Isolation of two salt-tolerant strains from activated sludge and its COD degradation characteristics from saline organic wastewater

The efficient biological treatment of saline wastewater has been limited by the low activities of microorganisms under saline conditions. High salinity poses unbalance osmotic stress across the cell wall and even leads to cell plasmolysis. In this work, we aim to isolate salt-tolerant bacterial strains from activated sludge, and apply them for degrading chemical oxygen demand (COD) of saline organic wastewater. Two salt-tolerant strains were screened and isolated from activated sludge, which was domesticated with salty water for over 300 days. The two strains were identified as Bacillus cereus (strain A) and Bacillus anthracis (strain B) through 16S rRNA sequencing. The degradation characteristics of strain A were explored. The results showed the relative membrane permeability of strain A remained stable under high salt stress, which glycine and proline play an important role to maintain cell osmotic. The protein and soluble sugar amounts of strain were increased by higher salt concentrations. In simulating saline wastewater, the optimum culture temperature, pH, salinity, influent COD concentration and inoculation amount of strain A were 35 °C, 9, 4%, 8000 mg L−1, 6%, respectively. Optimal conditions could provide guidance for the treatment of practical saline wastewater. The linear regression model of each impact factor built based on the result PB experiment revealed that cross-linking time has the most significant influence on COD removal for salt-tolerant strains. It will provide theoretical basis for biological treatment of saline organic wastewater.

Consortium Application of Endophytic Bacteria and Fungi Improves Grain Yield and Physiological Attributes in Advanced Lines of Bread Wheat

Increasing human population places pressure on agriculture. To feed this population, two time increase in the current wheat production is needed. Today agriculture is becoming input intensive with more reliance on synthetic fertilizers and agrochemicals to fulfil the feed demand of the growing numbers. Use of synthetic fertilizer since last few years is impacting the soil quality. In this scenario, the use of beneficial endophytic microbes is an attractive strategy to overcome the use of synthetic products. To investigate the effect of consortium application of endophytic bacteria and fungus on plant growth, grain yield moisture status, a pot experiment was conducted in different wheat lines. It comprised four treatments like control, application of bacterial strain Bacillus sp. MN54, fungal strain Trichoderma sp. MN6, and their consortium (Bacillus sp. MN54 + Trichoderma sp. MN6). The effect of consortium application was more prominent and significantly different from the sole application of bacteria and fungus. The results showed that with a consortium application of endophytic bacteria and fungus, there was 28.6, 4.3, -6.3 and -3.7% increases in flag leaf area, chlorophyll content, relative membrane permeability and water content respectively. Consortia of endophytic microbes also resulted in the yield enhancement through the betterment of various yield attributes like number of spikelet’s, grains per spike and grain yield per plant (32.2, 25.8 and 30.8%, respectively). So, consortia of endophytic microbes can greatly promote the progress of plants in dry land agriculture and increase the yield in an environmentally sustainable way.

Silicon ameliorates the adverse effects of salt stress on sainfoin (Onobrychis viciaefolia) seedlings

The objective of this study was to investigate whether the application of silicon (Si) ameliorates the detrimental effects of salinity stress on sainfoin (Onobrychis viciaefolia). Three-week-old seedlings were exposed to 0 and 100 mmol/L NaCl with or without 1 mmol/L Si for 7 days. The results showed that salinity stress significantly reduced plant growth, shoot chlorophyll content and root K⁺ concentration, but increased shoot malondialdehyde (MDA) concentration, relative membrane permeability (RMP) and Na⁺ concentrations of shoot and root in sainfoin compared to the control (no added Si and NaCl). However, the addition of Si significantly enhanced growth, chlorophyll content of shoot, K⁺ and soluble sugars accumulation in root, while it reduced shoot MDA concentration, RMP and Na⁺ accumulation of shoot and root in plants under salt stress. It is clear that silicon ameliorates the adverse effects of salt stress on sainfoin by limiting Na⁺ uptake and enhancing selectivity for K⁺, and by adjusting the levels of organic solutes. The present study provides physiological insights into understanding the roles of silicon in salt tolerance in sainfoin.

EFFECT OF LEAF RUST DISEASE ON VARIOUS MORPHO-PHYSIOLOGICAL AND YIELD ATTRIBUTES IN BREAD WHEAT

Leaf rust of wheat caused by Puccinia triticina is one of the most important diseases in the Pakistan and cause both yield and quality reduction. To investigate the effect of leaf rust of wheat on morph-physiological processes and grain yield, a field experiment was conducted using different wheat lines and varieties. The morpho-physiological attributes of the infected plant leaves were badly affected by the infection of leaf rust of wheat. The experiment comprised two treatments, one was inoculated with leaf rust spores manually and Morocco as a spreader while other keeping as a control. The results showed that there was -42.92, -23.72, -23.01, and -11.42, % decrease in chlorophyll content, flag leaf area, specific flag leaf area and relative water content in leaf rust (diseased) plot respectively while 21.24, 160.16% increase in relative dry weight and relative membrane permeability in the leaf rust plot. The results also revealed that leaf rust of wheat also reduces the yield components like number of grains per spike, spike length and 1000 grain weight (-52.38, -43.37 and -45.50 respectively). Thus, it could be concluded that leaf rust of wheat affect the morph-physiological process of wheat plants and badly reduce the yield as well.

