Non-aerated Cultures Research Articles

Wzrost pomidorów na pożywce azotanowej lub amonowej w obecności różnych form i zróżnicowanych ilości żelaza [The development of tomato plants growing on nutrient solutions containing either nitrates or ammonium salts, in presence of various forms and doses of iron

In all the experiments the tomato plants seemed to grow better both in aerated and nonaerated cultures in the solutions containing nitrates, than in those with ammonium salts. The best development of plants was observed in aerated cultures containing a full dose of ferric citrate. The positive effect of ferric versenate was manifested rather in the nonaerated cultures containing lower doses of this compound.

Opuntia ficus-indica cladodes as feedstock for ethanol production by Kluyveromyces marxianus and Saccharomyces cerevisiae.

The feasibility of ethanol production using an enzymatic hydrolysate of pretreated cladodes of Opuntia ficus-indica (prickly pear cactus) as carbohydrate feedstock was investigated, including a comprehensive chemical analysis of the cladode biomass and the effects of limited aeration on the fermentation profiles and sugar utilization. The low xylose and negligible mannose content of the cladode biomass used in this study suggested that the hemicellulose structure of the O. ficus-indica cladode was atypical of hardwood or softwood hemicelluloses. Separate hydrolysis and fermentation and simultaneous saccharification and fermentation procedures using Kluyveromyces marxianus and Saccharomyces cerevisiae at 40 and 35 °C, respectively, gave similar ethanol yields under non-aerated conditions. In oxygen-limited cultures K. marxianus exhibited almost double the ethanol productivity compared to non-aerated cultures, although after sugar depletion utilization of the produced ethanol was evident. Ethanol concentrations of up to 19.5 and 20.6 g l−1 were obtained with K. marxianus and S. cerevisiae, respectively, representing 66 and 70 % of the theoretical yield on total sugars in the hydrolysate. Because of the low xylan content of the cladode biomass, a yeast capable of xylose fermentation might not be a prerequisite for ethanol production. K. marxianus, therefore, has potential as an alternative to S. cerevisiae for bioethanol production. However, the relatively low concentration of fermentable sugars in the O. ficus-indica cladode hydrolysate presents a technical constraint for commercial exploitation.

Effect of light intensity on the photosynthetical responses ofGracilaria lemaneiformisin non-aerated and aerated cultures

The economic red macroalga Gracilaria lemaneiformis was selected to study light intensity effects on its grow th,photosynthesis,effective quantum efficiencies( Yield) and pigments contents in aerated and non-aerated cultures. Three different light intensities w ere as follow s: 50 μmol /( m2· s)( low light intensity),100 μmol /( m2·s)( moderate light intensity),and 200 μmol/( m2·s)( high light intensity). The results show ed that the highest grow th rate of G. lemaneiformis w as observed w hen alga w as treated w ith moderate light intensity,and too low or too high light intensity inhibited its grow th. The relative grow th rates of aerated cultured algae,under the low light intensity,moderate light intensity and high light intensity,w ere increased by 26. 85%,31. 82% and 40. 56%,respectively. In aerated culture,the photosynthetic rate and the photosynthetic efficiency of alga treated w ith low light intensity increased by 8. 14% and 4. 26%,and the respiration rate of alga under high light intensity decreased by 20. 70%,and Yield increased by 44. 16%. The results suggested that reduced grow th w as mainly due to the limited photosynthesis in case of low light intensity,or could be ascribed to the increased respiration in case of high light intensity. Aerated culture could relieve the negative effect on the grow th rate of alga as a result of for low light or high light intensity.

