Influence of Iodine and Bromine on Growth of Some Red Algae in Axenic Culture

Some red algae in axenic culture have been cultivated with different additions of iodine and bromine. Polysiphonia urceolata appeared to have an absolute demand for iodine. Additions could be made either as organically bound iodine or as inorganic iodine. A linear correlation between amount of added iodide and growth was found for iodide concentrations from 1 μmol up to at least 8 μmμmumol per 1. Nemalion proved to be indifferent to iodide additions, while Goniotrichum elegans was inhibited by concentrations higher than 0.4 μumol per 1, which corresponds to that of natural seawater. High additions of iodine generally inhibited growth of nonaxenic algae. Acrochaetium made an exception, being stimulated by 4 μumol per I. Bromine in the same concentration as that of seawater, viz. 814.3 μmol pa 1 inhibited growth of most species, but amounts smaller than 50 μumol had in some experiments a slightly increasing effect. Bromine seems, however, not to play an essential part in the metabolism of Polysiphonia urceolata.     

Marine Brown Algae Requiring Vitamin B12

The brown algae Lithosiphon pusillus, Ectocarpus fasciculatus and Pylaiella litoralis were cultivated in bacteria-free cultures in artificial sea water, ASP 6F. The growth was tested with different additions of vitamins and other metabolites. Lithosiphon pusillus and Ectocarpus fasciculatus were found to require vitamin B₁₂ for optimal growth. The zoospores of Pylaiella litoralis, when cultured in medium Asp 6F with kinetin added, had an absolute requirement for vitamin B₁₂.     

Effect of nitrogen and phosphorus availability on the growth response of Eucalyptus grandis to high CO2

The response of Eucalyptus grandis seedlings to elevated atmospheric CO₂ concentrations was examined by growing seedlings at either 340 or 660 n mol CO₂ mol^-1 for 6 weeks. Graded increments of phosphorus and nitrogen fertilizers were added to a soil deficient in these nutrients to establish if the growth response to increasing nutrient availability was affected by CO₂ concentration. At 660 μmol CO₂ mol^-1, seedling dry weight was up to five times greater than at 340 μmol CO₂ mol^-1. The absolute response was largest when both nitrogen and phosphorus availability was high but the relative increase in dry weight was greatest at low phosphorus availability. At 340 μmol CO₂ mol^-1 and high nitrogen availability, growth was stimulated by addition of phosphorus up to 76 mg kg 1 soil. Further additions of phosphorus had little effect. However, at 660 μmol CO₂ mol^-1, growth only began to plateau at a phosphorus addition rate of 920mg kg^-1 soil. At 340 μmol CO₂ mol^-1 and high phosphorus availability, increasing nitrogen from 40 to 160mg kg^-1 soil had little effect on plant growth. At high CO₂, growth reached a maximum at between 80 and 160mg nitrogen kg^-1 soil. Total uptake of phosphorus was greater at high CO₂ concentration at all fertilizer addition rates, but nitrogen uptake was either lower or unchanged at high CO₂ concentration except at the highest nitrogen fertilizer rate. The shoot to root ratio was increased by CO₂ enrichment, primarily because the specific leaf weight was greater. The nitrogen and phosphorus concentration in the foliage was lower at elevated CO₂ concentration partly because of the higher specific leaf weight. These results indicate that critical foliar concentrations currently used to define nutritional status and fertilizer management may need to be reassessed as the atmospheric CO₂ concentration rises.     

Nickel dependence of factor F430 content in Methanobacterium thermoautotrophicum

Factor F₄₃₀ is a yellow compound of unknown structure present in methanogenic bacteria. It has recently been shown to contain nickel. In this communication the influence of the nickel concentration in the growth medium on the factor F₄₃₀ content of Methanobacterium thermoautotrophicum and on the nickel content of factor F₄₃₀ was studied. It was found: (1) The content of factor F₄₃₀ in the cells was strongly dependent on the nickel concentration of the growth medium. Cells grown on media with 2.5 M NiCl₂ contained 28 times as much factor F₄₃₀ per g as those grown on media with 0.075 M NiCl₂; (2) factor F₄₃₀ was synthesized in nickel deprived cells only upon the addition of nickel Nickel uptake paralleled factor F₄₃₀ synthesis; (3) independent of the nickel concentration in the growth medium, the extinction coefficient at 430 nm of factor F₄₃₀ per mol nickel was always near 22,500 cm^-1 (mol Ni)^-1. These findings indicate that nickel is an essential component of factor F₄₃₀.Dedicated to Professor Otto Kandler on the occasion of his 60th birthday     

