Efficiency of nitrogen and phosphorus removal by six macrophytes from eutrophic water

Abstract

Increased nitrogen and phosphorus pollution causes eutrophication in water bodies. Using aquatic plants to remove nutrients from water is an attractive phytoremediation. It is a cost-effective, environment-friendly, and efficient way that reduces water body eutrophication by the plant. It is important to choose suitable macrophytes to remove excess N and P under different nutrient conditions. In this study, six macrophyte species (Polygonum orientale, Juncus effuses, Iris pseudocorus, Phragmites australis, Iris sanguinea, Typha orientalis) were tested. Simulation experiment was conducted under five N and P levels. The removal rate, relative growth rate, and the dynamic nutrition concentration of cultivated solution were investigated. Of all the treatment, a 23–95% reduction in N removal and a 29–92% reduction in P removal were recorded. The results showed I. sanguinea is a promising species to treat various eutrophic waters and the other five species can be used specifically to treat certain types of water. The data provided a theoretical guidance to plant species selection for phytoremediation of polluted water bodies for the purpose of water quality improvement around the different reservoir in northern China.     

丝状真菌液体深层发酵过程菌丝聚集的调控机制

丝状真菌是微生物发酵产品的重要表达体系,其液体深层发酵过程的典型特征是环境因素显著影响菌丝聚集,菌丝聚集影响发酵体系流变特性,进而影响质量传递、热量传递和动量传递,最终影响目标产物生物合成和生产效率。文中首先综述了丝状真菌形态调控的方法和策略,在此基础上针对丝状真菌菌丝生长和聚集过程的两大典型特征——顶端延伸生长和分枝生长,综述和展望了钙信号传导途径和几丁质生物合成途径对调控菌体聚集这一形态的重要意义。     

氨基酸和霉菌水提物对深层发酵桦褐孔菌菌丝体黄酮积累及其抗氧化活性的影响

黄酮类化合物是桦褐孔菌菌丝体中多酚类化合物的重要组成部分,也是该菌治疗众多疾病的有效成分之一。然而人工培养桦褐孔菌黄酮等酚类化合物积累甚少,导致药理活性的明显下降。为此,我们研究了3种氨基酸和4种霉菌水提物对深层发酵桦褐孔菌黄酮的积累及其抗氧化能力的影响。在所试验的3种氨基酸和4种霉菌水提物中,L-酪氨酸,黄曲霉和毛霉水提物能有效地增加该菌黄酮的积累。人工培养菌体中的黄酮至少由4种黄酮苷组成,苷元分别是槲皮素、柚皮素、山奈酚和异鼠李素。深层发酵菌丝体具有一定的抗氧化能力,并与总黄酮的含量呈正相关。由L-酪氨酸,黄曲霉和毛霉水提物调控生长的桦褐孔菌菌丝体,能有效地清除超氧阴离子、羟基自由基和DPPH自由基。     

Cross‐taxon congruence of multiple diversity facets of freshwater assemblages is determined by large‐scale processes across China

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Livestock disturbances in Mediterranean temporary ponds: A mesocosm experiment with sheep manure and simulated trampling

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Ecological influences on larval chironomid communities in shallow lakes: implications for palaeolimnological interpretations

1. To correctly interpret chironomid faunas for palaeoenvironmental reconstruction, it is essential that we improve our understanding of the relative influence of ecosystem variables, biotic as well as physicochemical, on chironomid larvae. To address this, we analysed the surface sediments from 39 shallow lakes (29 Norfolk, U.K., 10 Denmark) for chironomid head capsules, and 70 chironomid taxa (including Chaoborus) were identified. 2. The shallow lakes were selected over large environmental gradients of aquatic macrophytes, total phosphorus (TP) and fish communities. Redundancy analysis (RDA) identified two significant variables that explained chironomid distribution: macrophyte species richness (P < 0.001) and TP (P < 0.005). Generalised linear models (GLM) identified specific taxa that had significant relationships with both these variables. Macrophyte percentage volume infested (PVI) and species richness were significant in classifying the lake types based on chironomid communities under twinspan analysis, although other factors, notably nutrient concentrations and fish communities, were also important, illustrating the complexities of classifying shallow lake ecosystems. Lakes with plant species richness >10 all had relatively diverse (Hill’s N2) chironomid assemblages, and lakes with Hill’s N2 >10 all had TP <250 μg L⁻¹ and total fish densities <2 fish per m². 3. Plant density (PVI), and perhaps more importantly species richness, were primary controls on the distribution of chironomid communities within these lakes. This clearly has implications for palaeoenvironmental reconstructions using zoobenthos remains (i.e. chironomids) and suggests that they could be used to track changes in benthic/pelagic production and could be used as indicators of changing macrophyte habitat. 4. Measuring key biological gradients, in addition to physicochemical gradients, allowed the major controls on chironomid distribution to be assessed more directly, in terms of plant substrate, food availability, competition and predation pressure, rather than implying indirect mechanisms through relationships with nutrients. Many of these variables, notably macrophyte abundance and species richness, are not routinely measured in such studies, despite their importance in determining zoobenthos in temperate shallow lakes. 5. When physical, chemical and ecological gradients are considered, as is often the case with palaeo‐reconstructions rather than training sets chosen to maximise one gradient, complex relationships exist, and attempting to reconstruct a single trophic variable quantitatively may not be appropriate or reliable.     

