Biomass Doubling Time Research Articles

Impact of High Light Intensity and Low Temperature on the Growth and Phenylpropanoid Profile of Azolla filiculoides.

Exposure to high light intensity (HL) and cold treatment (CT) induces reddish pigmentation in Azolla filiculoides, an aquatic fern. Nevertheless, how these conditions, alone or in combination, influence Azolla growth and pigment synthesis remains to be fully elucidated. Likewise, the regulatory network underpinning the accumulation of flavonoids in ferns is still unclear. Here, we grew A. filiculoides under HL and/or CT conditions for 20 days and evaluated the biomass doubling time, relative growth rate, photosynthetic and non-photosynthetic pigment contents, and photosynthetic efficiency by chlorophyll fluorescence measurements. Furthermore, from the A. filiculoides genome, we mined the homologs of MYB, bHLH, and WDR genes, which form the MBW flavonoid regulatory complex in higher plants, to investigate their expression by qRT-PCR. We report that A. filiculoides optimizes photosynthesis at lower light intensities, regardless of the temperature. In addition, we show that CT does not severely hamper Azolla growth, although it causes the onset of photoinhibition. Coupling CT with HL stimulates the accumulation of flavonoids, which likely prevents irreversible photoinhibition-induced damage. Although our data do not support the formation of MBW complexes, we identified candidate MYB and bHLH regulators of flavonoids. Overall, the present findings are of fundamental and pragmatic relevance to Azolla's biology.

Determination of the dependence of humic acids on the growth parameters of Rhodococcus microorganisms in the presence of hexadecane

The stimulating effect of humic acids of peats of various origin at a concentration of 50 mg / L on the growth and reproduction of oil-degrading microorganisms Rhodococcus erythropolis S67 and Rhodococcus erythropolis X5 was detected by spectrophotometric and gravimetric methods. It was established that the maximum growth parameters (the specific growth rate, the biomass doubling time) were observed for microorganisms Rhodococcus erythropolis S67 in the presence of humic acids of read fen peat. The indicators in the system “microorganism R. erythropolis X5 - hexadecane - humic acids of sphagnum highmoor peat” were 2.6 times higher than in the system “microorganism R. erythropolis X5 -hexadecane”. Growth parameters for R.erythropolis X5 were 2 times higher than the parameters for R.erythropolis S67, which was 2 times higher than the growth parameters of the control. It was found that humic acids in the solution reduced stress conditions for the microorganisms Rhodococcus erythropolis S67 and Rhodococcus erythropolis X5. That contributed to their more rapid biodegradation of the substrate hexadecane, as well as the growth and reproduction of bacteria by increasing the solubility of the organic substrate and creating on the cell surface monolayer screen, which was a mesh filter of humic acid molecules.

Modeling the growth dynamics of water lettuce, Pistia stratiotes L. in wastewater

This study was aimed at assessing water lettuce (Pistia stratiotes L.) biomass growth, which was tested at the Faculty of Civil Engineering and Architecture of Nis under partially controlled conditions during a 70-day-long test, with a mixture of communal wastewater and water from the shaft at the hydraulic engineering demonstration facility as a source of nutrient matter. The biomass measured after the 70-day experiment ranged from 4.31 to 4.71 kg WW/m2 (average 4.48 kg WW/ m2). The daily absolute growth rate (AGR) was 58.81 g/m2 day, the daily increase rate (DIR) was 16.16 %/day, the average daily relative growth rate (RGR) was 0.0359 g/g day, and the biomass doubling time (DT) was 32.94 days. The following models were used to model the dynamics of water lettuce biomass growth: the exponential model (average MSE 0.0485, average coefficient of determination (R2) to 0.9757); the logistic model (mean squared error (MSE) 0.0049, R2 0.9976), and the sigmoidal model (average MSE 0.0003, average R2 0.9999). All models have a high accuracy; however, the exponential models give a continuous increase in biomass over time, practically to infinity, without taking into account that under conditions of increased plant density and reduced availability of resources, biomass growth slows down and, therefore, they are not suitable for application in real conditions. The logistic model (environmental capacity 6.1680 kg/m2 after about 150 days, ti 53.8587 days, ta 32.8295 days, tb 74.8879), and sigmoidal model (environmental capacity 5.2903 kg/m2 after about 150 days, ti 50.2972 days, ta 34.3072 days, tb 66.2872 days) adequately describe the biomass growth of the growth phase of water lettuce with high precision, which is essential for planning appropriate preventive and active measures to control the spread of water lettuce as an invasive plant and minimize negative impacts on waterbodies in Serbia.

