He Kun, Shi Xiaolong, Tao Zhongming, Hu Xing, Sun Liang, Wang Rui, Gu Yian, Xu Hong, Qiu Yibin, Lei Peng
State Key Laboratory of Materials-Oriented Chemical Engineering, College of Food Science and Light Industry, Nanjing Tech University, Nanjing 211816, China.
Microorganisms. 2024 Oct 5;12(10):2016. doi: 10.3390/microorganisms12102016.
The exopolysaccharide (EPS) produced by NX-11, referred to as alhagan, enhances plant stress resistance, improves soil properties, and exhibits notable rheological properties. Despite these benefits, the exact bio-synthetic process of alhagan by NX-11 remains unclear. This study focused on sequencing the complete genome of NX-11 and identifying an alhagan synthesis gene cluster ( to ). Gene annotation revealed that alhagan biosynthesis in NX-11 follows the Wzx/Wzy-dependent pathway. Furthermore, transcriptome analysis of NX-11 highlighted significant upregulation of four glycosyltransferase genes (, , , and ) within the alhagan synthesis gene cluster. These glycosyltransferases are crucial for alhagan synthesis. To delve deeper into this process, two upregulated and uncharacterized glycosyltransferase genes, and , were knocked out. The resulting mutants, ΔalhH and ΔalhK, showed a notable decrease in EPS yield, reduced molecular weight, and altered monosaccharide compositions. These findings contribute to a better understanding of the alhagan biosynthesis mechanism in NX-11.
由NX-11产生的胞外多糖（EPS），称为阿拉甘聚糖，可增强植物抗逆性、改善土壤性质并具有显著的流变学特性。尽管有这些益处，但NX-11合成阿拉甘聚糖的确切生物合成过程仍不清楚。本研究聚焦于对NX-11的全基因组进行测序并鉴定一个阿拉甘聚糖合成基因簇（至）。基因注释显示，NX-11中阿拉甘聚糖的生物合成遵循Wzx/Wzy依赖性途径。此外，对NX-11的转录组分析突出了阿拉甘聚糖合成基因簇内四个糖基转移酶基因（、、和）的显著上调。这些糖基转移酶对阿拉甘聚糖的合成至关重要。为了更深入地研究这一过程，敲除了两个上调且未表征的糖基转移酶基因和。所得突变体ΔalhH和ΔalhK的EPS产量显著降低、分子量减小且单糖组成改变。这些发现有助于更好地理解NX-11中阿拉甘聚糖的生物合成机制。
