Growth and Geotropic Responses of Avena Coleoptiles to 4-Amino-3,5,6-Trichloropicolinic Acid

The elongation and geotropic responses of coleoptile sections of Avena sativa L. to various concentrations of 4-amino-3,5,6-trichloropicolinic acid (Tordon) proved to be qualitatively similar to those previously reported for 2,3,6-trichlorobenzoic acid (TCBA). Tordon stimulated growth in a range of concentrations from 1 × 10^?6 to 1 × 10^?4M but higher concentrations were inhibitory. Geotropic curvature was extensively depressed by 1 × 10^?5 and 1 × 10^?4M Tordon, concentrations which accelerated elongation. A similar differential effect has been reported for TCBA and other auxins. Several other picolinic acids and related compounds were tested, but only very slight responses were noted.     

Biocatalytic reduction of short‐chain carboxylic acids into their corresponding alcohols with syngas fermentation

Short‐chain carboxylic acids generated by various mixed‐ or pure‐culture fermentation processes have been considered valuable precursors for production of bioalcohols. While conversion of carboxylic acids into alcohols is routinely performed with catalytic hydrogenation or with strong chemical reducing agents, here, a biological conversion route was explored. The potential of carboxydotrophic bacteria, such as Clostridium ljungdahlii and Clostridium ragsdalei, as biocatalysts for conversion of short‐chain carboxylic acids into alcohols, using syngas as a source of electrons and energy is demonstrated. Acetic acid, propionic acid, n‐butyric acid, isobutyric acid, n‐valeric acid, and n‐caproic acid were converted into their corresponding alcohols. Furthermore, biomass yields and fermentation stoichiometry from the experimental data were modeled to determine how much metabolic energy C. ljungdahlii generated during syngas fermentation. An ATP yield of 0.4–0.5 mol of ATP per mol CO consumed was calculated in the presence of hydrogen. The ratio of protons pumped across the cell membrane versus electrons transferred from ferredoxin to NAD⁺ via the Rnf complex is suggested to be 1.0. Based on these results, we provide suggestions how n‐butyric acid to n‐butanol conversion via syngas fermentation can be further improved. Biotechnol. Bioeng. 2013; 110: 1066–1077. © 2012 Wiley Periodicals, Inc.     

Activity of Various Growth Substances in the Avena First Internode Test

The elongation growth of the Avena first internode segments was studied in the presence of one or several of the following growth substances: indoleacetic acid (IAA), 6-fur-furylamino purine (FAP, kinetin), 6-benzylamino purine (BAP), gibberellin A₃ (GA₃) and A₄₊₇ (GA₄₊₇), and abscisic acid (ABA). The cytokinins at concentrations of 10^?7 to 10^?6M stimulated growth with 4 to 6 per cent but this effect was not statistically significant. Concentrations higher than 5 × 10^?6M inhibited growth. FAP and BAP (from 10^?8M to 10^?6M) had no significant interaction with any other growth substance used. The two-factor interactions of IAA × ABA, IAA × GA₃, and GA₃× ABA, as well as the three-factor interaction IAA × ABA × GA₃ were significant. However, the IAA × ABA interaction was significant only when high concentration (10^?6M) of ABA was used. The growth inhibition produced by 10^?7 and 10^?6M ABA was overcome by about equimolar concentrations of IAA. The stimulation of growth by GA₃ and GA₄₊₇ (10^?9 to 10^?7M) was prevented by simultaneous application of ABA, and it was reduced significantly by application of IAA (10^?7 to 10^?8M). GA3 at 10^?8M combined with different concentrations of IAA gave slightly higher elongation than IAA alone but the observed values were significantly lower than expected assuming independent additive action.     

Uptake and respiration of organic compounds and heterotrophic growth in Pediastrum duplex (Meyen)*

SUMMARY. Axenic cultures of Pediastrum duplex, a green alga prominent in Lake Kinneret, Israel, assimilated and respired amino acids, acetate, glucose, glycollate and glycerol under conditions of light or darkness. Increased rates of uptake and respiration were observed in nutrient (P and N) depleted medium. Although ineffective in moderate light (30–100 μ Einstein m^?2 s^?1) glycerol, glucose and leucine, but not glycollate, stimulated growth and yields under faint light (～ 2 μ Einstein m^?2 s^?1). In the dark, glycerol (and sometimes leucine) permitted growth. Kinetic studies with leucine indicated an active uptake mechanism effective at substrate concentrations from 0.5 to 47 μg 1^?1.     

