Inter-population variability of leaf morpho-anatomical and terpenoid patterns of Pistacia atlantica Desf. ssp. atlantica growing along an aridity gradient in Algeria

Three Algerian populations of female Pistacia atlantica shrubs were investigated in order to check whether their terpenoid contents and morpho-anatomical parameters may characterize the infraspecific variability. The populations were sampled along a gradient of increasing aridity from the Atlas mountains into the northwestern Central Sahara.As evidenced by Scanning Electron Microscopy, tufted hairs could be found only on seedling leaves from the low aridity site as a population-specific trait preserved also in culture. Under common garden cultivation seedlings of the high aridity site showed a three times higher density of glandular trichomes compared to the low aridity site. Increased aridity resulted also in reduction of leaf sizes while their thickness increased. Palisade parenchyma thickness also increases with aridity, being the best variable that discriminates the three populations of P. atlantica.Analysis of terpenoids from the leaves carried out by GC-MS reveals the presence of 65 compounds. The major compounds identified were spathulenol (23 μg g⁻¹ dw), α-pinene (10 μg g⁻¹ dw), verbenone (7 μg g⁻¹ dw) and β-pinene (6 μg g⁻¹ dw) in leaves from the low aridity site; spathulenol (73 μg g⁻¹ dw), α-pinene (25 μg g⁻¹ dw), β-pinene (18 μg g⁻¹ dw) and γ-amorphene (16 μg g⁻¹ dw) in those from medium aridity and spathulenol (114 μg g⁻¹ dw), α-pinene (49 μg g⁻¹ dw), germacrene D (29 μg g⁻¹ dw) and camphene (23 μg g⁻¹ dw) in leaves from the high aridity site. Terpene concentrations increased with the degree of aridity: the highest mean concentration of monoterpenes (136 μg g⁻¹ dw), sesquiterpenes (290 μg g⁻¹ dw) and total terpenes (427 μg g⁻¹ dw) were observed in the highest arid site and are, respectively, 3-, 5- and 4-fold higher compared to the lower arid site. Spathulenol and α-pinene can be taken as chemical markers of aridity. Drought discriminating compounds in low, but detectable concentrations are δ-cadinene and β-copaene. The functional roles of the terpenoids found in P. atlantica leaves and principles of their biosynthesis are discussed with emphasis on the mechanisms of plant resistance to drought conditions.     

Composition of epicuticular wax layer of two species of Mandevilla (Apocynoideae,Apocynaceae) from Rio de Janeiro,Brazil

The chemical composition of epicuticular waxes of Mandevilla guanabarica and Mandevilla moricandiana was comparatively analyzed by extraction in n-hexane and chloroform. The mean wax content per unit of leaf area in the n-hexane extract was about 13–30 μg cm⁻² for M. guanabarica, containing 20–28% n-alkanes and 55–63% triterpenes; for M. mori-candiana, the mean content was 19 μg cm⁻², containing 73% n-alkanes and 14% triterpenes. In the chloroform extract, the wax yield was 40–80 μg cm⁻² for M. guanabarica, with about 9–11% n-alkanes and 75–82% triterpenes; while for M. moricandiana, the wax yield was 110 μg cm⁻², with 52% n-alkanes and 14% triterpenes. The major compounds identified were lupeol, pentacyclic triterpenes of the α- and β-amyrin class, and n-alkanes such as nonacosane, hentriacontane and tritriacontane. These results indicate that the quantitative chemical profiles of epicuticular waxes of M. guanabarica and M. moricandiana are distinct and could be used as an additional feature in taxonomic identification.     

Salinity increases the triterpenoid content of a salt secretor and a non-salt secretor mangrove

