Incidence of Aeromonas species in influent and effluent of urban wastewater purification plants

Influent and effluent samples from urban wastewater plants were examined for presumptive Aeromonas. Removal efficiency was comparatively low for both presumptive Aeromonas (96.5%) and faecal coliforms (95.8%). Starch ampicillin agar (SA) medium was superior to mA medium for selectivity, with 32.3% of typical colonies confirmed as Aeromonas spp., and for the recovery of Aer. veronii biotype veronii.     

Treatment of hydroponic wastewater by denitrification filters using plant prunings as the organic carbon source

This study investigated the feasibility of using pre-treated plant liquors as organic carbon sources for the treatment of hydroponic wastewater containing high nitrate-N (>300 mg N/L). The waste plant material was pre-treated to extract organic carbon-rich liquors. When this plant liquor was used as an organic carbon source in denitrification filters at the organic carbon:nitrogen dose rate of 3C:N, nitrate removal efficiencies were >95% and final effluent nitrate concentrations were consistently <20mg N/L. However, at this dose rate, relatively high concentrations (>140 mg/L) of organic carbon (fBOD5) remained in the final effluents. Therefore, a 'compromise' organic carbon:nitrogen dose rate (2C:N) was trialled, at which nitrate removal efficiencies were maintained at >85%, final effluent nitrate concentrations were consistently below 45 mg N/L, and effluent fBOD5 concentrations were <25mg/L. This study has demonstrated that waste plant material is a suitable carbon source for the removal of nitrate from hydroponic wastewater in a denitrification filter.     

Use of wastewater as a nutrient solution in a closed gravel hydroponic culture of giant reed (Arundo donax)

The objective of this experimental work was to examine the efficiency of giant reed (Arundo donax L.), as a source of biomass production and as a biofiltering device for sewage effluents. Two giant reed populations were cultivated in a closed gravel hydroponic system, where pig's waste was used as a nutrient solution. The results showed that stem biomass production varied from 12 to 23 kg DM m(-2) yr(-1), more than the ordinary production in the soil. According to stem analysis, for the first two years, there was an average infiltration rate of 31 g m(-2) yr(-1) total N, 7.5 g m(-2) yr(-1) total P, 18.8 g m(-2) yr(-1) K, 2.1 g m(-2) yr(-1) Ca, 2.1 g m(-2) yr(-1) Mg, 0.27 g m(-2) yr(-1) Fe, 0.02 g m(-2) yr(-1) Mn, 0.14 g m(-2) yr(-1) Zn and 0.08 g m(-2) yr(-1) Cu. During the third year, when a nutrient solution with added P was used, the average infiltration rate for most elements increased by 46% and for P by 169%.     

Comparative effects of selenite and selenate on growth and selenium accumulation in lettuce plants under hydroponic conditions

The effects of different concentrations of selenite (2–30 μM) and selenate (2–60 μM) on biomass production, leaf area, and concentrations of photosynthetic pigments in lettuce plants were investigated. On the basis of the obtained results, the threshold of toxicity for the selenite and selenate has been designated. The toxicity thresholds for selenite and selenate were determined at concentrations of 15 and 20 μM, respectively. Next, four selenium (Se) concentrations (2, 4, 6 or 15 μM), below or near the toxicity boundary, have been selected for the lettuce biofortification experiment. In the biofortified plants, the oxidant status (levels of lipid peroxidation and H₂O₂ concentrations), as well as Se and sulphur (S) accumulation were analysed. In the edible parts of the lettuce, the Se concentration was higher for selenate presence compared to selenite; however, this difference was not as obvious as it was noted in the case of the roots, where selenite application caused the high accumulation of Se. An application of 15 μM Se as selenite caused a decline in the biomass and an intensification of prooxidative processes in the plant’s tissues and as toxic should be excluded from further biofortification experiments. These results indicate that an application of either selenate or selenite to the nutrient solution at concentrations below 15 μM can be used for biofortification of lettuce with Se, evoking better plant growth and not inducing significant changes in the oxidant status, the concentration of assimilation pigments and S accumulation.     