An oxidoreduction potential shift control strategy for high purity propionic acid production by Propionibacterium freudenreichii CCTCC M207015 with glycerol as sole carbon source

The effects of oxidoreduction potential (ORP) regulation on the process of propionic acid production by Propionibacterium freudenreichii CCTCC M207015 have been investigated. Potassium ferricyanide and sodium borohydride were determined as ORP control agents through serum bottle experiment. In batch fermentation, cell growth, propionic acid and by-products distribution were changed with ORP levels in the range of 0–160 mV. Based on these analysis results, an ORP-shift control strategy was proposed: at first 156 h, ORP was controlled at 120 mV to obtain higher cell growth rate and propionic acid formation rate, and then it was shifted to 80 mV after 156 h to maintain the higher propionic acid formation rate. By applying this strategy, the optimal parameters were obtained as follows: the propionic acid concentration 45.99 g L^?1, productivity 0.192 g L^?1 h^?1, the proportion of propionic acid to total organic acids 92.26 % (w/w) and glycerol conversion efficiency 76.65 %. The mechanism of ORP regulation was discussed by the ratio of NADH/NAD⁺, ATP levels, and metabolic flux analysis. The results suggest that it is possible to redistribute energy and metabolic fluxes by the ORP-shift control strategy, and the strategy could provide a simple and efficient tool to realize high purity propionic acid production with glycerol as carbon source.     

INFLUENCE OF IRRADIANCE ON THE FATTY ACID COMPOSITION OF PHYTOPLANKTON1

Eight species of marine phytoplankton commonly used in aquaculture were grown under a range of photon flux densities (PEDs) and analyzed for their fatty acid (FA) composition. Fatty and composition changed considerably at different PFDs although no consistent correlation between the relative proportion of a single FA and μ or chl a · cell^?1 was apparent. Within an individual species the percentage of certain fatty acids covaried with PFDs, growth rate and/or chl a · cell^?1. The light conditions which produced the greatest proportion of the essential fatty acids was species specific. Eicosapentaenoic acid. 20:5ω3 increased from 6.1% to 15.5% of the total fatty acids of Chaetoceros simplex Ostenfield grown at PFDs which decreased from 225 μE · m^?2· s^?1 to 6 μE · m^?2· s^?1, respectively. Most species had their greatest proportion of 20: 5ω3 at low levels of irradiance. Conversely, docosahexaenoic acid, 22:6ω3, decreased from 9.7% to 3.6% of the total fatty acids in Pavlova lutheri Droop as PFD decreased. The percentage of 22:6ω3 generally decreased with decreasing irradiances. In all diatoms the percentage of 16:0 was significantly correlated with PFD, and in three of five diatoms, with growth rate (μ). Results suggest that fatty acid composition is a highly dynamic component of cellular physiology, which responds significantly to variation in PFD.     

Negative chemotaxis inSpirochaeta aurantia

A repellent-gradient tube assay for negative chemotaxis inSpirochaeta aurantia was developed and used to demonstrate that acids, alcohols, and sulfide were effective chemorepellents. The threshold concentrations (the lowest concentration of a repellent that elicited a detectable response) for benzoic acid, salicylic acid, and butyric acid were 3×10^–5 M. For acetic acid, propionic acid,p-aminobenzoic acid, propanol, butanol, and sulfide, threshold concentrations were 10^–3 to 10^–4 M. For formic acid, glyoxylic acid, glycolic acid, lactic acid, malonic acid, succinic acid, fumaric acid, methanol, ethanol, ethanediol, and propanediol, threshold concentrations were 10^–2 to 10^–3 M. Compounds such as methylamine, ethanolamine, formaldehyde, benzene, toluene, phenol, indol, nickel, and various amino acids did not elicit a repellent response. The results of competition experiments suggest that the repellents identified are recognized by three distinct receptors: a weak acid receptor, an alcohol receptor, and a sulfide receptor. The repellent responses to weak acids were maximal at pH 5.5 and decreased with increasing pH, whereas the response to propanol was unaffected by pH over a range of 5.5–8.0. The demonstration of negative chemotaxis inS. aurantia and the identification of distinct classes of repellents will allow further experimentation directed at understanding chemosensory mechanisms in spirochetes.     

