Insight in the PCB-degrading functional community in long-term contaminated soil under bioremediation

Purpose  

A small-scale bioremediation assay was developed in order to get insight into the functioning of a polychlorinated biphenyl (PCB) degrading community during the time course of bioremediation treatment of a contaminated soil. The study was conducted with the aim to better understand the key mechanisms involved in PCB-removal from soils.     

Compatibility with killer explains the rise of RNAi-deficient fungi

The RNA interference (RNAi) pathway is found in most eukaryotic lineages but curiously is absent in others, including that of Saccharomyces cerevisiae. We show that reconstituting RNAi in S. cerevisiae causes loss of a beneficial double-stranded RNA virus known as killer virus. Incompatibility between RNAi and killer viruses extends to other fungal species in that RNAi is absent in all species known to possess double-stranded RNA killer viruses, whereas killer viruses are absent in closely related species that retained RNAi. Thus, the advantage imparted by acquiring and retaining killer viruses explains the persistence of RNAi-deficient species during fungal evolution.     

Long-term fertilization effects on crop yields,soil fertility and sustainability in the Static Fertilization Experiment Bad Lauchstädt under climatic conditions 2001–2010

The Static Fertilization Experiment Bad Lauchstädt (1902) consists of a crop rotation of sugar beets, spring barley, potatoes and winter wheat. Three farmyard manure (FYM) treatments and six mineral fertilizer treatments are combined orthogonally. Comparing the first and last decades, crop yields nearly doubled. In unfertilized plots, yields and N uptake by crops also increased when comparing first and last decades. On average for the decade 2001–2010, N uptake in unfertilized plots amounted 51.6 kg ha^?1. Although soil organic carbon (SOC) levels for unfertilized plots remain almost unchanged, SOC increases slowly in the most highly fertilized treatment, resulting in a gradual widening of differences in SOC between the most extreme treatments to 0.952%. Climate change and increased harvesting and root residues due to rising yields are suggested as an explanation. Except for the plot with the highest application of mineral and organic fertilizer, in all treatments more N was taken up by crops than was applied by fertilizers. Higher FYM input leads to more unfavourable N balances because N release from FYM cannot be controlled. Considering atmospheric N input, only in the exclusively mineral fertilized treatment is N balanced out. Similar results are found for C balances: the exclusively mineral fertilized treatment shows the most favourable C balance.     

Stickstoffaufnahme und ‐Freisetzung durch Ruderalzönosen auf Dauerbrachen im Mitteldeutschen Trockengebiet

Auf einer selbstbegrünten Dauerbrache ohne Pflegemaßnahmen (seit 1991) wurden in 4–6 wöchigen Abständen die Trockenmasse (TM) und die N‐Mengen im Pflanzenspross und in verschiedenen Streufraktionen untersucht. In Abhängigkeit von der dominierenden Pflanzenart wurden bis zu 2700 g TM/m² (= 270 dt TM/ha) gebildet. Darin waren bis zu 48 g N/m² (=48g N/ha) enthalten. Nach dem Absterben der Pflanzenbestände bildet sich Streu, die sich auf diesem Standort akkumulierte. In Abhängigkeit von der Güllebelastung des Bodens (hohe Belastung, geringe Belastung, unbelastet) wurde das Maximum der Streu‐TM mit 1345, 1506 bzw. 970 g TM/m² nach 4, 5 bzw. 6 Jahren Brachedauer erreicht. Die N‐Mengen in der Streu stiegen bis zum letzten untersuchten Jahr 1995 allmählich an. Die maximalen Jahresmittelwerte betrugen bei hoher Güllebelastung 27, bei geringer Güllebelastung 31 und ohne Gülle 10 g N/m²(= 270, 310 bzw. 100 kg N/ha). Die N‐Freisetzung aus der Streu begann noch im gleichen Jahr. Sie war im Wesentlichen auf der unbelasteten Parzelle nach 2 Jahren, auf den Gülleparzellen nach 3 Jahren abgeschlossen. Zukünftig müssen die Teilprozesse der N‐Freisetzung aus der Streu und ihre Wechselwirkungen sowie der Einbau des unkrautbürtigen? in die Boden‐N‐Fraktionen und die Wiederaufnahme durch die nächsten Pflanzengenerationen intensiver untersucht werden.     