The present study describes the effect of salinity on the triterpenoid content of the salt secretor mangrove Avicennia marina and the non-secretor Rhizophora stylosa. Mangrove seedlings were grown for eight months in 0%, 0.5%, 1.5%, 2.0% and 3.0% salt concentration. The growth of both species was increased by salt with maximal stimulation at 1.5%, and this elevation appeared to be attenuated by increasing the salt concentration above 1.5%. The triterpenoid compositions of three types of chemical structures, lupane (lupeol, lupenone), oleanane (β-amyrin, taraxerol, germanicol), and ursane (α-amyrin), were studied. In addition, the phytosterol components campesterol, stigmasterol and β-sitosterol were analyzed. The total triterpenoid contents in the roots and leaves of A. marina for the 0% group were 87.0 and 66.2 μg g⁻¹, respectively, and increased significantly to 173.1 and 142.6 μg g⁻¹ with 3% salinity. The higher salinity also significantly increased the total concentration of phytosterols in the leaves and roots of this species. A similar increase in the concentration of both triterpenoids and phytosterols was observed in the roots and leaves of R. stylosa with increasing salt concentration. Thus, the triterpenoid concentration was increased by salinity in the roots and leaves of both A. marina and R. stylosa irrespective of their differences in salt management by salt excretion or by a non-excretion mechanism. Comparison of the triterpenoid concentration in four species of growing mangrove seedlings revealed a correlation between the total triterpenoid content and the salt tolerance based on the habitat zonation on Iriomote Island. A. marina thrives closest to sea and had the highest content of triterpenoids (173.1 μg g⁻¹ in 3% salt group). Therefore, it is likely that the triterpenoid content play an important role in mangrove plants for protection from salinity in both salt-secretors and non-secretors.     

Atmospheric phenanthrene transfer and effects on two grassland species and their root symbionts: A microcosm study

The objective of this work was to determine the transfer of phenanthrene (PHE) from air to grassland plants and soil compartments and its effects on the plant growth and symbiotic root microorganisms (arbuscular mycorrhizal fungi and Rhizobium nodules). The experimental procedure exposed Trifolium pratense L. or Lolium perenne L. to atmospheric PHE pollution (150 μg m⁻³) over the course of one month. PHE was transferred from the air to the leaves and to the soil surfaces. In leaves, PHE was mostly absorbed in the inner leaf tissues, representing 92% and 73% of the total PHE amount quantified in leaves, respectively for clover and ryegrass. In soils, most of PHE contamination was recovered in the top layer (0-1 cm) and did not readily diffuse into the deep layer (1-10 cm). The highest PHE concentration recovered in deep roots (1.8 and 4.5 μg g⁻¹ dry weight (DW), respectively for clover and ryegrass) related to the lowest PHE concentration recovered in its associated soil suggested a PHE translocation from shoots to roots within the two plant species. The large PHE amount quantified in clover shoots (124 μg g⁻¹ DW) induced a significant diminution by 30% of the shoot biomass whereas root biomass remained stable. Efficient mycorrhizal symbiosis was maintained during exposure whereas the Rhizobium nodule symbiosis was altered in the surface of soil. By contrast, neither biomass accumulation nor symbiotic association was affected in ryegrass, probably due to a lower sensitivity of this species to PHE exposure. Perspectives of carbon allocation and nitrogen nutrition perturbations are suggested in clovers.     

Primary production,respiration and calcification of the temperate free-living coralline alga Lithothamnion corallioides

Calcification and primary production responses to irradiance in the temperate coralline alga Lithothamnion corallioides were measured in summer 2004 and winter 2005 in the Bay of Brest. Coralline algae were incubated in dark and clear bottles exposed to different irradiances. Net primary production reached 1.5 μmol C g⁻¹ dry wt h⁻¹ in August and was twice as high as in January–February. Dark respiration showed significant seasonal variations, being three-fold higher in summer. Maximum calcification varied from 0.6 μmol g⁻¹ dry wt h⁻¹ in summer 2004 to 0.4 μmol g⁻¹ dry wt h⁻¹ in winter 2005. According to P–E curves and the daily course of irradiance, estimated daily net production and calcification reached 131 μg C g⁻¹ dry wt and 970 μg CaCO₃ g⁻¹ dry wt in summer 2004, and 36 μg C g⁻¹ dry wt and 336 μg CaCO₃ g⁻¹ dry wt in winter 2005. The net primary production of natural L. corallioides populations in shallow waters was estimated at 10–600 g C m⁻² y⁻¹, depending on depth and algal biomass. The mean annual calcification of L. corallioides populations varied from 300 to 3000 g CaCO₃ m⁻². These results are similar to those reported for tropical coralline algae in terms of carbon and carbonate productivity. Therefore, L. corallioides can be considered as a key element of carbon and carbonate cycles in the shallow coastal waters where they live.     

