N-[2-Naphthyl]-glycine hydrazide,a potent inhibitor of DNA-dependent RNA polymerase ofMycobacterium tuberculosis H37RV

N-[2-Naphthyl]-glycine hydrazide has been shown for the first time as a potent inhibitor of the DNA-dependent RNA polymerase (EC 2.7.7.6) ofMycobacterium tuberculosis H₃₇R_v. At a concentration of 10^-9 M, the compound shows maximum inhibition of the enzyme, the inhibition being less at higher concentrations. It is suggested that the novel type of inhibition pattern may be due to hydrophobic interactions occurring between the molecules of the compound at higher concentrations. The finding that there is a shift in the λ_max of the compound could also account for this phenomenon. The effect of this compound was also tested on DNA-dependent RNA polymerases from an eukaryotic fungus,Microsporum canis. At a concentration of 10⁻⁹ M it inhibits RNA polymerase II (32%) but not RNA polymerasesI andIII     

Spatial distribution of extractable organohalogens in northern pink shrimp in the North Atlantic

Extractable organohalogens (EOX) are organic compounds that contain chlorine, bromine and/or iodine, which can be separated from the matrix by liquid/liquid or liquid/solid extraction. A combination of instrumental neutron activation analysis (INAA) and solvent extraction methods has been developed for the determination of EOX from the shrimpPandalus borealis. Levels of EOX were evaluated for spatial trends for shrimp caught in several areas off the Labrador coast, off the coast of Nova Scotia, and off the coast of Maine. Muscle contained 1.09–6.05 Μg EOCl/g tissue and 105–498 Μg extractable organochlorine (EOCl)/g lipid; 0.0607–0.288 Μg extractable organobromine (EOB)r/g tissue and 4.74-10.5 Μg EOBr/g lipid; and 0.014–0.048 Μg extractable organoiodine (EOI)/g tissue and 1.03–1.76 Μg EOI/g lipid, respectively. The levels of EOC1 in roe were 1.60–12.34 Μg/g tissue and 39.0-146 Μg/g lipid. In roe, the EOBr levels were 0.707–1.03 Μg/g tissue and 6.96–13.5 Μg/g lipid; and EOI levels were 0.123–0.349 Μg/g tissue and 1.42–4.11 Μg/g lipid. The EOCl, EOBr, and EOI levels in roe increased noticeably from north to south along the coast of Labrador. Samples taken from the coast of Maine and from Canso Hole were typically higher in EOCl levels than those taken from Labrador. The results for EOBr and EOI were in the same range as those from Labrador.     

Resolution and Synthesis of (S)-1-(2-Naphthyl)ethanol with Immobilized Pea Protein: As a New Biocatalyst

(S)-1-(2-Naphthyl)ethanol was yielded by immobilized pea (Pisum sativum L.) protein (IPP) from (R, S) 2-naphthyl ethanol (>99% ee, yield; about 50%), in which the (R)-enantiomer was selectively oxidized to 2-acetonaphthone. IPP could be reused consecutively at least three times without any decrease of yield and optical purity.     

Photorespiratory ammonium release by the cyanobacterium Anabaena cylindrica in the presence of methionine sulfoximine

A release of ammonium by non-nitrogen-fixing Anabaena cylindrica (grown on NH₄Cl) in the presence of MSX (methionine sulfoximine) and absence of any external nitrogen source was found. In the light the release was maximal at 0.2 mM MSX, a concentration which did not affect net CO₂ fixation nor the glycollate excretion, but inhibited the glutamine synthetase activity and the reassimilation of ammonium. It is suggested that the major source of the ammonium released is the photorespiratory conversion of glycine to serine as (1) the release was stimulated by increase in light intensity, (2) high CO₂ (3%) lowered the release, if not given as a longer pretreatment (as CO₂ or HCO ₃ ^- ) when a stimulation was observed, (3) glyoxylate and glutamate stimulated the release, the latter compound particularly under nitrogen-deficient conditions and (4) isonicotinic acid hydrazide caused a reduced release of ammonium. Furthermore, a substantial part of the ammonium released by N₂-fixing A. cylindrica in presence of MSX may thus originate from the glycollate pathway. The data show that in the light the glycine to serine conversion is active in cyanobacteria with a concomitant production of ammonium which is assimilated by glutamine synthetase.Abbreviations MSX L-methionine-Dl-sulfoximine - INH isonicotinic acid hydrazide - RuDP ribulose 1,5-diphosphate - Hepes N-2-hydroxyethylpiperazine-N-2-ethanesulfonic acid - GS glutamine synthetase - GOGAT glutamate synthase - DTT Dl-dithiothreitol     

