Microalgae are a type of photosynthetic cellular factory capable of efficient CO2 capture, biofuel production and wastewater treatment. However, the large-scale harvesting of microalgae still faces technological bottlenecks, and microbial flocculation has distinct advantages. In this study, a highly efficient flocculating bacterium named EbZL-1 is screened from the sediment samples of Jingyue Lake at Donghua University. It is identified as Enterobacter through 16S rDNA sequencing and a strain identification kit. The flocculation ability of EbZL-1 is tested through singlefactor and multifactorial analysis experiments by using Kaolin suspension as standard flocculating liquid. The results show that the flocculation rate of EbZL-1 can reach 96. 6% within 10 min, which is superior to that of the commercial polyaluminum chloride ( 95. 0%, 120 min ). The optimal culture conditions for the bacterium to achieve the above flocculation rate are a carbon source of 11. 69 g/ L glucose, a nitrogen source of 1. 04 g/ L ammonium nitrate, a medium pH value of 7. 8, a shaker rotation speed of 160 r/ min, an inoculation amount of 45 μL (1. 2 × 105 CFU/ mL), and a culture time of 12 h to reach the logarithmic growth phase. The optimal flocculation conditions are Ca2+ as a flocculant aid with the pH value of the Kaolin suspension being 7. 0. In the flocculation and sedimentation experiment of chlorella, the flocculation rate of EbZL-1 is higher than 95%, and the chlorella cells after flocculation are found to be undamaged upon inspection, demonstrating the advantages of the microbial flocculation technology. Further investigation into the mechanism of flocculation reveals that EbZL-1 can complete the rapid sedimentation of large particles by tight adsorption. In summary, the flocculating bacterium EbZL-1 has application value in the large-scale harvesting of microalgae and wastewater treatment.
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