Effects of raw and diluted municipal sewage effluent with micronutrient foliar sprays on the growth and nutrient concentration of foxtail millet in southeast Iran

In this study, the effect of irrigation with raw or diluted municipal sewage effluent accompanied by foliar micronutrient fertilizer sprays was examined on the growth, dry matter accumulation, grain yield, and mineral nutrients in foxtail millet plants. The experimental design was a split plot with three irrigation sources: raw sewage, 50% diluted sewage, and well water comprising the main treatments, and four combinations of Mn and Zn foliar sprays as sub-treatments that were applied with four replications. The experiment was conducted in 2009 at the Zabol University research farm in Zabol, south Iran. The applied municipal sewage effluent contained higher levels of micronutrients and macronutrients and exhibited greater degrees of electrical conductivity compared to well water. Because of the small scale of industrial activities in Zabol, the amount of heavy metals in the sewage was negligible (below the limits set for irrigation water in agricultural lands); these contaminants would not be severely detrimental to crop growth. The experimental results indicated that irrigation of plants with raw or diluted sewage stimulates the measured growth and productivity parameters of foxtail millet plants. The concentrations of micronutrients and macronutrients were also positively affected. These stimulations were attributed to the presence of high levels of such essential nutrients as N, P, and organic matter in wastewater. Supplied in sewage water alone, Mn and Zn were not able to raise the productivity of millet to the level obtained using fertilizers at the recommended values; this by itself indicated that additional nutrients from fertilizers are required to obtain higher levels of millet productivity with sewage farming. Despite the differences in nutrient concentrations among the different irrigation water sources, the micronutrient foliar sprays did not affect the concentrations of micronutrients and macronutrients in foxtail millet plants. These results suggested that municipal sewage effluent could be utilized efficiently as an important source of water, and that the nutrients used in growing foxtail millet with sewage water irrigation did not have any significant harmful effect on crop productivity. In contrast, the nutrients proved beneficial to soil fertility and millet productivity and quality.     

Anaerobic digestates are useful nutrient sources for microalgae cultivation: functional coupling of energy and biomass production

We investigated the extent to which nitrogenous and phosphorus nutrients from liquid anaerobic digestates could be recycled for photosynthetic growth of a microalga, Scenedesmus sp. AMDD. Digestates recovered from the anaerobic digestion of cow manure and swine manure and a co-digestion of swine manure and algal biomass were diluted in distilled water and used for algal growth with and without supplemental CO₂ addition. Nutrient assimilation and final biomass yield were retarded in all but the swine manure/algae co-digestate cultures supplemented with high CO₂. Swine manure digestate cultures supplemented with the typical complement of micronutrients normally added with a commonly used growth medium or with Fe/EDTA failed to grow any better than unamended controls. When the culture medium was prepared by blending swine manure digestate with 25 or 50 % algal biomass digestate, diluting it with lake water or by supplementing with magnesium, nutrient assimilation and final algal biomass yields were maximized, indicating that magnesium was critically limiting for algal growth in swine manure digestates. Magnesium amendment thus appears to be essential if nutrients from swine manure digestates are recycled for algal growth. No such requirement is necessary for recycling nutrients from digestates generated wholly or in part from algal biomass.     

Adaptation of anaerobic biomass to saline conditions: Role of compatible solutes and extracellular polysaccharides