1H NMR and GC/MS metabolomics of earthworm responses to sub-lethal DDT and endosulfan exposure

The metabolic response of the earthworm Eisenia fetida to two pesticides, dichlorodiphenyltrichloroethane (DDT) and endosulfan, was characterized in contact tests using proton nuclear magnetic resonance (¹H NMR) and principal component analysis (PCA). PCA loading plots suggested that maltose, leucine and alanine were important metabolites contributing to the differences in dosed and control earthworms for both compounds at doses of 0.5, 1.0 and 2.0 μg/cm². Gas chromatography/mass spectrometry (GC/MS) was used to quantify the metabolites identified in E. fetida and determine if the changes in maltose, leucine and alanine following exposure to DDT and endosulfan (at 0.5 and 1.0 μg/cm²) were reproducible and greater than the natural variability. Quantification by GC/MS suggested that maltose was not a reliable biomarker since it both increased and decreased in earthworms exposed to DDT and increased by just 3% with exposure to endosulfan. Leucine was not stable with the GC/MS derivitization method used in this study and could not be confirmed as a reliable biomarker. However, alanine consistently increased for both DDT and endosulfan exposed E. fetida. Alanine showed considerable variability in control earthworms (±41.6%), yet the variability in alanine to glycine ratios was just ±10.5%. Increases in the alanine to glycine ratio were statistically significant at the P = 0.05 level for the 1.0 μg/cm² DDT dose and both the 0.5 and 1.0 μg/cm² endosulfan doses, suggesting that deviations from the normal homeostatic ratio of 1.5 for alanine to glycine is a potential biomarker of DDT and endosulfan exposure warranting further study. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. Environmental Metabolomics Special Issue of Metabolomics.     

Photorespiration in C3–C4 intermediate species of Alternanthera and Parthenium: Reduced ammonia production and increased capacity of CO2 refixation in the light

The pattern of photorespiratory ammonia (PR–NH₃) formation and its modulation by exogenous bicarbonate or glycine were investigated in C₃–C₄ intermediates of Alternanthera (A. ficoides and A. tenella) and Parthenium hysterophorus in comparison to those of C₃ or C₄ species. The average rates of PR–NH₃ accumulation in leaves of the intermediates were slightly less than (about 25% reduced) those in C₃ species, and were further low in C₄ plants (40% of that in C₃). The levels of PR–NH₃ in leaf discs decreased markedly when exogenous bicarbonate was present in the incubation medium. The inhibitory effect of bicarbonate on PR–NH₃ accumulation was pronounced in C₃ plants, very low in C₄ species and was moderate in the C₃–C₄ intermediates. Glycine, an intermediate of photorespiratory metabolism, raised the levels of PR–NH₃ in leaves of not only C₄ but also C₃–C₄ intermediates, bringing the rates close to those of C₃ species. The rate of mitochondrial glycine decarboxylation in darkness in C₃–C₄ intermediates was partially reduced (about 80% of that in C₃ species), corresponding to the activity-levels of glycine decarboxylase and serine hydroxymethyltransferase in leaves. The intermediates had a remarkable capacity of reassimilating photorespiratory CO₂ in vivo, as indicated by the apparent refixation of about 85% of the CO₂ released from exogenous glycine in the light. We suggest that the reduced photorespiration in the C₃–C₄ intermediate species of Alternanthera and Parthenium is due to both a limitation in the extent of glycine production/decarboxylation and an efficient refixation/recycling of internal CO₂.Abbreviations GDC glycine decarboxylase - GS glutamine synthetase - GOGAT glutamate-oxoglutarate aminotransferase - -HPMS -hydroxy-2-pyridinemethanesulfonic acid - INH isonicotinyl hydrazide - MSO L-methionine sulfoximine - PR–NH₃ photorespiratory-ammonia - SHMT serine hydroxymethyltransferase     

Optical resolution of two isomeric naphthylalanines by immobilized enyzmes

Optical resolution of β-(1-naphthyl)alanine and β-(2-naphthyl)alanine have been efficiently carried out through enzymatic hydrolysis of their methyl ester and/or N-acetyl ester derivatives by immobilized enzymes. Difficulties related to the lipophilic character of these amino acids were overcome by using emulsions of n-butyl acetate–water as reaction medium. The use of an automatic recirculating apparatus allowed reproducible and repetitive use of the immobilized biocatalysts.     

