Production and Optimization of Bacterial Exopolysaccharides for Mitigation of NaCl-Salinity in Vicia faba seedling growth

Document Type : Novel Research Articles

Authors

1 Assiut Uiversity, Faculty of Science

2 Assiut unversity, faculty of science

3 Assiut University, Faculty of Science

4 botany and microbiology department, faculty of science, Assiut university

10.21608/aunj.2024.334097.1100

Abstract

Exopolysaccharides (EPS) are high molecular weight polymers produced by several microorganisms, have unique properties to adapt to harsh environmental conditions, and play an important role in mitigation of abiotic stress. This work aimed to study the production of EPS by halophilic bacteria and their application on seed germination under salinity stress. Eight cellulolytic halophilic bacteria were screened for exopolysaccharides production. The highly EPS producer isolate was molecularly identified as Ornithinbacillus sp. strain BM10, accession number MZ648228. This bacterial strain produced about 7.32± 0.33 g L−1 of EPS at optimum growth conditions. The effect of bacterial EPS on seeds germination and early seedling growth of Vicia faba (Giza 843) at different salinity levels (0, 50 and 150 mM NaCl) has been studied. The morpho-physiological characteristics and the growth parameters of faba bean seedlings were negatively affected by NaCl stress. The EPS treatment (soaking for 6 hours) could alleviate salt stress on seeds germination (with a 20% increase in seed germination at 50 and 150 mM NaCl). As well as, water content, fresh and dry weight of seedling were enhanced. Also, photosynthetic pigment contents were increased by applying EPS. Chlorophylls (a + b) were improved by 165% in seedlings treated with bacterial EPS and grown in 150 mM NaCl. The Bacterial EPS can improve seed germination in stress environments and increase yield due to the role of EPS in salt stress reduction. Nevertheless, more research authentication would be needed before large scale/field application.

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