Kinetic model for growth of Phaeodactylum tricornutum in intensive culture photobioreactor

A kinetic model has been developed to estimate the specific growth rate of Phaeodactylum tricornutum in batch cultures. The cultures were carried out in a laboratory scale photobioreactor. Some factors like pH, temperature and irradiance were studied. In the first case, an optimum pH of 7.8 and a specific growth rate of 0.064 h −1 were achieved for certain nitrate conditions and illumination. The temperature influence has been modelled by a modified Sinclair model. The optimum temperature was achieved at 20.4 °C in aerated cultures and at 22.3 °C in non-aerated cultures. Better adaptation to low temperatures than high ones has been obtained. The experiments carried out with different irradiances drive to a simple Monod's equation for the irradiance influence on growth, with semi-saturation irradiance of 10.2 μEinstein −2 s −1 in aerated cultures and of 6.8 μEinstein m −2 s −1 in non-aerated cultures.

English

The influence aeration and light intensity could have on biomass production and protein biosynthesis in a Spirulina sp. isolated from an oil-polluted brackish water marsh is examined.  Biomass, proximal composition and amino acid composition obtained from aerated cultures of the organism were compared with non-aerated cultures after a 35 days incubation period. Cultures of the organism were also grown in ordinary sunlight, and artificial light intensities of ca.7.5 and 15 mEm-2S-1. Results showed that both aeration and exposing the cultures of the organism to artificial illumination improved biomass production and protein biosynthesis in the Spirulina sp. compared to sunlight illuminated and non aerated cultures. These results would be useful in optimizing growth conditions for maximum biomass and protein yields from the organism.   Key words: Spirulina, aeration, light intensity, biomass, protein.

Expression of the Fis protein is sustained in late‐exponential‐ and stationary‐phase cultures of Salmonella enterica serovar Typhimurium grown in the absence of aeration

The classic expression pattern of the Fis global regulatory protein during batch culture consists of a high peak in the early logarithmic phase of growth, followed by a sharp decrease through mid-exponential growth phase until Fis is almost undetectable at the end of the exponential phase. We discovered that this pattern is contingent on the growth regime. In Salmonella enterica serovar Typhimurium cultures grown in non-aerated SPI1-inducing conditions, Fis can be detected readily in stationary phase. On the other hand, cultures grown with standard aeration showed the classic Fis expression pattern. Sustained Fis expression in non-aerated cultures was also detected in some Escherichia coli strains, but not in others. This novel pattern of Fis expression was independent of sequence differences in the fis promoter regions of Salmonella and E. coli. Instead, a clear negative correlation between the expression of the Fis protein and of the stress-and-stationary-phase sigma factor RpoS was observed in a variety of strains. An rpoS mutant displayed elevated levels of Fis and had a higher frequency of epithelial cell invasion under these growth conditions. We discuss a model whereby Fis and RpoS levels vary in response to environmental signals allowing the expression and repression of SPI1 invasion genes.

Effect of aeration on brood production and size of <i>Moina micrura</i> Kurz, 1874 (Crustacea: Anomopoda)

The effect of aeration in laboratory cultures of Moina micrura was studied and compared with non-aerated cultures with respect to egg production in egg-bearing females, the number of eggs per egg-bearing female and the biomass of the organisms in the cultures. The number of egg-bearing females, the number of eggs per egg-bearing female and the biomass of Moina were significantly higher (P < 0.05) in aerated compared to non-aerated cultures. Dissolved oxygen and pH levels were significantly higher (P < 0.05) in aerated than in non-aerated cultures while the reverse was the case with conductivity and ammonia. Results of the study indicate that aeration has a positive impact on the growth and reproduction of the freshwater cladoceran, Moina micrura. Key Words: culture, Moina micrura, aeration, egg production, biomass. Journal of Aquatic Sciences Vol.19(2) 2004: 107-112

The effect of anthracene and phenanthrene on the growth, photosynthesis, and SOD activity of the green alga Scenedesmus armatus depends on the PAR irradiance and CO2 level.