Cry2A toxins from <Emphasis Type="Italic">Bacillus thuringiensis</Emphasis> expressed in insect cells are toxic to two lepidopteran insects

The cry2Aa and cry2Ab genes from a Brazilian Bacillus thuringiensis strain were introduced into the genome of the baculovirus Autographa californica multiple nucleopolyhedrovirus (AcMNPV) in order to evaluate the heterologous proteins expression in insect cells and their toxicity to different insects. The recombinant viruses (vAcCry2Aa and vSynCry2Ab) were amplified in Trichoplusia ni (BTI-Tn5B1-4) cells and used to infect Spodoptera frugiperda larvae. Total extracts from S. frugiperda infected with the recombinant viruses were analysed by SDS-PAGE, which detected the presence of polypeptides around 65 kDa. Cuboid-shaped protein crystals were observed in insect extracts by light and scanning electron microscopy. Bioassays, using the heterologous proteins showed toxicity against second instar A. gemmatalis larvae (Cry2Aa) with a LC₅₀ of 1.03 μg/ml and second instar S. frugiperda larvae (Cry2Ab) with a LC₅₀ of 3.45 μg/ml. No toxic activity was detected for Aedes aegypti and Culex quinquenfaciatus.     

An acid stable trypsin-chymotrypsin inhibitor from horse gram (Dolichos biflorus)

An inhibitor of trypsin and chymotrypsin was purified from horse gram (Dolichos biflorus) beans. The concentration of the inhibitor which provided total inhibition was 0.27 Μg/Μg tryptic enzyme and 0.46 Μg/Μg chymotryptic enzyme. The inhibitor was stable at 37‡C between pH of 3 to 11 and at 97‡C, upto pH 5.0 only. While the activities were rapidly lost in 0.1N NaO H the loss was only 5 0% in 0.1N HCl when kept for 2 h at 97‡C. On heating at pH 7.8, it remained stable upto 80‡C with a gradual loss in activities at 97‡C and a total loss occurring by autoclaving at 15 psi for 10 min. Reduction of disulphide bonds by 2-mercapto-ethanol, pronase digestion and boiling in the presence of 1 M NaCl led to reduction in the activities. However, the inhibitor was resistant to the action of pepsin and subtilisin and to urea at 37‡C.     

Mercury ions inhibit photosynthetic electron transport at multiple sites in the cyanobacteriumSynechococcus 6301

Inhibition of electron transport activities in the spheroplasts ofSynechococcus 6301 by HgCl² is dependent on the concentration of mercury ions. The inhibition of whole chain electron transport activity occurs at low concentration of Hg²⁺ (6 ΜM@#@). This inhibition occurs mostly due to interaction of Hg²⁺ on plastocyanin. At an elevated concentration (24 ΜM@#@), mercury induces inhibition chiefly in photosystem II catalyzed electron transport. At this concentration it also alters both the absorption and emission characteristics of the phycocyanin. The photosystem I catalyzed electron transport was inhibited by 50% only at high concentrations (36 ΜM@#@) of HgCl₂. However, electron transport catalyzed by photosystems I and II from reduced duroquinone to methylviologen which involves intersystem electron transport is extremely sensitive to mercury (low concentration 6–9 ΜM) like that of whole chain assay indicating that the observed inhibition in whole chain electron transport at low concentrations is mostly contributed by the damage involving other intersystem electron transport carrier(s) like plastocyanin. Thus mercury ions depending on the concentration affects the electron transport at multiple sites in the spheroplasts ofSynechococcus.     

Platinum(II) and copper(I) 1-(2-diphenylphosphino-1-naphthyl) isoquinoline complexes: Synthesis and phosphorescence at ambient conditions

The compounds Pt(quinap)(CN)₂, and [Cu(quinap)I]₂ with quinap = 1-(2-diphenylphosphino-1-naphthyl)isoquinoline were synthesized. Quinap is a bidentate ligand which contains a isoquinoline and an arylphosphine group with CT acceptor properties. Accordingly, the Pt(II) and Cu(I) quinap complexes are characterized by a phosphorescence originating from the lowest-energy MLCT triplets with some IL admixture.     