This study investigated the role of compatible solutes, extracellular polysaccharides (EPS), and nutrients on anaerobic biomass when stressed with salinity. When 1 mM of osmoregulants glycine betaine, α-glutamate and β-glutamate were added separately to serum bottles containing biomass not adapted to sodium, and fed with glucose and 35 g NaCl/L, all the compatible solutes were found to alleviate sodium inhibition, although glycine betaine was found to be the most effective. The effect of glycine betaine on different anaerobic bacterial groups under salinity stress was monitored using VFAs, and showed that methanogens were more protected than propionate utilisers. Moreover, the addition of 1 mM of glycine betaine to anaerobic biomass not adapted to salinity resulted in significantly higher methane production rates compared with anaerobic biomass that was exposed for 4 weeks to 35 g NaCl/L. Interestingly, under saline batch conditions when the medium was replaced totally the culture produced less methane than when only new substrate was added due to compatible solutes cycling between the media and the cell. The elimination of macronutrients from the medium was found to have a more pronounced negative effect on biomass under saline compared with nonsaline conditions, and because of the synthesis of N-compatible solutes sufficient nutrients should always be present. On the other hand, the absence from the medium of micronutrients did not further reduce biomass activity under salinity. Finally, a higher production of EPS was obtained from biomass exposed to higher salt concentrations, and its composition was found to change under different saline conditions and time. As a result, biomass under saline conditions had a slightly higher mean flock size compared with the biomass that was not subjected to salt.     

Kinetics of mineral nutrient uptake by Saponaria officinalis L. suspension cell cultures in different media

The uptake of mineral nutrients from two media with different mineral composition, a classical MSA medium and a modified MH2 medium, by Saponaria officinalis (soapwort) cells was studied over a growth cycle of 14 days, by continuous measurement of mineral consumption without opening the culture flasks. The mineral composition of the MH2 medium was found to be better suited to S. officinalis cells. Culture on MSA medium showed that copper is probably a factor limiting growth, that phosphate is rapidly exhausted from this medium, that its strong ammonium concentration is antagonistic to the absorption of potassium and, lastly, that sodium and chlorine may be considered as non-essential elements. Received: 13 March 1998 / Revision received: 9 June 1998 / Accepted: 1 July 1998     

The Effect of Nutrient Medium Composition on the Growth Cycle of Catharanthus roseus G. Don Cells Grown in Batch Culture

Growth of C. roseus cell suspension culture was defined in termsof dry weight, cell number, mitotic index, and packed cell volume.Removal of major nutrients from the medium was monitored asa function of culture growth. Phosphate and sucrose were theonly macronutrients completely exhausted. Utilization of thesetwo nutrients occurred parallel with increments in dry weightand cell number. Increasing the nutrient medium levels of sucroseand phosphate prolonged growth of this culture; lag and exponentialphases were extended; cell number and dry weight yield weredoubled. Dry weight assimilation was enhanced by increasingthe nutrient medium level of sucrose, whereas increments incell number were related to phosphate level. Two alkaloid fractions(fractions 1 and 2) were identified in this cell line. Fraction2 alkaloid level declined as the nutrient medium supply of nitrogenwas depleted.     

Production of Biomass and Ginsenosides from Adventitious Roots of Panax ginseng in Bioreactor Cultures

Organic nutrients play a central role during Panax ginseng adventitious root culture in bioreactor systems. To understand how the nutrient elements were uptaken during the adventitious root growth as well as the production of biomass and natural ginsenosides, a biotechnological approach to identifying the nutritional physiology of ginseng in a commercial‐scale bioreactor was necessary. Normal MS medium nutrient in the bioreactor culture of adventitious roots resulted in slow growth, low biomass, and Rg and Rb ginsenoside contents. When the ginsenoside production increased to higher levels, a group of regulatory nutritional elements that have the potential to interact with biomass was identified. The effects of the salt strength of the medium, of macroelements, metal elements, the ammonia/nitrate ratio, sucrose concentration, and osmotic agents on the growth, the formation of biomass and the production of ginsenosides from adventitious roots were investigated. Appropriate conditions allowed for a maximum ginsenoide production of up to 12.42 [mg/g DW] to be obtained after 5 weeks of culture. The results demonstrated that the key organic nutrients can be regulated to improve the biomass and growth, and increase the ginsenoside yield in bioreactor cultures of P. ginseng adventitious roots.     

