Antimicrobial activities of Asafoetida and Shirazi thyme essential oils improve the vase life of gerbera cut flowers

This study was conducted to evaluate the chemical composition of asafoetida (Ferula assa-foetida) essential oil (FAEO) and Shirazi thyme (Zataria multiflora) EO (ZMEO) and their impact on vase life of gerbera cut flowers (Gerbera jamesonii cv. Rosalyn). Five concentrations of both, ZMEO and FAEO including 0, 100, 200, 300 and 400 mg L^?1 used as continuous vase solution for gerbera cut flowers. EOs used in this study were extracted by hydrodistillation method using Clevenger apparatus. They were analyzed by GC and GC–MS for determination of the active compounds. Thirty five compounds were identified in ZMEO, mainly including thymol (40.1%), p-cymene (15.5%) and carvacrol (6.5%). Also, thirty compounds were identified in FAEO. The main components were trans propenyl sec-butyl disulfide (21.7%), eudesmol (10-epu-γ) (19.2%) and cis propenyl sec-butyl disulfide (10.2%). The results showed that both ZMEO and FAEO at all concentrations could act as an effective antibacterial compounds and this property increased by increasing their concentration. The results of this research showed that ZMEO increased the vase life at all concentrations but high concentrations of FAEO increased mortality percentage and reduced the vase life of cut flowers. The relative fresh weight and vase solution uptake of gerbera cut flowers increased by the applied EOs treatments. ZMEO at 400 mg L^? 1 and FAEO at 300 and 400 mg L^? 1 resulted the least stem color change. Overall, 200 mg L^? 1 ZMEO and 100 mg L^? 1 FAEO were the best treatments for maintenance of gerbera cut flowers quality during vase life.     

<Emphasis Type="Italic">In vitro</Emphasis> effects of GA<Subscript>3</Subscript> on morphogenesis of CIP potato explants and acclimatization of plantlets in field

Improvement of potato has been accomplished using conventional and non-conventional approaches coupled with numerous tissue culture procedures. The aim of the present study was to assess the efficacy of gibberellic acid (GA₃) on the morphogenesis of International Potato Center (CIP) potato explants and acclimatization of plantlets in the field. Nodal segments as an explant source (1–1.5 cm) were isolated from 31 CIP potato plantlets and were inoculated into Murashige and Skoog (MS) medium supplemented with 0.0 (control), 0.1, 0.5, or 1.0 mg L^?1of GA₃. The variation in growth parameters of the cultivars was then observed. The highest shoot induction occurred in MS medium containing 1.0 mg L^?1 GA₃ with an increase in the inter-nodal distance between nodes as compared to other treatments. Higher concentration (1.0 mg L^?1) of GA₃ significantly increased plant height and root length in the treated germplasm however; this concentration was inhibitory to the number of nodes and roots per plant. The number of leaves was significantly increased in plants receiving GA₃ treatment at lower concentration (0.1 mg L^?1). The 31 CIP genotypes were transplanted to the field and checked for yield quality traits. It was concluded from the results that GA₃ had significant effects on morphogenesis and was effective in the acclimatization of CIP potato plantlets in field.     

Effects of plant growth regulators and sucrose on post harvest physiology,membrane stability and vase life of cut spikes of gladiolus