Butyric acid fermentation in a fibrous bed bioreactor with immobilized Clostridium tyrobutyricum from cane molasses

Butyrate fermentation by immobilized Clostridium tyrobutyricum was successfully carried out in a fibrous bed bioreactor using cane molasses. Batch fermentations were conducted to investigate the influence of pH on the metabolism of the strain, and the results showed that the fermentation gave a highest butyrate production of 26.2 g l⁻¹ with yield of 0.47 g g⁻¹ and reactor productivity up to 4.13 g l⁻¹ h⁻¹ at pH 6.0. When repeated-batch fermentation was carried out, long-term operation with high butyrate yield, volumetric productivity was achieved. Several cane molasses pretreatment techniques were investigated, and it was found that sulfuric acid treatment gave better results regarding butyrate concentration (34.6 ± 0.8 g l⁻¹), yield (0.58 ± 0.01 g g⁻¹), and sugar utilization (90.8 ± 0.9%). Also, fed-batch fermentation from cane molasses pretreated with sulfuric acid was performed to further increase the concentration of butyrate up to 55.2 g l⁻¹.     

Influence of exogenous salicylic acid on flavonolignans and lipoxygenase activity in the hairy root cultures of Silybum marianum

Silymarin is one of the most potent antioxidant so far developed from plant sources used as hepatoprotectants. Influence of different concentrations (0, 1, 2, 4, 6 and 8 mg/50 ml culture) and exposure time (24, 48, 72, 96 and 120 h) of salicylic acid on lipoxygenase activity, linoleic acid content, growth and production of silymarin in hairy root cultures of S. marianum were investigated. Detection and identification of flavonolignans was carried out by high performance liquid chromatograph method. Salicylic acid enhanced silymarin production (1.89 mg g⁻¹ DW). The optimal feeding condition was the addition of salicylic acid (6 mg/50 ml culture) after 24 h in which the silymarin content was 2.42 times higher than the control (0.78 mg g⁻¹ DW). The content of silybin, isosilybin, silychristin, silydianin and taxifolin were 0.703, 0.017, 0.289, 0.02 and 0.863 mg g⁻¹ DW respectively in these samples, while in non-treated hairy roots were 0.027, 0.046, 0.23, 0.022 and 0.453 respectively. Lipoxygenase activity also affected by elicitation. lipoxygenase activity increased 24 h after treatment by ∼1.57- fold (0.21 Δ OD₂₃₄/mg protein min⁻¹). Upon elicitation with salicylic acid, linoleic acid content of hairy roots (38.26 mg g⁻¹ DW) were also elevated after 24 h, in which the linoleic acid content was 2.37 times higher than the control (16.1 mg g⁻¹ DW). It is feasible that elicitation with salicylic acid regulates the jasmonate pathway, which in turn mediates the elicitor-induced accumulation of silymarin.     

Development of chemically defined media supporting high cell density growth of Ketogulonicigenium vulgare and Bacillus megaterium

The immediate precursor of L-ascorbic acid, or vitamin C, is 2-keto-l-gulonic acid (2-KLG). This is commonly produced commercially by Ketogulonicigenium vulgare and Bacillus megaterium, using corn steep liquor powder (CSLP) as an organic nitrogen source. In this study, the effects of the individual CSLP components (amino acids, vitamins, and metal elements) on 2-KLG production were evaluated, with the aim of developing a complete, chemically defined medium for 2-KLG production. Forty components of CSLP were analyzed, and key components were correlated to biomass, 2-KLG productivity, and consumption rate of L-sorbose. Glycine had the greatest effect, followed by serine, biotin, proline, nicotinic acid, and threonine. The combination of 0.28 g L⁻¹ serine, 0.36 g L⁻¹glycine, 0.18 g L⁻¹ threonine, 0.28 g L⁻¹proline, 0.19 g L⁻¹nicotinic acid, and 0.62 mg L⁻¹biotin in a chemically defined medium produced the highest maximum biomass concentration (4.2 × 10⁹ cfu mL⁻¹), 2-KLG concentration (58 g L⁻¹), and yield (0.76 g g⁻¹) after culturing for 28 h.     