A new approach to kelp mariculture in Chile: production of free-floating sporophyte seedlings from gametophyte cultures of Lessonia trabeculata and Macrocystis pyrifera

Substantial amounts of Macrocystis and Lessonia are traditionally harvested and exported from Chile as raw material for alginate. Because of intense mariculture of abalone (Haliotis ssp.), herbivorous molluscs that feed on brown kelps, pressure on local populations of Macrocystis and Lessonia has increased to critical levels within the past 5 years, strongly supporting efforts to produce algae maricultured biomass. Here, we present our results on the development of new techniques for large‐scale kelp mariculture in Chile. We have abandoned the traditional technique of direct spore seeding onto inoculation lines. Instead, we used gametophyte cultures that were manipulated to enter gametogenesis and to produce synchronous batches of 10⁴–10⁵ embryos. Juvenile sporophytes were cultured under permanent aeration and agitation, floating unattached in contamination‐free glass bottles up to 10 L, plexiglass cylinders and 800 L greenhouse tanks. When holdfast initials were formed at a size of 8 cm, the sporophytes were spliced into Nylon rope fragments and transferred to the sea. Twelve months after initiation of gametogenesis in the laboratory, Macrocystis pyrifera attained 14 m length and 80 kg fresh weight m^?1 line in the sea. For Lessonia trabeculata 6 months after gametogenesis initiation, 0.25 kg fresh weight m^?1 was attained in the sea.     

Antibacterial Polyketides from the Marine Alga-Derived Endophitic Streptomyces sundarbansensis: A Study on Hydroxypyrone Tautomerism

Polyketide 13 [=2-hydroxy-5-((6-hydroxy-4-oxo-4H-pyran-2-yl)methyl)-2-propylchroman-4-one] and three related known compounds 7, 9 and 11 were obtained and structurally characterized from Streptomyces sundarbansensis strain, an endophytic actinomycete isolated from the Algerian marine brown algae Fucus sp. Compound 13 was obtained as the major metabolite from optimized culture conditions, by using Agar state fermentation. Due to tautomeric equilibrium, 13 in CD₃OD solution was able to incorporate five deuterium atoms, as deduced by NMR and ESI-MS/MS analysis. The 2-hydroxy-γ-pyrone form was established for these metabolites based on the comparison of their experimental IR spectra with the DFT calculated ones, for both the corresponding 4-hydroxy-α-pyrone and 2-hydroxy-γ-pyrone forms. During antibacterial evaluation, compound 13 stood out as the most active of the series, showing a selective activity against the gram positive pathogenic methicillin-resistant S. aureus (MRSA, MIC = 6 μΜ), with a bacteriostatic effect.     

Diversity of five glutenin loci within durum wheat (Triticum turgidum L. ssp. durum (Desf.) Husn.) germplasm grown in Algeria

The HMW and B‐LMW glutenin subunits composition of 120 durum wheat germplasm grown in Algeria was examined using SDS‐PAGE. All together, 39 glutenin patterns were detected, including eight for HMW and 21 for B‐LMW glutenin subunits. Twenty‐six different alleles were identified for the five glutenin loci studied, that is, Glu‐A1 (3), Glu‐B1 (7), Glu‐A3 (5), Glu‐B3 (9) and Glu‐B2 (2). Two new alleles were found at Glu‐B3 locus: Glu‐B3new₁ encodes for five subunits (7 + 8 + 14 + 16 + 18) and Glu‐B3new₂ codes for five subunits (4 + 6* + 12 + 15 + 15*), of which subunit 15* with mobility between bands 15–16 was not described previously. At the Glu‐1 loci, the Glu‐A1c/Glu‐B1e allelic composition was predominant. For the B‐LMW glutenins, the most common allelic composition was Glu‐A3a/Glu‐B3a/Glu‐B2a. The collection analysed shows glutenin alleles and allele combinations related to high gluten strength. This information could be useful to select varieties with improved quality and also as a source of genes to develop new lines when breeding for quality.     