Obtaining Callus Culture of Sage Medicinal (<i>Salvia officinalis</i> L.) and its Characteristics

Introduction. Cultivation of biomass of plant cells as a method of obtaining raw materials has existed for quite a long time. Plant cells cultivated in vitro act as a source of valuable secondary metabolites such as phenols, alkaloids, phytosteroids, glycosides, etc. It is important to create conditions under which the accumulation of valuable biologically active substances will be observed in the strains. Cultivation involves the use of complex multicomponent nutrient media containing a certain set of macro-, microelements, vitamins, growth stimulants. Salvia officinalis has a wide spectrum of pharmacological action. Due to the limited growing area of medicinal sage, as well as the deterioration of the ecological situation in the growing regions, the use of a phytobiotechnological method for obtaining raw materials is relevant.Aim. The aim of the study is to obtain a viable callus culture of salvia officinalis (Salvia officinalis L.).Materials and methods. Leaves of an intact plant sage medicinal, of the Lamiaceae family (Salvia officinalis, Lamiaceae) were used as explants. The explants were pre-sterilized with 6 % sodium hypochlorite solution for 20 minutes and 70 % ethanol for 1 minute. It was cultivated on a nutrient medium according to the Murasig – Skoog recipe. Determination of cell viability using vital dyes was assessed using microscopy (digital microscope Bresser LCD 50x-2000x, Germany). High performance thin layer chromatography was performed using a HPTLC PRO SYSTEM (CAMAG AG, Switzerland).Results and discussion. After two weeks of cultivation, the formation of primary callus was observed on the surface of the explants. Visually, it was a thin layer of intensely dividing undifferentiated light yellow cells. During cultivation, the biomass of the resulting callus increased, it became looser and acquired a darker shade, and the nutrient medium also began to darken. The detected cells during microscopy can be divided into two types: the first type is cells of the meristematic type, the second type is cells of the parenchymal type. Microscopy showed that more than 95 % of all visualized cells are alive. In the following passages, no significant changes in the morphotype of the culture were noted. In the eleventh passage, a study of the growth activity of the strain was carried out. The maximum specific growth rate of 0.42 day-1 is observed on the 14–18th day of growth, while the biomass doubling time is the smallest and corresponds to the value of 1.66 days. During one cultivation cycle, the amount of biomass increases by 7.73 times. The results of a qualitative analysis by the method of high-performance thin-layer chromatography (HTPLC) show that the qualitative composition of the biomass of medicinal sage is generally close to that of intact plants.Conclusion. A viable stable strain of plant cells of salvia officinalis was obtained on a nutrient medium according to the Murasig – Skoog recipe with a half content of micro- and macrosols and phytohormones 2,4-D (6 mg/ml) and kinetin (1 mg/ml). For the following passages, it is recommended to use a nutrient medium according to the Murasig – Skoog recipe with a full content of micro and macrosols and phytohormones naphthylacetic acid (1 mg/ml) and kinetin (1 mg/ml). The bulk of the obtained heterogeneous callus is made up of cells of the meristematic and parenchymal type. The qualitative composition of BAS biomass of medicinal sage is generally close to that of intact plants.

Metabolic and Proteomic Analysis of Chlorella sorokiniana, Chloroidium saccharofilum, and Chlorella vulgaris Cells Cultured in Autotrophic, Photoheterotrophic, and Mixotrophic Cultivation Modes.

