Mitigating drought stress in wheat plants (Triticum Aestivum L.) through grain priming in aqueous extract of spirulina platensis.

BACKGROUND: The study focuses on the global challenge of drought stress, which significantly impedes wheat production, a cornerstone of global food security. Drought stress disrupts cellular and physiological processes in wheat, leading to substantial yield losses, especially in arid and semi-arid regions. The research investigates the use of Spirulina platensis aqueous extract (SPAE) as a biostimulant to enhance the drought resistance of two Egyptian wheat cultivars, Sakha 95 (drought-tolerant) and Shandawel 1 (drought-sensitive). Each cultivar's grains were divided into four treatments: Cont, DS, SPAE-Cont, and SPAE + DS. Cont and DS grains were presoaked in distilled water for 18 h while SPAE-Cont and SPAE + DS were presoaked in 10% SPAE, and then all treatments were cultivated for 96 days in a semi-field experiment. During the heading stage (45 days: 66 days), two drought treatments, DS and SPAE + DS, were not irrigated. In contrast, the Cont and SPAE-Cont treatments were irrigated during the entire experiment period. At the end of the heading stage, agronomy, pigment fractions, gas exchange, and carbohydrate content parameters of the flag leaf were assessed. Also, at the harvest stage, yield attributes and biochemical aspects of yielded grains (total carbohydrates and proteins) were evaluated. RESULTS: The study demonstrated that SPAE treatments significantly enhanced the growth vigor, photosynthetic rate, and yield components of both wheat cultivars under standard and drought conditions. Specifically, SPAE treatments increased photosynthetic rate by up to 53.4%, number of spikes by 76.5%, and economic yield by 190% for the control and 153% for the drought-stressed cultivars pre-soaked in SPAE. Leaf agronomy, pigment fractions, gas exchange parameters, and carbohydrate content were positively influenced by SPAE treatments, suggesting their effectiveness in mitigating drought adverse effects, and improving wheat crop performance. CONCLUSION: The application of S. platensis aqueous extract appears to ameliorate the adverse effects of drought stress on wheat, enhancing the growth vigor, metabolism, and productivity of the cultivars studied. This indicates the potential of SPAE as an eco-friendly biostimulant for improving crop resilience, nutrition, and yield under various environmental challenges, thus contributing to global food security.

Filter cake extract from the beet sugar industry as an economic growth medium for the production of Spirulina platensis as a microbial cell factory for protein.

BACKGROUND: Beet filter cake (BFC) is a by-product of sugar beet processing, which is difficult to dispose of and involves severe environmental concerns. Spirulina platensis is a microalga with a high protein content essential for human and animal nutrition. The present study aimed to utilize the beet filter cake extract (BFCE) to produce Spirulina platensis commercially. However, the cultivation of S. platensis on BFCE to produce economically single-cell protein has not been reported previously. RESULTS: The batch experiment revealed the maximum dry weight at Zarrouk's medium (0.4 g/L) followed by 0.34 g/L in the treatment of 75% BFCE. The highest protein content was 50% in Zarrouk's medium, followed by 46.5% in 25% BFCE. However, adding a higher concentration of 100% BFCE led to a protein content of 31.1%. In the adaption experiment, S platensis showed an increase in dry cell weight and protein content from 25 to 75% BFCE (0.69 g/L to 1.12 g/L and 47.0% to 52.54%, respectively) with an insignificant variation compared to Zarrouk's medium (p ≤ 0.05), indicating that S. platensis can be economically produced when cultivated on 75% BFCE The predicated parameters from response surface methodology were NaNO3 (2.5 g/L), NaHCO3 (0.67 g/L), BFCE (33%) and pH = 8, which resulted in biomass yield and protein content (0.56 g/L and 52.5%, respectively) closer to that achieved using the standard Zarrouk's medium (0.6 g/L and 55.11%). Moreover, the total essential amino acid content was slightly higher in the optimized medium (38.73%) than SZM (36.98%). CONCLUSIONS: Therefore, BFCE supplemented medium could be used as a novel low-cost alternative growth medium for producing a single-cell protein with acceptable quantity and quality compared to the standard Zarrouk's medium.

Effect of drought on yield of ten wheat cultivars linked with their flag leaf water status, fatty acid profile and shoot vigor at heading.

Flag leaf and shoot growth at heading stage as well as ultimate yield capacity of ten wheat cultivars were assessed in a pot experiment under normal and drought conditions. Drought was imposed by withholding 25% of field capacity from the 45- day old plants for 21 days followed by normal irrigation until maturity. Leaf succulence degree and stomatal opening area as well as shoot biomass, density and distribution decreased in all cultivars in response to drought but to different degrees. On contrary, leaf sclerophylly degree and water saturation deficit increased in all cultivars as a result of drought. At the same time, drought caused marked alterations in leaf transpiration rate, hair features, abscisic acid content, osmotic adjustment and fatty acid profile of the concerned cultivars; with ultimate variable capacity for yield. The drought- induced changes in the estimated traits were graphically represented in a single map then they were correlated with each other. The considered cultivars could be eventually clustered based on their drought response; with Sids cultivars being the most drought tolerant whereas Shandaweel 1 and Giza 168 being the most sensitive.

Characterization and optimization of abamectin-a powerful antiparasitic from a local Streptomyces avermitilis isolate.

Abamectin (ABA) constitutes a big commodity for pharmaceutical companies because it generates about one billion dollar annual sale. Avermectins (AVMs) and their naturally occurring analogues, milbemycins (MILs), meilingmycins (MEIs), ivermectin (IVE), abamectin (ABA), and nemadectin (NEM), represent one of the most developed antiparasitic agents. Abamectin is a mixture of avermectin B1a and avermectin B1b. The production of abamectin by Streptomyces avermitilis is a complicated process and separation of two fractions is quite difficult; commercial product contains more than 80% of Bla and less than 20% of B1b components. The main goal of the study was the identification and optimization of fermentation conditions to raise the production of abamectin from Egyptian S. avermitilis. The qualitative and quantitative analysis of avermectins was carried out by thin layer chromatography (TLC) and 6538 Q-TOF with Agilent 1290 UHPLC. The process of identification was carried out by using production medium containing 30 g/L corn starch, and 0.725 g/L CaCO3, pH 7, 8% inoculum size and incubated at 32.5 °C. The enhancement of the production of abamectin is a big challenge with commercial and industrial importance, as its output is insufficient for human consumption.

Drought-induced change in yield capacity of ten wheat cultivars in relation to their vegetative characteristics at heading stage.

Ten wheat (Triticum aestivum L.) cultivars were tested in a semi-field experiment for drought response in terms of their flag leaf vigor, whole shoot growth and ultimate yield capacity. At booting stage, 25% of field capacity was held for 3 weeks, then the plants were normally irrigated. Based on split plot analysis of the pooled data, the order in which the source of variation could affect the estimated traits was watering level, then cultivar and finally the combination of both. At p ≤ 0.05, significant positive linear correlation was recorded between the drought-induced change in grain total carbohydrate content and leaf total carbohydrate content, between biological yield and each of water use efficiency for biomass and evapotranspiration efficiency as well as between economic yield and each of leaf catalase activity, water use efficiency for grain and hundred kernel mass. On contrary, significant negative correlation was recorded between the drought-induced change in shoot evapotranspiration rate and each of leaf proline content and shoot water content. Based on the drought-induced change in the estimated vegetative and yield traits, cluster analysis could sequester the concerned cultivars into drought-tolerant, moderate and sensitive ones; with Sids 13 being the most drought-tolerant cultivar as well as Shandaweel 1 and Giza 168 as the most drought-sensitive ones.