Effects of post-harvest application of two plant growth regulators viz., gibberellic acid (GA₃) and benzyl adenine (BA) with sucrose in the vase solution on cell membrane stability and vase life of gladiolus were investigated. The vase solution treatment combinations of GA₃ and BA with sucrose significantly increased the membrane stability index and enhanced the vase life as compared to the sucrose alone treatments or the controls. Vase solution treatment of GA₃ (50 mg l⁻¹), followed by BA (50 mg l⁻¹) with sucrose (50 g l⁻¹) significantly increased solution uptake, fresh weight and dry weight of cut spikes. The same treatments also enhanced the concentration of reducing and non-reducing sugars in gladioli petals 4 days after treatment (DAT). Cut spikes in vase solution enriched with 50 mg l⁻¹ GA₃ + 50 g l⁻¹ sucrose showed higher antioxidative enzyme activities of superoxide dismutase (SOD) and glutathione reductase (GR), lower lipoxygenase (LOX) activity and lipid peroxidation (measured as TBARS). Petal membrane stability index was also highest in cut spikes 6 DAT with 50 mg l⁻¹ GA₃ + 50 g l⁻¹ sucrose vase solution. Treatment of gladiolus cut spikes with 50 mg l⁻¹ GA₃ + 50 g l⁻¹ sucrose vase solution showed two fold increase in vase life and improved flower quality with a higher number of open flower per spike at any one time. These results suggest that post-harvest application of GA₃ (50 mg l⁻¹) with sucrose (50 g l⁻¹) maintains higher spike fresh and dry weight, improves anti-oxidative defence, stabilizes membrane integrity leading to a delay in petal cell death.     

Effects of different plant growth regulators and chemicals spray on post harvest physiology and vase life of heliconia inflorescence cv. Golden Torch

Effects of post harvest spray application of plant growth regulators, gibberellic acid (GA) and benzyl adenine (BA), alar (Daminozide) and chemicals like bovine serum albumin (BSA) and potassium permagnate (KMnO₄) on post harvest quality of heliconia inflorescence were investigated. Post harvest spray treatments significantly influenced post harvest quality and life of heliconia inflorescence as compared to control. Spray treatments of GA (100 mg l^?1) and BSA (50 mg l^?1) effectively increased water uptake and retained fresh weight of cut inflorescence. The same treatments also reduce the levels of catalase (CAT) and peroxidase (POD) enzymatic activity and decreased the lipid peroxidation (measured as TBARS) in the bract tissue. Percent absolute integrity of bract cell membrane (PAI) was also high in GA (100 mg l^?1) and BSA (50 mg l^?1) spray treated cut inflorescence on 8th, 10th and 12th day of vase life. Post-harvest spray treatment of GA (100 mg l^?1) showed significant increase (by almost twofold) in the vase life of heliconia inflorescence as compared to control. These results suggest that post-harvest spray of GA (100 mg l^?1) or BSA (50 mg l^?1) maintains higher inflorescence fresh weight, improve water uptake and reactive oxygen species (ROS) scavenging capacity, stabilizes absolute integrity of cell membrane leading to a delay in bract cell death in heliconia inflorescence cv. Golden Torch.     

In vitro propagation and assessment of genetic stability of micropropagated Samanea saman (rain tree) using microsatellite markers

An efficient in vitro propagation of Samanea saman (rain tree) protocol has been successfully developed using nodal explants from a 20-year-old tree. Higher percentage (76 %) of explants produced up to five shoots per explant on Murashige and Skoog (MS) medium supplemented with 2 mg L^?1 6-benzyladenine (BA), 0.1 mg L^?1 gibberellic acid (GA₃) and 100 mg L^?1 casein hydrolysate after 3 weeks of culture. When explants were subcultured to fresh medium after harvesting first batch of shoots, more shoots could be generated (another eight shoots per explant). Shoot elongation was achieved (3 cm) when shoots were cultured on MS medium supplemented with 0.25 mg L^?1 BA and 0.75 mg L^?1 GA₃. In vitro generated shoots rooted on MS medium fortified with 0.75 mg L^?1 indole-3-butyric acid plus 0.1 % of activated charcoal. A higher percentage of explant response and shoots per explant were obtained on MS medium with BA and GA₃. Each responsive nodal explant yields an average of 15 rooted plants within a period of 10 weeks. Rooted plantlets were successfully acclimatized in green house with a survival rate of 90 %. Micropropagated plants were tested for genetic stability using simple sequence repeats (SSR) markers. Use of the 12 high-resolution SSR markers revealed the exact same genetic profile between the mother tree (donor) and micropropagated plants, suggesting the genetic fidelity of our micropropagation protocol. The same protocol was also used successfully in propagating a “Golden Rain Tree” although response of explant and efficiency of propagation was much lower. This protocol will be useful for germplasm preservation/large scale production of true-to-type clones of desirable genotypes.     