Potential of Chlorella vulgaris culture for waste treatment from anaerobic biomass biodigestion at the Piaszczyna (Poland) integrated facility

Many strains of microalgae are potentially useful for industrial purposes. Microalgal biomass and microalgae‐derived substances are becoming valuable products with a widening range of applications including biofuels and human food. In this study, the possibility of using the methane waste from biomass biodigestion in the cultivation of Chlorella vulgaris biomass with simultaneous waste treatment was investigated. The methane waste from biomass biodigestion was obtained from a multifunctional facility (Piaszczyna, Poland) producing bioethanol from plant biomass with several steps to reuse the wastes, heat, and carbon dioxide. The growth and biomass yield, as well as photosynthetic performance of C. vulgaris on diluted waste, were similar to the results obtained on the standard mineral medium. The cultivation of C. vulgaris was the waste, treatment step that significantly reduced chemical oxygen demand. The results indicated that the waste contained micro‐ and macronutrients sufficient to sustain the growth of C. vulgaris cell culture up to 2 g of dry biomass per liter of culture. The results contributed to the development of the waste treatment step in the Piaszczyna facility that allowed for a further decrease in emissions and may lead to development of microalgae biomass‐based products in the facility portfolio.     

Decreased mineral availability enhances rock phosphate solubilization efficiency in <Emphasis Type="Italic">Aspergillus niger</Emphasis>

Microbial solubilization of rock phosphate (RP) is mainly achieved by the production of organic acids and medium acidification through H⁺ release. During RP solubilization, mineral nutrient availability is likely to be critical for determining how much carbon is channeled either for metabolite synthesis or for microbial growth, influencing organic acid release by microorganisms. Thus, the objective of this work was to study the relationships between the concentration of mineral nutrients in the growth medium and the efficiency of RP solubilization by Aspergillus niger FS1. For this, the fungus was grown in Czapek medium containing 0, 1, 2, 10, 50, and 100 % of its original concentration of mineral nutrients. Decreasing mineral availability in the growth medium led to decreases in fungal biomass and solubilized P, and increases in titratable acidity and solubilization efficiency as expressed by mg solubilized P per g fungal biomass (Y_P/B), indicating a shift in fungal metabolism from biomass production to organic acid release. The transfer of pre-grown biomass to media with or without added minerals confirmed that lower mineral availability increases Y_P/B and led to the solubilization of 76 % of P present in Patos RP. These observations open new perspectives on improving RP solubilization systems by manipulating mineral nutrient availability in the medium, with consequent gains in cost reduction.     

Micronutrient Requirements for Growth and Hydrocarbon Production in the Oil Producing Green Alga Botryococcus braunii (Chlorophyta)

The requirements of micronutrients for biomass and hydrocarbon production in Botryococcus braunii UTEX 572 were studied using response surface methodology. The concentrations of four micronutrients (iron, manganese, molybdenum, and nickel) were manipulated to achieve the best performance of B. braunii in laboratory conditions. The responses of algal biomass and hydrocarbon to the concentration variations of the four micronutrients were estimated by a second order quadratic regression model. Genetic algorithm calculations showed that the optimal level of micronutrients for algal biomass were 0.266 μM iron, 0.707 μM manganese, 0.624 μM molybdenum and 3.38 μM nickel. The maximum hydrocarbon content could be achieved when the culture media contained 10.43 μM iron, 6.53 μM manganese, 0.012 μM molybdenum and 1.73 μM nickel. The validation through an independent test in a photobioreactor suggests that the modified media with optimised concentrations of trace elements can increase algal biomass by 34.5% and hydrocarbon by 27.4%. This study indicates that micronutrients play significant roles in regulating algal growth and hydrocarbon production, and the response surface methodology can be used to optimise the composition of culture medium in algal culture.     

