Screening and Taxonomic Characterization of the Efficient Flocculating Bacterium EbZL-1 and Its Application in Microalgae Harvesting
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 single-factor 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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