Heat shock increases oxidative stress to modulate growth and physico-chemical attributes in diverse maize cultivars

The present investigation was conducted to appraise the physiochemical adjustments in contrasting maize cultivars, namely, PakAfgoi (tolerant) and EV-5098 (sensitive) subjected to heat shock. Seven-day-old seedlings were exposed to heat shock for different time intervals (1, 3, 6, 24, 48 and 72 h) and data for various physiochemical attributes determined to appraise time course changes in maize. After 72 h of heat shock, the plants were grown under normal conditions for 5 d and data for different growth attributes and photosynthetic pigments recorded. Exposure to heat shock reduced growth and photosynthetic pigments in maize cultivars. The plants exposed to heat shock for up to 3 h recovered growth and photosynthetic pigments when stress was relieved. A time course rise in the relative membrane permeability, hydrogen peroxide (H2O2) and malondialdehyde contents was recorded particularly in the EV-5098 indicating that heat shock-induced oxidative stress. Activities of different enzymatic antioxidants greatly altered due to heat shock. For instance, an increase in superoxide dismutase activity was recorded in both maize cultivars. The activity of ascorbate peroxidase was greater in Pak-Afgoi. However, the peroxidase and catalase activities were higher in plants of EV-5098. Heat shock caused a significant rise in the proline and decline in the total free amino acids. Overall, the performance of Pak-Afgoi was better in terms of having lesser oxidative damage and greater cellular levels of proline. The results suggested that oxidative stress indicators (relative membrane permeability, H2O2 and malondialdehyde) and proline can be used as markers for heat shock tolerant plants.

Physiological Responses ofKosteletzkya virginicato Coastal Wetland Soil

Effects of salinity on growth and physiological indices ofKosteletzkya virginicaseedlings were studied. Plant height, fresh weight (FW), dry weight (DW), and net photosynthetic rate (Pn) increased at 100 mM NaCl and slightly declined at 200 mM, but higher salinity induced a significant reduction. Chlorophyll content, stomatal conductance (Gs), intercellular CO2concentration (Ci), and transpiration rate (E) were not affected under moderate salinities, while markedly decreased at severe salinities except for the increasedCiat 400 mM NaCl. Furthermore, no significant differences ofFv/Fmand ΦPSII were found at lower than 200 mM NaCl, whereas higher salinity caused the declines ofFv/Fm, ΦPSII, and qP similar toPn, accompanied with higher NPQ. Besides, salt stress reduced the leaf RWC, but caused the accumulation of proline to alleviate osmotic pressure. The increased activities of antioxidant enzymes maintained the normal levels of MDA and relative membrane permeability. To sum up,Kosteletzkya virginicaseedlings have good salt tolerance and this may be partly attributed to its osmotic regulation and antioxidant capacity which help to maintain water balance and normal ROS level to ensure the efficient photosynthesis. These results provided important implications forKosteletzkya virginicaacting as a promising multiuse species for reclaiming coastal soil.

Sodium Is Not Required for Chloride Efflux via Chloride/Bicarbonate Exchanger from Rat Thymic Lymphocytes

Sodium-dependent Cl−/HCO3-exchanger acts as a chloride (Cl−) efflux in lymphocytes. Its functional characterization had been described when Cl−efflux was measured upon substituting extracellular sodium (Na+) by N-methyl-D-glucamine (NMDG). For Na+and Cl−substitution, we have used D-mannitol or NMDG. Thymocytes of male Wistar rats aged 7–9 weeks were used and intracellular Cl−was measured by spectrofluorimetry using MQAE dye in bicarbonate buffers. Chloride efflux was measured in a Cl−-free buffer (Cl−substituted with isethionate acid) and in Na+and Cl−-free buffer with D-mannitol or with NMDG. The data have shown that Cl−efflux is mediated in the absence of Na+in a solution containing D-mannitol and is inhibited by H2DIDS. Mathematical modelling has shown that Cl−efflux mathematical model parameters (relative membrane permeability, relative rate of exchanger transition, and exchanger efficacy) were the same in control and in the medium in which Na+had been substituted by D-mannitol. The net Cl−efflux was completely blocked in the NMDG buffer. The same blockage of Cl−efflux was caused by H2DIDS. The study results allow concluding that Na+is not required for Cl−efflux via Cl−/HCO3-exchanger. NMDG in buffers cannot be used for substituting Na+because NMDG inhibits the exchanger.

Response of Maize Seedlings to Cadmium Application after Different Time Intervals

Present study was conducted to appraise the inhibitory effects of cadmium applied at different time intervals on various growth and biochemical parameters in two maize lines, Maize-TargetedMutagenesis 1 and 2 (MTM-1 and MTM-2). Twenty-day-old seedlings were exposed to 0, 3, 6, 9, and 12 mg CdCl2 kg−1 sand. Both maize lines exhibited significant perturbations in important biochemical attributes being employed for screening the crops for cadmium tolerance. The results showed that a higher concentration of cadmium (12 mg CdCl2 kg−1) considerably reduced the plant growth in line MTM-1 on the 5th, 10th, and 15th day after the treatment. In contrast, irrespective of exposure time, the plant biomass and leaf area did not show inhibitory effects of cadmium, specifically at 3 mg CdCl2 kg−1 in line MTM-2. In addition, MTM-2 was found to be more tolerant than line MTM-1 in terms of lower levels of hydrogen peroxide (H2O2), malondialdehyde (MDA) contents, and relative membrane permeability (RMP). Moreover, H2O2, MDA, RMP, and anthocyanin increased at all levels of cadmium in both lines, but a significant decline was observed in photosynthetic pigments, total free amino acids, and proline contents in all treatments particularly on the 10th and 15th day after treatment.