不同低聚糖对生物絮团形成及其菌群结构的影响

Effects of different oligosaccharides on the formation of bioflocs and the structure of the bacterial community

本研究旨在探究不同低聚糖对生物絮团形成及生物絮团菌群结构特征的影响。以葡萄糖(GLU)为对照,采用低聚木糖(XOS)、低聚果糖(FOS)、甘露寡糖(MOS)、大豆低聚糖(SBOS)、低聚麦芽糖(MTOS)作为碳源构建生物絮团,氯化铵为氮源,碳氮比(C/N)为15。结果显示,SBOS组与其他各组相比,显著提高水中悬浮颗粒物含量及生物絮团体积,其他低聚糖组与对照组相比差异不显著。氨氮逐渐下降然后趋于稳定,SBOS组与对照组和其他实验组相比,显著降低了氨氮水平,其中除FOS组外,其他实验组降低氨氮能力均高于对照组。亚硝态氮降解作用均没有显著差异。硝态氮呈现先降低后升高的趋势,除XOS组外均可降低硝态氮的积累,其中SBOS组与MTOS组显著降低硝态氮的积累。XOS组与对照组相比,显著降低生物絮团菌群的丰度与微生物多样性指数。从门水平上分析,变形菌门在各实验组中均丰度最大,各低聚糖组与对照组相比,对拟杆菌门、变形菌门均有不同程度提高,其中FOS组显著提高变形菌门与拟杆菌门的丰度。从属水平上分析,实验组与对照组相比均降低蛭弧菌比例,其中FOS组与对照组及其他实验组相比,显著提高unclassified_f_Rhodobacteraceae的丰度,显著降低norank_f_Microscillaceae与norank_f_Enterobacteriaceae丰度。研究表明,低聚糖作为碳源构建生物絮团,可改善水质,优化菌群结构,提高有益菌数量,降低有害菌数量。本研究为低聚糖作为碳源应用于生物絮团提供理论依据。

To investigate the effects of different oligosaccharides on the formation of biofloc and the structural characteristics of biofloc flora.Using glucose(GLU)as control,xylo-oligosaccharides(XOS),fructooligosaccharides(FOS),mannan-oligosaccharides(MOS),soybean oligosaccharides(SBOS),and maltose oligosaccharides(MTOS)were used as carbon sources to culture biofloc,ammonium chloride was used as nitrogen source and C/N was 15.The results showed that suspended particulate matter content and biofloc volume in the SBOS group were significantly increased(P<0.05)compared with other groups,and there were no significant differences between other oligosaccharide groups and the control group(P>0.05).Ammonia nitrogen gradually decreased and then stabilized.Compared with the control group and other experimental groups,the level of ammonia nitrogen in the SBOS group was significantly decreased(P<0.05).Except for the FOS group,the ability to reduce ammonia nitrogen in other experimental groups was higher than that in the control group.There was no significant difference in nitrite nitrogen degradation(P>0.05).Nitrate nitrogen showed a trend of decrease first and then increased,and the accumulation of nitrate nitrogen was decreased in all groups except the XOS group,and the accumulation of nitrate nitrogen was significantly decreased in the SBOS group and MTOS group(P<0.05).Compared with the control group,the abundance of biofloc and microbial diversity index was significantly decreased in the XOS group(P<0.05).From the analysis of phyla level,proteobacteria had the highest abundance in all experimental groups.Compared with the control group,proteobacteria and Proteobacteria in oligosaccharide groups were improved,and the abundance of Proteobacteria and Bacteroidetes in the FOS group was significantly increased(P<0.05).Regarding subordinate level,the proportion of Bdellovibrio decreased in the experimental group compared with the control group(P>0.05).Compared with the control group and other experimental groups,the FOS group significantly increased the abundance of unclassified_f_Rhodobacteraceae and significantly decreased the abundance of unclassified_f_Rhodobacteraceae and norank_f_Enterobacteriaceae(P<0.05).The results show that the biofloc constructed by oligosaccharide as carbon source can improve water quality,optimize bacterial community structure,increase the number of beneficial bacteria,and reduce the number of harmful bacteria.This study provides some theoretical basis for applying of oligosaccharides as carbon source in biofloc.