School of Environmental Sciences, Jawaharlal Nehru University, New Delhi, 110067, India.
CSIR-Indian Institute of Toxicology Research, 31 MG Marg, Lucknow, 226 001, India.
Sci Rep. 2019 Mar 12;9(1):4270. doi: 10.1038/s41598-019-41052-0.
In the present study, genomic analysis of a previously reported carbon dioxide (CO) sequestering bacterium Serratia sp. ISTD04 was performed along with exopolysaccharide (EPS) production. Genomic analysis identified key and accessory enzymes responsible for CO sequestration. EPS synthesis genes were discovered in the genome and identified 8 putative clusters responsible for lipopolysaccharide, stewartan, emulsan, polysaccharide B, capsular polysaccharide and fatty acid-saccharide production. The production of EPS was found to be 0.88 ± 0.08, 1.25 ± 0.13 and 1.44 ± 0.10 g L on glucose, bicarbonate (NaHCO) and NaHCO plus glucose respectively at pH 7.8. After optimizing process parameters, the EPS production increased more than 3 folds. The morphology of strain and elemental composition of EPS was characterized by SEM-EDX. The functional groups, monomer composition, linkage analysis and structure of purified EPS was characterized by FTIR, GC-MS and H and C NMR. Glucose, galactose, mannose and glucosamine are the monomers detected in the EPS. EPS was further applied for bioflocculation (kaolin test) and dye removal. The EPS showed 68% ± 0.9 flocculating activity and decolorized cationic dye acridine orange (80%) and crystal violet (95%). The results highlight CO sequestration and EPS production potential of Serratia sp. ISTD04 that can be harnessed in future.
在本研究中，对以前报道的二氧化碳（CO）固定细菌 Serratia sp. ISTD04 进行了基因组分析，并进行了胞外多糖（EPS）的生产。基因组分析确定了负责 CO 固定的关键和辅助酶。在基因组中发现了 EPS 合成基因，并鉴定了 8 个推定簇，负责脂多糖、Stewart 多糖、乳化多糖、多糖 B、荚膜多糖和脂肪酸-糖的产生。发现 EPS 的产量分别为 0.88±0.08、1.25±0.13 和 1.44±0.10 g/L，在 pH 7.8 时分别以葡萄糖、碳酸氢盐（NaHCO ）和 NaHCO 加葡萄糖为底物。在优化工艺参数后，EPS 产量增加了 3 倍以上。用 SEM-EDX 对菌株的形态和 EPS 的元素组成进行了表征。用 FTIR、GC-MS 和 H 和 C NMR 对 EPS 的功能基团、单体组成、键合分析和结构进行了表征。在 EPS 中检测到葡萄糖、半乳糖、甘露糖和葡糖胺等单体。进一步将 EPS 应用于生物絮凝（高岭土试验）和染料去除。EPS 显示出 68%±0.9 的絮凝活性，并使阳离子染料吖啶橙（80%）和结晶紫（95%）脱色。这些结果突出了 Serratia sp. ISTD04 的 CO 固定和 EPS 生产潜力，未来可以加以利用。