Influence of aluminum in nutrient solutions on chemical composition in upland rice cultivars

Summary Aluminum toxicity is an important growth limiting factor for upland rice production on oxisols of cerrado region in Brazil. Data related to the effect of Al on uptake of nutrients for rice crop are limited. The effect of five Al concentrations (0, 10, 20, 40 and 60 ppm) in culture solution on the chemical composition of 30 upland rice cultivars was studied.Aluminum concentration and content in plant tissues were increased with higher levels of Al in all cultivar. In the roots Al content was higher as compared with the tops. Critical toxic level of Al in the tops of 21 days old plants varied from 100 to 417 ppm depending on the cultivars. Rice cultivars responded differently to Al treatments with respect to nutrients uptake. Increased Al concentrations in the solution exerted an inhibiting effect on the concentrations and contents of N, P, K, Ca, Mg, S, Na, Zn, Fe, Mn, B and Cu. Thus the inhibition was more effective for macronutrients in the plant tops in following order: Mg>Ca>P>K>N>S>Na. Whereas for micronutrients it was in the order of Mn>Zn>Fe>Cu>B. Morphological, physiological and biochemical effects of Al, toxicity responsible for the reduction in plant nutrient uptake, are discussed.     

Batch Production of Protein from Ethane and Ethane-Methane Mixtures

A culture of Graphium grows upon natural gas and a mineral salt solution. Ethane is the preferred substrate but methane is co-utilized. A stirred-tank type fermentor was used to study batch growth. Maximum production rate of biomass was 80 mg/liter.hr, at pH 4, using simple synthetic supporting medium with ammonium sulfate as a nitrogen source. This rate was observed after 40 hr of fermentation. A doubling time of 3.7 hr was observed. The corresponding specific growth rate was 0.187 per hr. A magnetic drive fermentor was used to study the effect of continuous recycle of gases in a gas-tight system. The rate of oxygen utilization is approximately 2.1 times higher than for ethane. Oxygen must not be allowed to become limiting in recycle gases. The calculated efficiency of overall biomass synthesis averages 30%. Hyphal and unicellular tissue of Graphium contains 52% protein. It compares favorably with standard FAO protein in its content of amino acids.     

Seeking salt: herbivorous prairie insects can be co‐limited by macronutrients and sodium

The canonical factors typically thought to determine herbivore community structure often explain only a small fraction of the variation in herbivore abundance and diversity. We tested how macronutrients and relatively understudied micronutrients interacted to influence the structure of insect herbivore (orthopteran) communities. We conducted a factorial fertilisation experiment manipulating macronutrients (N and P, added together) and micronutrients (Ca, Na and K) in large plots (30 × 30 m²) in a Texas coastal prairie. Although no single or combination of micronutrients affected herbivore communities in the absence of additional macronutrients, macronutrients and sodium added together increased herbivore abundance by 60%, richness by 15% and diversity by 20%. These results represent the first large‐scale manipulation of single micronutrients and macronutrients in concert, and revealed an herbivore community co‐limited by macronutrients and Na. Our work supports an emerging paradigm that Na may be important in limiting herbivore communities.     

Relationships between macro- and micronutrient nutrition of slash pine on three coastal plain soils

Summary Slash pine seedlings on Bladen, Leon, and Lakeland soils responded differently to P and N fertilization. Seedling growth was increased by all treatments on Bladen soil, whereas responses by seedlings on the other soils were nil. All soils were low in extractable P with both Bladen and Lakeland yielding 0.85 ppm P. Growth response to fertilizer was positive on Bladen soil because soil and tissue levels of P were raised above “critical” levels and other nutrients were present in adequate quantities. Tissue analyses indicated, and subsequent experiments utilizing macro- and micronutrients proved, that excess P applications reduced certain micronutrients to growth-limiting levels on both Leon and Lakeland soils. Best growth on Leon soil occurred when P and N were supplemented with Cu. On the Lakeland soil macronutrients supplemented with Cu, Mn, or Zn produced greatest growth. Toxicity levels of five micronutrients on the latter soil also were determined. Journal Series No. 3506, Florida Agricultural Experiment Station, Gainesville. Research supported by Cooperative Research in Forest Fertilization program.     

