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Evaluation of metal ions on the production and flocculating activity of polysaccharide-based bioflocculant from Paenibacillus mucilaginosus

Jiayi Tang, Suijian Qi, Zhigang Li, Qun An, Man Qu, Mingquan Xie, BoYang, Yonghua Wang

The effect of metal ions on the production and flocculating activity of polysaccharide-based bioflocculants (PSBs) by Paenibacillus mucilaginosus GIM1.16 were studied in liquid culture. In single-factor experiments, supplementing withMg2+, Ca2+ or Fe3+ to the culture medium could increase the PSBs production by 197%, 44%, 109%and increase the flocculating activity by 19%, 9%, 15%compared to that in basal medium, which showed more important and positive effects than Zn2+ and Cu2+. Response surface methodologywas then employed to further optimize the concentrations of these metal ions, and the maximum PSBs production (2.236 g/L) was achieved with 1150 ìM MgSO4, 290.1 ìM CaCl2 and 19.1 ìM FeCl3. The results of batch fermentation for PSBs under the optimal conditions further confirmed that adding a small amount of metal ions to the mediumnot only could shorten the fermentation period for about 12 h, but also increase the conversion rate of carbon source and the flocculating activity of PSBs by 199%and 26.3%, respectively. The work in this paper is significant for improving the production and feasibility of PSBs.