Ontogenetic variation in chemical and physical characteristics of adaxial apple leaf surfaces

The reaction of plants to environmental factors often varies with developmental stage. It was hypothesized, that also the cuticle, the outer surface layer of plants is modified during ontogenesis. Apple plantlets, cv. Golden Delicious, were grown under controlled conditions avoiding biotic and abiotic stress factors. The cuticular wax surface of adaxial apple leaves was analyzed for its chemical composition as well as for its micromorphology and hydrophobicity just after unfolding of leaves ending in the seventh leaf insertion. The outer surface of apple leaves was formed by a thin amorphous layer of epicuticular waxes. Epidermal cells of young leaves exhibited a distinctive curvature of the periclinal cell walls resulting in an undulated surface of the cuticle including pronounced lamellae, with the highest density at the centre of cells. As epidermal cells expanded during ontogenesis, the upper surface showed only minor surface sculpturing and a decrease in lamellae. With increasing leaf age the hydrophobicity of adaxial leaf side decreased significantly indicated by a decrease in contact angle. Extracted from plants, the amount of apolar cuticular wax per area unit ranged from only 0.9 microgcm(-2) for the oldest studied leaf to 1.5 microgcm(-2) for the youngest studied leaf. Differences in the total amount of cuticular waxes per leaf were not significant for older leaves. For young leaves, triterpenes (ursolic acid and oleanolic acid), esters and alcohols were the main wax components. During ontogenesis, the proportion of triterpenes in total mass of apolar waxes decreased from 32% (leaf 1) to 13% (leaf 7); absolute amounts decreased by more than 50%. The proportion of wax alcohols and esters, and alkanes to a lesser degree, increased with leaf age, whereas the proportion of acids decreased. The epicuticular wax layer also contained alpha-tocopherol described for the first time to be present also in the epicuticular wax. The modifications in the chemical composition of cuticular waxes are discussed in relation to the varying physical characteristics of the cuticle during ontogenesis of apple leaves.     

Sorgoleone,a sorghum root exudate: Algicidal activity and acute toxicity to the ricefish Oryzias latipes

The discovery of natural and natural-based compounds has resulted in its application as an alternative to synthetic algicides to control harmful algae in aquatic systems. Of the many natural-product-based algicides, sorgoleone, a natural plant product from Sorghum bicolor root exudates has been investigated for its controlling effect on different algal species and its acute fish toxicity. Growth of the blue green algal species Microcystis aeruginosa Kützing was completely inhibited by the crude methanol extract of sorghum root at 20 μg mL⁻¹. The most noticeable inhibition was observed in the bioassay of n-hexane soluble extract, where 98% growth inhibition occurred in M. aeruginosa at the concentration of 1.25 μg mL⁻¹. Sorgoleone very effectively controlled blue green algae inhibiting 97% of M. aeruginosa at 0.5 μg mL⁻¹ and 99% of Anabaena affinis Lemmermann at 4 μg mL⁻¹. In contrast, inhibition of the green algae species Chlorella vulgaris Beijerinck and Scenedensmus spp. at 16 μg mL⁻¹ sorgoleone was 87 and 68%, respectively. There were no mortalities or adverse effects observed in any of the fish exposed to water control, solvent control, and a nominal concentration of 1 μg mL⁻¹ during the test period. The no observed effect concentration (NOEC) value was 1.5 μg mL⁻¹ for the tested fish (O. latipes). Sorgoleone can be considered as an effective and an ecologically and environmentally sustainable approach to controlling harmful algae.     

Lactic acid production by Lactobacillus sp. RKY2 in a cell-recycle continuous fermentation using lignocellulosic hydrolyzates as inexpensive raw materials

Continuous lactic acid fermentations were conducted using lignocellulosic hydrolyzates and corn steep liquor as inexpensive raw materials. Lactic acid concentrations decreased with increases in the dilution rate, whereas the residual substrate concentrations increased. However, lactic acid yields were maintained at more than 0.90 g g⁻¹ over all cases experimented. The cell-recycle cultivation system exerted positive effects on fermentation efficiency, including volumetric productivity, which is attributable to the retention of cells in the bioreactor. The cell-recycle continuous fermentation of lignocellulosic hydrolyzates yielded a lactic acid productivity of 6.7 g l⁻¹ h⁻¹ for a dilution rate of 0.16 h⁻¹ using 30 g l⁻¹ of corn steep liquor and 1.5 g l⁻¹ of yeast extract as nutrients. The productivity (6.7 g l⁻¹ h⁻¹) acquired by the cell-recycle continuous fermentation of lignocellulosic hydrolyzates was 1.6 times higher than the lactic acid productivity yielded in the continuous fermentation without cell-recycle system.     

