Assessment of zinc solubilization potential of zinc-resistant Pseudomonas oleovorans strain ZSB13 isolated from contaminated soil

Zinc is an essential micronutrient that is required for optimum plant growth. It is present in soil in insoluble forms. Bacterial solubilization of soil unavailable form of Zn into available form, is an emerging approach to alleviate the Zn deficiency for plants and human beings. Zinc solubilizing bacteria (ZSB) could be a substitute for chemical Zn fertilizer. The present study aimed to isolate and characterize bacterial species from the contaminated soil and evaluate their Zn solubilizing potential. Zn resistant bacteria were isolated and evaluated for their MIC against Zn. Among the 13 isolated bacterial strains ZSB13 showed maximum MIC value upto 30mM/L. The bacterial strain with the highest resistance against Zn was selected for further analysis. Molecular characterization of ZSB13 was performed by 16S rRNA gene amplification which confirmed it as Pseudomonas oleovorans. Zn solubilization was determined through plate assay and broth medium. Four insoluble salts (zinc oxide (ZnO), zinc carbonate (ZnCO3), zinc sulphite (ZnS) and zinc phosphate (Zn3(PO4)2) were used for solubilization assay. Our results shows 11 mm clear halo zone on agar plates amended with ZnO. Likewise, ZSB13 showed significant release of Zn in broth amended with ZnCO3 (17 and 16.8 ppm) and ZnO (18.2 ppm). Furthermore, Zn resistance genes czcD was also enriched in ZSB13. In our study, bacterial strain comprising Zn solubilization potential has been isolated that could be further used for the growth enhancement of crops.

Dietary l-glutamic acid N,N-diacetic acid improves short-term maintenance of zinc homoeostasis in a model of subclinical zinc deficiency in weaned piglets

This study compared the Zn response in selected tissues of weaned piglets fed L-glutamic acid, N,N-diacetic acid (GLDA), while challenged with short-term subclinical Zn deficiency (SZD). During a total experimental period of eight days, 96 piglets were fed restrictively (450 g/d) a high phytate (9 g/kg) diet containing added Zn at 0, 5, 10, 15, 20, 25, 45 and 75 mg/kg with and without 200 mg/kg of GLDA. No animals showed signs of clinical Zn deficiency and no phenotypical differences were observed. Broken line analysis of Zn status parameters such as liver Zn and apparently absorbed Zn indicated that the gross Zn requirement threshold was around 55 mg/kg diet. Supplementation of Zn above this threshold led to a saturation of the response in apparently absorbed Zn and linear increase in liver Zn. Bone and serum Zn responded to the dose in a linear fashion, likely due to the time-frame of Zn homoeostatic adaptation. Inclusion of GLDA into the diets yielded a higher intercept for bone Zn (P < 0·05). Liver Zn accumulation and MT1A gene expression was higher for piglets receiving GLDA (P < 0·05), indicating higher Zn influx. This study indicates that a strong chelator such as GLDA mitigates negative effects of phytate in plant-based diets, by sustaining Zn solubility, thereby improving nutritional Zn availability.

Efficiency of Zinc in Plants, its Deficiency and Sensitivity for Different Crops

Optimal crop nutrition is a significant factor in increasing agricultural vintage and quality of products. Zinc (Zn) is an immobile important micronutrient, which is taken up by plants in Zn2+ form to complete their life cycle efficiently. It plays a critical metabolic role in plants and is an important constituent of proteins and other large-molecules, and serves as structural and functional unit, or controlling cofactor for a wide range of enzymes. The Zn is needed in small and in appropriate amounts for plants main physiological processes to work normally. These processes play critical roles in photosynthetic activity of plants and forming carbohydrates, synthesis of protein, reproduction and seed development, growth, and disease protection. After Zn deficiency in plants, these physical functions are decreased, and plant health and productivity suffer greatly, subsequent in reduced production or even failure of crops and often bad quality of crop products. Plant Zn deficiencies occur on variety of soils and are severe due to a combination of symptoms like chlorosis, resetting, dieback and suppressed or irregular vegetative development. In addition, various crops require varying amount of Zn. So the knowledge regarding this is not up to date. The present review discusses the Zn importance in plants, its deficiency in soil and required level of Zn for crops.