Boron application increases growth of Brazilian Cerrado grasses

Nutrients are known to limit productivity of plant communities around the world. In the Brazilian Cerrado, indirect evidences point to phosphorus as the main limiting nutrient, but some fertilization experiments suggest that one or more micronutrients might play this role. Boron is one of the essential micronutrients for plants. Agronomically, it received some attention, but it has mostly been neglected in ecological studies assessing the effects of nutrients on plant growth. Through field fertilization and mesocosm experiments in a degraded area in the Cerrado, we show that boron addition increased biomass production of herbaceous vegetation. This could be related to a lower aluminum uptake in the boron fertilized plants. Even considering that plant growth was promoted by boron addition due to aluminum toxicity alleviation, this is the first study reporting boron limitation in natural, noncultivated plant communities and also the first report of this kind in vegetative grasses. These results contribute to disentangling patterns of nutrient limitation among plant species of the species‐rich, aluminum‐rich, and nutrient‐poor Cerrado biome and highlight the potential role of micronutrients, such as boron, for growth of noncrop plants. Understanding how nutrient limitation differs among functional groups in the highly biodiverse areas founded on ancient tropical soils may help managing these plant communities in a changing world.     

Liposomes replace serum for cultivation of fermenting mycoplasmas

Cholesterol and albumin are limiting factors in the growth of Mycoplasma species. These nutrients are usually supplied in the culture medium by the addition of serum. The growth of M. pneumoniae in a serum-free medium containing an ethanolic cholesterol suspension and albumin was about one-half the level attained in serum-containing medium. M. gallisepticum and M. fermentans were not cultivable in the cholesterol suspension medium even after supplements were included. In another culture medium containing phosphatidylcholine-cholesterol liposomes and albumin as serum replacements, the growth of M. pneumoniae was approximately equal to that in serum-containing medium, and the growth of M. gallisepticum and M. fermentans was significantly greater than that in medium containing serum. M. fermentans produced even higher yields in liposome medium supplemented with arginine. These fermenting mycoplasmas readily adapted to the liposome medium and by the fifth or sixth serial passage produced thick confluent growth on the lower surface of culture bottles. To obtain maximum growth, we serially transferred the mycoplasmas at least 10 times in serum-free medium before quantitations of growth were made. This is the first report of a serum-free mycoplasma medium of high growth-promoting ability.     

Liposomes replace serum for cultivation of fermenting mycoplasmas.

Cholesterol and albumin are limiting factors in the growth of Mycoplasma species. These nutrients are usually supplied in the culture medium by the addition of serum. The growth of M. pneumoniae in a serum-free medium containing an ethanolic cholesterol suspension and albumin was about one-half the level attained in serum-containing medium. M. gallisepticum and M. fermentans were not cultivable in the cholesterol suspension medium even after supplements were included. In another culture medium containing phosphatidylcholine-cholesterol liposomes and albumin as serum replacements, the growth of M. pneumoniae was approximately equal to that in serum-containing medium, and the growth of M. gallisepticum and M. fermentans was significantly greater than that in medium containing serum. M. fermentans produced even higher yields in liposome medium supplemented with arginine. These fermenting mycoplasmas readily adapted to the liposome medium and by the fifth or sixth serial passage produced thick confluent growth on the lower surface of culture bottles. To obtain maximum growth, we serially transferred the mycoplasmas at least 10 times in serum-free medium before quantitations of growth were made. This is the first report of a serum-free mycoplasma medium of high growth-promoting ability.     