Chlorella is one of the most well-known microalgal genera, currently comprising approximately a hundred species of single-celled green algae according to the AlgaeBase. Strains of the genus Chlorella have the ability to metabolize both inorganic and organic carbon sources in various trophic modes and synthesize valuable metabolites that are widely used in many industries. The aim of this work was to investigate the impact of three trophic modes on the growth parameters, productivities of individual cell components, and biochemical composition of Chlorella sorokiniana, Chloroidium saccharofilum, and Chlorella vulgaris cells with special consideration of protein profiles detected by SDS-PAGE gel electrophoresis and two-dimensional gel electrophoresis with MALDI-TOF/TOF MS. Mixotrophic conditions with the use of an agro-industrial by-product stimulated the growth of all Chlorella species, which was confirmed by the highest specific growth rates and the shortest biomass doubling times. The mixotrophic cultivation of all Chlorella species yielded a high amount of protein-rich biomass with reduced contents of chlorophyll a, chlorophyll b, carotenoids, and carbohydrates. Additionally, this work provides the first information about the proteome of Chloroidium saccharofilum, Chlorella sorokiniana, and Chlorella vulgaris cells cultured in molasses supplementation conditions. The proteomic analysis of the three Chlorella species growing photoheterotrophically and mixotrophically showed increased accumulation of proteins involved in the cell energy metabolism and carbon uptake, photosynthesis process, and protein synthesis, as well as proteins involved in intracellular movements and chaperone proteins.

Morphological Phenotypes, Cell Division, and Gene Expression of Escherichia coli under High Concentration of Sodium Sulfate

Sodium and sulfate ions are among the suggested abundant ions on Europa, a moon of Jupiter. In order to investigate the potential habitability of Europa, we study the effects of sodium sulfate (Na2SO4) on a non-halophilic bacterium by subjecting Escherichia coli (E. coli) to a wide range of Na2SO4 concentrations (0–1.0 m). We discover that, as the concentration of sodium sulfate increases, the biomass doubling time increases and the cell growth is completely inhibited at m Na2SO4. Furthermore, we find that E. coli exhibits three distinct morphological phenotypes—(i) shortened, (ii) normal, and (iii) elongated/filamented cells at m and m Na2SO4. We have examined the expression of different genes involved in sodium and sulfate transport (nhaA, nhaB, cysZ, sbp), osmotically driven transport of water (aqpZ), sulfate metabolism (cysN), fatty acid production (fabA), and a global transcriptional regulator (osmZ). Our results suggest that the expression of these genes is not affected significantly at high concentrations of sodium sulfate in the exponential growth phase. Using our experimental data and the existing data in the literature, we show that the osmotic pressure difference may play a major role in determining the growth inhibition of E. coli and B. subtilis at high concentrations of salt.

Efficient Agrobacterium tumefaciens-mediated stable genetic transformation of green microalgae, Chlorella sorokiniana.

The online version contains supplementary material available at 10.1007/s13205-021-02750-7.

Interactive effects of light quality and culturing temperature on algal cell size, biomass doubling time, protein content, and carbohydrate content.

Light management strategy can be used to improve algal biomass and nutrient production. However, the response of algal metabolism to different light qualities, especially their interaction with other environmental factors, is not well understood. This study focuses on the interactive effects of light quality and culturing temperature on algal protein content and carbohydrate content of C. reinhardtii. Three LED light sources (blue light, red-orange light, and white-yellow light) were applied to grow algae in batch cultures with a light intensity of 105 μmol/m2s under the temperatures of 24 °C to 32 °C. The protein and carbohydrate content were measured in both the late exponential growth phase and the late stationary growth phase. The results revealed that there was an interactive effect of light quality and culturing temperature on the protein and carbohydrate content. The combined conditions of blue light and a temperature of 24 °C or 28 °C, which induced a larger algal cell size with a prolonged cell cycle and a low division rate, resulted in the highest protein content; the protein mass fraction and concentration were 32% and 52% higher than that under white-yellow light at 32 °C. The combined conditions of red-orange light and a temperature of 24 °C, which promoted both the cell division and size growth, enhanced the carbohydrate content; the carbohydrate mass fraction and concentration were 161% and 155% higher than that under white-yellow light at 24 °C. When there was temperature stress (32 °C) or nutrient stress, the effect of light quality reduced, and the difference of protein and carbohydrate content among the three light qualities decreased. KEY POINTS: • Studied light quality-temperature interactive effect on protein, carbohydrate synthesis. • Protein content was high under low cell division rate. • Carbohydrate content was high under high cell division and cell size growth rate.