Effect of Soil Application of Zinc on Growth, Yield and Zinc Concentration in Rice Varieties

Zinc (Zn) deficiency is widespread nutrient disorder in lowland rice growing areas in Asia, especially in Bangladesh. Intensive cropping with modern varieties causes depletion of inherent nutrient reserves in soils. The application of Zn fertilizers results in higher crop productivity and increases Zn concentration in crops. A field experiment was conducted to evaluate the effect of Zn application on growth, yield, and grain-Zn concentration in eight varieties of rice. The experiment was laid out in a split plot design with a distribution of Zn rates (0 kg ha-1 and 3 kg ha-1 from ZnO) to the main plots and rice varieties (BRRI dhan49, BRRI dhan52, BRRI dhan56, BRRI dhan57, Kalizira, Biroin, Gainja and Khirshapath) to the sub-plots. Zinc application improved effective tillers hill-1, grains panicle-1 and 1000-grain weight which impacted the grain yield of rice. Among the eight rice varieties, a significant increase of grain yield was recorded in BRRI dhan49, BRRI dhan52, BRRI dhan56 and BRRI dhan57 due to application of Zn. Zinc concentration of grain significantly increased in all rice varieties except Biroin. The highest grain-Zn concentration (19.1 mg kg-1) was noted in BRRI dhan57 with 3 kg ha-1 Zn and the lowest value (11.3 mg kg-1) was observed in BRRI dhan52 without Zn application. The highest percent increase of grain Zn concentration over control was obtained in high yielding rice variety BRRI dhan49 and the lowest Zn concentration was found in local rice variety Biroin.

Expression of IRT1 gene in barley seedlings under zinc deficiency at optimal and low temperatures

<p class="042abstractstekst">The deficiency or excess of zinc (Zn) cause negative effect on plant metabolism and development. Therefore, plants have established a tightly controlled system, including protein transporters to balance the uptake and utilization of metal ions. In this study, the relative expression of <em>HvIRT1</em> gene, encoding the transmembrane protein IRT1 was analyzed in shoots and roots of barley (<em>Hordeum vulgare </em>‘Nur’) under zinc deficiency at optimal (22 °C) or low (4 °C) temperatures. The Zn deficiency (0 μmol) caused an increase in <em>HvIRT1</em> gene expression under both optimal temperature condition and cold. Although, the difference in mRNA content of <em>HvIRT1</em> gene in roots of barley under optimal and low temperature was not observe. However, the <em>HvIRT1 </em>expression in leaves was higher at optimal temperature compare with cold condition. Moreover, long-term (7 days) of low temperature influence along with zinc deficiency leads to a significant decrease in the amount of <em>HvIRT1</em>transcripts in leaves, that corresponds to a decrease of photosynthesis rate and biomass accumulation. Overall, these findings suggest that <em>HvIRT1 </em>gene play an important role in plant’s response to zinc deficiency under optimal temperatures condition as well as at cold.</p>

Bioactive Nutrient Fortified Fertilizer: A Novel Hybrid Approach for the Enrichment of Wheat Grains With Zinc

Zinc (Zn) is a critical micronutrient that synergizes nutrient use efficiency, and improves plant growth and human health. Low Zn bioavailability in soils affects produce quality and agricultural productivity worldwide ultimately inducing deficiency in humans and animals. Zn deficiency is a leading cause of malnutrition in underdeveloped countries where a widespread population depends upon staple cereals for daily intake of calories. Modern cereal cultivars are inherently low in Zn, eventually, plants need to be enriched with soil application of ZnSO4, but due to higher fixation losses, it becomes an inefficient source. Rhizosphere microbiome contains Zn-solubilizing bacteria (ZSB) that improve Zn bioavailability, thus increase the root function, Zn uptake, and plant growth. Niha Corp developed a hybrid process of bioactive nutrient fortified fertilizer (BNFF), which has been used to formulate Zabardast Urea (ZU) by coating bioactive Zn (BAZ) and ZSB on urea. Data obtained for 15 wheat varieties from 119 farmer field demonstration plots and eight replicated trials on 42 locations across multi-environment conditions conclude that ZU significantly improved the plant biomass and yield by 12% over non-Zn control and produced grains with 57 μg/g Zn contents, which can meet a major part of the recommended dietary allowance (RDA) of humans. The study recommends that this microbe-mediated hybrid invention (ZU) is a feasible approach to boost Zn bioavailability and Zn use efficiency, with enhanced yield and quality that may contribute to improve human health. To the best of our knowledge, this is the first wide-scale field testing of Zn enrichment in the grains of bread wheat using an innovative BNFF Urea Z technology.