Optimization of nutrient levels in the medium increases the efficiency of callus induction and plant regeneration in recalcitrant indian barley (<Emphasis Type="Italic">Hordeum vulgare</Emphasis> L.) <Emphasis Type="Italic">in vitro</Emphasis>

Summary The present study reports that a revised nutrient concentration in the basal medium improved shoot bud induction and subsequent plant regeneration in barley (Hordeum vulgare L. var. BL-2). Cultures were raised from immature embryos on MSB₅ medium supplemented with picloram. Concentrations of five nutrients were varied. The effect of these nutrients was investigated on (1) induction, (2) induction and subculture, and (3) induction, subculture and regeneration stages. The basal MSB₅ medium was not optimal for each phase of barley culture. Decreased ammonium nitrate, increased potassium dihydrogen phosphate, sodium molybdate, cobalt chloride, and addition of glycine enhanced shoot bud induction and plant regeneration. The different media that were optimal for immature embryo culture were: MSB₅ medium supplemented with 20.70 μM picloram, 10.30 mM NH₄NO₃, 6.25 mM KH₂PO₄, 2.06 μM Na₂MoO₄, 0.55 μM CoCl₂, and 26.64 μM glycine (for induction); MSB₅ medium supplemented with 12.47 μM picloram, 10.30 mM NH₄NO₃, and 0.55 μM CoCl₂ (for subculture); and MSB₅ medium supplemented with 0.2 μM picloram and 10.3 mM NH₄NO₃ (for regeneration). Primary cultures required 6wk (without transfer) for morphogenic callus formation. Callus required 4wk of subculture and another 4wk on regeneration medium for optimal plant regeneration. The revised medium could also promote regeneration of the recalcitrant barley genotype RD-2552. Histological analysis showed that the major pathway of differentiation was through shoot bud formation.     

Decarboxylation of glycine contributes to carbon isotope fractionation in photosynthetic organisms

Carbon isotope effects were investigated for the reaction catalyzed by the glycine decarboxylase complex (GDC; EC 2.1.2.10). Mitochondria isolated from leaves of pea (Pisum sativum L.) and spinach (Spinacia oleracea L.) were incubated with glycine, and the CO₂ evolved was analyzed for the carbon isotope ratio (δ¹³C). Within the range of parameters tested (temperature, pH, combination of cofactors NAD⁺, ADP, pyridoxal 5-phosphate), carbon isotope shifts of CO₂ relative to the C₁-carboxyl carbon of glycine varied from +14‰ to −7‰. The maximum effect of cofactors was observed for NAD⁺, the removal of which resulted in a strong ¹²C enrichment of the CO₂ evolved. This indicates the possibility of isotope effects with both positive and negative signs in the GDC reaction. The measurement of δ¹³C in the leaves of the GDC-deficient barley (Hordeum vulgare L.) mutant (LaPr 87/30) plants indicated that photorespiratory carbon isotope fractionation, opposite in sign when compared to the carbon isotope effect during CO₂ photoassimilation, takes place in vivo. Thus the key reaction of photorespiration catalyzed by GDC, together with the key reaction of CO₂ fixation catalyzed by ribulose-1,5-bisphosphate carboxylase, both contribute to carbon isotope fractionation in photosynthesis. This revised version was published online in June 2006 with corrections to the Cover Date.     

The Role of Intracellular Glutathione in Inorganic Mercury-Induced Toxicity in Neuroblastoma Cells

It is well known that antioxidants containing sulfhydryl (−SH) groups are protective against the toxic effects of mercury. The current study was designed to elucidate the mechanism(s) of the cytoprotective effects of glutathione (GSH) and N-acetylcysteine (NAC) against the toxicity of inorganic mercury (HgCl₂) in neuroblastoma cells (N-2A). The obtained results demonstrated the protective effects of these compounds in a dose dependant manner up to 95 and 74% cell viability, respectively as compared to the control of HgCl₂ of 10%. The administration of buthionine sulfoximine (BSO), an inhibitor of GSH synthesis, increased the toxicity of HgCl₂ in a dose dependent manner. Moreover, BSO treatment attenuated the levels of the cellular free −SH concentrations at low concentrations (1–100 μM) of HgCl₂. The data also show that cellular thiol concentrations were augmented in the presence of GSH and NAC and these compounds were cytoprotective against HgCl₂ and this is due to up regulating of GSH synthesis. A reduction in intracellular levels of GSH was observed with treatment of HgCl₂. In addition, the ratio of GSH/GSSG increased from 16:1 to 50:1 from 1 to 10 μM concentration of HgCl_2. The ratio of GSH/GSSG then decreased from 4:1 to 0.5:1 with the increase of concentration of HgCl₂ between 100 μM and 1 mM due to the collapse of the N-2A cells. It was of interest to note that the synthesis of GSH was stimulated in cells exposed to low concentration of HgCl₂ when extra GSH is available. These data support the idea that the loss of GSH plays a contributing role to the toxic effects of HgCl₂ and that inorganic mercury adversely affects viability, through altering intracellular −SH concentrations. The data further indicate that the availability of GSH to the cells may not be sufficient to provide protection against mercury toxicity and the de novo synthesis of intracellular GSH is required to prevent the damaging effects of mercury.     

