大肠杆菌对链状弯壳藻生长特性的影响

Effects of Escherichia coli on the growth characteristics of Achnanthidium catenatum

目的:探究细菌与链状弯壳藻共培养时对其生长特性的影响,了解链状弯壳藻改变存在状态、形成水华的原因.方法:研究了不同大肠杆菌(Escherichia coli)添加量对链状弯壳藻生物量、多细胞群体形成、胞外多糖含量等的影响.结果:大肠杆菌对链状弯壳藻的生长存在抑制作用,表现为总细胞密度随添加菌液浓度(0.2%~2%)的增加而减少;但细菌的存在对链状弯壳藻单细胞形成群体具有促进作用,其中1%的菌液浓度最有利于链状弯壳藻形成群体,群体细胞的密度约为对照的5倍.与1%菌液浓度共培养的链状弯壳藻胞外多糖含量是对照的2.3倍,且链状弯壳藻的胞外多糖含量与群体细胞密度正相关(P<0.05).结论:细菌的存在是链状弯壳藻形成多细胞链状群体的重要因素.

Objective:To explore the influence of bacteria on the growth of A.catenatum when mixed cultured,and to understand the reason that the A.catenatum group contribute to water bloom because of its morphological change.Methods:The influence of the concentration of E.coli on the biomass,cell number of catenoid colony and extracellular polysaccharide content of A.catenatum were studied.Results:E.coli could inhibit the growth of A.catenatum and the total cell density decreased with the increase of the concentration(0.2%-2%)of the added bacteria.However,the presence of bacteria couldpromote single cells aggregate into catenoid colony of A.catenatum,and 1%bacterial concentration was the most favorable concentration for the formation of catenoid colony and the cell density of colony was about five times that of the control.When the concentration of E.coli was 1%,the extracellular polysaccharide content of A.catenatum was 2.3 times that of the control,and the content of the extracellular polysaccharide was positively correlated with the cells density of A.catenatum(P<0.05).Conclusion:It is suggested that co-culture with bacteria is an important factor for the formation of catenoid colony of A.catenatum.