Evaluation of Microbial Degradation of Crude Oil in a Polluted Tropical Soil

This research is aimed at determining the growth and capacity of microorganisms to degrade crude oil following biostimulationwith NPK fertilizer and sawdust amendment. The contaminated soil was treated simultaneously with the nutrient amendment in treatments A, B, C, D, E, F, G, H and I and the population of microorganisms involved in the degradation of TPH monitored.Optimum conditions for effective degradation of the contaminant were determined and the kinetics of the process evaluated. Physicochemical and biological parameters like soil pH, texture, total petroleum hydrocarbon (TPH), total nitrogen, totalphosphorus, hydrocarbon-degrading bacteria (HDB), and hydrocarbon-degrading fungi (HDF) in the native, control and treatedsoils were analyzed using standard analytical method and procedures. The HDB/HDF population measured for TPH degradationat intervals established the efficiency and kinetics of the bioremediation process. However, HDB growth rate in the treatmentswere between 0.1840 and 0.1931. The utilization of nitrogen and phosphorus by microorganisms was between 81.5% and 92.8%.TPH degradation in the treatments was between 98.14% and 99.05% and degradation rates between -0.0419 day-1 and -0.0479day-1. However, optimum treatment was achieved in 105 days with an efficiency of 99.05% in the first-order kinetics at degradation constant of -0.0479 day-1, degradation half-life of 14.47 days, the microbial growth rate of 0.1921 day-1, and biomass doubling time; 3.61 days. Arousal of the population of indigenous microorganisms at the study site through the application of nutrients and a permeable medium resulted in massive biotransformation of the pollutants to non-toxic environmentally friendly forms.

Random mutagenesis of super Koji (Aspergillus oryzae): improvement in production and thermal stability of \u03b1-amylases for maltose syrup production

BackgroundAlpha-amylases hydrolyze 1,4 α-glycosidic bonds of starch and produce malto-oligosaccharides. It is an important enzyme generally applied in textile, food and brewing industries. Enhancement in thermal stability and productivity of enzymes are the two most sought after properties for industrial use. The Aspergillus oryzae (Koji) has Generally Recognized as Safe (GRAS) status and safe for use in food industry. Hence, Koji strain’s development for the screening of potent mutants, hyper producer of thermostable α-amylases, with desired attributes is the need of the time.ResultsA process has been developed to improve super Koji (A. oryzae cmc1) strain through γ-rays treatment. The doses i.e. 0.60, 0.80, 1.00, 1.20 & 1.40 KGy gave more than 3.0 log kill. Initially, 52 Koji mutants resistant to 1% (w/v) Triton X-100 were selected. 2nd screening was based on α-amylases hyper production and 23 mutants were sorted out by measuring clearing zones index (CI). Afterwards nine potent mutants, resistant to 2-deoxy D-glucose, were screened based on CI. These were further analyzed for thermal stability and productivity of α-amylase under submerged conditions. The mutants’ M-80(10), M-100(6) & M-120(5) gave about four fold increases in α-amylases productivity. The half life of M-100(6) α-amylase at 55 °C was 52 min and was highest among the mutants. Liquid Chromatography-Mass Spectrometry (LC-MS) analysis confirmed that mutants did not produce aflatoxins. Field Emission Scanning Electron Microscopy (FESEM) of Koji mycelia depicted that exposure to gamma rays increased rigidity of the mycelium. The potent Koji mutant M-100(6) was grown on soluble starch in 10L fermenter and produced 40.0 IU ml-1 of α-amylases with specific activity of 2461 IU mg-1 protein. Growth kinetic parameters were: μ = Specific growth rate= 0.069 h-1, td = Biomass doubling time= 10.0 h, Yp/x = Product yield coefficient with respect to cell mass = 482 U g-1; qp= Specific rate of product formation= 33.29 U g-1 h-1.ConclusionIt was concluded that the developed five step screening process has great potential to generate potent mutants for the hyper production of thermostable enzymes through γ-rays mediated physical mutagenesis. The developed thermostable α-amylases of super Koji mutantM-100(6) has immense potential for application in saccharification process for maltose syrup production. Moreover, the developed five step strain’s development process may be used for the simultaneous improvement in productivity and thermal stability of other microbial enzymes.