Effect of deltamethrin on the gills of Aphanius dispar: a microscopic study

Aphanius dispar, a freshwater fish (mean total length ± sd, 3.42 ± 0.33 cm) was exposed to different concentrations of deltamethrin (2.25, 2.50 and 3.00 μg L⁻¹), an insecticide used to control Dubas bug, Ommatissus lybicus in Oman. The histopathological changes in the structure of the gills in fish exposed to deltamethrin was studied using light, transmission and scanning electron microscopy. In light microscopy, the fish exposed to 2.25 μg L⁻¹ deltamethrin, showed hypertrophy and hyperplasia of chloride cells, while in 2.50 μg L⁻¹, additional changes like vacuolization, lifting of the lamellar epithelium and fusion of secondary lamellae were observed. The most severe alteration including vacuolization, desquamation of cells and dilation of intercellular space was recorded at 3.00 μg L⁻¹. Transmission and scanning electron microscopy, supports the findings of light microscopy and further document the ultrastructural damage caused, especially in exposure to 2.50 and 3.00 μg L⁻¹. Al l changes observed are described in detail. The deltamethrin exposure concentration of 2.25 μg L⁻¹ seems to be a threshold above which any small increase in concentration results in severe damage. All present results have been compared with those of previous studies on gill damage caused by various chemical substances. The impacts of the damage on the functioning of gills as a respiratory organ are discussed.     

Effects of Bacillus thuringiensis toxin Cry1Ac and cytoplasmic polyhedrosis virus of Helicoverpa armigera (Hübner) (HaCPV) on cotton bollworm (Lepidoptera: Noctuidae)

In this study, interactions on the mortality and debilitating effects between Cry1Ac, a toxic protein produced by Bacillus thuringiensis (Berliner) and HaCPV (Chinese strain) on first and third instars larvae of Helicoverpa armigera were evaluated in laboratory. When first instar was exposed to combination of Bt cotton leaf discs containing HaCPV (6 × 10⁶, 1 × 10⁷, and 3 × 10⁷ PIB ml⁻¹) the effect on mortality was additive, when such instar larvae exposed to combination of Cry1Ac (0.9, 2.7, or 8.1 μg g⁻¹) and the same concentrations of HaCPV the effect on mortality was additive except for the combination of Cry1Ac (0.3 μg g⁻¹) and HaCPV concentrations that showed synergism. When third instars of H. armigera were infected using a suspension containing both HaCPV and Cry1Ac, most combinations of them showed additive effect except for the combination of Cry1Ac (0.3 μg g⁻¹) and HaCPV (3 × 10⁷ PIB ml⁻¹) that showed synergism. However, when they exposed to Bt cotton leaf discs and HaCPV the effect on mortality was synergism except combination of Bt cotton leaf discs and HaCPV (6 × 10⁶ PIB ml⁻¹) that showed additive. Most of the combinations are showed additive effect in the toxicity and in combinations of Cry1Ac at lowest and HaCPV at highest concentrations synergism is observed. Not only were larval growth and development delayed, but pupation and pupal weight also decreased when larvae were fed on artificial diet containing Cry1Ac and HaCPV or transgenic Bt cotton leaf discs specially in first instar.     

In silico optimization and low structured kinetic model of poly[(R)-3-hydroxybutyrate] synthesis by Cupriavidus necator DSM 545 by fed-batch cultivation on glycerol

Glycerol was utilized by Cupriavidus necator DSM 545 for production of poly-3-hydroxybutyrate (PHB) in fed-batch fermentation. Maximal specific growth rates (0.12 and 0.3 h⁻¹) and maximal specific non-growth PHB production rate (0.16 g g⁻¹ h⁻¹) were determined from two experiments (inocula from exponential and stationary phase). Saturation constants for nitrogen (0.107 and 0.016 g L⁻¹), glycerol (0.05 g L⁻¹), non-growth related PHB synthesis (0.011 g L⁻¹) and nitrogen/PHB related inhibition constant (0.405 g L⁻¹), were estimated. Five relations for specific growth rate were tested using mathematical models. In silico performed optimization procedures (varied glycerol/nitrogen ratio and feeding) has resulted in a PHB content of 70.9%, shorter cultivation time (23 h) and better PHB yield (0.347 g g⁻¹). Initial concentration of biomass 16.8 g L⁻¹ and glycerol concentration in broth between 3 and 5 g L⁻¹ were decisive factors for increasing of productivity.     