The influence of carbon dioxide-depletion on growth and sinking rate of two planktonic diatoms in culture

Growth in relation to CO₂-depletion and CO₂-enrichment was investigated for the freshwater diatoms Asterionella formosa and Fragilaria crotonensis in batch cultures. Algal concentration and pH were measured during growth cycles, and inorganic carbon quantities determined by potentiometric Gran titrations and from pH-alkalinity relationships. After the primary growth with CO₂-depletion and pH increase, successive CO₂-enrichments induced further such cycles and produced a final three- to fivefold increase in algal biomass over that of unenriched controls. The extent of CO₂-depletion, and pH rise, was greater in later cycles, indicative of some cellular adaptation. Values of pH reached 9·7 for Asterionella and 9·9 for Fragilaria. The lowest residual quantities of free CO₂ were 0·1 and 0·03 μmol 1^-1 for Asterionella and Fragilaria respectively, which were less than 0·05% of the corresponding residual quantities of total CO₂. The primary limitation of CO₂-uptake and growth was probably related to the concentration of free CO₂, given the relative excess of other major nutrients (N, P, Si) in he media used. Limited of CO₂-uptake could be restored without CO₂ additions if the CO₂ present was redistributed between its several forms (increasing free CO₂) by the addition of strong acid, although growth was still restricted.

Limitation of CO₂-uptake, either by CO₂-depletion or the addition of an inhibitor of photo-synthesis (DCMU), increased the sinking rate of Asterionella cells from 0·3 to 1 m day^-1. The possible ecological implications of CO₂-pH-growth and CO₂-pH-buoyancy relationships are discussed, which may contribute to the frequent paucity of diatoms during summer in manv productive lakes.     

Effects of atmospheric CO2 enrichment and root restriction on leaf gas exchange and growth of banana (Musa)

The effects of atmospheric CO₂ enrichment and root restriction on photosynthetic characteristics and growth of banana (Musa sp. AAA cv. Gros Michel) plants were investigated. Plants were grown aeroponically in root chambers in controlled environment glasshouse rooms at CO₂ concentrations of 350 or 1 000 μmol CO₂ mol^-1. At each CO₂ concentration, plants were grown in large (2001) root chambers that did not restrict root growth or in small (20 1) root chambers that restricted root growth. Plants grown at 350 μmol CO₂ mol^-1 generally had a higher carboxylation efficiency than plants grown at 1 000 μmol CO₂ mol^-1 although actual net CO₂ assimilation (A) was higher at the higher ambient CO₂ concentration due to increased intercellular CO₂ concentrations (C_i resulting from CO₂ enrichment. Thus, plants grown at 1 000 μmol CO₂ mol^-1 accumulated more leaf area and dry weight than plants grown at 350 μmol CO₂ mol^-1. Plants grown in the large root chambers were more photosynthetically efficient than plants grown in the small root chambers. At 350 μmol CO₂ mol^-1, leaf area and dry weights of plant organs were generally greater for plants in the large root chambers compared to those in the small root chambers. Atmospheric CO₂ enrichment may have compensated for the effects of root restriction on plant growth since at 1 000 μmol CO₂ mol^-1 there was generally no effect of root chamber size on plant dry weight.     

Interactive effects of nitrogen and phosphorus on the acclimation potential of foliage photosynthetic properties of cork oak,Quercus suber,to elevated atmospheric CO2 concentrations