The usefulness of CHAPS as a non-cytotoxic stabilizing agent in purification of growth factors

Among several detergents, a zwitterionic detergent, 3-[(3-cholamidopropyl)dimethylammonio]-1-propane sulfonate (CHAPS), was found to be least cytotoxic for cultured mammalian cells. CHAPS improved the activity recovery and elution profile of crude and purified fibroblast growth factors (FGFs) during chromatographies. Diluted preparations of FGFs were stabilized by CHAPS against the loss during storage. Amino acid sequence analysis was not disturbed by CHAPS. CHAPS was removable by reversed-phase high-performance liquid chromatography. These results indicate that CHAPS is useful as a non-cytotoxic stabilizing agent in purification of various kinds of bioactive polypeptides.Abbreviations -MEM Alpha Modification of Eagle's Minimal essential medium - CHAPS 3-[(3-cholamidopropyl)dimethylammonio]-1-propane sulfonate - CHAPSO 3-[(3-cholamidopropyl)dimethylammonio]-2-hydroxy-1-propane sulfonate - CS Calf Serum - EGF Epidermal Growth Factor - FGF Fibroblast Growth Factor - HPLC High-Performance Liquid Chromatography - NGF Nerve Growth Factor - NOG 1-O-n-octyl--D-glucopyranoside - NP-40 Nonidet P-40 - PBS Phosphate-Buffered Saline - SB 12 3-(dodecylmethylammonio)-1-propane sulfonate - SDS Sodium Dodecyl Sulfate - TGF- and Transforming Growth Factor type and      

Kenyan medicinal plants used as antivenin: a comparison of plant usage

The importance of medicinal plants in traditional healthcare practices, providing clues to new areas of research and in biodiversity conservation is now well recognized. However, information on the uses for plants for medicine is lacking from many interior areas of Himalaya. Keeping this in view the present study was initiated in a tribal dominated hinterland of western Himalaya. The study aimed to look into the diversity of plant resources that are used by local people for curing various ailments. Questionnaire surveys, participatory observations and field visits were planned to illicit information on the uses of various plants. It was found that 35 plant species are commonly used by local people for curing various diseases. In most of the cases (45%) under ground part of the plant was used. New medicinal uses of Ranunculus hirtellus and Anemone rupicola are reported from this area. Similarly, preparation of "sik" a traditional recipe served as a nutritious diet to pregnant women is also not documented elsewhere. Implication of developmental activities and changing socio-economic conditions on the traditional knowledge are also discussed.     

Removal of nitrate and phosphorus from hydroponic wastewater using a hybrid denitrification filter (HDF)

A laboratory-scale hybrid-denitrification filter (HDF) was designed by combining a plant material digester and a denitrification filter into a single unit for the removal of nitrate and phosphorus from glasshouse hydroponic wastewater. The carbon to nitrate (C:N) ratio for efficient operation of the HDF was calculated to be 1.93:1 and the COD/BOD₅ ratio was 1.2:1. When the HDF was continuously operated with the plant material replaced every 2 days and 100% internal recirculation of the effluent, a high level of nitrate removal (320–5 mg N/L, >95% removal) combined with a low effluent sBOD₅ concentration (<5 mg/L) was consistently achieved. Moreover, phosphate concentrations in the effluent were maintained below 7.5 mg P/L (>81% reduction). This study demonstrates the potential to combine a digester and a denitrification filter in a single unit to efficiently remove nitrate and phosphate from hydroponic wastewater in a single unit.     

A feasibility study of a Salix viminalis gravel hydroponic system to renovate primary settled wastewater

A Salix viminalis/gravel system based on hydroponics was developed for wastewater renovation in order to avoid the problems of soil damage and pollution associated with long-term application of wastewater to soil. For such a system to work the mineral elements applied must match closely the requirements of the tree species. To examine this the growth and nutrient uptake of S. viminalis in wastewater was compared with that in Long Ashton nutrient solution (1/4 strength). S. viminalis grew more slowly in wastewater than in Long Ashton solution, but exhibited no obvious deficiency or toxicity symptoms. Since industrial wastewaters often contain metals, the extent to which copper might inhibit wastewater treatment in this system was also examined. S. viminalis was grown in wastewater amended with 10 and 100 ppm copper. Trees were unaffected by wastewater with 10 ppm copper when compared to trees grown in wastewater alone. Wastewater containing with 100 ppm copper was too toxic for the trees to thrive and wastewater treatment was reduced. Treatment efficiencies for unamended wastewater were 57.7% for nitrogen, 90.6% for phosphorus and 24.9% for potassium. These efficiencies are much greater than those quoted for a Salix/soil system, and thus Salix/gravel systems may have potential for wastewater treatment in environmentally sensitive areas or situations.     

