Saponin-like substances inhibit α-galactosidase production in the endosperm of fenugreek seeds

When fenugreek (Trigonella foenum-graecum L.) endosperms plus testa (endosperms), which had been isolated from 5-h-imbibed seeds, were incubated for at least 2 h under germination conditions, they leaked substances which, like exogenous abscisic acid (ABA), inhibited the production of fenugreek endosperm -galactosidase. However, unlike ABA, 8 h treatment with these inhibitors had no effect on fenugreek endosperms which had been isolated from 15-h-imbibed seeds and leached for 2 h. This indicated that either their inhibitory action was on processes which were related to the production of -galactosidase and had been completed by this time, or that there might be factors present which inactivate these inhibitors. It was also concluded that the action of the endosperm leachate could not be attributed to the presence of ABA. The activity of the leachate decreased when it originated from endosperms imbibed for periods longer than 25 h and thin-layer chromatography (TLC) of extracts from these endosperms showed decreased contents of the leachable inhibitors as imbibition proceeded. From the seed leachate, which had a TLC pattern and inhibitory action similar to that of the endosperm, were isolated three substances which, when applied to endosperms, inhibited the production of -galactosidase activity. According to their chromatographic behaviour and their reaction with specific reagents, there are strong indications that these substances are saponins. These diffusible saponin-like substances were located in both endosperm and perisperm and their physiological role is discussed.Abbreviations ABA abscisic acid - PEG polyethylenglycol - TLC thin-layer chromatography We wish to thank the Alexander S. Onasis Public Benefit Foundation for a grant to K.Z. and Dr. J.S.G. Reid (University of Stirling, Scotland) for a kind gift of fenugreek seeds.     

Allelopathic effects ofEupatorium riparium on population regulation of two species ofGalinsoga and soil microbes

Summary Allelopathic effect ofEupatorium riparium Regel, a dominant ruderal weed at higher altitudes in Meghalaya state in north-eastern India, was studied on two common sympatric annual weeds,Galinsoga ciliata (Raf.) andG. parviflora Cav. and on soil microbes. Seed germination and radicle and plumule growth of both species ofGalinsoga were suppressed by the aqueous extract and leachate ofE. riparium. Although the leaf leachate, leaf and litter extracts and litter bed caused considerable reduction in leaf area and seed and dry matter production in both species ofGalinsoga, the effect was much more pronounced onG. parviflora. The inhibitory effect was directly correlated with the concentration of the extract and leachate. The soil microbial population and growth of theGalinsoga spp. declined considerably in the experimental pots where the soil had earlier received leachate of different plant parts ofE. riparium growing in it. The presence of the partly decomposed litter ofE. riparium in the pots reduced soil microbial population and growth of the two weeds much more strongly as compared to the litter in the advanced stages of decomposition. The study also revealed that the abundance and colony growth of the two test fungiviz. Trichoderma viride andAspergillus flavus were differentially affected by the allelopathy ofE. riparium; T. viride being favoured andA. flavus inhibited.     

Removal of Contaminating Metals from Soil by Sulfur-Based Bioleaching and Biogenic Sulfide-Based Precipitation

The potential of a hybrid process incorporating sulfur-based bioleaching and sulfide-based precipitation for treatment of metal-contaminated soil was examined in batch-type experiments. The sulfur-based soil bioleaching process with Acidithiobacillus sp. could be initiated at a wide range of initial pH from 4.0 to 6.3. After 15 days, 98% of Zn, 89% of Cu and 79% of Cd was bioleached. The gaseous sulfides recycling from Desulfovibrio sp.-mediated sulfate-reducing reactor via N₂ sparging efficiently treated metal-loaded soil leachate. With a sulfide/metal ratio of 3.0, 88% of Zn, 100% of Cu and 95% of Cd were precipitated, resulting in effluent metal concentrations of 3.5 mg Zn²⁺/L, 0.2 mg Cu²⁺/L and 0.03 mg Cd²⁺/L.

Supplemental materials are available for this article. Go to the publisher's online edition of Geomicrobiology Journal to view the supplemental file.     

Phytoremediation of landfill leachate waste contaminants through floating bed technique using water hyacinth and water lettuce

Abstract

In the present study, the effectiveness of water hyacinth and water lettuce was tested for the phytoremediation of landfill leachate for the period of 15?days. Fifteen plastic containers were used in experimental setup where aquatic plants were fitted as a floating bed with the help of thermo-pole sheet. It was observed that both plants significantly (p?<?0.05/p?<?0.01/p?<?0.001) reduce the physicochemical parameters pH, TDS, BOD, COD and heavy metals like Zn, Pb, Fe, Cu and Ni from landfill leachate. Maximum reduction in these parameters was obtained at 50% and 75% landfill leachate treatment and their removal rate gradually increased from day 3 to day 15 of the experiment. The maximum removal rate for heavy metals such as for Zn (80–90%), Fe (83–87%) and Pb (76–84%) was attained by Eichhornia crassipes and Pistia stratiotes. Value of bioconcentration and translocation factor was less than 1 which indicates the low transport of heavy metals from roots to the above-ground parts of the plants. Both these plants accumulate heavy metals inside their body without showing much reduction in growth and showing tolerance to all the present metals. Therefore, results obtained from the study suggest that these aquatic plants are suitable candidate for the removal of pollution load from landfill leachate.     

