ECONOMIC MAXIMIZATION OF ALFALFA ANTIMICROBIAL EFFICACY USING STRESSFUL FACTORS

Objective: The present study addresses the effect of water deficit stress on the antimicrobial capacity of alfalfa (Medicago sativa) plants. Methods: Methanolic extracts of alfalfa plants grown in different soil types, varying in sand proportion, either alone or combined with various levels of water regimes were assessed for antibacterial and antifungal activities following cup plate method. The phytochemical profiles of plant extracts were also qualitatively screened using appropriate chemical reagents. Moreover, data were intensively processed via two different statistical designs. Results: Increasing sand amount induced the inhibitory effect of plant extracts on Escherichia coli, Klebsiella pneumonia, Proteus vulgaris, Salmonella typhi, Mucor circinelloides, Rhizopus azygosporus and R. microsporus with less pronounced action on Shigella flexneri, Staphylococcus epidermidis, Candida albicans and Emericella quadrillineata; as well as a reversed influence on Pseudomonas aerugenosa and Streptococcus pyrogenes. Furthermore, withholding irrigation water enhanced the plant suppressive action on E. coli, Salmonella typhi, Staphylococcus epidermidis, Candida albicans and R. microsporus with less marked or reversed influence on the other tested microbes. However, Pseudallescheria ellipsoidea, two species of Penicillium and five of Aspergillus could resist the studied plant extracts. The results also revealed that the extracts of water-unsatisfied plants generally contained higher amounts of alkaloids, amino acids, flavonoids, glycosides, phytosterols, saponins, steroids, tannins, terpenoids and reducing sugars.Conclusion: The employed biological evaluations point out to promising antimicrobial efficiency of alfalfa plants particularly when stressed

Does Exogenous Application of Kinetin and Spermine Mitigate the Effect of Seawater on Yield Attributes and Biochemical Aspects of Grains?

A pot experiment was conducted to evaluate the effect of grain presoaking in kinetin ( 0.1 mM), spermine (0.3 mM) and their interaction on yield components and biochemical aspects of yielded grains of wheat plants irrigated with 25% seawater . Seawater induced marked reduction in biochemical aspects of yielded grains especially carbohydrates content, nitrogenous constituents, total protein and nucleic acids contents as well as proline and organic acids (citric and keto-acids) content. Conversely, seawater stress increased phosphorus and ions (Na+, K+ and Cl-) content. Application of kinetin or spermine appeared to mitigate the effect of seawater stress on wheat yield and the biochemical aspects of yielded grains. The effect was more pronounced with kinetin + spermine treatment

Wheat can acclimate to seawater by pretreatment with kinetin and spermine through osmotic adjustment and solutes allocation

A key issue in salt adaptation is the osmotic adjustment, therefore, during ear emergence the effect of exogenous application of kinetin and spermine on osmotic pressure (OP) and solutes allocation (total soluble sugars, total soluble nitrogen, proline, organic acids and inorganic ions (Na+, K+, Ca2+, Mg2+ and Cl-) were quantified in flag leaf of wheat plants irrigated by seawater at 25%. Seawater salinity induced significant increase in osmotic pressure. Furthermore, seawater stress induced marked increase in total soluble sugars, total soluble nitrogen, proline, organic acids, as well as Na+, K+, Ca++, Mg++, Cl- and P+++ in wheat flag leaf. On the other hand, seawater decreased SPR, SAR and PAR in flag leaves of wheat plants. Grain priming with kinetin, spermine or their interaction appeared to mitigate the ill effect of seawater on wheat plants by increasing its own capability to be more tolerant against seawater salinity by inducing additional increase in osmotic pressure and the osmolytes concentrations in flag leaf during ear emergence. Moreover, the effect was more pronounced with the interaction of kinetin and spermine treatment

Impact of osmotic stress on seedling growth observations, membrane characteristics and antioxidant defense system of different wheat genotypes

The objective of the present study was to find out a straightforward technique for screening the tolerance of ten wheat genotypes to two levels of osmotic stress at early seedling stage. Data revealed that polyethylene glycol-induced drought had general negative effect on seedling morphological characters indicated by plumule and radicle length, number of adventitious roots as well as seedling biomass and water content. Water deficit could also suppress membrane integrity by stimulating lipid peroxidation with marked increase in membrane leakage and subsequent decrease in its stability index. For all the addressed germination parameters and seedling membrane features, the impact of severe drought was more pronounced than that of moderate drought. Simultaneously, moderate stress could activate peroxidase, polyphenol oxidase and ascorbic peroxidase of the studied genotypes; but these enzymes were inhibited by severe stress. The activity of catalase, superoxide dismutase and glutathione reductase was conversely retarded by drought whether at moderate or severe level. More interestingly, a novel function “Stress Impact Index; SII” was introduced to rank the estimated morpho-physiological traits (SIItrait) as well as the considered genotypes (SIIgenotype) according to their sensitivity to stress. Values of SIItrait implied that germination parameters were generally affected by drought more intensively than membrane characteristics and finally came the antioxidant enzymes with the least degree of suppression when applying stress. Based on the magnitudes of SIIgenotype, Sids 13 seemed to be the most drought-tolerant wheat cultivar while Shandawel 1 could be the most sensitive one at their juvenile growth stage

Plackett–Burman screening of physico-chemical variables affecting Citrus peel-mediated synthesis of silver nanoparticles and their antimicrobial activity

Abstract With the growing resistance of pathogenic microbes to traditional drugs, biogenic silver nanoparticles (SNPs) have recently drawn attention as potent antimicrobial agents. In the present study, SNPs synthesized with the aid of orange (Citrus sinensis) peel were engineered by screening variables affecting their properties via Plackett–Burman design. Among the variables screened (temperature, pH, shaking speed, incubation time, peel extract concentration, AgNO3 concentration and extract/AgNO3 volume ratio), pH was the only variable with significant effect on SNPs synthesis. Therefore, SNPs properties could be enhanced to possess highly regular shape with zeta size of 11.44 nm and zeta potential of − 23.7 mV. SNPs purified, capped and stabilized by cloud point extraction technique were then checked for their antimicrobial activity against Bacillus cereus, Listeria innocua, Listeria monocytogenes, Staphylococcus aureus, Enterobacter cloacae, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Salmonella typhimurium and Candida albicans. The maximum antimicrobial activity of SNPs was recorded against E. coli, L. monocytogenes and C. albicans with clear zone diameter of 33.2, 31.8 and 31.7 mm, respectively. Based on minimum inhibition concentration and minimum bactericidal concentration of SNPs (300 mg/l) as well as their effect on respiratory chain dehydrogenases, cellular sugar leakage, protein leakage and lipid peroxidation of microbial cells, E. coli was the most affected. Scanning electron microscopy, protein banding and DNA fragmentation proved obvious ultrastructural and molecular alterations of E. coli treated with SNPs. Thus, biogenic SNPs with enhanced properties can be synthesized with the aid of Citrus peel; and such engineered nanoparticles can be used as potent antimicrobial drug against E. coli