The assembly of plants used as nectar sources by hummingbirds in a Cerrado area of Central Brazil

Studies on hummingbird–plant interactions commonly use a pollination approach emphasizing mutualistic relationships. But floral resources are often used opportunistically by these birds. Plant–pollinator assemblies and pollination sustainability will depend both on the well-adapted plants and other potential floral resources. The Cerrado, Neotropical savannas of Central Brazil, has ca. 7.5 % of its flora supposedly adapted to hummingbird pollination. But detailed information about flowers effectively used by hummingbirds at community level is still lacking. Hence, we recorded all plant species visited by hummingbirds, to determine how these nectariferous flowers were distributed in time and space in different plant formations of a Cerrado area, and also the hummingbird species that visit them. The study was conducted between March 2007 and December 2008 in the Panga Ecological Station. Data regarding flowering phenology, floral morphology and visitation were collected monthly. Forty-six nectariferous species from 39 genera and 17 families were recorded, most with annual flowering dynamics and tubular flowers. But only 21 species had a combination of traits fitting classic ornithophilous syndrome. For the remaining species hummingbird visitation was ascertained from observations at the study site or other sites in the region. Eight hummingbird species occurred in the area and were recorded visiting directly 36 plant species. The study area presented a relatively low number of ornithophilous plants, but a great habitat diversity and many non-ornithophilous plants that hummingbirds used as nectar sources. Therefore, in the studied Cerrado, the diversity of environments and nectariferous plants favour the maintenance of resident and migrant hummingbirds.     

Isolation of lignans as seed germination and plant growth inhibitors from Mediterranean plants and chemical synthesis of some analogues

Lignans and lignins are among the main metabolic products of phenylpropanoid metabolism in vascular plants. They are compounds representing the building blocks of plant cell walls. Moreover they have a broad range of biological activities such as antitumoral, antimitotic, antiviral and cytotoxic and are thought to be involved in the plant defense against pathogens and pests. In this paper we report a survey of the past and current literature about lignans and neolignans and their germination inhibitory activity on cultivated and wild species from plants of the Mediterranean area. Some examples of synthetic methodologies of these molecules have also been reported.     

Studies of the response of peach and nectarine plants to gibberellin biosynthesis inhibitors in a hydroponic system

In small rooted peach and nectarine plants grown in a hydroponic system, low paclobutrazol (PBZ) levels applied to the roots suppressed shoot and root development, but to a different degree. A much stronger retarding effect was observed on the shoot, with a very limited effect on roots, resulting in a reduced shoot:root ratio. The effect of the inhibitor on the roots was a rapid increase in root diameter, with increased root branching upon recovery from the inhibiting effect. Root thickening, a typical response to PBZ, was detected also in nectarines when only the top was treated with the inhibitor, indicating a basal movement of PBZ, thus contradicting the accepted notion that its translocation is only acropetal. Root thickening was the earliest detected morphological response to PBZ, being observed already 3 days after exposure to the retardant. The return to a normal diameter was abrupt. Uniconazol (UNI) had a much stronger retarding effect on peach plants than did similar concentrations of PBZ. Reduced top growth resulted in a reduction in water consumption.Abbreviations PBZ paclobutrazol - UNI uniconazol - GA Gibberellin - GBI gibberellin biosynthesis inhibitor - ABA abscisic acidThis research was supported by Grant no. 1-779-84 from the US-Israel Binational Agricultural Research and Development Fund (BARD).Contribution from the Agricultural research organization, The Volcani Center, Bet Dagan, Israel. No. 1506-E, 1994 series.     

Microsensors as a tool to determine chemical microgradients and bacterial activity in wastewater biofilms and flocs

Microsensors used in microbial ecology are reviewed with emphasis on new sensor developments (NO₃ ^-, NO₂ ^-, NH₄ ⁺, CO₂, H₂, H₂S and CH₄ microsensors as well as fiberoptical microsensors for O₂, temperature and pH). Examples of microsensor applications in biofilms and activated sludge flocs are presented, where sulfate reduction and denitrification were studied.     