Formation of ethanol and higher alcohols by immobilized zymomonas mobilis in continuous culture

Cells of Zymomonas mobilis ATCC 10988 were immobilized in 1.5% calcium alginate and packed in a column bioreactor for a series of fermentations utilizing 10.0% glucose media with the addition of one of the following amino acids or keto acids: L-leucine, L-isoleucine, L-valine, α-ketoisocaproic acid, α-ketobutyric acid, or α-ketoisovaleric acid. This was done in order to study the rates of production of higher alcohols during ethanolic fermentations at varying dilution rates while under the influence of amino acids or keto acids. Results indicate that the EHRLICH mechanism is operative in Zymomonas sp. α-Ketobutyrate enhanced the production of n-propanol and act-amyl alcohol. α-Ketoisocaproic acid stimulated the production of isoamyl alcohol. α-Ketoisovaleric acid increased the levels of isobutanol. The amino acids also gave rise to their corresponding alcohols but to a far lesser degree than did the keto acids. During high glucose utilization, ethanol yields ranged from 87% to 94% of theoretical with productivity ranging from 60.08 g/l/h in one fermentation (at a dilution rate of 1.35 h^?1) to 70.42 g/l/h in another (at a dilution rate of 1.58 h^?1). At dilution rates of 1.58 h^?1, higher alcohol productivity rose to as high as 4,313 mg/l/h in the presence of α-ketoisocaproic acid, 1,734.49 mg/l/h using α-ketoisovaleric acid, and 1,618.05 mg/l/h in α-ketobutyric acid. The concomitant production of ethanol and higher alcohols in all of the fermentations indicates that glucose is required for the production of the higher alcohols from their corresponding amino acids or keto acids.     

Isolation and Identification of n-Butane-assimilating Bacterium

A bacterial strain capable of assimilating gaseous n-alkanes was newly isolated from activated sludge by enrichment culture technique using n-butane as the sole carbon source. The strain was identified as Pseudomonas butanovora sp. nov. It utilised n-alkanes of C₂~C₉, primary alcohols and carboxylic acids for growth, but did not utilize sugars and C₁ compounds. The cell yields on gaseous n-alkanes, such as ethane, propane and n-butane, were 80% or more. The maximum specific growth rate on n-butane was 0.22 hr^?1 at 30°C, pH 7.0. Dried cells of this new isolate grown on n-butane contained 73% pure protein.     

In vivo evidence for the involvement of phospholipase A and protein kinase in the signal transduction pathway for auxin-induced corn coleoptile elongation

Auxin-induced elongation of com coleoptiles is accompanied by cell wall acidification, which depends upon H⁺-pump activity. We tested the hypothesis that phospholipase A and a protein kinase are involved in the pathway of auxin signal transduction leading to H⁺ secretion, and elongation of corn coleoptiles. Initially, the pH of the bath solution at 50–100 μm from the surface of a coleoptile segment (pH_o) ranged between 4.8 and 6.6 when measured with an H⁺-sensitive microelectrode. Twenty or 50 μM lysophosphatidylcholine, 50 μM linolenic acid or 50 μM arachidonic acid induced a decline in pH_o by 0.3 to 2.1 units. The effect was blocked by 1 mM vanadate, suggesting that lysophosphatidylcholine or linolenic acid induced acidification of the apoplast by activating the H⁺-pump. Lysophosphatidylcholine and linolenic acid also accelerated the elongation rate of the coleoptiles. While linolenic acid and arachidonic acid, highly unsaturated fatty acids, promoted pH_o decrease and coleoptile elongation, linoleic acid, oleic acid, and stearic acid, fatty acids with a lesser extent of unsaturation, had no such effects. The effects of lysophosphatidylcholine, linolenic acid, and arachidonic acid on H⁺ secretion were not additive to that of indoleacetic acid (IAA), suggesting that lysophospholipids, fatty acids and auxin use similar pathways for the activation of the H⁺-pump. The phospholipase A₂ inhibitors, aristolochic acid and manoalide, inhibited the IAA-induced pH_o decrease and coleoptile elongation. The general protein kinase inhibitors, H-7 or staurosporine, blocked the IAA- or lysophosphatidylcholine-induced decrease in pH_o. H-7 also inhibited the coleoptile elongation induced by IAA or lysophosphatidylcholine. These results support the hypothesis that phospholipase A is activated by auxin, and that the products of the enzyme, lysophospholipids and fatty acids, induce acidification of the apoplast by activating the H⁺-pump through a mechanism involving a protein kinase, which in turn promotes com coleoptile elongation.     