Nitrogen nutrition of Canna indica: Effects of ammonium versus nitrate on growth, biomass allocation, photosynthesis, nitrate reductase activity and N uptake rates

The effects of inorganic nitrogen (N) source (NH₄⁺, NO₃⁻ or both) on growth, biomass allocation, photosynthesis, N uptake rate, nitrate reductase activity and mineral composition of Canna indica were studied in hydroponic culture. The relative growth rates (0.05-0.06 g g⁻¹ d⁻¹), biomass allocation and plant morphology of C. indica were indifferent to N nutrition. However, NH₄⁺ fed plants had higher concentrations of N in the tissues, lower concentrations of mineral cations and higher contents of chlorophylls in the leaves compared to NO₃⁻ fed plants suggesting a slight advantage of NH₄⁺ nutrition. The NO₃⁻ fed plants had lower light-saturated rates of photosynthesis (22.5 μmol m⁻² s⁻¹) than NH₄⁺ and NH₄⁺/NO₃⁻ fed plants (24.4-25.6 μmol m⁻² s⁻¹) when expressed per unit leaf area, but similar rates when expressed on a chlorophyll basis. Maximum uptake rates (V_max) of NO₃⁻ did not differ between treatments (24-35 μmol N g⁻¹ root DW h⁻¹), but V_max for NH₄⁺ was highest in NH₄⁺ fed plants (81 μmol N g⁻¹ root DW h⁻¹), intermediate in the NH₄NO₃ fed plants (52 μmol N g⁻¹ root DW h⁻¹), and lowest in the NO₃⁻ fed plants (28 μmol N g⁻¹ root DW h⁻¹). Nitrate reductase activity (NRA) was highest in leaves and was induced by NO₃⁻ in the culture solutions corresponding to the pattern seen in fast growing terrestrial species. Plants fed with only NO₃⁻ had high NRA (22 and 8 μmol NO₂⁻ g⁻¹ DW h⁻¹ in leaves and roots, respectively) whereas NRA in NH₄⁺ fed plants was close to zero. Plants supplied with both forms of N had intermediate NRA suggesting that C. indica takes up and assimilate NO₃⁻ in the presence of NH₄⁺. Our results show that C. indica is relatively indifferent to inorganic N source, which together with its high growth rate contributes to explain the occurrence of this species in flooded wetland soils as well as on terrestrial soils. Furthermore, it is concluded that C. indica is suitable for use in different types of constructed wetlands.     

Effects of Bacillus thuringiensis toxin Cry1Ac and Beauveria bassiana on Asiatic corn borer (Lepidoptera: Crambidae)

In this study, interactions between Cry1Ac, a toxic crystal protein produced by Bacillus thuringiensis (Berliner), and Beauveria bassiana on the mortality and survival of Ostrinia furnacalis was evaluated in the laboratory. The results showed that Cry1Ac is toxic to O. furnacalis. Not only were larval growth and development delayed, but pupation, pupal weight and adult emergency also decreased when larvae were fed on artificial diet containing purified Cry1Ac toxin. When third instars O. furnacalis were exposed to combination of B. bassiana (1.8 × 10⁵, 1.8 × 10⁶ or 1.8 × 10⁷ conidia ml⁻¹) and Cry1Ac, (0.2 or 0.8 μg g⁻¹), the effect on mortality was additive, however, the combinations of sublethal concentrations showed antagonism between Cry1Ac (3.2 or 13 μg g⁻¹) and B. bassiana (1.8 × 10⁵ or 1.8 × 10⁶ conidia ml⁻¹). When neonates were reared on sublethal concentrations of Cry1AC until the third instar, and survivors exposed B. bassiana conidial suspension, such treatments showed additive effect on mortality of O. furnacalis except for the combination of Cry1Ac (0.2 μg g⁻¹) and B. bassiana (1.8 × 10⁶ conidia ml⁻¹) that showed antagonism.     

Enhanced 2,3-butanediol production by Klebsiella oxytoca using a two-stage agitation speed control strategy

Batch fermentative production of 2,3-butanediol by Klebsiella oxytoca was investigated using various oxygen supply methods though varying agitation speed. Based on the analysis of three kinetic parameters including specific cell growth rate (μ), specific glucose consumption rate (q_s) and specific 2,3-butanediol formation rate (q_p), a two-stage agitation speed control strategy, aimed at achieving high concentration, high yield and high productivity of 2,3-butanediol, was proposed. At the first 15 h, agitation speed was controlled at 300 rpm to obtain high μ for cell growth, subsequently agitation speed was controlled at 200 rpm to maintain high q_p for high 2,3-butanediol accumulation. Finally, the maximum concentration of 2,3-butanediol reached 95.5 g l⁻¹ with the yield of 0.478 g g⁻¹ and the productivity of 1.71 g l⁻¹ h⁻¹, which were 6.23%, 6.22% and 22.14% over the best results controlled by constant agitation speeds.     