Leaf gas-exchange and chemical composition were investigated in seedlings of Quercus suber L. grown for 21 months either at elevated (700 μmol mol^–1) or normal (350 μmol mol^–1) ambient atmospheric CO₂ concentrations, [CO₂], in a sandy nutrient-poor soil with either ‘high’ N (0.3 mol N m^–3 in the irrigation solution) or with ‘low’ N (0.05 mol N m^–3) and with a constant suboptimal concentration of the other macro- and micronutrients. Although elevated [CO₂] yielded the greatest total plant biomass in ‘high’ nitrogen treatment, it resulted in lower leaf nutrient concentrations in all cases, independent of the nutrient addition regime, and in greater nonstructural carbohydrate concentrations. By contrast, nitrogen treatment did not affect foliar N concentrations, but resulted in lower phosphorus concentrations, suggesting that under lower N, P use-efficiency in foliar biomass production was lower. Phosphorus deficiency was evident in all treatments, as photosynthesis became CO₂ insensitive at intercellular CO₂ concentrations larger than ≈ 300 μmol mol^–1, and net assimilation rates measured at an ambient [CO₂] of 350 μmol mol^–1 or at 700 μmol mol^–1 were not significantly different. Moreover, there was a positive correlation of foliar P with maximum Rubisco (Ribulose-1,5-bisphosphate carboxylase/oxygenase) carboxylase activity (V_cmax), which potentially limits photosynthesis at low [CO₂], and the capacities of photosynthetic electron transport (J_max) and phosphate utilization (P_max), which are potentially limiting at high [CO₂]. None of these potential limits was correlated with foliar nitrogen concentration, indicating that photosynthetic N use-efficiency was directly dependent on foliar P availability. Though the tendencies were towards lower capacities of potential limitations of photosynthesis in high [CO₂] grown specimens, the effects were statistically insignificant, because of (i) large within-treatment variability related to foliar P, and (ii) small decreases in P/N ratio with increasing [CO₂], resulting in balanced changes in other foliar compounds potentially limiting carbon acquisition. The results of the current study indicate that under P-deficiency, the down-regulation of excess biochemical capacities proceeds in a similar manner in leaves grown under normal and elevated [CO₂], and also that foliar P/N ratios for optimum photosynthesis are likely to increase with increasing growth CO₂ concentrations. Symbols: A, net assimilation rate (μmol m^–2 s^–1); A_max, light-saturated A (μmol m^–2 s^–1); α, initial quantum yield at saturating [CO₂] and for an incident Q (mol mol^–1); [CO₂], atmospheric CO₂ concentration (μmol mol^–1); C_i, intercellular CO₂ concentration (μmol mol^–1); C_a, CO₂ concentration in the gas-exchange cuvette (μmol mol^–1); F_B, fraction of leaf N in ‘photoenergetics’; F_L, fraction of leaf N in light harvesting; F_R, fraction of leaf N in Rubisco; Γ*, CO₂ compensation concentration in the absence of R_d (μmol mol^–1); J_max*, capacity for photosynthetic electron transport; J_mc, capacity for photosynthetic electron transport per unit cytochrome f (mol e^–[mol cyt f]^–1 s^–1); K_c, Michaelis-Menten constant for carboxylation (μmol mol^–1); K_o, Michaelis-Menten constant for oxygenation (mmol mol^–1); M_A, leaf dry mass per area (g m^–2); O, intercellular oxygen concentration (mmol mol^–1); [P_i], concentration of inorganic phosphate (mM); P_max*, capacity for phosphate utilization; Q, photosynthetically active quantum flux density (μmol m^–2 s^–1); R_d*, day respiration (CO₂ evolution from nonphotorespiratory processes continuing in the light); Rubisco, ribulose-1,5-bisphosphate carboxylase/oxygenase; RUBP, ribulose-1,5-bisphosphate; T_l, leaf temperature (°C); U_TPU*, rate of triose phosphate utilization; V_cmax*, maximum Rubisco carboxylase activity; V_cr, specific activity of Rubisco (μmol CO₂[g Rubisco]^–1 s^–1] *given in either μmol m^–2 s^–1 or in μmol g^–1 s^–1 as described in the text.     

Soil CO2 concentration does not affect growth or root respiration in bean or citrus

Contrasting effects of soil CO₂ concentration on root respiration rates during short-term CO₂ exposure, and on plant growth during long-term CO₂ exposure, have been reported. Here we examine the effects of both short- and long-term exposure to soil CO₂ on the root respiration of intact plants and on plant growth for bean (Phaseolus vulgaris L.) and citrus (Citrus volkameriana Tan. & Pasq.). For rapidly growing bean plants, the growth and maintenance components of root respiration were separated to determine whether they differ in sensitivity to soil CO₂. Respiration rates of citrus roots were unaffected by the CO₂ concentration used during the respiration measurements (200 and 2000 μmol mol⁻¹), regardless of the soil CO₂, concentration during the previous month (600 and 20 000 μmol mol⁻¹). Bean plants were grown with their roots exposed to either a natural CO₂ diffusion gradient, or to an artificially maintained CO₂ concentration of 600 or 20 000 μmol mol⁻¹. These treatments had no effect on shoot and root growth. Growth respiration and maintenance respiration of bean roots were also unaffected by CO₂ pretreatment and the CO₂ concentration used during the respiration measurements (200–2000 μmol mol⁻¹). We conclude that soil CO₂ concentrations in the range likely to be encountered in natural soils do not affect root respiration in citrus or bean.     