Accumulation of l-Glutamic Acid from Dibasic Carboxylic Acids by a Hydrocarbon Utilizing Bacterium

In order to know the substrate specificity in a hydrocarbon utilizing bacterium, the following materials were examined: n-alkanes, n-alkenes, monohydric alcohols, aldehydes, monobasic carboxylic acids, dihydric alcohols and dibasic carboxylic acids.

It was found that dibasic carboxylic acids were well utilized, and a great deal of l-glutamic acid was accumulated from them. Then suberic acid, which is C₈ dibasic carboxylic acid, was compared with n-dodecane in the effects of thiamine, penicillin, C/N ratio and substrate concentration on l-glutamic acid accumulation and cell growth.     

Production of propionic acid by microbiological way. Part 2. Effect of the pH value on cell growth and acid production

The batch propionic acid fermentation of sugar cane molasses by Propionibacterium acidi propionici PP-1 was studied at various pH values ranging from 5 to 7. The optimum pH range for cell growth was between 6 and 7, whereas the specific growth rate decreased with the pH in the acidic range down to 0.197 h^?1 at pH 5. The propionic acid yield increased with decreasing pH; it changed from 22% (wt/wt) at pH 7 to 38% at pH 5. It has been obvious that this process is inhibited by the products of the fermentation and more severely in the acidic range where the acids are in an unionized state. A generalized equation of the non-competetive inhibition was adjusted for each pH value, and kinetic inhibition constants were estimated.     

The utilization of short-chain monocarboxylic acids as carbon sources for the production of gamma-linolenic acid by Mucor strains in fed-batch culture

The Fischer-Tropsch reaction water, which contains C₂ to C₅ monocarboxylic acids, generated as a co-product of the Sasol industrial oil-from-coal process, constitutes a potential cheap carbon substrate for the production of gamma-linolenic acid (GLA) by selced Mucor species. Three strains of Mucor were each grown in an air-lift reactor operated in a fed-batch, pH-stat mode under N-limitation with a mixture of C₂ to C₅ monocarboxylic acids as both pH titrant and carbon source. The production of GLA from this substrate was evaluated. Growth typically resulted in the rapid assimilation of acetic, n-butyric and n-valeric acids. Although propionic, iso-butyric and iso-valeric acids were assimilated to varying degrees, these acids accumulated in the culture. Mucor circinelloides CBS 203.28 gave the best results in that it assimilated 36% to 100% of each acid, had a biomass yield coefficient of 0.3 (calculated on acids utilized), and contained 28% crude oil, 84% of which comprised neutral lipids with a GLA content of 14.4%, giving 33 mg GLA/g biomass. GLA accumulation coincided with a decrease in the stearic-acid content of the neutral-lipid fraction. The results were comparable with previous results obtained with acetic acid and glucose as sole carbon sources, demonstrating the feasibility of producing GLA from the above mixture of organic acids.     