Quercetin and silver nitrate modulate organogenesis in <Emphasis Type="Italic">Carissa carandas</Emphasis> (L.)

An in vitro organogenesis protocol for Carissa carandas L. was developed using an auxin transport inhibitor (quercetin) and silver nitrate (AgNO₃), an inhibitor of ethylene action, in association with cytokinins in the culture medium. This protocol produced the maximum number of shoots from aseptic seedling-derived shoot apex explants of C. carandas. The highest rate of shoot multiplication was recorded on MS medium containing 2.0 mg L^?1 6-benzylaminopurine; 0.5 mg L^?1 kinetin, and 0.75 mg L^?1 quercetin at after 4 wk of culture. Similar results were obtained when MS medium fortified with 2.0 mg L^?1 BAP, 0.5 mg L^?1 kinetin, and 1.5 mg L^?1 AgNO₃ was used. However, successful rooting was achieved on quarter strength MS medium with 0.5 mg L^?1 indole-3-acetic acid. In this study, an inhibitor of auxin transport and ethylene action maximized shoot multiplication in medium fortified with cytokinins. The established rapid micropropagation method could be used to conserve elite genotypes of C. carandas.     

Micropropagation, <Emphasis Type="Italic">in vitro</Emphasis> flowering,and tuberization in <Emphasis Type="Italic">Brachystelma glabrum</Emphasis> Hook.f., an endemic species

Brachystelma glabrum Hook.f. is an endemic plant species of Eastern Ghats, India. In this study, efficient protocols for in vitro micropropagation, flowering, and tuberization of this plant were developed. Sterilized shoot tip and nodal explants were cultured on Murashige and Skoog (MS) medium supplemented with different plant growth regulators (PGRs) and additives for shoot induction and multiplication. Both shoot tip and nodal explants showed the best response (90 and 100%, respectively) on MS medium supplemented with thidiazuron (TDZ) at 1.0 mg L^?1. The microshoots multiplied best on MS + TDZ (1.0 mg L^?1) in combination with α-naphthaleneacetic acid (NAA) at 0.5 mg L^?1 and coconut water (CW) at 25%. The highest number of in vitro flowers (4.0 flowers per microshoot) was observed on MS medium supplemented with a combination of N6-benzyladenine (BA) and indole-3-butyric acid (IBA), each at 1.5 mg L^?1. In vitro-derived shoots produced aerial tubers on MS + TDZ (2.0 mg L^?1) + IBA (0.5 mg L^?1) and basal tubers on MS + TDZ at 2.0 mg L^?1. In vitro shoots were best rooted on half-strength (½) MS + NAA at 0.5 mg L^?1. The rooted plantlets were successfully acclimatized in pots with 70% survival after a hardening period of 1 mo. This protocol provides an effective method for the conservation of this endemic plant species.     

The role of abscisic acid (ABA) in ethylene insensitive Gladiolus (Gladiolus grandiflora Hort.) flower senescence

Gladiolus flowers are ethylene insensitive and the signals that start catabolic changes during senescence of gladiolus flower are largely not known. Therefore, experiments were performed to understand the role of abscisic acid (ABA) in ethylene insensitive floral senescence in gladiolus (Gladiolus grandiflora Hort.). It was observed that ABA accumulation increased in attached petals of gladiolus flowers as they senesced. Exogenous application of ABA in vase solution accelerated senescence process in the flowers due to change in various senescence indicators such as enhanced membrane leakage, reduced water uptake, reduced fresh weight and ultimately vase life. Enhancement of in vivo ABA level in petals by creating osmotic stress also upregulates the same parameters of flower senescence as those occurring during natural senescence and also akin to exogenous application of ABA. Attempts to increase vase life of flowers by application of putative ABA biosynthesis inhibitor fluridone in vase solution to counteract ABA effect were unsuccessful. In contrast, ABA action was mitigated by application of GA₃ in holding solution along with ABA which is basically an antagonist of ABA action. The present study provides valuable insights into the role of ABA as a hormonal trigger in ethylene insensitive senescence process and therefore would be helpful for dissecting the complex mechanism underlying ABA-regulated senescence process in gladiolus.     