Effect of inorganic carbon on photoautotrophic growth of microalga Chlorococcum littorale

The growth rate of a highly CO₂‐tolerant green alga, Chlorococcum littorale, was investigated in semi‐batch cultures at a temperature of 22°C, a light intensity of 170 μmol‐photon m^?2 s^?1 and CO₂ concentrations ranging from 1 to 50% (v/v) at atmospheric pressure. In the experiments, solutions were bubbled with CO₂ and N₂ gas mixtures to adjust CO₂ concentrations to minimize the influence of O₂. Growth rate, which was defined in terms of a specific growth rate μ, decreased with increasing CO₂ concentration at the conditions studied. The inhibition of growth by CO₂ gas could be attributed to the concentration of inorganic carbon in the culture medium. A growth model is proposed where key assumptions are the formation of bicarbonate ion HCO as substrate for algal growth and equilibrium between CO₂ inhibitor. The proposed growth model based on the Monod equation agreed with the experimental data to within 5% and provides better correlation than the conventional inhibition model, especially in the high CO₂ concentration region. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009     

Metabolism of Acetivibrio cellulolyticus during optimized growth on glucose,cellobiose and cellulose

Summary The growth of Acetivibrio cellulolyticus in 2.5 l batch cultures was optimized by controlling the growth pH at 6.7, the dissolved inorganic sulphide concentration at 0.4–0.6 mM, and by constant removal of hydrogen from the cultures by sparging with N₂/CO₂ or N₂ gas. An initial ethanol concentration of 0.15% (w/v) in cellobiose media resulted in specific growth rates which were reduced by about 75% compared to growth rates of 0.17 h^–1 in control cultures. Acetivibrio cellulolyticus had to be adapted for growth on glucose and ¹⁴C-radiotracer studies indicated that glucose was metabolized by the Embden-Meyerhof pathway. The specific growth rate (=0.03h^–1) and molar growth yield (Y_glucose=21.5) were considerably lower than those obtained (=0.17 h^–1, Y_cellobiose=68.9) in cellobiose media. A Y_ATP of 12.8 was obtained during growth on cellobiose. The mol product formed per mol Avicel cellulose fermented (on anhydroglucose equivalent basis) were 3.70 H₂, 2.64 CO₂, 0.73 acetate, 0.39 ethanol and 0.03 total soluble sugars on glucose basis. Maximum cellulase activity was observed in cellulose-grown cultures.National Research council of Canada No. 20826     

Utilisation of iodine from different sources in pigs

Balance experiments have demonstrated that growing pigs fed a ration consisting of wheat, barley, extracted soya meal, dicalciumphosphate, and iodine‐free feeding salt utilised 48.8% of the received iodine.

The tested supplementary iodine sources included potassium iodide (KI), ethylenediamine dihydroiodide (EDDI), iodine humate (HUI) prepared from iodine acid (HIO₃), and the product P containing 0.004% iodine in an oil base (P). The amount of the supplemented iodine was in all cases 1 mg per 1 kg feed.

The utilisation of iodine from the supplements reached 93.6, 92.6, 90.7, and 67.9% for KI, EDDI, P, and HUI, respectively. The values were significantly higher compared with controls (P < 0.01). Compared with KI and EDDI, the utilisation of iodine from HUI was significantly lower (P < 0.01). The lower availability of iodine from HUI was probably due to the high binding capacity of humate.

The amount of urinary iodine excreted by control pigs receiving in the non‐supplemented ration 147.5 μg iodine per day, was 40.3 μg per day (27.3%). In the pigs receiving in the supplemented ration 1647.5 μg iodine per day, the amount of urinary iodine reached 734.9 to 805.0 μg per day (44.6 to 48.9%). The corresponding values of faecal excretion were 75.6 μg iodine per day (51.2%) for the control pigs and 106.2 to 121.1 μg iodine per day (6.45 to 7.35%) for the pigs fed the supplemented rations. A high amount of 528.6 μg iodine per day (32.1%) was excreted in the faeces by pigs of the group HUI.     