Production of the Anticancer Compound Withaferin A from Genetically Transformed Hairy Root Cultures of Withania Somnifera

Withanolides (WTDs), well-known medicinally important compounds of Withania somnifera, including the anticancer compound withaferin A (WFA), are biosynthesized from their dedicated precursor squalene. Condensation of farnesyl pyrophosphate (FPP) molecules to produce squalene is catalyzed by squalene synthase (SQS). In the present study, the Arabidopsis thaliana squalene synthase gene ( AtSQS1) was transformed in W. somnifera by Agrobacterium tumefaciens C58C1 (pRiA4). The AtSQS1 gene was detected in 87.88 % of induced transformed hairy roots (THRs). The results showed that the growth index (GI) of THRs after five weeks of culture was 2-fold higher than that of adventitious hairy roots (AHRs). The biomass doubling time of THRs and AHRs was 18 and 30 days, respectively. Quantitative evaluation of WFA in the studied roots showed that THRs contain 1.51-fold more WFA (330±0.87μg g−1 dry weight (DW)) than AHRs (218±0.17μg g−1 DW). These findings can be used for the production of WFA as a valuable anticancer compound through controlled and scaled up cultures of W. somnifera THRs.

Comparative ecophysiology of bloom-forming macroalgae in the Indian River Lagoon, Florida: Ulva lactuca, Hypnea musciformis, and Gracilaria tikvahiae

Macroalgal blooms are ecological responses to nutrient enrichment in shallow seagrass-dominated estuaries. For decades the Indian River Lagoon (IRL) a biodiverse estuary in east-central Florida, has experienced persistent blooms of red drift macroalgae, including Gracilaria and Hypnea spp. Since 2013, extensive blooms of green macroalgae, such as Chaetomorpha and Ulva spp., have developed. To better understand IRL nutrient effects on bloom-forming macroalgae, field and laboratory studies (2012) assessed nitrogen (N) versus phosphorus (P) limitation and morphological/physiological characteristics in relatively urbanized (Titusville, FL) versus rural (Fort Pierce, FL) IRL segments. Field studies indicated Ulva lactuca, Hypnea musciformis, and Gracilaria tikvahiae all grew fastest in Titusville (average±SD; 0.49±0.07, 0.35±0.03, and 0.14±0.05 doublings d−1, respectively). However, U. lactuca had the most rapid biomass doubling time (2days). Laboratory nutrient enrichment assays revealed 3-fold increases in rapid light curve (RLC) maximum values and 2-fold faster growth at high concentrations of N and P for U. lactuca. This superior growth and photosynthesis was attributed to higher surface area:volume ratios averaging (± coefficients of variation, %) 565.2±2.15cm2gdrywt.−1 compared to lower ratios for H. musciformis (110.7±3.97cm2gdrywt.−1) and G. tikvahiae (91.1±1.81cm2g dry wt.−1). Finely- and coarsely-branched H. musciformis and G. tikvahiae were similar photosynthetically but not morphologically based on a functional/form model. These data provide a physiological basis explaining bloom distributions and the recent success of green macroalgae in the increasingly eutrophic IRL.

Focusing on the Optimization for Scale up in Airlift Bioreactors and the Production of Chlamydomonas reinhardtii as a Model Microorganism

The aim of this work is to use optimization as a tool for scale up in airlift bioreactors and apply this approach to a real life process. To put this approach into practice, Chlamydomonas reinhardtii, a green microalgae, was used as a model microorganism. The effects of the design parameters on the performance of the bioreactors were monitored through the changes in mixing and circulation times. As the first step, the effective parameters (draft tube diameter and height, water level over the draft tube, volumetric flow rate of air, and sparger-draft tube distance) in the 1.1 L airlift bioreactor were determined and optimized by the 5-factor, 3-level Box-Behnken design for response surface methodology. A draft tube with a 38-250 mm dimension was selected resulting in a mixing time of 9.94 s with a 1.05 L min-1 air flow rate. In the second step the optimized values were applied to a larger airlift bioreactor of 11 L for C. reinhardtii productions. Comparable biomass productivities (0.87-0.90 g L-1 day-1) and doubling times (25-27 h) in both systems was a good indication of the success of the scale-up approach.