Applicability of one-stage partial nitritation and anammox in MBBR for anaerobically pre-treated municipal wastewater

Energy consumption of municipal wastewater treatment plants can be reduced by the anaerobic pre-treatment of the main wastewater stream. After this pre-treatment, nitrogen can potentially be removed by partial nitritation and anammox (PN/A). Currently, the application of PN/A is limited to nitrogen-rich streams (>500 mg L^?1) and temperatures 25–35 °C. But, anaerobically pretreated municipal wastewater is characterized by much lower nitrogen concentrations (20–100 mg L^?1) and lower temperatures (10–25 °C). We operated PN/A under similar conditions: total ammonium nitrogen concentration 50 mg L^?1 and lab temperature (22 °C). PN/A was operated for 342 days in a 4 L moving bed biofilm reactor (MBBR). At 0.4 mg O₂ L^?1, nitrogen removal rate 33 g N m^?3 day^?1 and 80 % total nitrogen removal efficiency was achieved. The capacity of the reactor was limited by low AOB activity. We observed significant anammox activity (40 g N m^?3 day^?1) even at 12 °C, improving the applicability of PN/A for municipal wastewater treatment.     

An efficient protocol for <Emphasis Type="Italic">in vitro</Emphasis> regeneration and conservation of Shirui lily (<Emphasis Type="Italic">Lilium mackliniae</Emphasis> Sealy): a lab-to-land approach to save the rare endangered Asiatic lily species

An efficient protocol for direct and indirect shoot regeneration and proliferation from bulb scales of Shirui lily (Lilium mackliniae Sealy), an endangered Asiatic lily species endemic to the Shirui hill peak, Manipur, India, has been developed. Bulb scales were isolated from mature bulbs and cultured on Murashige and Skoog (MS) basal medium supplemented with different concentrations of 6-benzylaminopurine (BAP), kinetin (KIN), or thidiazuron (TDZ). For direct shoot regeneration from bulb scale explants, 0.5 mg L^?1 BAP yielded the highest shoot induction (3.5 shoots per scale; a 96.7% response). For indirect de novo organogenesis, optimum callus induction was achieved with 2.0 mg L^?1 2,4-dichlorophenoxyacetic acid (2,4-D), and shoot organogenesis was higher (16.2) when subcultured onto 0.5 mg L^?1 BAP medium. Multiple shoot regeneration and pseudo-bulb formation protocols were assessed; the highest shoot proliferation (10.1) occurred with 0.5 mg L^?1 BAP and 1.0 mg L^?1 gibberellic acid (GA₃). Rooting response was 96% with 0.5 mg L^?1 1-naphthalene acetic acid (NAA), with multiple roots per shootlet. Plantlet survival was increased to 92.5% during the hardening-off process by using hydroponics with Hoagland’s solution in a mist chamber. Clonal fidelity was assessed through random amplified polymorphic DNA (RAPD) analysis comparing the mother plant and regenerated plantlets. After confirming genetic uniformity, the pseudo-bulblets with four to six leaves and three to four roots were successfully established at the Shirui hills peak. This in vitro regeneration and ex vitro conservation approach could be helpful to save this rare endangered species in a sustainable way.     

