一株微生物絮凝剂产生菌的培养条件优化研究

On optimization study of cultivation conditions of a flocculant-producing strain

从沈阳市浑河河水底泥中筛选出一株高效稳定的微生物絮凝剂产生菌BS-5。考察了碳源、氮源、培养时间、培养温度、初始pH值、摇床转速等因素对BS-5所产絮凝剂的影响。结果表明,可溶性淀粉是其良好的碳源,NaNO3位最佳氮源,最适宜培养时间为32h,培养温度为30℃,初始pH值为6～7,摇床转速为150r/min。在此条件下,对高岭土悬浮液的絮凝效率可高达97.5%。和其他微生物产生菌培养基相比较,BS-5培养基组成成分简单,价格低廉,培养时间短,可以减少生产时间和生产费用,可解决微生物絮凝剂生产成本较高的问题。

The present article introduces the authors＇ research of an optimum method on the cultivation conditions of a flocculant-pmducing Strain. As is known, biopolymer flocculant is a dynamic process resulting in the formation of stable aggregates or flocculants due to the synthesis of extraceUular polymers by living cells. But, the use of biopolymer flocculants has been restricted to some extent for its high cost. A new biopolymer flocculant was produced by using Bacillus sp. BS - 5, which was separated from the river-bed sludge of Hunhe river, Shenyang. Since BS-5 is a colorless, transparent, mucilaginous, gram-negative, mobile, oxidase-negative and catalase-positive rod with bacterial capsule, the shape of the lawn is round, with trim brimmed, and a gibbous surface. Moreover, the article has also stud- ied the effects of carbon and nitrogen sources and cultivation time, cultivation temperature, the initial pH and rotary shaker revolution on bioflocculant-pmducing properties of stain BS - 5 were also studied respectively. The results indicate that the optimal cultivation conditions of strain BS - 5 are： the soluble starch is its best carbon source while NaNO3 is the best nitrogen source. Meanwhile, the desirable cultivation time is 32 hours at the cultural temperature 30 ℃ with the initial pH value 6 ～ 7 and the rotation speed 150r/min. Under the above conditions, the strain can produce a strong-activating flocculant, with flocculating rate of above 97.5% for Kaolin suspension. During the period of cultivation, strain BS-5 has the function of adjustment pH value. In comparison with other bioflocculant-producing strains, the constituents of culture medium are simple and cheep without yeast extraction. And at the same time, the cultivation time of most hioflocculant-producing strains is over 48 hours, much longer than BS-5. Therefore, simple cultivation medium compositions and short cultivation time of BS-5 can save the cost and time, which makes it one of the possible solutions to the problem of high cost of bioflocculant production.