Formate and glucose stimulation of methane and hydrogen production in rumen liquor

Membrane-inlet mass spectrometry was used to investigate the effects of increasing the concentration of the rumen metabolites, formate and glucose, upon CH₄ and H₂ production during fermentation by unfractionated rumen liquor. Additions of formate up to 3.6 mM stimulated CH₄ and then excess H₂ production. Each addition caused a large accumulation of H₂ (>40 µM), which returned to in situ concentrations after periods of more than 1 h. Glucose additions up to 2.0 mM gave linear increases in CH₄ and H₂ production. The conversion of substrate carbon into CH₄ was found to decrease from 34% to 9% for formate, as concentrations were increased (1.6–3.6 mM); approximately 13.5% of the glucose carbon was converted to CH₄.     

Carbon dioxide biofixation by Chlorella vulgaris at different CO2 concentrations and light intensities

In order to develop an effective CO₂ mitigation process using microalgae for potential industrial application, the growth and physiological activity of Chlorella vulgaris in photobioreactor cultures were studied. C. vulgaris was grown at two CO₂ concentrations (2 and 13% of CO₂ v/v) and at three incident light intensities (50, 120 and 180 μmol m^?2 s^?1) for 9 days. The measured specific growth rate was similar under all conditions tested but an increase in light intensity and CO₂ concentration affected the biomass and cell concentrations. Although carbon limitation was observed at 2% CO₂, similar cellular composition was measured in both conditions. Light limitation induced a net change in the growth behavior of C. vulgaris. Nitrogen limitation seemed to decrease the nitrogen quota of the cells and rise the intracellular carbon:nitrogen ratio. Exopolysaccharide production per cell appeared to be affected by light intensity. In order to avoid underestimation of the CO₂ biofixation rate of the microalgae, exopolysaccharide production was taken into account. The maximum CO₂ removal rate (0.98 g CO₂ L^?1 d^?1) and the highest biomass concentration (4.14 g DW L^?1) were determined at 13% (v/v) CO₂ and 180 μmol m^?2 s^?1. Our results show that C. vulgaris has a real potential for industrial CO₂ remediation.     

Growth kinetics of Aeromonas hydrophila in freshwaters supplemented with various organic and inorganic nutrients

Freshwaters of varying natural nutrient enrichment were used as growth media for the culture of an autochthonous, heterotrophic, freshwater bacterium, Aeromonas hydrophila. The growth rate of the bacterium in eutrophic waters was increased to the greatest extent by adding carbon, as glucose; generation times decreased by up to 65%. Additions of carbon and phosphorus increased the maximal cell densities by over 25-fold. In oligotrophic waters, bacterial growth was most strongly promoted by the simultaneous additions of carbon (as glucose) and phosphorus (as KH₂PO₄). In these waters, stationary phase densities were increased as much as 100-fold, with a corresponding 70% increase in growth rate. These data provide at least a partial explanation for the previously observed correlation between A. hydrophila densities and the trophic states of freshwaters.The authors are with the Department of Microbiology, Morrill Hall, University of Rhode Island, Kingston, Rhode Island 02881, USA     

GROWTH,PHOTOSYNTHESIS AND MAINTENANCE METABOLIC COST IN THE DIATOM PHAEODACTYLUM TRICORNUTUM AT VERY LOW LIGHT LEVELS 1

The compensation point for growth of Phaeodactylum tricornutum Bohlin is less than 1 μmol. m^?2s^?1. Growth at low PFDs (<3.5 μmol. m^?2.s^?1) does not appear to reduce the maximum quantum efficiency of photosynthesis (ø_m) or to greatly inhibit the potential for light-saturated, carbon-specific photosynthesis (P_m^c). The value for ø_m in P. tricornutum is 0.10–0.12 mol O₂-mol photon^?1, independent of acclimation PFD between 0.75 and 200 μmol.m^?2.s^?1 in nutrient-sufficient cultures. P_m^c in cells of P. tricornutum acclimated to PFDs <3.5 μmol m^?2?s^?1 is approximately 50% of the highest value obtained in nutrient-sufficient cultures acclimated to growth-rate-saturating PFDs. In addition, growth at low PFDs does not severely restrict the ability of cells to respond to an increase in light level. Cultures acclimated to growth at lees than 1% of the light-saturated growth rate respond rapidly to a shift-up in PFD after a short initial lag period and achieve exponential growth rates of 1.0 d^?1 (65% of the light- and nutrient-saturated maximum growth rate) at both 40 and 200 μmol.m^?2.s^?1     

