An Exploration of Seaweed Polysaccharides Stimulating Denitrifying Bacteria for Safer Nitrate Removal

• Main Authors: Hui Zhang, Lin Song, Xiaolin Chen, Pengcheng Li
• Format: Article
• Language: English
• Published: MDPI AG 2021-06-01
• Series: Molecules
• Subjects: seaweed polysaccharides; denitrifying bacteria; nitrate removal; growth promotion
• Online Access: https://www.mdpi.com/1420-3049/26/11/3390

Excessive use of nitrogen fertilizer in intensively managed agriculture has resulted in abundant accumulation of nitrate in soil, which limits agriculture sustainability. How to reduce nitrate content is the key to alleviate secondary soil salinization. However, the microorganisms used in soil remediation cause some problems such as weak efficiency and short survival time. In this study, seaweed polysaccharides were used as stimulant to promote the rapid growth and safer nitrate removal of denitrifying bacteria. Firstly, the growth rate and NO₃⁻-N removal capacity of three kinds of denitrifying bacteria, <i>Bacillus subtilis</i> (BS), <i>Pseudomonas stutzeri</i> (PS) and <i>Pseudomonas putida</i> (PP), were compared. The results showed that <i>Bacillus subtilis</i> (BS) had a faster growth rate and stronger nitrate removal ability. We then studied the effects of <i>Enteromorpha linza</i> polysaccharides (EP), carrageenan (CA), and sodium alginate (AL) on growth and denitrification performance of <i>Bacillus subtilis</i> (BS). The results showed that seaweed polysaccharides obviously promoted the growth of <i>Bacillus subtilis</i> (BS), and accelerated the reduction of NO₃⁻-N. More importantly, the increased NH₄⁺-N content could avoid excessive loss of nitrogen, and less NO₂⁻-N accumulation could avoid toxic effects on plants. This new strategy of using denitrifying bacteria for safely remediating secondary soil salinization has a great significance.