Phytodesalination of landfill leachate using Puccinellia nuttalliana and Typha latifolia

Abstract

Landfilling has been widely used for solid waste disposal; however, the generation of leachate can pose a major threat to the surrounding environment in the form of soil salinity. Two native plants of North America Puccinellia nuttalliana (alkaligrass) and Typha latifolia (cattail) were selected in this study to investigate bioaccumulation of sodium (Na⁺) and chloride (Cl^?) under controlled greenhouse conditions. The treatments include irrigation of the plants using fertilizer (F), landfill leachate (LL), and tap water (control, C). Plants cultivated after one season (12?weeks) were harvested by separating aboveground tissues and roots, and soil from each treatment was collected for analysis. The results show that alkaligrass irrigated with LL had 2.13% more biomass yield than control, but 17.63% less than that with F. However, cattail yielded 19.70% more biomass with the irrigation of LL than C and 3.04% less compared to F. Alkaligrass and cattail accumulated 6.85 and 7.00?g Na⁺/Kg biomass with the irrigation of LL, respectively. Alkaligrass and cattail irrigated with LL accumulated 120.14% and 94.47% more Cl^? than C. When alkaligrass and cattail were irrigated with LL, the electrical conductivity of soil was reduced by 71.70% and 45.36%, respectively. This study demonstrated that using North American native halophytes could be a cost-effective and promising approach for phytoremediation of landfill leachate.     

The Beauty is a beast: Does leachate from the invasive terrestrial plant Impatiens glandulifera affect aquatic food webs?

Invasive alien species are a major threat to ecosystems. Invasive terrestrial plants can produce allelochemicals which suppress native terrestrial biodiversity. However, it is not known if leached allelochemicals from invasive plants growing in riparian zones, such as Impatiens glandulifera, also affect freshwater ecosystems. We used mesocosms and laboratory experiments to test the impact of I. glandulifera on a simplified freshwater food web. Our mesocosm experiments show that leachate from I. glandulifera significantly reduced population growth rate of the water flea Daphnia magna and the green alga Acutodesmus obliquus, both keystone species of lakes and ponds. Laboratory experiments using the main allelochemical released by I. glandulifera, 2‐methoxy‐1,4‐naphthoquinone, revealed negative fitness effects in D. magna and A. obliquus. Our findings show that allelochemicals from I. glandulifera not only reduce biodiversity in terrestrial habitats but also pose a threat to freshwater ecosystems, highlighting the necessity to incorporate cross‐ecosystem effects in the risk assessment of invasive species.     

Detection of hatching inhibitors and hatching factor stimulants for golden potato cyst nematode, Globodera rostochiensis, in potato root leachate

In a comparison of four potato varieties, in-soil hatch of the golden potato cyst nematode (Globodera rostochiensis) was positively correlated to in vitro hatch in response to potato root leachate (PRL). The in-soil hatch of cysts of G. rostochiensis to two of the four varieties was significantly less than that of the control (cysts in gravel without potato plants) in the first 2 wk after plant emergence, suggesting the production of hatching inhibitors (HIs) by young potato plants. The hatching factor: hatching inhibitor ratio of PRL was positively associated with the net hatching activity of the PRL. Four zones of HI activity were resolved following gel permeation chromatography of PRL on Sephadex G-10. Hatch-inactive chemicals, which stimulated the activity of hatching factors (HFs) in PRL (hatching factor stimulants, HSs), were also isolated from PRL, hatch levels induced by individual HFs responding differently to the same HS preparation. The complex interactions between individual HFs and other hatching chemicals in PRL was illustrated when addition of the hatch-active potato glycoalkaloid α-solanine caused both inhibition and stimulation of PRL-induced hatch, depending on the α-solanine concentration.     

The efficiency of evapotranspiration of landfill leachate in the soil–plant system with willow Salix amygdalina L.

The application of a specific species of willow—Salix amygdalina L., marked by high transpiration ability—is a cheap and effective method of landfill leachate disposal. A 2-year study examined the effectiveness of leachate evapotranspiration from soil–plant systems with willow species S. amygdalina L. Evapotranspiration from soil–plant systems planted with willow was from 1.28 up to 5.12 times higher than evaporation from soil surface barren of vegetation. This proves the usefulness of soil–plant systems with willow in landfill leachate treatment through vaporization. Evapotranspiration efficiency, as opposed to total amount of water added into the lysimeter, was not strong enough to vaporize all input of the landfill leachate in the lysimeters. This may indicate that the ground water requires isolation when soil systems remain under landfill leachate irrigation. Linear dependence between willow biomass growth and transpiration was observed to be significant (p < 0.05). Additionally, the research showed that the application of sewage sludge into the soil caused an increase in vaporization efficiency.     

Treatment of fresh leachate with high-strength organics and calcium from municipal solid waste incineration plant using UASB reactor

Treatment of a fresh leachate with high-strength organics and calcium from municipal solid waste (MSW) incineration plant by an up-flow anaerobic sludge blanket (UASB) reactor was investigated under mesophilic conditions, emphasizing the influence of organic loading rate (OLR). When the reactor was fed with the raw leachate (COD as high as 70,390-75,480 mg/L) at an OLR of 12.5 kg COD/(m³ d), up to ∼82.4% of COD was removed suggesting the feasibility of UASB process for treating fresh leachates from incineration plants. The ratio of volatile solids/total solids (VS/TS) of the anaerobic sludge in the UASB decreased significantly after a long-term operation due to the precipitation of calcium carbonate in the granules. Scanning electron microscopy (SEM) observation shows that Methanosaeta-like species were in abundance, accompanied by a variety of other species. The result was further confirmed by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) and sequencing.