown mixo-, hetero-, and autotrophically were found to contain enzymes of the tricarboxylic acid (TCA) cycle, as well as malate synthase, an enzyme of the glyoxylate cycle. Cells grown organotrophically in a medium with yeast extract exhibited the activity of the key enzymes of the Embden-Meyerhof-Parnas and Entner-Doudoroff pathways. An increased content of carbon dioxide (up to 5 vol%) in the auto- and mixotrophic media enhanced the activity of the enzymes involved in the terminal reactions of the TCA cycle and the enzymes of the pentose phosphate pathway. Carbon dioxide was fixed in the Calvin cycle. The highest activity of ribulose bisphosphate carboxylase was detected in cells grown autotrophically at the atmospheric content of CO2 in the air used for aeration of the growth medium. The activities of pyruvate carboxylase, phosphoenolpyruvate carboxylase, phosphoenolpyruvate carboxykinase, and phosphoenolpyruvate carboxytransphosphorylase decreased with the increasing content of CO2 in the medium.

Cell Growth and Ajmalicine Accumulation in a Full Habituated Catharanthus roseus Cell Line C_ (20)hi

Abstract: A full habituated cell line C_ 20hi was screened from 2,4_D dependent line (C_ 20D) of Catharanthus roseus (L.) G. Don. The investigation involved the cell growth, ajmalicine production and enzyme activity related to indole alkaloid biosynthesis in both cell lines. These results indicated that C_ 20hi cells grew faster than C_ 20D cells, and average ajmalicine content in C_ 20hi cells was 18.4 times more than that in C_ 20D when cultured in the production medium. In the growth medium, average ajmalicine content in C_ 20hi cells was 31.9 times more than that in C_ 20D cells, while the cell growth has no obvious difference. The comparison of enzyme activities in C_ 20hi and C_ 20D cells indicated that tryptophan decarboxylase (TDC), strictosidine synthase (SSS) and geraniol_10_dehydrogenase (G10H) activities have no close relation to ajmalicine accumulation, although the activities of these enzymes were higher when cells were cultured in the production medium than in the growth medium. The C_ 20hi cells are relatively stable in five years of culture.

Effect of bacterial growth medium composition on antifungal activity of bacillus sp. strains used in biological control of fusarium head blight

Abstract: Several microbial strains belonging to different taxa, isolated from various parts of the world, have been shown to have the ability to antagonize Fusarium graminearum to different extents under various conditions. Some of these microbial strains are being developed as biological control agents (BCAs) for control of FHB. Different BCAs have different mechanisms of antagonizing FHB, such an enzymes, antibiotics, parasitism, and/or competition for nutrients. We have studied four different Bacillus sp. strains that show promise for use as BCAs to control FHB. All these strains seem to belong to a phylogenetic group designated as the Bacillus subtilis group (group II). Among the many antibiotics that B. subtilis and its relatives are known to make are cyclic lipopeptides such as iturin. If one or more iturin-like antibiotics are needed for these bacterial strains to control FHB, it is important that a growth medium be used for culturing the BCAs that encourages production of such antibiotics. In previous studies, we have usually grown the four BCAs in potato-dextrose broth (PDB), which may not have been an optimal growth medium for production of iturin-like antibiotics. Other researchers working with B. subtilis have found that dextrose (glucose) is not an optimal carbon source for iturin production, and that the nitrogen source in the growth medium also has a large influence on the amount of iturin produced. All four of our BCAs grew well in a defined growth medium previously described in the literature that may stimulate antibiotic production of our BCAs more than does PDB. The defined medium contains mannitol as a carbon source, and glutamic acid as a nitrogen source, along with inorganic salts. We have conducted studies with both the broth and agar-solidified form of this medium, finding that the bacteria grow well in both. Plate assays were conducted to test the ability of the BCAs to antagonize F. graminearum on the agar-solidified form of this growth medium. Antagonism against the fungus was apparent, suggesting that antibiotic was being produced in the medium. Presence of iturin in the growth medium will be tested for chromatographically, and compared to amounts produced in PDB. In addition, greenhouse groundbed trials will compare the effect that BCA cells grown in the defined broth medium have upon wheat challenged with FHB, to the effect that BCA cells grown in PDB have upon wheat challenged with FHB. In uniform field trials to compare the ability of different microbial BCAs to control FHB, it should be recognized that different microbial BCAs can have different mechanisms of antagonism, and that different growth media may promote these mechanisms to varying degrees. Formulation and optimization of growth media for commercial production and application of BCAs to control FHB should also bear this in mind.