自湖泊沉积物中分离得到一株产胞外多糖的细菌菌株ZX-5，通过16S rRNA基因测序和系统发育树分析，表明该菌株为类芽孢杆菌（Paenibacillus sp.）；使用硫酸-苯酚法测定胞外多糖产量，同时对pH、温度、碳源、碳源浓度、氮源、氮源浓度等6个发酵条件进行单因素试验和响应面试验，并对二次模型进行方差分析，结果表明，蔗糖浓度、温度和硝酸钠浓度对产糖量影响较大，且存在显著的交互作用，对其进行响应面试验，得出最佳产糖条件为初始蔗糖浓度200 g/L、硝酸钠3 g/L、K2HPO4·3H2O 3 g/L、KH2PO4 1 g/L，MgSO4·7H2O 0.50 g/L，pH 6，发酵温度20 ℃。该最优条件下菌株摇瓶发酵的胞外多糖产量为34.55 g/L，是基础水平17.15 g/L的2.01倍。ZX-5菌株胞外多糖的保湿性能研究结果表明，在干燥环境中，38 h该多糖的水分残留率为50%，具有优于甘油和壳聚糖的保湿特性。该研究在获得类芽孢杆菌ZX-5产胞外多糖最佳工艺条件的基础上，研究了多糖保湿性能，为其后续深入研究和开发奠定了基础。

An exopolysaccharide-producing bacterial strain ZX-5 was isolated from lake sediments, and identified as Paenibacillus sp. by 16S rRNA gene sequencing and phylogenetic tree analysis. The yield of exopolysaccharides was determined by the sulfuric acid-phenol method. In the meantime, single factor tests and response surface tests were carried out on six fermentation conditions including pH, temperature, carbon source and concentration, and nitrogen source and concentration, with the analysis of variance performed on the quadratic model. Results showed that sucrose concentration, temperature and sodium nitrate concentration had a great influence on sugar production, and there were significant interactions. Response surface tests revealed that the optimal sugar-producing conditions were: the initial sucrose concentration, 200 g/L; sodium nitrate, 3 g/L; K2HPO4·3H2O, 3 g/L; KH2PO4, 1 g/L; MgSO4·7H2O, 0.50 g/L; pH, 6.00; fermentation temperature, 20 ℃. Under the optimal conditions, the yield of exopolysaccharides from shake-flask fermentation with strain ZX-5 was 34.55 g/L, which was 2.01 times the base level of 17.15 g/L. The investigations on the moisturizing properties of the exopolysaccharides from the strain ZX-5 showed that in a dry environment, the moisture residual rate of the exopolysaccharide after 38 h was 50%, which had better moisturizing properties than glycerin and chitosan. In this study, on the basis of the optimal processing conditions for exopolysaccharide production by Paenibacillus ZX-5, the moisture retention property of the polysaccharide was studied, which laid a foundation for subsequent in-depth research and development.

河南省高等学校重点科研项目（20A180009）；国家自然科学基金项目（31370147）