Yang Lijie, Chen Zhen, Zhang Ying, Lu Fuping, Liu Yihan, Cao Mingfeng, He Ning
Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, People's Republic of China.
The Key Lab for Synthetic Biotechnology of Xiamen City, Xiamen University, Xiamen, 361005, People's Republic of China.
Bioresour Bioprocess. 2023 Mar 8;10(1):17. doi: 10.1186/s40643-023-00638-3.
A novel extracellular polymeric substance (EPS) with flocculating activity produced by Pseudomonas fluorescein isolated from soil was studied in this paper. Firstly, atmospheric and room temperature plasma (ARTP) was applied to get a mutant of P. fluorescein with higher EPS production. A mutant T4-2 exhibited a 106.48% increase in flocculating activity compared to the original strain. The maximum EPS yield from T4-2 was enhanced up to 6.42 g/L, nearly 10 times higher than the original strain on a 3.6-L bioreactor with optimized fermentation conditions. Moreover, the flocculating activity of the mutant reached 3023.4 U/mL, 10.96-fold higher than that of T4. Further identification showed that EPS from mutant T4-2 was mainly composed of polysaccharide (76.67%) and protein (15.8%) with a molecular weight of 1.17 × 10 Da. The EPS showed excellent adsorption capacities of 80.13 mg/g for chromium (VI), which was much higher than many reported adsorbents such as chitosan and cellulose. The adsorption results were described by Langmuir isotherm and pseudo-second-order kinetic model. The thermodynamic parameters (ΔG, ΔH and ΔS) revealed that the adsorption process was spontaneous and exothermic. Adsorption mechanisms were speculated to be electrostatic interaction, reduction, and chelation.
本文研究了从土壤中分离出的荧光假单胞菌产生的一种具有絮凝活性的新型胞外聚合物（EPS）。首先，采用常压室温等离子体（ARTP）技术获得了一株EPS产量更高的荧光假单胞菌突变体。与原始菌株相比，突变体T4-2的絮凝活性提高了106.48%。在优化发酵条件的3.6-L生物反应器中，T4-2的EPS最大产量提高到6.42 g/L，比原始菌株高出近10倍。此外，突变体的絮凝活性达到3023.4 U/mL，比T4高10.96倍。进一步鉴定表明，突变体T4-2的EPS主要由多糖（76.67%）和蛋白质（15.8%）组成，分子量为1.17×10 Da。该EPS对六价铬的吸附容量高达80.13 mg/g，远高于许多已报道的吸附剂，如壳聚糖和纤维素。吸附结果用Langmuir等温线和准二级动力学模型描述。热力学参数（ΔG、ΔH和ΔS）表明吸附过程是自发的且放热的。推测吸附机制为静电相互作用、还原和螯合作用。
