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Updated: Oct 14, 2025
Author Spotlight: Optimized Transformation Protocol for Chlorella vulgaris Using Agrobacterium tumefaciens
Published on: October 27, 2023
A bacterial strain Citrobacter W4 facilitates the bio-flocculation of wastewater cultured microalgae Chlorella
Jiawen He1, Wanqing Ding1, Wei Han1
1State Key Lab of Urban Water Resource and Environment, School of Civil and Environmental Engineering, Harbin Institute of Technology Shenzhen, Shenzhen 518055, China; Shenzhen Engineering Laboratory of Microalgal Bioenergy, Harbin Institute of Technology (Shenzhen), Shenzhen 518055, China.
Abstract:
A bacteria strain Citrobacter W4 isolated from the microalgae sewage culture system showed flocculating activity against Chlorella pyrenoidosa. In this work, operation parameters under outdoor conditions were optimized. When the bacterial-algal ratio was 4:1, G value was 26.30 s-1, and harvesting time was 6 h, the harvesting efficiency achieved 87.37 ± 2.96% without ions addition and pH adjustment. The microbial community structure analysis showed Citrobacter W4 was dominant in the harvesting process. Flocculating active substances were on the surface and metabolites of Citrobacter W4. The main component of bacteria flocculating active substances was protein. Polysaccharides and carboxylic acid also promoted flocculation. The flocculation mechanisms were mainly adsorption bridging, net catching, and sweeping, not electric neutralization. The quality of FAMEs was improved after flocculation. The cost of 1 kg dried microalgae flocculated by Citrobacter W4 was $1.35. The novel flocculating bacteria showed the potential to harvest microalgae cost-effectively and environmentally friendly.