Development of a Polygonum minus cell suspension culture system and analysis of secondary metabolites enhanced by elicitation

Polygonum minus has been reported to contain valuable metabolites and to date, there is no report on using cell culture technique for metabolite production in P. minus. Naphthalene acetic acid (NAA) concentrations in the range of 2–6 mg L^?1 were used in a matrix of combinations with dichlorophenoxyacetic acid (2,4-D) concentrations in the range of 2–10 mg L^?1 as plant growth regulators (PGRs) to induce callus cultures. Media that were supplemented with 2 mg L^?1 2,4-D + 4 mg L^?1 NAA, 2 mg L^?1 2,4-D + 6 mg L^?1 NAA and 6 mg L^?1 2,4-D + 8 mg L^?1 NAA were effective for callus induction (93.3 % of the explants produced callus). To establish cell culture, the best growth was obtained from medium that was supplemented with 1 mg L^?1 2,4-D + 2 mg L^?1 NAA. From a 1-g inoculum size, the fresh weight increases exponentially after 5–10 days of culture, and a 26.71 g maximum fresh weight was obtained after 25 days of culture. The cell culture medium was then analyzed using gas chromatography–mass spectrometry (GC–MS). Jasmonic acid (100, 50, 25 and 5 μM), salicylic acid (100, 50, 25 and 5 μM), yeast extract (500, 250 and 100 mg L^?1) and glass beads were used in this research as elicitors. The cell cultures were then incubated with the different elicitors for 1, 2, 3 and 4 days. Several compounds with high peak area percentages were detected, including 2-furancarboxaldehyde, 5-hydroxymethyl, furfural, and 2-cyclopenten-1-one, 2-hydroxy. These results show the diversity of metabolites released by P. minus cell into the culture medium under control conditions.     

Enhanced production of gibberellin A4 (GA4) by a mutant of Gibberella fujikuroi in wheat gluten medium

Mutants of Gibberella fujikuroi with different colony characteristics, morphology and pigmentation were generated by exposure to UV radiation. A mutant, Mor-189, was selected based on its short filament length, relatively high gibberellin A₄ (GA₄) and gibberellin A₃ (GA₃) production, as well as its lack of pigmentation. Production of GA₄ by Mor-189 was studied using different inorganic and organic nitrogen sources, carbon sources and by maintaining the pH of the fermentation medium using calcium carbonate. Analysis of GA₄ and GA₃ was done by reversed-phase high-performance liquid chromatography and LC-MS. The mutants of G. fujikuroi produced more GA₄ when the pH of the medium was maintained above 5. During shake flask studies, the mutant Mor-189 produced 210 mg l^?1 GA₄ in media containing wheat gluten as the nitrogen source and glucose as the carbon source. Fed-batch fermentation in a 14 l agitated fermenter was performed to evaluate the applicability of the mutant Mor-189 for the production of GA₄. In 7-day fed-batch fermentation, 600 mg l^?1 GA₄ were obtained in the culture filtrate. The concentration of GA₄ and GA₃ combined was 713 mg l^?1, of which GA₄ accounted for 84% of the total gibberellin. These values are substantially higher than those published previously. The present study indicated that, along with maintenance of pH and controlled glucose feeding, the use of wheat gluten as the sole nitrogen source considerably enhances GA₄ production by the mutant Mor-189.     

Complete and simultaneous removal of ammonium and m-cresol in a nitrifying sequencing batch reactor

The kinetic behavior, oxidizing ability and tolerance to m-cresol of a nitrifying sludge exposed to different initial concentrations of m-cresol (0–150 mg C L^?1) were evaluated in a sequencing batch reactor fed with 50 mg NH₄ ⁺-N L^?1 and operated during 4 months. Complete removal of ammonium and m-cresol was achieved independently of the initial concentration of aromatic compound in all the assays. Up to 25 mg m-cresol-C L^?1 (C/N ratio of 0.5), the nitrifying yield (Y-NO₃ ^?) was 0.86 ± 0.05, indicating that the nitrate was the main product of the process; no biomass growth was detected. From 50 to 150 mg m-cresol-C L^?1 (1.0 ≤ C/N ≤ 3.0), simultaneous microbial growth and partial ammonium-to-nitrate conversion were obtained, reaching a maximum microbial total protein concentration of 0.763 g L^?1 (247 % of its initial value) and the lowest Y-NO₃ ^? 0.53 ± 0.01 at 150 mg m-cresol-C L^?1. m-Cresol induced a significant decrease in the values of both specific rates of ammonium and nitrite oxidation, being the ammonium oxidation pathway the mainly inhibited. The nitrifying sludge was able to completely oxidize up to 150 mg m-cresol-C L^?1 by SBR cycle, reaching a maximum specific removal rate of 6.45 g m-cresol g^?1 microbial protein-N h^?1. The number of SBR cycles allowed a metabolic adaptation of the nitrifying consortium since nitrification inhibition decreased and faster oxidation of m-cresol took place throughout the cycles.     