Short-term (24-h) experiments were performed to examine the effect of phenanthrene (PHE) and anthracene (ANT) on algae grown in a batch culture system at irradiances of 12, 33, 48, and 64 W m(-2) of the PAR range. Cultures were aerated (0.1 or 2% CO(2)) or nonaerated. As a result of aeration the concentration of ANT dropped from 0.45 mg L(-1) at the beginning of the experiment (t(0)) to an undetectable value after 10 h. The PHE concentration dropped from 9.36 mg L(-1) at t0 to 0.17 mg L(-1) after 24 h. ANT at nominal concentrations exceeding 0.05 mg L(-1) inhibited the growth of the algae in a concentration- and irradiance-dependent manner. The algistatic effect of ANT observed at 64 and 48 W m(-2) was independent of the CO(2) level, whereas the growth inhibition at 33 and 12 W m(-2) was much greater in cultures aerated with 2% than with 0.1% CO(2). PHE inhibited the growth only at a concentration of 10 mg L(-1) (about 50% of the control) regardless of the irradiance or the CO(2) concentration. The toxicity of both PHE and ANT was similar in aerated (0.1% CO(2)) and nonaerated cultures. ANT and PHE had a distinct effect on the photosynthesis. At 0.1% CO(2), the irradiance-dependent inhibition (ANT) and stimulation (PHE) of the photosynthesis was observed. The inhibitory effect of ANT was enhanced when algae were grown at 2% CO(2), but at the same CO(2) concentration PHE did not affect the photosynthesis. ANT stimulated the total superoxide dismutase (SOD) activity in the cells, this effect being generally more pronounced at elevated CO(2) levels and increasing with the irradiance. The total SOD activity was 250-300% higher in cells treated with PHE aerated with 0.1% CO(2). At 2% CO(2) no effect of PHE on the enzyme's activity was noted. The results obtained indicate that ANT acts as a photosensitizer causing an oxidative damage of cells, while PHE seems to affect the macromolecular synthesis.

Culture experiments with Oithona oculata Farran, 1913 (Copepoda: Cyclopoida), and its advantages as food for marine fish larvae

Culture experiments were made with Oithona oculata Farran, 1913, a coastal water copepod, at Tunas de Zaza and Santa Cruz del Sur, Cuba. A 1 1/2-year semicontinuous experimental-scale polyculture with the rotifer Brachionus rotundiformis (type “S”) in outdoor tarpaulin 2.5-m 3 tanks was established, with Nannochloropsis oculata (20×10 6 cells ml −1) and baker's yeast (1–2 g/10 6 rotifers day −1) as food, reaching a mean density of 5 copepods ml −1 and a maximum density of 8 copepods ml −1, with a daily harvest of 25% of the total volume. A 1-year batch-culture pilot-scale system was also established in indoor concrete 20-m 3 tanks using N. oculata (8–20×10 6 cells ml −1) as food, reaching a mean density of 7 copepods ml −1 and a maximum density of 10 copepods ml −1. Copepod monocultures maintained in polycarbonate 1000-l outdoor tanks were fed a mixture of five species of microalgae ( Chaetoceros ceratosphorum, Tetraselmis tetrathele, Chlorella spp., Dunaliella tertiolecta and N. oculata) at an average density of 2×10 6 cells ml −1. In these nonaerated cultures, final concentrations of 13 copepods ml −1 were obtained in 15-day cultures. Recommendations for improving pelagic copepod culture are presented and their advantages as live food for rearing marine fish larvae are analyzed.

Effect of aeration and dilution rate on nisin Z production during continuous fermentation with free and immobilized Lactococcus lactis UL719 in supplemented whey permeate

The influence of dilution rate (D) and aeration on soluble and cell-bound nisin Z production was investigated during continuous free (FC) and immobilized cell (IC) cultures with Lactococcus lactis subsp. lactis biovar diacetylactis UL719 in supplemented whey permeate. Maximum total bacteriocin titres during non-aerated continuous FC and IC cultures were obtained for low D, with 1490 and 1090 IU mL−1 for 0.15 h−1 or 0.25 and 0.5 h−1, respectively. For both systems, aeration increased nisin total production with maximum titres of 2560 and 2430 IU mL−1 for low D, respectively, as well as specific production. Volumetric productivity was the highest for an intermediate D of 0.4 h−1 during FC cultures (460 IU mL−1 h−1 for both aerated and non-aerated cultures), while it increased continuously with D during IC cultures, reaching high values of 1090 and 1760 IU mL−1 h−1 at 2.0 h−1 without and with aeration, respectively. In comparison with previous data for FC batch cultures, data from this study may indicate that during continuous fermentations at steady state, some steps in nisin biosynthesis are limiting. In these conditions, nisin production by immobilized cells is reduced.

