| 摘要: |
| 【目的】从养殖水体的生物絮团中分离鉴定产絮菌，并对其絮凝条件进行优化。【方法】采用五点采样法采集生物絮团样品，平板划线法分离细菌，以4 g/L高岭土悬浊液为絮凝率测定系统，根据目标菌株的形态特征、API系统鉴定以及16S rRNA序列分析以鉴定其种属，建立生长曲线以得到絮凝活性最佳培养时间，采用单因素试验方法对其培养条件（培养基初始pH、培养温度、摇床转速）和絮凝条件（高岭土悬浊液pH、发酵液投加量、助凝剂）等进行优化。【结果】分离筛选得到1株絮凝菌菌株G201441，该菌属于苏云金芽孢杆菌（Bacillus thuringiensis）（GenBank登录号为KP747687）；培养48 h后其发酵液絮凝效果最好；该菌最佳培养条件为：培养基初始pH值8.0，培养温度30 ℃，摇床转速150 r/min；最佳絮凝条件为：高岭土悬浊液pH值7.0，发酵液投加量8%（体积分数），助凝剂为Ca2+。【结论】筛迭得到的产絮菌G201441具有较高的絮凝活性，最适条件下其发酵液对高岭土悬浊液的絮凝率可达92%。 |
| 关键词: 生物絮团 絮凝剂产生菌 苏云金芽孢杆菌 培养条件 絮凝条件 |
| DOI： |
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| 基金项目:“十二五”农村领域国家科技计划课题“池塘优势生物群落调控管理技术研究”(2012BAD25B01)；广东省海洋渔业科技推广专项“内陆池塘复合净化技术示范与推广”（B201400C01） |
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| Isolation and identification of a flocculant-producing bacterium strain and optimization of its culturing conditions |
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WU Jingrong,WANG Guangjun,LI Zhifei,et al
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| Abstract: |
| 【Objective】A flocculant producing bacterium strain was isolated and identified from bio-floc of aquaculture water,and its optimal flocculation conditions were obtained.【Method】Samples were collected using five point sampling method,bacterium was separated with streak plate,and kaolin suspension (4 g/L) was used as an assay system for measuring the flocculation activity.The flocculation-producing performance and stability were studied through subculture.This bacterial species was identified and characterized based on its morphological characteristics,API system and the partial sequences of its 16S rRNA.Its growth curve was established to obtain optimal incubation time.Using the single factor test method,culturing conditions including initial pH,temperature and shaker operation,and flocculation conditions including pH of kaolin suspension,inoculation dosage and coagulant for this strain were optimized.【Result】The strain G201441 was identified as Bacillus thuringiensis (GenBank accession number KP747687).According to its growth curve,this bacterium reached the maximum flocculation activity 48 h after culturing.The results showed that an initial pH of 8.0 was optimal for its growth when cultured at 30 ℃ on a shaker operated at 150 r/min.The optimal flocculation conditions for this strain were determined:kaolin suspension at pH 7.0 with inoculation dosage of volume fraction of 8% and coagulant Ca2+.【Conclusion】The isolated Bacillus thuringiensis G201441 displayed high flocculation activity with a stable performance in the flocculation subculture.The flocculation rate reached 92% under these optimized conditions for 0.4% kaolin suspension. |
| Key words: bio-floc flocculant-producing bacteria Bacillus thuringiensis culture conditions floculation conditions |