Response of secondary vegetation in Eastern Amazonia to relaxed nutrient availability constraints

This study evaluated the effect of nutrient application on the regrowth dynamics of secondary fallow vegetation in an intensely exploited shifting cultivation area in the eastern Amazon region of Brazil. The importance of N, P, K, Ca, Mg, S and a mixture of micronutrients was tested in a minus-one-trial by comparison with a full complement of nutrients and unfertilized control plots. Fertilizers were applied three times during the experiment and their effects were monitored over a period of 2 1/2 years. Prior to the second fertilization, one third of each experimental plot was cleared of the vegetation cover and planted in maize, prior to the third fertilizer application these subplots were planted in sorghum. Biomass of maize and sorghum were used to indicate nutrient constraints and fertilizing effects due to the different treatments. Both crops were limited by P- and N-availability, with greater responses to P. The initial fertilization did not affect the biomass accumulation of the secondary vegetation during the first 15 months, but two additional applications significantly increased biomass in the complete fertilizer treatment compared to the unfertilized control. Biomass accumulation was primarily P-limited, N-limitation was apparent but not significant. The remaining nutrients did not affect plant growth. Fertilization favored production of nutrient-rich leaves. Application of readily available nutrients gave grasses a competitive edge over slower reacting woody vegetation. Fertilization also caused significant shifts in the contribution of woody species to biomass accumulation, as could be demonstrated for two prominent pioneer tree species. Growth response to fertilization as well as the primary limiting nutrient varied among seven dominant species monitored in the secondary vegetation. We conclude that growth of tropical secondary vegetation can be nutrient limited and it might respond significantly to additional nutrients by increasing biomass production.     

Growth and nutrition of small Betula pendula plants at different relative addition rates of iron,manganese and zinc

In order to investigate the dependence of growth rate upon plant concentrations of iron, manganese and zinc, Betula pendula seedlings were cultivated in a hydroponic system. In three different experiments, all essential nutrient elements except iron, manganese or zinc, were titrated in non-growth limiting amounts at low external concentrations. The solution was continuously recirculated and sprayed on the roots. The micronutrients (Fe, Mn and Zn) were added as addition rates, R_A (day^-1), relative to the calculated internal amount in the plants. No chelates were added to the culture solution.At steady-state nutrition, plant relative growth rate showed a linear dependence upon the internal concentration of the limiting micronutrient. These data do not support the Steenbjerg effect where negative correlations between growth and plant nutrient concentrations have been reported. Steady-state nutrition was associated with very different growth responses to the different limiting nutrients.     

Effects of wheat plant inoculation with cytokinin-producing microorganisms on plant growth at increasing level of mineral nutrition

Triticum durum Desf. plants were grown for 11 days in sand culture on nutrient solutions with optimum or lowered content of mineral nutrients. Thereafter, the level of mineral nutrition was increased in some portion of deficient plants. Two days before, plants were inoculated with cytokinin-producing microorganisms of the Bacillus genus. Nutrition deficiency resulted in a decrease in the rate of plant biomass accumulation, which was correlated with the level of active cytokinins in both roots and shoots. After improving the mineral nutrition of noninoculated plants, the rate of their biomass accumulation increased and, by the end of experiment, their shoot fresh weight was 1.5-fold higher than in deficient plants; however, it was still by 20% lower than in plants continuously growing at optimum mineral nutrition. Inoculation resulted in the considerable increase in the cytokinin content in shoots as compared with all other treatments. In this case, after the improvement of plant mineral nutrition, the rates of growth and relative biomass accumulation increased sharply; as a result, these plants had the highest dry and fresh weights. Thus, inoculation with cytokinin-producing bacteria was beneficial for plant growth after their transfer from deficient to sufficient mineral nutrition.     

Photosynthetic development of Ocimum basilicum cells on transition from phosphate to fructose limitation

Continuous culture was used to establish a steady state in fructose excess. Phosphate in the Murashige and Skoog type medium was found to be limiting growth; when phosphate concentration in the medium feed was doubled, the concentration of dry biomass and of all biomass elements increased After doubling the phosphate concentration fructose became limiting. Ocimun basilicum cells responded to the transition from phosphate limitation to fructose limitation by becoming greener and more photosynthetic; consequently, the yield on fructose increased.