Propagation and corm development of Brodiaea in liquid cultures

In vitro propagation of several species of the Brodiaea complex, corm production and preparation for acclimatization were studied. Clusters of protocorm-like bodies (PLB) formed on small corm sections grown in vitro in agar medium, were transferred to liquid cultures. Ancymidol, included in the liquid proliferation medium in shake flasks or bioreactors, decreased biomass production by about 50%. Aeration in a bioreactor at 0.2 or 1.6 volumes of air per volume of medium min −1 (vvm) yielded similar levels of biomass production. Production of PLB freely circulated in the bioreactor was 159% higher than that for entrapped PLB. It is suggested that circulation was more important for biomass production in the bioreactor than the aeration rate. Aeration reduced ethylene concentration to 26% of the level found in non-aerated cultures. Silver thiosulfate (STS) significantly reduced the level of ethylene to 68% of non-treated cultures. However, the altered levels of ethylene did not affect biomass production. The ratio of inoculum size to media volume affected the growth value. An increase of 263% in corm production was obtained when the PLB of different genotypes were grown on a medium containing 5% sucrose compared with those grown on a medium containing 1% sucrose. Corms differentiated in vitro displayed a similar morphology to corms developed in vivo. Corms on hormone-free medium with decreased ammonium nitrate content and with the addition of mannitol as osmoticum showed increased dormancy. The combination of elevated temperatures, increased light intensity and reduced relative humidity also contributed to the induction of dormancy in corms.

Occurrence and phylogenetic significance of glucose utilization by charophycean algae: glucose enhancement of growth in Coleochaete orbicularis

Two critical innovations had a profound influence upon the evolutionary history of plants: the nutritionally dependent embryo and apoplastic phloem loading processes. Both depend upon the ability of the plant cell membrane to transport sugars. The evolutionary origin of sugar transport by plants is, therefore, of special phylogenetic importance. Recent evidence suggests that hexoses such as glucose are the main form of sugar transported apoplastically across the placental junction between gametophyte and sporophyte of the moss Polytrichum (Renault et al., 1992, Plant Physiology 100: 1815–1822). There is also considerable evidence that hexose transport may be involved in apoplastic phloem loading in Arabidopsis and other flowering plants. Results of numerous molecular, biochemical, immunofluorescence, and ultrastructural studies indicate that bryophytes and charophycean algae are related to the ancestors of vascular plants. This report demonstrates that the charophyte Coleochaete orbicularis exhibits enhanced growth in the presence of glucose under conditions in which inorganic carbon sources are limiting. Computer image analysis was used to demonstrate that nonaerated cultures of C. orbicularis grown for 7 weeks in an inorganic medium supplemented with 1% glucose produce as much as 13.6 times the biomass of clonal cultures grown for the same length of time in the same medium without glucose. Furthermore, addition of 1% glucose to nonaerated cultures yielded chlorophyll a concentration 20 times higher after 4 weeks growth than cultures grown under the same conditions without added glucose. This and other evidence derived from comparative growth measurements strongly suggest that Coleochaete takes up (or loads) glucose. Experimental results also suggest that hexose uptake by charophytes (such as Coleochaete) that typically grow in low alkalinity waters might provide a supplementary source of organic carbon when dissolved carbon dioxide levels are low. This capability could have served as an evolutionary precursor to hexose import by plant embryos, as well as leptom and phloem loading in bryophytes and vascular plants.