Optimization of submerged culture requirements for the production of mycelial growth and exopolysaccharide by Cordyceps jiangxiensis JXPJ 0109

AIMS: The objective of the present study was to investigate the optimal culture requirements for mycelial growth and exopolysaccharide production by Cordyceps jiangxiensis JXPJ 0109 in submerged culture. METHODS AND RESULTS: The effects of medium ingredients (i.e. carbon and nitrogen sources, and growth factor) and other culture requirements (i.e. initial pH, temperature, etc.) on the production of mycelia and exopolysaccharide were observed using a one-factor-at-a-time method. More suitable culture requirements for mycelial growth and exopolysaccharide production were proved to be maltose, glycerol, tryptone, soya bean steep powder, yeast extract, medium capacity 200 ml in a 500-ml flask, agitation rate 180 rev min(-1), seed age 4-8 days, inoculum size 2.5-7.5% (v/v), etc. The optimal temperatures and initial pHs for mycelial growth and exopolysaccharide production were at 26 degrees C and pH 5 and at 28 degrees C and pH 7, respectively, and corresponding optimal culture age were observed to be 8 and 10 days respectively. According to the primary results of the one-factor-at-a-time experiments, the optimal medium for the mycelial growth and exopolysaccharide production were obtained using an orthogonal layout method to optimize further. Herein the effects of medium ingredients on the mycelial growth of C. jiangxiensis JXPJ 0109 were in the order of yeast extract > tryptone > maltose > CaCl2 > glycerol > MgSO4 > KH2PO4 and the optimal concentration of each composition was 15 g maltose (food-grade), 10 g glycerol, 10 g tryptone, 10 g yeast extract, 1 g KH2PO4, 0.2 g MgSO4, and 0.5 g CaCl2 in 1 l of distilled water, while the order of effects of those components on exopolysaccharide production was yeast extract > maltose > tryptone > glycerol > KH2PO4 > CaCl2 > MgSO4, corresponding to the optimal concentration of medium was as follows: 20 g maltose (food-grade), 8 g glycerol, 5 g tryptone, 10 g yeast extract, 1 g KH2PO4, and 0.5 g CaCl2 in 1 l of distilled water. CONCLUSIONS: Under the optimal culture requirements, the maximum exopolysaccharide production reached 3.5 g l(-1) after 10 days of fermentation, while the maximum production of mycelial growth achieved 14.5 g l(-1) after 8 days of fermentation. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first report on the submerged culture requirements for mycelial growth and exopolysaccharide in C. jiangxiensis, and this two-step optimization strategy in this study can be widely applied to other microbial fermentation processes.     

Morphological characterization and germination of aerial and submerged spores of the entomopathogenic fungus Verticillium lecanii

Under solid-state and liquid-state cultivations, the entomopathogenic fungus Verticillium lecanii F091 produced different types of spores. The aerial spores (AS) on cooked rice formed clusters on the tips of conidiophores, while the submerged spores (SS) were dispersed in the medium. The aerial spore appeared relatively uniform in size, which was 6.1 ± 0.9 m long, and 2.2 ± 0.3 m wide. The submerged spore varied in shape and size, with a mean length of 5.0 ± 1.0 m and width of 1.9 ± 0.5 m. Under scanning electron microscopy, the AS had a tendency to have rough, brittle surface characteristics; however, the SS appeared smooth on the surface. These spores were compared in two different germination media. On SMAY (Sabouraud maltose, agar, yeast extract, and neopeptone) coated coverslips, the AS did not show germ tubes until 8 h of incubation; while the SS showed many germ tubes. However, over 90% spore germination ratio was reached for both types of spores at 18-h of incubation. In the liquid medium, the SS germinated rapidly and many spores even produced spores on the spores; while the AS germinated, grew, and branched in the submerged culture gradually, and some sporulated on the tips of the short branches, or on the mycelia until 18 h of incubation. Evidently, the germination, growth patterns of aerial or submerged spores differed greatly under the different culture conditions. The virulence of the pathogen in relation to the type of spore of V. lecanii is discussed.