废水中紫色光养细菌产胞外多糖性能比较及高产菌株特性研究

COMPARISON BETWEEN PURPLE PHOTOTROPHIC BACTERIA IN EXOPOLYSACCHARIDE-PRODUCING PERFORMANCE IN WASTEWATER AND CHARACTERIZATION OF HIGH-YIELD STRAIN

利用废水生产胞外多糖是一种既能实现废水处理又能达到废水资源化的双赢方法,也是目前胞外多糖研究的热点。为得到能在废水中高产胞外多糖的紫色光养细菌(Purple Phototrophic Bacteria,PPB)菌株,本研究首先以化学合成培养基和不同比例豆制品废水和玉米淀粉废水混合培养基培养11株PPB,提取并测定其胞外多糖,结果发现不同菌株产胞外多糖能力不同,且有机废水较化学合成培养基更有利于菌株分泌胞外多糖。经两轮筛选得到一株产胞外多糖能力较高的菌株J4,高产培养基为豆制品废水,胞外多糖含量高达140 mg g-1菌体干重。且J4在豆制品废水中的生长试验表明,菌株J4不仅降低了废水的化学需氧量COD(>90%),同时分泌大量胞外多糖。通过Sephadex G-50柱层析结果发现该胞外多糖的分子量较大,具有一定的研究价值。综上,本试验获得了高产菌株J4,同时发现利用有机废水能够得到大量的PPB胞外多糖,为获得低价的多糖材料提供了一定依据。

Production of exopolysaccharide （EPS） using wastewater is an optimal approach to treating wastewater by turning it into resource and hence a hot pot in the study of EPS. To screen out a high-EPS-producing strain of Purple Phototrophic Bacteria （PPB）, an in-lab experiment was carried out cultivating 11 strains of PPB in a kind of chemically composed medium and media of organic wasterwater composed of wastewaters from soybean-prosessing and corn starch production at different ratios, separately. In the end of the experiment, the media were analyzed for extraction of EPS and for comparison. Results show that the strains of PPB varied in EPS producing capacity and that organic wastewater was more conducive to EPS production than the chemical medium. After two cycles of comparison, Strain J4 was screened out to be the highest- EPS-producing strain. In the wastewater from soybean processing, Strain J4 produced as high as 140 mg g-1 cell dry weight of EPS and as a result, it reduced wastewater COD by over 90%. The analysis with Sephadex G-50 chromatography shows that the EPS produced by J4 is high in molecular weight and has a certain research value. To sum up, through the cultivation experiment, a strain of high-EPS-producing PPB, J4 was obtained, and was proved to be able to produce large volumes of EPS by organic wastewater, which could be used as a basis for finding and producing cheap polysaccharide materials.