The Effect of Nonanal on Dipodascus aggregatus

Biotin can not replace nonanal for Dipodascus aggregatus. The growth-promoting effect of nonanal (80 μW) remained unchanged when the concentration of biotin was increased from 2 μm per 1 to 200 μm per I. Oleic acid stimulated the growth of D. aggregates. However, unlike nonanal, oleic acid promoted growth even if cells from the exponential phase of growth were used as inoculum. The concentrations of oleic acid required to produce growth–stimulation were considerably higher than the concentrations of nonanal required to promote growth. The growth-stimulating effect f nonanal seems to be different from t he effect of oleic acid. The incorporation of ₁C-ghtCOM by D. aggregates was stimulated by the addition of nonanal (80μm) to the growth medium. The uptake of glucosamine was not affected by nonanal (80 or 160 μM in the presence of ethanol, 0.8 to 100μ in the absence of ethanol). Hexokinase activity in cell-free homogenates was not affected by the addition of nonanal over a concentration range from 0.0059 to 1250μM.     

Formation of Valine in the Presence of Sodium Acrylate Monomer by Glutamic Acid Producing Bacteria

Glutamic acid producing bacteria accumulated a large amount of valine in the presence of the excess biotin, when sodium acrylate monomer (Na-AM) was added at the earlier phase of culture. Brevibacterium roseum ATCC 13825, particularly, accumulated the large amount of valine among bacteria tested and the conditions of valine accumulation by this strain were investigated.

The most effective addition time of Na-AM was at the earlier phase of logarithmic phase. The optimal concentration of Na-AM for the accumulation of valine was 1.0 per cent (v/v). Most effective nitrogen sources were the combination of 1.0 per cent urea and 0.2 per cent ammonium sulphate. The additions of Mn²⁺ and Fe²⁺ increased valine accumulation. By the excess concentration of biotin for growth, 20 μg/liter or more, did not affected valine accumulation, while the presence of the suboptimal condition of biotin for growth was not good for the formation of valine even in the presence of Na-AM. The accumulation of valine reached 9.0 mg/ml from 75.0 mg/ml of glucose in the presence of 50 μg/liter of biotin and 1.0 per cent (v/v) of Na-AM.

This strain possessed considerable activity of valine formation regardless of the addition of Na-AM and promoted the accumulation of valine by the addition of Na-AM.     

Availability of iodide and iodate to spinach (Spinacia oleracea L.) in relation to total iodine in soil solution

A greenhouse pot experiment was carried out to investigate the availability of iodide and iodate to soil-grown spinach (Spinacia oleracea L.) in relation to total iodine concentration in soil solution. Four iodine concentrations (0, 0.5, 1, 2 mg kg⁻¹) for iodide (I⁻) and iodate (IO₃⁻) were used. Results showed that the biomass productions of spinach were not significantly affected by the addition of iodate and iodide to the soil, and that iodine concentrations in spinach plants on the basis of fresh weights increased with increasing addition of iodine. Iodine concentrations in tissues were much greater for plants grown with iodate than with iodide. In contrast to the iodide treatments, in iodate treatment leaves accounted for a larger fraction of the total plant iodine. The soil-to-leaf transfer factors (TF_leaf) for plants grown with iodate were about tenfold higher than those grown with iodide. Iodine concentrations in soil solution increased with increasing iodine additions to the soil irrespective of iodine species. However, total iodine in soil solution was generally higher for iodate treatments than iodide both in pots with and without spinach. According to these results, iodate can be considered as potential iodine fertilizer to increase iodine content in vegetables.     

Penicillin V production by Penicillium chrysogenum in the presence of Fe3+ and in low-iron culture medium

Late-exponential-phasePenicillium chrysogenum mycelia grown in a complex medium possessed an intracellular iron concentration of 650 μmol/L (2.2±0.6 μmol per g mycelial dry mass). This iron reserve was sufficient to ensure growth and antibiotic production after transferring mycelia into a defined low-iron minimal medium. Although the addition of Fe³⁺ to the Fe-limited cultures increased significantly the intracellular iron levels the surplus iron did not influence the production of penicillin V. Supplements of purified majorP. chrysogenum siderophores (coprogen and ferrichrome) into the fermentation media did not affect the β-lactam production and intracellular iron level. Neither 150 nor 300 μmol/L extracellular Fe³⁺ concentrations disturbed the glutathione metabolism of the fungus, and increased the oxidative stress caused by 700 mmol/L H₂O₂. Nevertheless, when iron was applied in the Fe^II oxidation state the oxidative cell injuries caused by the peroxide were significantly enhanced.