Oxytetracycline production by Streptomyces rimosus: gas and temperature patterns in a solid-state column reactor

During oxytetracycline production by Streptomyces rimosus TM-55 on sweet potato residue in a solid-state column reactor, the moisture content increased by between 2 and 5% (w/w) during incubation, from an initial content of 70 to 73%, and pH initially increased from 6.0 to 7.3, followed by a gradual decrease to 6.2. Appropriate aeration enhanced oxytetracycline production, while mixing only once daily decreased it. The temperatures in the centre and upper layers of each reactor were higher than elsewhere in static non-aerated cultures. The maximum CO2 concentration ranged from 2.9 to 3.2% (v/v) and the minimum O2 concentration was 11.0 to 17.2% (v/v) in static cultures. Under optimal conditions, each gram of dry substrate produced the equivalent potency of 12 mg oxytetracycline.

Improvement of growth rate and cell productivity by aeration rate in cultures of the marine microalga Dunaliella tertiolecta

The effect of different aeration rates and CO 2 supply regimes on mass cultures of the marine microalga Dunaiella tertiolecta was studied. Eight aeration rates in the range 0–6.51 litres of air min −1 litre of culture −1 were tested. The results were compared to those obtained in non-aerated cultures into which pure CO 2 was introduced and to cultures into which air enriched with CO 2 was bubbled. The growth rate and final cellular density of D. tertiolecta in a sea-water-based medium increased with the aeration rate in the culture vessel. The maximal cellular density was 12.46×10 6 cells ml −1 under an air flow rate of 6.51 litres min −1 litre of culture −1, but evaporation and salinity increased sharply at this high aeration rate. The final cell density was proportional to the air flow rate and CO 2 following the range (figures being litres of air min −1 litre of culture −1): 6.51 = 3.72>1.86> CO 2 = (0.93+ CO 2)>0.93>0.46>0.23>0.11>0 (Mann-Whitney test p<0.05). When D. tertiolecta was grown under a CO 2 supply within the optimal pH levels but without aeration, the cultures reached a cell density of 7×10 6 cells ml −1. D. tertiolecta growth rate was inversely proportional to pH, the upper boundary for maximal growth rate being pH 9.2. Oxygen in the culture media produced by the photosynthetic activity of the microalgae did not inhibit growth. The dissolved CO 2 concentration in sea-water was the limiting factor for D. tertiolecta growth. At a pH value of 8.3, D. tertiolecta was not able to take up carbon in the form of carbonates dissolved in sea-water.

Fatty acid production by heterotrophic Chlorella saccharophila

The fatty acid composition of the alga Chlorella saccharophila was investigated under different growth conditions. Using glucose as the sole carbon source, heterotrophically-grown Chlorella saccharophila produced a greater proportion of the polyunsaturated fatty acids (C18: 2 and C18: 3) than photosynthetic cultures, with linoleic acid (C18: 2) predominating. An unexpected discovery was the observation that at the lowest glucose concentration (2.5 gl−1) the lipid content of the algae increased to between 36–47% of the cell weight, depending on the temperature. At glucose concentrations of 5 g l−1 or more, the lipid content fell to 10–12% of the cell, although total fatty acid yield was higher due to higher biomass concentrations. Aeration of heterotrophic cultures promoted the production of unsaturated fatty acids compared to non-aerated cultures.