Molecularly-imprinted microspheres for selective extraction and determination of melamine in milk and feed using gas chromatography–mass spectrometry

Molecularly-imprinted polymers in the form of microspheres were synthesized using the dispersion polymerization protocol; cyromazine was used as dummy template, while methacrylic acid, ethylene glycol dimethacrylate and acetonitrile (MeCN) were used as functional monomer, cross-linker, and porogen, respectively. When compared with the non-imprinted polymer, the molecularly-imprinted polymers (MIPs) showed outstanding affinity toward melamine in MeCN with a maximum binding concentration (B_max) of 53.20 nmol mg⁻¹ MIPs, imprinting effect of 4.6, and a dissociation constant (K_d) of 90.45 μM. After optimization of the molecularly-imprinted solid-phase extraction conditions, a new method was developed to determine the melamine in milk and feed with gas chromatography–mass spectrometry. The performance of this method has been evaluated in the tainted milk and feed in terms of recovery, precision, linearity, the limit of detection (LOD) and limit of quantitation (LOQ). Recovery ranged in samples from 93.1 to 101.3% with intra-day and inter-day relative standard deviation values below 5.34%. The LOD and LOQ of melamine in milk and feed were 0.01 μg mL⁻¹ (μg g⁻¹) and 0.05 μg mL⁻¹ (μg g⁻¹), respectively.     

Ethanol production from sweet sorghum juice using very high gravity technology: Effects of carbon and nitrogen supplementations

Ethanol production from sweet sorghum juice by Saccharomyces cerevisiae NP01 was investigated under very high gravity (VHG) fermentation and various carbon adjuncts and nitrogen sources. When sucrose was used as an adjunct, the sweet sorghum juice containing total sugar of 280 g l⁻¹, 3 g yeast extract l⁻¹ and 5 g peptone l⁻¹ gave the maximum ethanol production efficiency with concentration, productivity and yield of 120.68 ± 0.54 g l⁻¹, 2.01 ± 0.01 g l⁻¹ h⁻¹ and 0.51 ± 0.00 g g⁻¹, respectively. When sugarcane molasses was used as an adjunct, the juice under the same conditions gave the maximum ethanol concentration, productivity and yield with the values of 109.34 ± 0.78 g l⁻¹, 1.52 ± 0.01 g l⁻¹ h⁻¹ and 0.45 ± 0.01 g g⁻¹, respectively. In addition, ammonium sulphate was not suitable for use as a nitrogen supplement in the sweet sorghum juice for ethanol production since it caused the reduction in ethanol concentration and yield for approximately 14% when compared to those of the unsupplemented juices.     

Chemical profile of the North American native Myriophyllum sibiricum compared to the invasive M. spicatum

Myriophyllum spicatum L. is a nonindigenous invasive plant in North America that can displace the closely related native Myriophyllum sibiricum Komarov. We analyzed the chemical composition (including: C, N, P, polyphenols, lignin, nonpolar extractables, and sugars) of M. spicatum and M. sibiricum and determined how the chemistry of the two species varied by plant part with growing environment (lake versus tank), irradiance (full sun versus 50% shading), and season (July through September). M. spicatum had higher concentrations of carbon, polyphenols and lignin (C: 47%; polyphenols: 5.5%; lignin: 18%) than M. sibiricum (C: 42%; polyphenols: 3.7%; lignin: 9%) while M. sibiricum had a higher concentration of ash under all conditions (12% versus 8% for M. spicatum). Apical meristems of both species had the highest concentration of carbon, polyphenols, and tellimagrandin II, followed by leaves and stems. Tellimagrandin II was present in apical meristems of both M. spicatum (24.6 mg g⁻¹ dm) and M. sibiricum (11.1 mg g⁻¹ dm). Variation in irradiance from 490 (shade) to 940 (sun) μmol of photons m⁻² s⁻¹ had no effect on C, N, and polyphenol concentrations, suggesting that light levels above 490 μmol of photons m⁻² s⁻¹ do not alter chemical composition. The higher concentration of polyphenols and lignin in M. spicatum relative to M. sibiricum may provide advantages that facilitate invasion and displacement of native plants.