Root Growth Activity of Barban in Relation to Auxin and Other Growth Factors

The effect of barban (4-Cl-2-butynyl-N-3-Cl-phenylcarbamate) on the growth of roots of wheat seedlings has been studied. In concentrations of 10^?7 to 5 · 10^?7M barban causes rapid inhibitions of cytokineses and cell elongation, the effects of which are spontaneously reversible. The reversion of the meristem inhibition is enhanced by thymidylic acid and indole-3-acetic acid (IAA). Initiation of cell elongation is slowed down or ceases during cytostasis; its reversal, on the other hand, is promoted by IAA and kinetin but inhibited by Fe. The final cell elongation attained is strongly reduced by barban and reversed under transient aberrant elongation. This inhibition and the recovery appear both to be additive to cell elongation actions of auxin and antiauxin but reversed by nucleic acid components. The inhibition of elongation is increased by Fe. The following explanation for this phenomenon is suggested: the primary effect of barban is known to be the blocking of metaphases under anaesthesis; this blocking then leads to reduced activation of IAA, kinetin and other metabolites. Auxin is required for cell divisions and initiation of elongation: the apical root growth equals in this respect that of shoot apices and lateral meristems. Initiation of cell elongation is closely dependent upon metabolites produced in dividing meristematic cells, whereas the limitation of cell stretching is independent of the meristem activity. No explanation is offered for the role of Fe.     

Negative Phototaxis in Blepharisma japonicum

The protozoan Blepharisma japonicum showed negative phototaxis caused by transient reversal of the direction of ciliary beat and changes of swimming velocity induced with varying intensities of light. The ciliary reversal occurred at 1–2 sec after a sudden increase in light intensity. When light intensity was decreased, no response was observed. Moreover, the ciliates swam fast in light areas but slowly in dark areas; the mean velocity of swimming was 80 μ m/sec at 5 × 10² lux but reached about 400 μMm/sec at 5 × 10³ lux. In addition, the cell body elongated in response to light application; the mean length of the body was 308 μm at 5 × 10² lux, which increased to 397 μ m at 10⁴ lux. Such body elongation seems to contribute to rapid swimming. Negative phototaxis may be an important behavior in B. japonicum because the organisms are killed by exposure to strong light.     

Promoting Effect of Fusicoccin on Seed Germination

The effects of fusicoccin on the germination of dormant, light-requiring or abscisic acid-inhibited seeds has been investigated. (1) Fusicoccin (10^?6M) induces germination in dormant wheat seeds (Triticum durum cv. Cappelli; 1972 crop) and stimulates it in seeds already relieved from dormancy (1971 crop), with an effect similar to that of gibberellic acid. (2) Fusicoccin (1.5 × 10^?6M) is more active than the two phytohormones gibberellic acid and benzyladenine and than white light in stimulating light-requiring lettuce seeds (Lactuca sativa cv. Grand Rapids) to germinate. Germination of radish seeds (Raphanus sativus) is also accelerated by fusicoccin, while benzyladenine and gibberellic acid are less active in this material. (3) Fusicoccin (1.5 × 10^?5M) removes almost completely the inhibitory effect of abscisic acid on germination of radish and lettuce seeds, whereas benzyladenine (10^?4M) and gibberellic acid (3 × 10^?4M) remove the inhibition only partially. The possible relationship between these results and previous information on growth by cell enlargement is discussed in terms of the mechanism of action of fusicoccin as compared with natural hormones.     

Synthesis of alkyl esters by cutinase in miniemulsion and organic solvent media

The main objective of this work was studying and testing the nature and influence of reaction media (organic solvent vs. miniemulsion system) on the synthesis of alkyl esters catalyzed by Fusarium solani pisi cutinase. Ester synthesis and cutinase selectivity for different chain length of acids and alcohols (ethyl and hexyl) were evaluated. In iso-octane, after 1 h of reaction, cutinase exhibits rates of esterification between 0.24 μmol x mg^–1 x min^–1 for ethyl oleate and 1.15 μmol x mg^–1 x min^–1 for ethyl butyrate, while in a miniemulsion system the rates were from 0.05 for ethyl heptanoate to 0.76 μmol x mg^–1 x min^–1 for ethyl decanoate. The reaction rate for the synthesis of hexyl esters in a miniemulsion system was from 0.19 for hexyl heptanoate to 1.07 μmol x mg^–1 x min^–1 for hexyl decanoate. High conversion yields of 95% at equilibrium after 8 h of reaction in iso-octane for pentanoic acid (C₅) with ethanol at equimolar concentration (0.1 M) was achieved. Additionally, this work showed that a significant and unexpected shift in cutinase selectivity occurred towards longer chain length carboxylic acids (C₈–C₁₀) in miniemulsion system as compared to organic solvent (iso-octane) and previous studies in reverse micellar systems. The possibility of working with higher concentration of substrates, without inhibitory effect on the enzyme, was another advantage of the miniemulsion system.     