The sniff as a unit of olfactory processing

Sniffing is a rhythmic motor process essential for the acquisition of olfactory information. Recent behavioral experiments show that using a single sniff rats can accurately discriminate between very similar odors and fail to improve their accuracy by taking multiple sniffs. This implies that each sniff has the potential to provide a complete snapshot of the local olfactory environment. The discrete and intermittent nature of sniffing has implications beyond the physical process of odor capture as it strongly shapes the flow of information into the olfactory system. We review electrophysiological studies-primarily from anesthetized rodents-demonstrating that olfactory neural responses are coupled to respiration. Hence, the "sniff cycle" might play a role in odor coding, by allowing the timing of spikes with respect to the phase of the respiration cycle to encode information about odor identity or concentration. We also discuss behavioral and physiological results indicating that sniffing can be dynamically coordinated with other rhythmic behaviors, such as whisking, as well as with rhythmic neural activity, such as hippocampal theta oscillations. Thus, the sniff cycle might also facilitate the coordination of the olfactory system with other brain areas. These converging lines of empirical data support the notion that each sniff is a unit of olfactory processing relevant for both neural coding and inter-areal coordination. Further electrophysiological recordings in behaving animals will be necessary to assess these proposals.     

Characteristics and mechanisms of the hydroponic bio-filter method for purification of eutrophic surface water

The hydroponic bio-filter method (HBFM) was adopted to purify eutrophic surface water. The average removal efficiency of total nitrogen (TN) and total phosphorus (TP) was 16.8% and 30.8%, respectively, at the hydraulic loading rate (HLR) of 3.0 m³ (m² d)⁻¹. The mass removal rate of TN and TP accordingly reached 1.0 and 0.1 g (m² d)⁻¹ separately. The sedimentation of particulate nitrogen and phosphorus played a major role in removal of nitrogen and phosphorus, which contribute 62.2% and 75.9%, respectively. The optimal HLR of HBFM ranged from 3.0 to 4.0 m³ (m² d)⁻¹. The sediment in midstream reached a maximum nitrification potential of 4.76 × 10⁻⁶ g (g h)⁻¹, while upstream it reached a maximum denitrification potential of 8.1 × 10⁻⁷ g (g h)⁻¹. The distribution of nitrification potential corresponded to the ammonium-oxidizing bacteria density. The key for improving nitrogen removal efficacy of HBFM system consisted of changing the nitrification/denitrification region distribution and accordingly enhancing the denitrification process. The sum of dissolved nitrogen removed by denitrification and plant assimilation was nearly equal to the amount released by sediment. Secateur length of Nasturtium officinale had some effect on its uptake rate. The length of cut should be less than 10 cm at a time. The harvesting frequency of once a month for N. officinale had no influence on nitrogen and phosphorus removal.     

Shoot and root growth of hydroponic maize (Zea mays L.) as influenced by K deficiency

Potassium (K) has major biophysical and biochemical functions in plant physiology. However, plant responses to K deficiency at the whole plant level are not always clearly related to these well-known functions of K at the cellular level. The objective of this study was to investigate the morphological response of maize to increasing K deficiency and test to what extent this morphological response can be interpreted in the light of the simple model proposed by Leigh and Wyn Jones, suggesting that biophysical functions are affected first. Maize was grown in a greenhouse under hydroponic conditions. For half of the plants, K was removed from the nutrient solution from the 4th visible leaf stage. The K content in the starved plants dropped from 100 to 30 mM, and was not fully compensated by an increase in other cations. Leaf elongation rates were reduced on K-deprived plants, whereas axile root elongation rates were slightly increased between 45°C days and 75°C days after starvation, and reduced thereafter. During the first part of the starvation period, i.e. under moderate K deficiency (K concentration above 40 mM), all measured variables suggest that the whole plant response may be interpreted as the consequence of the reduced leaf growth, probably due to insufficient turgor pressure or cell-wall extensibility. This general pattern of response is in agreement with the model of Leigh and Wyn Jones. However, during the second part of the starvation period, i.e. under more severe K deficiency (K concentration below 40 mM), malfunction of additional physiological processes (mostly related to biochemical functions like photosynthetic processes) must be considered to explain the plant morphological response.