​Yield Attributes, Yield and Nutrient Uptake of Rice (Oryza sativa L.) as Influenced by Zinc Fortified Briquettes in Medium Black Soil

Background: Briquettes is more efficient than conventionally applied nutrients as it reduce the loss of nutrients by obtaining higher yield and decreased the expenditure cost of fertilizers. Indian soils are 49 per cent deficient in zinc which is characterized by widespread Zn deficiency in human beings. Methods: Three different zinc fortified briquettes viz., UB-DAP, UB-suphala and UB-KAB were tested in field experiments during kharif season of 2016-19 to compare and calculate variations in yield, yield attributing characters and nutrients uptake by rice (Oryza sativa L.). Result: The results showed that treatment UB-KAB fortified with 10 kg ZnSO4.7H2O ha-1 (T8) registered higher growth, yield parameters and Zn concentration in grain indicating zinc-sulfate-heptahydrate (ZSHH) offers vital solution to curtail Zn malnutrition. Further, UB-KAB fortified through ZSHH (T8) significantly enhanced the grain (55.2 q ha-1) and straw (63.6 q ha-1) yield of rice over RDF and absolute control. Application of UB-KAB fortified with 10 kg ZnSO4.7H2O ha-1 (T8) significantly increased nutrient uptake of N (97.2 kg ha-1), P (20.2 kg ha-1), K (95.5 kg ha-1), Zn (262.4 g ha-1) and S (53.9 kg ha-1) over fertilizer control (75% RDF) and absolute control. The applications of KAB fortified with zinc sulphate assume great significance in improving rice productivity.

Effect of K and Zn Application on Biometric and Physiological Parameters of Different Maize Genotypes

Potassium (K) and zinc (Zn) are mineral nutrients required for adequate plant growth, enzyme activation, water retention and photosynthetic activities. However, Pakistani soils are alkaline and have serious problems regarding Zn deficiency. The current study aims at finding the nutrient–nutrient interaction of K and Zn to affect maize plants’ (i) physiological processes and (ii) productivity. For this purpose, a pot experiment was conducted at the research area of the Department of Soil Science, Faculty of Agricultural Science and Technology, Bahauddin Zakariya University, Multan. Two maize genotypes, DK-6142 (hybrid) and Neelam (non-hybrid), were used with three K fertilizer doses, i.e., 0, 60 and 100 kg ha−1 in all possible combinations with three Zn fertilizer doses, i.e., 0, 16 and 24 kg ha−1. The treatments were replicated under a completely randomized block design. The results elucidated that the combined application of K and Zn with K60 + Zn16 treatment significantly increased agronomic, productive, and physiological attributes. It has improved fresh biomass (89%), dry biomass (94%), membrane stability index (142%), relative water content (200%) and chlorophyll contents (191%) as compared to the control. Moreover, the mineral uptake of K and Zn was significantly improved with their maximum fertilization rate in hybrid genotype compared to non-hybrid and CK.

Gut Microbiota as a Mediator of Essential and Toxic Effects of Zinc in the Intestines and Other Tissues

The objective of the present study was to review the existing data on the association between Zn status and characteristics of gut microbiota in various organisms and the potential role of Zn-induced microbiota in modulating systemic effects. The existing data demonstrate a tight relationship between Zn metabolism and gut microbiota as demonstrated in Zn deficiency, supplementation, and toxicity studies. Generally, Zn was found to be a significant factor for gut bacteria biodiversity. The effects of physiological and nutritional Zn doses also result in improved gut wall integrity, thus contributing to reduced translocation of bacteria and gut microbiome metabolites into the systemic circulation. In contrast, Zn overexposure induced substantial alterations in gut microbiota. In parallel with intestinal effects, systemic effects of Zn-induced gut microbiota modulation may include systemic inflammation and acute pancreatitis, autism spectrum disorder and attention deficit hyperactivity disorder, as well as fetal alcohol syndrome and obesity. In view of both Zn and gut microbiota, as well as their interaction in the regulation of the physiological functions of the host organism, addressing these targets through the use of Zn-enriched probiotics may be considered an effective strategy for health management.

Beneficial Effect of Root or Foliar Silicon Applied to Cucumber Plants under Different Zinc Nutritional Statuses

Zinc (Zn) is an essential micronutrient involved in a large variety of physiological processes, and its deficiency causes mainly growth and development disturbances, as well as oxidative stress, which results in the overproduction and accumulation of reactive oxygen species (ROS). A possible environmentally friendly solution is the application of silicon (Si), an element that has shown beneficial effects under abiotic and biotic stresses on many crops. Si could be applied through the roots or leaves. The aim of this work is to study the effect of Si applied to the root or shoot in cucumber plants under different Zn statuses (sufficiency, deficiency, and re-fertilization). Cucumber plants were grown in hydroponics, with 1.5 mM Si applied at the nutrient solution or sprayed on the leaves. During the different Zn statuses, SPAD index, fresh weight, ROS, and Si, Zn, P, Cu and B mineral concentration were determined. The results suggested that Si application had no effect during sufficiency and deficiency periods, however, during re-fertilization foliar application of Si, it showed faster improvement in SPAD index, better increment of fresh weight, and a decrease in ROS quantity, probably due to a memory effect promoted by Si previous application during the growing period. In summary, Si application to cucumber plants could be used to prepare plants to cope with a future stress situation, such as Zn deficiency, due to its prompt recovery after overcoming the stress period.