The Stimulation Effect of Seaweed Polysaccharides on the Lower pH of the Salt-Tolerant Bacteria and Their Mechanism.

Soda saline-alkali soil, as a kind of saline soil, damages soil physicochemical properties agricultural production. Therefore, the restoration of soda saline-alkali soil is of great significance to maintain food supply and ecological security. Among the restoration methods of soda saline-alkali soil, microbial remediation is favored due to its environmental friendliness. However, it is mostly associated with problems such as difficulty in colonization and low efficiency due to nutritional deficiency of soda saline-alkali soil. In this study seaweed polysaccharide was used as an inducer to investigate whether and how it affected screened bacteria from the sea mud to remediate soda saline-alkali soil. The results showed seaweed polysaccharides can promote the growth of salt-tolerant bacteria which made pH lower for the culture process. This was mainly because the seaweed polysaccharides especially Grateloupia filicina polysaccharide could promote the secretion of more organic acids such as citrulline, phenylpyruvic acid and D-phenyl lactic acid by salt-tolerant bacteria, and up-regulate the metabolic pathways such as phenylalanine metabolism, purine metabolism and so on, which can stimulate salt-tolerant bacteria to reduce the pH in the environment. Additionally, Grateloupia filicina polysaccharide could improve the biodiversity of microbial community, change the structure of microbial communities. This study provided a new efficient and eco-friendly method to better restore soda saline-alkali soil.