Conversion of oat (<Emphasis Type="Italic">Avena sativa</Emphasis> L.) haploid embryos into plants in relation to embryo developmental stage and regeneration media

Obtaining oat DH lines is only effective via wide crossing with maize. Seven hundred haploid embryos from 21 single F₁ progeny obtained from wide crosses with maize were isolated, divided into four groups according to their size (<0.5 mm, 0.5–0.9 mm, 1.0–1.4 mm, and ≥1.5 mm), and transferred into 190–2 regeneration medium with different growth regulators: 0.5 mg L^?1 kinetin (KIN) and 0.5 mg L^?1 1-naphthaleneacetic acid (NAA); 1 mg L^?1 zeatin (ZEA) and 0.5 mg L^?1 NAA; or 1 mg L^?1 dicamba (DIC), 1 mg L^?1 picloram (PIC), and 0.5 mg L^?1 kinetin (KIN). Among all isolated embryos, approximately 46.1% were between 1.0–1.4 mm, while the smallest group of embryos (7.1%) were those <0.5 mm. The ability of haploid embryos to germinate varied depending on oat genotypes and the size of embryos. Haploid embryos <0.5 mm were globular and did not germinate, whereas embryos ≥1.5 mm had clearly visible coleoptiles, radicles, and scutella, and were able to germinate. Germination of oat haploid embryos varied depending on growth regulators in the regeneration medium. Most haploid embryos germinated on medium with 0.5 mg L^?1 NAA and 0.5 mg L^?1 KIN, while the fewest germinated on medium with 1 mg L^?1 DIC, 1 mg L^?1 PIC, and 0.5 mg L^?1 KIN. One hundred thirty germinated haploid embryos converted into haploid plants. Fifty oat DH lines were obtained after colchicine treatment.     

Embryogenesis,plant regeneration and cardiac glycoside determination in Digitalis ferruginea subsp. ferruginea L

The present study reports, for the first time, an efficient in vitro plant regeneration protocol for Digitalis ferruginea subsp. ferruginea L. (rusty foxglove). We have used different concentrations of gibberellic acid (GA₃) on Murashige and Skoog (MS) medium to assess the germination frequency of seeds. High frequency of germination was achieved on MS medium with 1.0 mg l^?1 GA₃. 6-Benzylaminopurine (BAP) combined with α-naphtaleneacetic acid (NAA) or 2, 4-dichlorophenoxy acetic acid (2, 4-D) in the induction MS medium induced both somatic embryogensis and shoot organogenesis. The highest percentage of callus growth (85 %) was obtained when hypocotyl explants were cultured on MS medium containing 0.5 mg l^?1 2, 4-D plus 1.0 mg l^?1 BAP. The maximum mean number of somatic embryos (7.3 ± 1.3 embryos) or shoots (12.0 ± 1.1 shoots) per callus was obtained when medium contained 0.25 mg l^?1 NAA plus 1.0 mg l^?1 BAP or 0.5 mg l^?1 NAA plus 2.0 mg l^?1 BAP. The regenerated shoots easily rooted on MS medium. Higher amounts of lanatoside C [13.2 ± 0.5 mg 100 g^?1 dry weight (dw)] and digoxin (2.93 ± 0.31 mg 100 g^?1 dw) accumulation were obtained when shoots were obtained by indirect regeneration. We also investigated derivatives of cardenolides, i.e., digitoxigenin (730 ± 180 mg 100 g^?1 dw), gitoxigenin (50 ± 20 mg 100 g^?1 dw) and digoxigenin (490 ± 170 mg 100 g^?1 dw) from natural samples.     

