The smallest space miners: principles of space biomining

As we aim to expand human presence in space, we need to find viable approaches to achieve independence from terrestrial resources. Space biomining of the Moon, Mars and asteroids has been indicated as one of the promising approaches to achieve in-situ resource utilization by the main space agencies. Structural and expensive metals, essential mineral nutrients, water, oxygen and volatiles could be potentially extracted from extraterrestrial regolith and rocks using microbial-based biotechnologies. The use of bioleaching microorganisms could also be applied to space bioremediation, recycling of waste and to reinforce regenerative life support systems. However, the science around space biomining is still young. Relevant differences between terrestrial and extraterrestrial conditions exist, including the rock types and ores available for mining, and a direct application of established terrestrial biomining techniques may not be a possibility. It is, therefore, necessary to invest in terrestrial and space-based research of specific methods for space applications to learn the effects of space conditions on biomining and bioremediation, expand our knowledge on organotrophic and community-based bioleaching mechanisms, as well as on anaerobic biomining, and investigate the use of synthetic biology to overcome limitations posed by the space environments.

Phenolics and Mineral Elements Composition in Underutilized Apple Varieties

(1) Background: The aim of this research is to study the importance of improving knowledge of old variety apples in terms of phytochemicals, antioxidant capacity and mineral elements. (2) Methods: Fifteen phenolic compounds (UHPLC-MS/MS techniques), eight mineral elements (Ca, K, Cu, Mn, Fe, Zn, Na and Mg), antioxidant capacity (DPPH%) and vitamin C content in four ancient apple varieties of Tuscany (‘Mora’, ‘Nesta’, ‘Panaia’ and ‘Ruggina’), with the ‘Golden Delicious’ cultivar as reference, were analyzed. (3) Results: Ancient cultivars exhibited a superior antioxidant capacity compared to commercial cultivars. ECTC and CGA were the polyphenols that mostly characterized the ancient apples. The contents of the elements of concern, Zn and Mn, were higher in the ancient cultivars ‘Panaia’ and ‘Ruggina’, while Na showed significant low concentration in ‘Nesta’, ‘Panaia’ and ‘Ruggina’ compared to ‘Golden Delicious’. The vitamin C content also indicated that ‘Mora’, ‘Panaia’ and ‘Ruggina’ old variety had an AsA content around 10 times higher than the ‘Golden Delicious’ apple. (4) Conclusions: Underutilized varieties could be an excellent source of bioactive phenolic phytochemicals, mineral nutrients and vitamins that may offer special nutraceutical benefits compared to other fruits.

Transient Nutrient Deficiencies in Pea: Consequences on Nutrient Uptake, Remobilization, and Seed Quality

Legume plants, such as peas, are of significant nutritional interest for both humans and animals. However, plant nutrition and thus, seed composition, depends on soil mineral nutrient availability. Understanding the impact of their deprivation on the plant mineral nutrient content, net uptake, and remobilization is of key importance but remains complex as the elements of the plant ionome are linked in intricate networks, one element deprivation impacting uptake and remobilization of other nutrients. To get a better insight into pea mineral nutrition, the transitory deprivations of 13 mineral nutrients were imposed during the vegetative growth phase. Thereafter, plants were grown under optimal mineral conditions until physiological maturity. Plant nutritional status and seed quality impacts caused by the deprivations were characterized using measurement of mineral nutrient concentration and plant biomass allocation. Our results highlight: (i) the preferential allocation of dry weight and elements to shoots at the expense of the roots under non-limiting conditions, and more particularly to the tendrils in comparison to the other shoot organs, (ii) the positive and/or negative impact of one mineral nutrient deprivation on other elements of the ionome, (iii) four different remobilization strategies for eight mineral nutrients, and (iv) possible strategies to improve seed quality via fine control of fertilization during a period of mineral nutrient deficiency.

The influence of toxic metals As, Cd, Ni and Pb on nutrients accumulation in Mentha piperita

Medicinal plants are, for a considerable part of the population, an important source of treatment for certain diseases. They contain essential nutrients for the human body such as magnesium, iron , and zinc. The present study shows the influence of the addition of As, Cd, Ni, Pb on mineral nutrients in different organs of Mentha piperita. The experiments were carried out in the laboratory for a period of three months (May-July). Mentha piperita plants were AsCd and AsCdNiPb exposed up to final concentrations corresponding to the soil intervention threshold according to Romanian Order no.756/1997 (25 mg/kg As, 5 mg/kg Cd, 150 mg/kg Ni and 100 mg/ kg Pb). Simultaneously with these experiments, a control experiment (M) was performed. To evaluate the effect of the addition of AsCd and AsCdNiPb on the accumulation and transfer of Ca, Cr, Cu, Mn, Mo, Fe and Zn, the transfer coefficient (TC), the translocation factor (TF), and the enrichment factor (EF) were calculated. A higher concentration of Ca, Cr, Cu, Fe, Mn, Mo, and Zn was observed especially in the mint root in the experiments in which AsCdNiPb was added compared to those in which only AsCd was added. The AsCdNiPb addition did not influence the translocation of micro and macronutrients from the root to the aerial (edible) parts of the plant. In the case of the AsCd, addition, the translocation of zinc from the root to the aerial parts (leaves and stem) of the plant was increased.