Iso-alkane oxidation by aPseudomonas Part I.—Metabolism of 2-methylhexane

Summary Pseudomonas cells adapted to 2-methylhexane oxidize 5-methylhexanoic andiso-valeric acids rapidly. The oxidation rates of 2-methylhexanoic and propionic acids are appreciably lower. It can be concluded that primary attack on the C₆ atom is distinctly favoured over that on C₁. By use of gas-liquid chromatography, 2-methylhexanoic, 5-methylhexanoic andiso-valeric acids were shown to be formed when heptane-grown cells were incubated with 2-methylhexane. When 2-methylhexane-grown cells were used the amount of 5-methylhexanoic acid decreased compared with the amount of the 2-methyl isomer. Moreover,iso-valeric acid could not be detected. The results make it probable that degradation of 2-methylhexanevia C₆, comprising 5-methylhexanoic andiso-valeric acid, is accompanied by a second pathway via 2-methylhexanoic acid. The latter pathway is of minor importance, in particular in 2-methylhexane-adaptedPseudomonas cells.     

Non-Reversibility of Gibberellin-Induced Inhibition of Regeneration in Begonia Leaves

With applied to the petioles of detached Begonia x cheimantha leaves before planting, Gibberellic acid (GA₃) inhibited the formation of adventitious buds and roots ill an apparently irreversible manner. Bud formation was entirely suppressed by 10^?6M and higher concentrations and a significant inhibition was still present at 10^?9M the lowest concentration tested. Root formation was not affected by GA₃ below 10^?7M and was possible even at 10^?4 M GA₃. Petiole elongation was stimulated by GA₃ with an optimum at 10^?5M. GA₃ also blocked the action of 6-benzyiamino-purine (BAP) and 1-naphthaleneacetic acid (NAA), compounds which are potent stimulators of bud and root formation, respectively. When applied simultaneously with GA₃ they were, at their optimal concentrations, devoid of any effect in counteracting or reversing the gibberellin-induced inhibitions. Abscisic acid and the growth retardants CCC and Phosfon also were unable to restore bud and root formation. In leaves initially treated with water or 10^?5M BAP, endogenous bud and root formation as well as BAP-induced bud formation were entirety suppressed when 10^?5M GA₃ was applied 8 days after the initial treatments. Even when delayed for 14 days GA₃ treatment inhibited BAP-induced bud formation, while treatment after 21 days bad little effect on bud and root formation. Development of pre-existing, visible bud primordia was not inhibited by GA₃. BAP and NAA competitively inhibited the action of GA₃ in petiole extension growth. The results are discussed in relation to results obtained in other plant systems. It is suggested that GA₃ acts by blocking of the organized cell divisions initiating the formation of bud and root primordia.     

Catalysis by polymer complexes. I. Enhanced esterolytic reactivity of hydroxamate–polymer complexes

N-methylmyristohydroxamic acid (1) bound to polymer micelles of laurylated poly(2- and 4-vinylpyridines) (lauryl group contet: 2VP-L, 30 mol%; 4VP-L, 33 mol%) quantitatively reacted with p-nitrophenyl acetate (NpAc) within a few seconds at 30°C, pH 8.95. Second order rate constants k_a were 34,000 M^?1 sec^?1 for 1–2VP-L and 11,400 M^?1 sec^?1 for 1–4VP-L at μ = 0.5, and they were pronouncedly improved by a decrease in ionic strength (k_a = 27,500–80,200 M^?1 sec^?1 at μ = 0.08). In contrast, poly(N-ethyl-4-vinylpyridinium bromide) hardly affected the nucleophilicity of the hydroxamate ion. Therefore, the enhancement was considered to be associated with some micellar characteristics. Typical saturation phenomena of the reaction rate were observed for p-nitrophenyl hexanoate (NpOCOPe) and 3-nitro-4-acetoxybenzoic acid (NpAcCOOH). It was suggested that binding of NpOCOPe is caused by the hydrophobic interaction, while that of NpAcCOOH is probably induced by the electrostatic interaction. It is demonstrated that the cationic polymer micelle enormously activates the bound hydroxamate anion, and these complexes would be of much interest as a biomimetic system for enzyme catalysis.