Optimizing micropropagation of drought resistant <Emphasis Type="Italic">Pyrus boissieriana</Emphasis> Buhse

The present study concentrated on introducing a micropropagation protocol for a drought resistant genotype from Pyrus boissieriana, which is the second most naturally widespread pear species in Iran with proper physiological and medicinal properties. Proliferating microshoot cultures were obtained by placing nodal segments on MS medium supplemented with BAP and IBA or NAA. The highest number of shoots (27 shoots per explant) were obtained with 1.5 mg l^?1 BAP and 0.05 mg l^?1 IBA, but this combination did not produce shoots of desirable length (>1.7 cm). Combination of 1.75 mg l^?1 BAP and 0.07 mg l^?1 IBA was the best for the shoot multiplication in P. boissieriana with a sufficient number of shoot production (22.33 shoots per explant) and relatively more appropriate shoot length. The larger and greenish leaves were obtained when PG was added to the best multiplication treatment. Microshoot elongation was carried out in 1/2 and 1/4 MS medium containing 50–100 mg l^?1 PG with different concentrations of IBA or NAA at intervals of 30–60 days. Significant increase in shoot length was detected after 45–60 days of culture in the presence of PG. The highest shoot length (8 cm) was recorded on 1/2 MS medium supplemented with 0.5 mg l^?1 IBA and 100 mg l^?1 PG. GA₃ negatively affected number and length of shoots and generally caused generation of red leaves. The highest percentage of root induction (100%) and root length (9 cm) were obtained on 1/6 strength MS medium supplemented with 0.005 mg l^?1 IBA. All plantlets were hardened when transferred to ex vitro conditions through a period of 25–30 days. The results suggest axillary shoot proliferation of P. boissieriana could successfully be employed for propagation of candidate drought resistant seedling.     

Comparison of growth of Tetraselmis in a tubular photobioreactor (Biocoil) and a raceway pond

Microalgae cultivation systems can be divided broadly into open ponds and closed photobioreactors. This study investigated the growth and biomass productivity of the halophilic green alga Tetraselmis sp. MUR-233, grown outdoors in paddle wheel-driven open raceway ponds and in a tubular closed photobioreactor (Biocoil) at a salinity of 7 % NaCl (w/v) between mid-March and June 2010 (austral autumn/winter). Volumetric productivity in the Biocoil averaged 67 mg ash-free dry weight (AFDW) L^?1 day^?1 when the culture was grown without CO₂ addition. This productivity was 86 % greater, although less stable, than that achieved in the open raceway pond (36 mg L^?1 day^?1) grown at the same time in the autumn period. The Tetraselmis culture in the open raceway pond could be maintained in semi-continuous culture for the whole experimental period of 3 months without an additional CO₂ supply, whereas in the Biocoil, under the same conditions, reliable semi-continuous culture was only achievable for a period of 38 days. However, stable semi-continuous culture was achieved in the Biocoil by the addition of CO₂ at a controlled pH of ~7.5. With CO₂ addition, the volumetric biomass productivity in the Biocoil was 85 mg AFDW L^?1 day^?1 which was 5.5 times higher than the productivity achieved in the open raceway pond (15 mg AFDW L^?1 day^?1) with CO₂ addition and 8 times higher compared to the productivity in the open raceway pond without CO₂ addition (11 mg AFDW L^?1 day^?1), when cultures were grown in winter. The illuminated area productivities highlight an alternative story and showed that the open raceway pond had a three times higher productivity (3,000 mg AFDW m^?2 day^?1) compared to the Biocoil (850 mg AFDW m^?2 day^?1). Although significant differences were found between treatments and cultivation systems, the overall average lipid content for Tetraselmis sp. MUR-233 was 50 % in exponential phase during semi-continuous cultivation.     