Meta-analysis of the relationship between ractopamine and dietary lysine levels on carcass characteristics in pigs

A meta-analysis was carried out to evaluate the relationship between ractopamine and dietary lysine levels on carcass characteristics in pigs. The database was composed by 29 articles published in international journals from 1990 to 2007, totalizing 155 treatments and 3786 pigs. Average inclusion of ractopamine was 15.3 ppm (ranging from 0 to 30 ppm) and daily average intake of ractopamine was 24.9 mg. Ractopamine addition increased (P < 0.05) hot carcass weight in 4%, loin area in 12% and lean meat content in 4%. Pigs supplemented with ractopamine presented decrease (P < 0.05) of 8% in backfat thickness at the tenth rib, 3% in backfat thickness at the last rib and 5% in mean backfat thickness. Each increase in 1 mg of ractopamine intake represented a reduction of 0.3 mm in tenth-rib (Y = 29.61-0.308 RAC + 0.025 RAC², R² = 0.81, RAC: ractopamine intake expressed in mg) and 0.5 mm at last-rib backfat thickness (Y = 30.52 + 0.519 RAC-0.0054 RAC², R² = 0.94). The use of ractopamine affected (P > 0.05) neither carcass length and dressing, nor meat marbling and color. Loin area was positively correlated (r = 0.27, P < 0.05) and mean backfat thickness was negatively correlated (r = − 0.27, P < 0.05) to dietary lysine concentration. Pigs supplemented with ractopamine whose daily intake of lysine per unit of metabolic weight was more than 195 mg presented (P < 0.05) loin area 4% higher and backfat thickness 10% lower than other animals. Supplemented pigs that received diets with lysine content superior to their calculated amino acid requirement presented weight gain 14% higher, lean meat content 17% higher, leaf fat 34% lower and loin area 6% higher when compared to other supplemented animals. Ractopamine increases lean meat content and reduces backfat thickness in carcass, however, the interaction between additive and nutritional components must be considered in diet formulation.     

Stimulatory effect on pea of Typha Angustifolia L. extracts and their chemical composition

In this study, the influence of aqueous and organic extracts of different plant parts (flowers, leaves, and stems) of Typha angustifolia on the germination and early seedling growth of field pea (Pisum sativum L.) was evaluated. Chemical composition of extracts of different plant parts of Typha was also determined. Aqueous (20, 40, 60, 80, and 100 g L^?1) and organic extracts (at 0.5, 1, and 2 mg mL^?1) were applied to the seeds of two pea cultivars, Douce de Provence and Lincoln, placed in Petri dishes. Application of extracts had a beneficial effect on germination and early seedling growth of both pea cultivars. However, aqueous extract of leaves showed the most beneficial effect at 60 and 40 g L^?1 for the cultivars Douce de Provence and Lincoln, respectively. The effect could be attributed to the allelochemicals present in the aqueous extracts. Petroleum ether and chloroform extracts of leaves had the most stimulating effect on the germination and early seedling growth of pea. Analysis of Typha extracts indicated the presence of vitamin E in leaves, which could be responsible forthis stimulation. Moreover, Typha leaves also had substantial amount of flavonoids. In conclusion, the allelopathic activity of of Typha was dependent on the plant part, the solvent nature, the concentration of the extracts tested, and on the pea cultivar. Application of leaf extract was the most effective in improving the germination rate and early seedling growth of pea.