Photobioreactor operation condition optimization for high-energy cyanobacterial biomass synthesis to produce third-generation biofuels

The distinctive features of cultivation of two strains of thermophilic cyanobacteria, Mastigocladus laminosus and Anabaena variabilis, in a pouring-off-filling-up type of photobioreactor are investigated. The dependence of the biomass growth rate and concentration doubling time on the carbon dioxide content in the injected air is studied and the culture medium composition is optimized. It is shown that tap water added with macro- and microelements, instead of analogous distilled water based nutrient medium, facilitates faster biomass growth. The minimum biomass doubling time is 0.9 day for Mastigocladus laminosus and 1.1 days for Anabaena variabilis when the carbon dioxide content in the injected air is 4 vol. %.

Strategies to Control a Common Carp Population by Pulsed Commercial Harvest

AbstractCommercial fisheries are commonly used to manage nuisance fishes in freshwater systems, but such efforts are often unsuccessful. Strategies for successfully controlling a nuisance population of common carp Cyprinus carpio by pulsed commercial harvest were evaluated with a combination of (1) field sampling, (2) population estimation and CPUE indexing, and (3) simulation using an exponential semidiscrete biomass dynamics model (SDBDM). The range of annual fishing mortalities (F) that resulted in successful control (F = 0.244–0.265) was narrow. Common carp biomass dynamics were sensitive to unintentional underharvest due to high rates of surplus production and a biomass doubling time of 2.7 years. Simulations indicated that biomanipulation never achieved successful control unless supplemental fishing mortality was imposed. Harvest of a majority of annual production was required to achieve successful control, as indicated by the ecotrophic coefficient (EC). Readily available biomass data and tools such as SDBDMs and ECs can be used in an adaptive management framework to successfully control common carp and other nuisance fishes by pulsed commercial fishing.Received February 28, 2012; accepted August 27, 2012

Estimating changes of isotopic fractionation based on chemical kinetics and microbial dynamics during anaerobic methane oxidation: apparent zero- and first-order kinetics at high and low initial methane concentrations

Changes in natural isotopic composition may be used to reveal metabolic pathways of substrate transformation by microbial communities (Vavilin in Ecol Model 240:84-92, 2012b). Anaerobic oxidation of methane (AOM) by sulfate has been described using a mathematical model based on chemical kinetics, microbial dynamics and equations for (13)C isotope accumulation in products as well as their redistribution between substrate and products. Experimental data for two batch cultures that originated from microbial mats covering methane seep chimneys in the Black Sea, previously obtained by Seifert et al. (Org Geochem 37:1411-1419, 2006) and Holler et al. (Env Microbiol Reports 1(5):370-376, 2009), were used to model AOM. During long-time incubation, changes of isotope signatures in CH(4) showed that in the Seifert et al. batch tests (low methane concentration), in contrast to the Holler et al. batch tests (high methane concentration), methane production occurred along with methane oxidation. In accordance with the model, apparent zero and first-order kinetics of methane oxidation were valid for the Holler et al. and Seifert et al. batch tests, respectively. The observed change of [Formula: see text] was explained by microbial kinetics reflecting that the rate is lower for heavy substrate microbial utilization when compared to light substrate microbial utilization. The model showed that small amounts of methanogenesis will change the carbon isotopic composition of methane because biogenic methane has a distinct isotopic composition and due to the large difference between the maximum specific rates of methane oxidation and production. The estimated biomass doubling time of methane-oxidizers for high and low methane concentration was 408/126 days and 4640/1160 days, respectively, depending on the value of the half-saturation constant K ( S ) (5 and 20 mM).