Toxin production by Bacillus cereus dairy isolates in milk at low temperatures

A total of 136 strains of Bacillus cereus isolated from milk and cream were evaluated for toxin production based on HeLa S3, Vero, and human embryonic lung (HEL) cell cytotoxicity in vitro. HEL cell monolayers were more susceptible than the other two cell lines. The percentage of isolates exhibiting HEL cytotoxicity was similar (43.0 and 48.4%) when the strains were grown in brain heart infusion broth containing 0.1% glucose (BHIG) at 7 and 24 h, respectively, at 30 degrees C. In milk, only 21.8% of isolates showed HEL cytotoxicity at 7 h, and the number increased significantly to 73.2% at 24 h at 30 degrees C. Further, 102 toxin-positive isolates were acclimatized to grow at 8 degrees C in milk. Ninety-four (92.2%) of the strains produced HEL cytotoxicity of various degrees with no strict correlation to bacterial cell numbers and also elicited vascular permeability reaction in rabbit skin. Under aerated growth conditions (agitation, 200 rpm) B. cereus elicited cytotoxicity in BHIG and in milk at temperatures of 30, 15, and 8 degrees C. However, in nonaerated (stagnant) cultures toxin production was diminished (BHIG) or completely lost (milk) at all temperatures. Toxin production at 8 degrees C was evaluated in two different types of commercial cardboard milk packages by inoculation with a potent toxigenic dairy isolate. No detectable HEL cytotoxicity was observed in milk in any of the packages either at stagnant conditions or during mechanical shaking. However, the same strain produced cytotoxin in whipped cream at 8 degrees C.

Gene expression in E. coli after treatment with streptozotocin

Gene induction by the methylating agents streptozotocin (STZ), N-nitrosourea (MNU), and N-methyl- N′-nitro- N-nitrosoguanidine (MNNG) was evaluated in E. coli fusion mutants. These mutants have fusions of the lac operon to genes induced by treatment with sublethal levels of alkylating agents and were previously selected from random insertions of the Mu-dl (Ap r lac) phage by screening for induction of β-galactosidase activity in the presence of methyl methanesulfonate or MNNG. The results demonstrate that STZ differs from MNNG and MNU in failing to induce aidC expression of aidC after exposure to MNU and MNNG occurs only in nonaerated cultures; aeration blocks the induction. Induction of aidD, alkA, aidB, and sfiA expressions occurs with all 3 agents although at markedly lower concentrations of MNNG and STZ compared to MNU. alkA and to a lesser extent aidD mutants of E. coli strains were more sensitive to these agents, while no differences were evident between wild-type and aidB or aidC fusion mutants.

Environmental Factors Determining Structural Transition in Herpetomonas samuelpessoai

Transition from promastigote to paramastigote and opisthomastigote forms of Herpetomonas samuelpessoai in culture is dependent on environmental factors, among which paramount importance is attributed to the oxygen tension, which seems to play a decisive role in determining the choice between the aerobic and the anaerobic modes of respiration. A decrease of the oxygen tension and consequently of the pH, provokes the occurrence of structural transition, particularly in nonaerated cultures. In airgassed media, the changes in PO2 and pH occur at comparatively later stages of the culture and the cell volume does not change appreciably. A direct relationship has been found between the modal cell volume and the extent of structural transition as evaluated by the cell concentrations of the different forms in culture.

Aeration sensitizes Streptococcus faecalis to hydroxyurea.

Hydroxyurea in up to 60 mM concentration did not inhibit growth or DNA synthesis in nonaerated cultures of Streptococcus faecalis ATCC 8043. In contrast, in cultures aerated by shaking already 1 mM hydroxyurea decreased the rate of net DNA synthesis and in higher concentrations of the drug the growth of the total cell mass also slowed down and the number of cells per chain increased from 1-2 to 10. The differential rate of DNA synthesis, but not the growth of the total cell mass, could be restored almost to the control level by adding thymidine to the medium. Thus there are at least two targets for hydroxyurea in the cells of S. faecalis grown in aerated cultures.

Non-aerated cultivation ofHalobacterium cutirubrum and its effect on cellular squalenes

Halobacterium cutirubrum was successfully cultivated under aerobic and microaerobic conditions. The early stationary phase of growth was obtained at 2.2 days and 45--55 days for aerated and non-aerated cultures, respectively. The dry cell yields were 0.7--1.2 gm/1 in all preparations grown to early stationary growth phase. The cellular ratio of squalene to dihydro- and tetra-hydrosqualene decreased proportionately with decreased aeration rates.