Antimalarial activity of endoperoxide compound 6-(1,2,6,7-tetraoxaspiro[7.11]nonadec-4-yl)hexan-1-ol

Plasmodium falciparum, the major causative parasite for the disease, has acquired resistance to most of the antimalarial drugs used today, presenting an immediate need for new antimalarial drugs. Here, we report the in vitro and in vivo antimalarial activities of 6-(1,2,6,7-tetraoxaspiro[7.11]nonadec-4-yl)hexan-1-ol (N-251) against P. falciparum and Plasmodium berghei parasites. The N-251 showed high antimalarial potencies both in the in vitro and the in vivo tests (EC₅₀ 2.3 × 10⁻⁸ M; ED₅₀ 15 mg/kg (per oral)). The potencies were similar to that of artemisinin in vitro and greater than artemisinin's activity in vivo (p.o.). In addition, N-251 has little toxicity: a single oral administration at 2000 mg/kg to a rat gave no health problems to it. Administration of N-251 to mice bearing 1% of parasitemia (per oral 68 mg/kg, 3 times a day for 3 consecutive days) resulted in a dramatic decrease in the parasitemia: all the 5 mice given N-251 were cured without any recurrence, with no diarrhea or weight loss occurring in the 60 days of experiment. N-251 deserves more extensive clinical evaluation, desirably including future trials in the human.     

Mutagenic and Genotoxic Effects of <Emphasis Type="Italic">cis</Emphasis>-(Dichloro)tetraammineruthenium(III) Chloride on Human Peripheral Blood Lymphocytes

Chemotherapeutic agents play an important role in cancer treatment mostly due their systemic action on human organism allowing access to liquid tumors and even metastases. Among these drugs, ruthenium compounds have been showing promising results to treat tumors and represent an important development of new antitumor therapy. This study presents the evaluation of cis-(dichloro)tetraammineruthenium(III) chloride, cis-[RuCl₂(NH₃)₄]Cl, genotoxic effects using human peripheral blood lymphocytes cultured in vitro. Mitotic index (MI), chromosome aberrations (CA), and DNA damage using the comet assay were analyzed. MI in human peripheral blood lymphocyte cultures treated with 1, 10, 100, and 1,000 μg mL⁻¹ cis-[RuCl₂(NH₃)₄]Cl were 5.9%, 4.6%, 3.9%, and 0%, respectively. Doxorubicin chloridate was used as the positive control. CA derived from 1, 10, and 100 μg mL⁻¹ concentrations were defined as spontaneous when compared with the negative control, and at the concentration of 1,000 μg mL⁻¹, the cell cycle was inhibited (IM = 0%). Results obtained for the comet assay using cis-[RuCl₂(NH₃)₄]Cl suggest that this compound has no genotoxic activity against cultured human peripheral blood lymphocytes.     

The antimutagenic effect of selenium on 7,12-dimethylbenz(a)anthracene and metabolites in the amesSalmonella/microsome system

The antimutagenic effect of selenium as sodium selenite, sodium selenate, selenium dioxide, and seleno-methionine was studied in the AmesSalmonella/microsome mutagenicity test using 7,12-dimethylbenz(a)anthracene (DMBA) and some of its metabolites. Selenium (20 ppm) as sodium selenite reduced the number of histidine revertants on plates containing up to 100 μg DMBA/plate. Increasing concentrations of selenium as sodium selenite, sodium selenate, and selenium dioxide up to 40 ppm Se progressively decreased the number of revertants caused by 50 μg DMBA. DMBA and its metabolites 7-hydroxymethyl-12-methylbenz(a)anthracene, 12-hydroxymethyl-7-methylbenz(a)anthracene, and 3-hydroxy-7,12-dimethylbenz(a)anthracene were mutagenic forSalmonella typhimurium TA100 in the presence of an S-9 mixture. Selenium supplementation as Na₂SeO₃ reduced the number of revertants induced by these metabolites to background levels. The antimutagenic effect of inorganic selenium compounds cannot be explained by toxicity of selenium as determined by viability tests withSalmonella typhimurium TA100. Selenium supplementation in all forms examined, except sodium selenate, decreased the rate of spontaneous reversion. Selenium as sodium selenate was slightly mutagenic at concentrations of 4 ppm or less. Higher concentration of Na₂SeO₄ inhibited the mutagenicity of DMBA. The present studies support the anticarcinogenic potential of selenium and indicate that form and concentration are important factors in this trace element's efficacy.     