Kinetics and thermodynamics of high level β-glucosidase production by mutant derivative of Aspergillus niger under submerged growth conditions

Gamma rays mediated mutagenesis and subsequent selection on 2-deoxy-D-glucose developed a highly catabolite de-repressed and stable β-glucosidase (BGL) hyper-producer mutant of local Aspergillus niger NIBGE, which has high potential for industrial applications. The M6 mutant showed highest constitutive production of BGL (14,900 IU/L) on glucose as compared to control (5,900 IU/L). Wheat bran was the best carbon source and BGL production by parent and mutant strain was 16,200 and 29,500 IU/L, respectively. Effect of inoculum density, pH, temperature and wheat bran concentration on the BGL production was determined in terms of kinetic growth parameters, that is, specific growth rate (m), biomass doubling time (td), product yield coefficient with respect to cell mass (Yp/x) and specific rate of product formation (qp). Optimal conditions for BGL production by parent and mutant strain were same: inoculum level= 0.184 mg cells/mL (10% v/v); optimum temperature= 30°C and pH= 5.0; wheat bran= 3% (w/v). The apparent subunit molecular mass of BGL from both strains was also same (130 kDa). Determination of thermodynamic parameters led to consider that the hyper-production of BGL by the mutant was due to decrease in: activation energy (Ea(p)), change in enthalpy (ΔH*(p)) and Gibbs free energy (ΔG*(p)) for product (BGL) formation. Key words: β-glucosidase, Aspergillus niger, activation energy, enthalpy, Gibbs free energy.

THE EFFECT OF POTATO LECTIN ONTO DIAZOTROF GROWTH ACTIVITY

It are presented the results of the research of рotato lectin effect onto the growth activity of bacteria Azotobacter and Azospirillum genera. Dependence of growth of microorganisms on its content in the nutrient medium containing of it at the level of 0,2–20 mсg/ml was studied. It have been established the optimal рotato lectin concentration for Аzotobacter vinelandii and Аzotobacter chroococcum M-70/2 (1,0 mсg/ml) and Azospirillum brasilense 410 (1,5 mcg/ml), when the bacteria population density, specific growth rate are increased, biomass doubling time is decreased.

Outdoor and Indoor Cultivation of Spirulina platensis in the Extreme South of Brazil

Water supplemented with 10% or 20% (v/v) of Zarrouk medium was used to cultivate Spirulina platensis in closed and open bioreactors under controlled conditions (30 degrees C, 32.5 micromol m(-2) s(-1), 12 h light/dark photoperiod) and in a greenhouse (9.4 to 46 degrees C, up to 2800 micromol m(-2) s(-1), variable day length photoperiod) using different initial biomass concentrations (X0) in the extreme south of Brazil (32.05 degrees S, 52.11 degrees W). Under controlled conditions the maximum specific growth rate (micromax) was 0.102 d(-1), the biomass doubling time (t(d)) was 6.8 d, the maximum dry biomass concentration (Xmax) was 1.94 g L(-1) and the maximum productivity (Pmax) was 0.059 g L(-)1 d(-1), while the corresponding values in the greenhouse experiments were micromax = 0.322 d(-1), t(d) = 2.2 d, Xmax = 1.73 g L(-1) and Pmax = 0.112 g L(-1) d(-1). Under controlled conditions the highest values for these parameters occurred when X0 = 0.15 g L(-1), while in the greenhouse X0 = 0.4 g L(-1) produced the highest values. These results show that the cultivation of S. platensis in greenhouses in the extreme south of Brazil is technically viable and that the S. platensis inoculum and the concentration of Zarrouk medium can be combined in such a way as to obtain growth and productivity parameters comparable, or superior, to those occurring in bioreactors under controlled conditions of temperature, illuminance and photoperiod.

High expression of transgene protein in Spirodela

The monocot family Lemnaceae (duckweed) is composed of small, edible, aquatic plants. Spirodela oligorrhiza SP is a duckweed with a biomass doubling time of about 2 days under controlled, axenic conditions. Stably transformed Spirodela plants were obtained following co-cultivation of regenerative calli with Agrobacterium tumefaciens. GFP activity was successfully monitored in different subcellular compartments of the plant and correlated with different targeting sequences. Transgenic lines were followed for a period of at least 18 months and more than 180 vegetative doublings (generations). The lines are stable in morphology, growth rate, transgene expression, and activity as measured by DNA-DNA and immunoblot hybridizations, fluorescence activity measurements, and antibiotic resistance. The level of transgene expression is a function of leader sequences rather than transgene copy number. A stable, transgenic, GFP expression level >25% of total soluble protein is demonstrated for the S. oligorrhiza system, making it among the higher expressing systems for nuclear transformation in a higher plant.