Nutrient Deficiency Affects the Growth and Nitrate Concentration of Hydroponic Radish

In hydroponics, a continuous supply of mineral nutrients is essential for plant growth. However, constitutive nutrient-rich conditions also increase the nitrate content in the plants, which can be harmful to human health. Here, we investigated the effect of nutrient deficiency on the growth and component composition of hydroponic radish by changing the timing of nutrient removal from the hydroponic solution. Radish plants that were 14 days old were transferred to four different nutrient conditions for 14 days: nutrient deficiency for 14 days (WW), full nutrient for 14 days (NN), nutrient deficiency for the last 7 days (NW), and nutrient deficiency for the first 7 days (WN). After the treatments, the NW plants had similar taproot growth to NN plants. In contrast, the WN plants significantly reduced taproot growth. The WW plants reduced the shoot and taproot weight and their water contents. The nitrate content in the taproots was reduced in the NW and WW plants. The WW plants contained lower total phenol and higher ascorbic acid and sugar contents. These results suggest that the uptake of nutrient minerals at the young growth stage is important for the growth of radish taproot. Nutrient deficiency management can be one of the most effective tools for regulating radish growth and composition.

Effects of Exogenous Application of Indole-3-Butyric Acid on Maize Plants Cultivated in the Presence or Absence of Cadmium

Auxins are plant hormones that affect plant growth, development, and improve a plant’s tolerance to stress. In this study, we found that the application of indole-3-butyric acid (IBA) had diverse effects on the growth of maize (Zea mays L.) roots treated without/with Cd. IBA caused changes in the growth and morphology of the roots under non-stress conditions; hence, we were able to select two concentrations of IBA (10−11 M as stimulatory and 10−7 M as inhibitory). IBA in stimulatory concentration did not affect the concentration of H2O2 or the activity of antioxidant enzymes while IBA in inhibitory concentration increased only the concentration of H2O2 (40.6%). The application of IBA also affected the concentrations of mineral nutrients. IBA in stimulatory concentration increased the concentration of N, K, Ca, S, and Zn (5.8–14.8%) and in inhibitory concentration decreased concentration of P, K, Ca, S, Fe, Mn, Zn, and Cu (5.5–36.6%). Moreover, IBA in the concentration 10−9 M had the most positive effects on the plants cultivated with Cd. It decreased the concentration of H2O2 (34.3%), the activity of antioxidant enzymes (23.7–36.4%), and increased the concentration of all followed elements, except Mg (5.5–34.1%), when compared to the Cd.

A study of triangular membership function and multiple regressions to calculate the MSW compost index

The municipal solid waste compost consists of elements with a varied composition, including light and heavy metal elements. For MSW compost to act as a soil conditioner, and to ensure agricultural stakeholders to believe in its use for crops production, validation of elements is obligatory. The triangular membership function evaluates each element of a fuzzy set for both discrete and continuous values, and regression analysis estimates the relationship between values. In this paper, a triangular membership function (μf) is studied and used to characterize the effect of individual elements available in the compost sample. The characterization determines the variation in the composition of elements in the compost sample and accordingly calculates its scorei. Furthermore, a reinvestigation is done by applying multiple regression analysis, especially on heavy metals, to compare their composition with light mineral nutrients and other supplementary elements. A relationship between R=4.12 and R2=0.067498635 is derived to determine the predicted value and defines the composition of heavy metals as attributed to another mineral nutrients. Furthermore, a correlation (Co) is derived to find the performance of the compost sample todecide whether both light and supplementary mineral nutrients are capable of minimizing the effect of heavy metals. A gratuity score (Gsi) is added to each heavy metal depending on the correlation value to form a composti. The scorei=88.11 and composti = 9.12 obtained, was summated to derive Ci=97.23, stating that the increase in score value declares that the compost sample is mature enough to be used for agriculture and enhance crops productivity.

The Effect of the Upregulated Expression of Fe Regulators IMA1 and bHLH104 in Arabidopsis on the Root Length and Fe Homeostasis Under Pi Starvation

Phosphate (Pi) and iron (Fe) are two essential mineral nutrients for plant growth and development. Pi starvation triggers the Fe local redistribution and over-accumulation, resulting in the reduction of the primary root, while represses the expression of Fe uptake genes. Nevertheless, the antagonistic mechanism between P and Fe nutrition in plant remain not addressed. Here, the effect of the upregulated expression of Fe regulators IMA1 and bHLH104 driven by the different-type promoters (proCaMV 35S, the promoters of Pi-starvation responsive genes proIPS1 and proPHT1;4) in response to Pi starvation was investigated in Arabidopsis. The results showed that the expression of Fe uptake genes IRT1 and FRO2 was successfully upregulated in proIPS1::IMA1, proPHT1;4::IMA1 and proIPS1::bHLH104 under Pi starvation while decreased in pro35S::IMA1, pro35S::bHLH104 and proPHT1;4::bHLH104, compared with that in the corresponding plants under Pi sufficiency. Although the length and Fe distribution in roots of them didn’t have significant difference with wild type under Pi starvation, the Fe distribution and total Fe contents were significantly increased in shoots of proIPS1::IMA1, proPHT1;4::IMA1 and proIPS1::bHLH104 while were decreased in proPHT1;4::bHLH104. The higher Fe concentrations in the Pi-starved transgenic plants also conferred the obviously tolerance to Fe deficiency. Their biomasses and total P concentrations showed no difference with wild type, regardless of Pi sufficiency or deficiency. Therefore, this approach would be a novel manipulation to modify Fe nutrient via coupling with Pi starvation in plants.