Physiological and cellular responses to fluoride stress in tea (<Emphasis Type="Italic">Camellia sinensis</Emphasis>) leaves

Tea (Camellia sinensis (L.) O. Kuntze) hyper-accumulates fluoride (F), mainly in the leaves. To understand how tea copes with the stress caused by F, we tracked photosynthesis, antioxidant defense, and cell ultrastructure under different F concentrations (0–50 mg L^?1). High F (≥5 mg L^?1) caused decreases in photosynthetic and chlorophyll fluorescence parameters. Activated oxygen metabolism was altered by F, as manifested in increasing lipid peroxidation, electrolyte leakage (EL), and accumulation of H₂O₂. The activities of ascorbate peroxidase (APX, EC 1.11.1.1) and catalase (CAT, EC 1.11.1.6) increased at 0–5 mg L^?1 F, but sharply decreased less than 10–50 mg L^?1 F. The activity of manganese superoxide dismutase (Mn-SOD, EC 1.15.1.1) decreased with increasing F concentration. Expression of genes encoding antioxidant enzymes were in accordance with their measured activities. The results suggest that the antioxidant enzymes in the tea plant can eliminate reactive oxygen species (ROS) at <5 mg L^?1 F, but not at 20–50 mg L^?1 F. High F increased the number of epidermal hairs on tea leaves and decreased the stomatal aperture, reducing water loss. The leaf cellular structure appeared normal under 1–50 mg L^?1 F, although starch grains in chloroplast increased with increasing F. Proline and betaine play important roles in osmotic regulation in tea plant tolerating F stress. ROS scavenging and greater number of epidermal hairs are likely parts of the tea plant F-tolerance mechanism.     

Study on russet-related enzymatic activity and gene expression in ‘Shine Muscat’ grape treated with GA3 and CPPU

Physiological (metabolite analysis) and molecular (gene expression) approaches were used to understand the mechanism underlying russet formation in response to the application of GA₃ and CPPU (Forchlorfenuron) in a Japanese table grape cultivar ‘Shine Muscat’. Several different concentrations of GA₃ and GA₃?+?CPPU [25?mg?L^?1 GA₃ (A), 25?mg?L^?1 GA₃?+?5?mg?L^?1 CPPU (B), 25?mg?L^?1 GA₃?+?10?mg?L^?1 CPPU (C), and 25?mg?L^?1 GA₃?+?15?mg?L^?1 CPPU (D)] were applied to grape berry clusters at two weeks after flowering (WAF). No russet was observed on the berries treated with the ‘C’ combination. Lower levels of phenylalanine ammonia-lyase (PAL) activity was observed in the treated samples, relative to the untreated material. Reduced peroxide (POD) activity was also observed in response to different treatments, while the expression of Peroxidase 17 and Phenylalanine ammonia-lyase G1 genes mirrored lignin content. Increased activity of 4-coenzyme A ligase (4CL) may contribute to decreasing the level of russet and help to improve grape berry quality.     

Kinetics of the aerobic co-metabolism of 1,1-dichloroethylene by Achromobacter sp.: a novel benzene-grown culture

Batch experiments were performed for the aerobic co-metabolism of 1,1-dichloroethylene (1,1-DCE) by Achromobacter sp., identified by gene sequencing of 16S rRNA and grown on benzene. Kinetic models were employed to simulate the co-metabolic degradation of 1,1-DCE, and relevant parameters were obtained by non-linear least squares regression. Benzene at 90 mg L^?1 non-competitively inhibited degradation of 1,1-DCE (from 125 to 1,200 μg L^?1). The maximum specific utilization (k_c) rate and the half-saturation constant (K_c) for 1,1-DCE were 54 ± 0.85 μg h^?1 and 220 ± 6.8 μg L^?1, respectively; the k_b and K_b for benzene were 13 ± 0.18 mg h^?1 and 28 ± 0.42 mg L^?1, respectively. This study provides a theoretical basis to predict the natural attenuation when benzene and 1,1-DCE occur as co-contaminants.