滇池高效聚磷菌Rhodococcus sp.H的分离鉴定及除磷特性研究

采用混合稀释平板法,从富营养化湖泊底泥滇池中分离出1株高效聚磷菌,经分子生物学鉴定,推测其为红球菌属(Rhodococcus sp.),将其命名为Rhodococcus sp.H,并对菌株H在不同理化因素条件下的生长及除磷特性进行了研究。结果表明,该菌株在接种培养24 h后即能完成对数增长期,在pH值为6~7、温度为30℃时能获得较高生物量和除磷率,最佳碳源为乙酸钠和乙醇,最佳氮源为牛肉膏和蛋白胨。当温度高于35℃或低于15℃、p H值高于9或低于5时,菌株的生长会受到明显抑制,除磷率较低。同时研究表明,该菌株的生长会影响其生长环境基质的p H值,在一定范围内具有较强的p H值调节能力。该菌株能够有效利用乙酸钠和乙醇等小分子碳源获得较大生物量和较高的除磷效率,但是不能将铵盐作为唯一的氮源来利用。

Identification and determination of phosphorus-removing features and accumulation organisms Rhodococcus sp.H from Dianchi Lake sediments

The paper is inclined to determine the phosphorus-removing features and its accumulation organisms from the Dianchi Lake,Kunming,Yunnan.For the research purpose,we have collected and isolated phosphate accumulated organisms by the dilution-plate method from the eutrophic sediment of the lake.The strain,named Rhodococcus sp.H,has been obtained by the classic methods for screening the microorganisms together with the gene analysis of the 16s rRNA.And,furthermore,we have also investigated the effects of the different culture conditions on the bacterial growth and the phosphorus removal efficiency.The logarithmic growth phase of strain H has been completed in a period of 24 h after incubation,whereas the maximum biomass has been kept up for a period of 24 h to 48 h after incubation.Briefly speaking,the optimized cultivating conditions can be summarized as follows:temperature required 30℃;the initial p H value 6-7;the best carbon source:sodium acetate and ethanol;and,the best nitrogen source:beef extract and peptone.Under the aforementioned optimized conditions,the phosphorus removal efficiency can be expected to be so high as to over 80%with the maximum growth velocity.On the contrary,if the temperature is merely below 15℃or just above 35℃with the pH values of less than 5 or above 8,the growth of strain H would be likely to be noticeably inhibited,and then eventually to get lower than by the demand of the phosphorus removal rate.The results of the different p H incubation experiments have finally confirmed that the p H values of the culture media with the different initial p H values prove to be in a range from 5.0 to 9.0,and,then,would turn to the similar values between 6.0-7.0 as a result of incubation.This may also imply that strain H would be able to affect the p H value during its growing period to some extent,with the p H value adjusted to its optimized sphere.Furthermore,the experimental results of the different carbon and nitrogen sources also show that small-molecular carbon sources,such as acetate and ethanol,could only be utilized by strain H,when the sole carbon source were to be macromolecules,such as xylose and lactose,the growth and phosphorus removal efficiency may tend to get lowered dramatically.Besides,one point has to be mentioned,that is,the ammonium salt can not be used as the unique nitrogen source to support the growth of strain H,but the beef extract and peptone can,when higher growth rate and phosphorus removal rate are exhibited in the process of incubation.