Vasighe Sadat Mirbagheri, Alireza Alishahi, Seyyed Hamidreza Hashemi Petroudi, Seyyed Mahdi Ojagh,
Volume 12, Issue 2 (4-2023)
Abstract
Chitosan (Cs) was extracted from shrimp shell and its derivative forms including N-alkyl (AlkCs) and nanoparticles (CsNPs) were prepared. First, the properties of nanoparticles were determined by dynamic light scattering (DLS) and the morphology of nanoparticles and N-alkylated by scanning electron microscopy (SEM). Then their antibacterial activity was evaluated by the test of minimum inhibitory (MIC) and lethal (MBC) concentration, diffusion on agar by disk, permeability of cell membrane by measurement of cytoplasmic beta-galactosidase release (ONPG). The type of apoptosis cell death was also examined by DAPI staining and changes in cell surface integrity by atomic force microscopy (AFM). The results showed that the nanoparticles are spherical with an average hydrodynamic diameter of 240 nm. N-alkyl had a rough surface structure compared to native chitosan. At the least of MIC (78 μg/ml) and MBC (100 μg/ml) points were observed for CsNPs (P < 0.05). Nanoparticles and N-alkyl of chitosan showed the highest diameter of growth inhibition zone at 1250 concentration compared to other disks (p <0.05). Outer membrane permeability of derivative forms of chitosan showed significant differences with native chitosan and cells of control. DAPI staining test showed higher cell death of chitosan-derived forms. DAPI staining test showed higher cell death of derivative of chitosan. The images obtained from AFM showed a change in the membrane integrity of the treated cells compared to spherical and clustered of control cells. Thus, the antibacterial properties of native chitosan improved by physical and chemical modification.
Volume 16, Issue 2 (3-2014)
Abstract
In order to assess the effect of salinity constraint on some agro-physiological and biochemical traits in Medicago sativa L., four Alfalfa populations (Tafilalet 1, Tafilalet 2, Demnate and Tata), originated from mountains and oasis of Morocco, were tested. The plants were grown under greenhouse conditions in pots filled with sand and peat under three salt treatments (0, 100 and 200 mM NaCl). Thereafter, plants were harvested 45 days after salt treatment and some agro-physiological and biochemical parameters related to salt tolerance, such as plant biomass, water content, membrane permeability, nutrients contents, nitrate reductase and acid phosphatase activities, were measured. Results showed that increase in NaCl concentration gradually reduced plant biomass, which displayed significant differences among the tested populations. Thus, Tata population appeared to be the most tolerant population to salinity, Tafilalet 1 population was the least tolerant one, while Tafilalet 2 and Demnate displayed moderate salinity tolerance. Variations in plant growth were associated with changes in physiological and biochemical parameters. Indeed, salinity caused a decrease in relative water content, perturbation of membrane permeability, and nutrients concentrations. Results also showed that salinity inhibited nitrate reductase activity in leaves of all tested populations, but acid phosphatase activity was increased in both leaves and roots of stressed plants. Salt tolerance of alfalfa populations was associated with high inorganic ion accumulation and the maintenance of membrane integrity and an adequate level in terms of nitrate reductase and acid phosphatase activities.