Characterization of glycinergic synapses in vertebrate retinas

Summary Glycine is one of the essential neurotransmitters modulating visual signals in retina. Glycine activates Cl^- permeable receptors that conduct either inhibitory or excitatory actions, depending on the Cl⁻ electrical–chemical gradient (E _Cl) positive or negative to the resting potential in the cells. Interestingly, both glycine-induced inhibitory and excitatory responses are present in adult retinas, and the effects are confined in the inner and outer retinal neurons. Glycine inhibits glutamate synapses in the inner plexiform layer (IPL), resulting in shaping light responses in ganglion cells. In contrast, glycine excites horizontal cells and On-bipolar dendrites in the outer plexiform layer (OPL). The function of glycinergic synapse in the outer retina represents the effect of network feedback from a group of centrifugal neurons, glycinergic interplexiform cells. Moreover, immunocytochemical studies identify glycine receptor subunits (α1, α2, α3 and β) in retinas, forming picrotoxin-sensitive α-homomeric and picrotoxin-insensitive α/β-heteromeric receptors. Glycine receptors are modulated by intracellular Ca²⁺ and protein kinas C and A pathways. Extracellular Zn²⁺ regulates glycine receptors in a concentration-dependent manner, nanomolar Zn²⁺ enhancing glycine responses, and micromolar Zn²⁺ suppressing glycine responses in retinal neurons. These studies describe the function and mechanism of glycinergic synapses in retinas.     

Limits of detection of a total reflection x-ray fluorescence system with double reflection module

An X-ray tube with a Mo target and Zr filter, operated at 45 kV/20 mA, was used to excite samples (5 ΜL deposited on a quartz support) and the total reflection angle condition was obtained with a double reflector module built with two 10-cm-long 7-mm-thick quartz crystals placed 50 Μm apart. A high-resolution spectrometer based on a Si(Li) detector coupled to a multichannel analyzer was used for X-ray detection and the spectra were interpreted with the AXIL software. The system was calibrated with standard chemical solutions containing Cr, Fe, Cu, Zn, and Pb, and Y was used as an internal standard to correct eventual geometric errors and high-voltage instabilities of the X-ray generator. The limits of detection were 19, 9, 5, and 4 ng/mL for Cr, Fe, Cu, and Zn, respectively, analyzed through characteristicKk _α X-rays, and 7 ng/mL for Pb, throughLk _α X-rays, considering 50 ΜL samples deposited and dried on a quartz support, to be excited/ detected for 1000 s.     

The optimal growth conditions for the biomass production of Isochrysis galbana and the effects that phosphorus, Zn2+, CO2, and light intensity have on the biochemical composition of Isochrysis galbana and the activity of extracellular CA

The effects of phosphorus, Zn²⁺, CO₂, and light intensity on growth, biochemical composition, and the activity of extracellular carbonic anhydrase (CA) in Isochrysis galbana were investigated. A significant change was observed when the concentration of phosphorus in the medium was increased from 5 μmol/L to 1000 μmol/L affecting I. galbana’s cell density, biochemical composition, and the activity of extracellular CA. Phosphorous concentration of 50 μmol/L to 500 μmol/L was optimal for this microalgae. The Zn²⁺ concentration at 10 μmol/L was essential to maintain optimal growth of the cells, but a higher concentration of Zn²⁺ (≥ 1000 μmol/L) inhibited the growth of I. galbana. High CO₂ concentrations (43.75 mL/L) significantly increased the cell densities compared to low CO₂ concentrations (0.35 mL/L). However, the activity of extracellular CA decreased significantly with an increasing concentration of CO₂. The activity of extracellular CA at a CO₂ concentration of 43.75 mL/L was approximately 1/6 of the activity when the CO₂ concentration was at 0.35 mL/L CO₂. Light intensity from 4.0 mW/cm² to 5.6 mW/cm² was beneficial for the growth, biochemical composition and the activity of extracellular CA. The lower and higher light intensity was restrictive for growth and changed its biochemical composition and the activity of extracellular CA. These results indicate that phosphorus, Zn²⁺, CO₂, and light intensity are important factors that impact growth, biochemical composition and the activity of extracellular CA in I. galbana.