Hoseinabadi Akram, Rasooli Iraj, Taran Mojtaba
Department of Biology, Shahed University, Tehran, IR Iran.
Department of Biology, Razi University, Kermanshah, IR Iran.
Jundishapur J Microbiol. 2015 Jul 27;8(7):e16965. doi: 10.5812/jjm.16965v2. eCollection 2015 Jul.
Biodegradable polyesters are candidates for the development of environmental friendly plastics. Poly-β-hydroxybutyrate (PHB) is a type of polyester from the hydroxyalkanoates family, synthesized by bacteria as an intracellular material and accumulated as granules in the cytoplasm.
The aim of this study was to isolate Poly β-hydroxybutyrate over producing bacteria and optimize the production medium.
A variety of PHB-accumulating bacterial strains were isolated from Kermanshah oil refinery sludge in Iran. Poly-β-hydroxybutyrate-producing bacterial strains were confirmed by the gas chromatography method. The strain with the highest rate of PHB production was selected. Use of sugar cane molasses, a by-product of the sugar refinery industry, was investigated for the production of PHB. Plackett-Burman statistical method was employed to obtain factors in cell growth and PHB production. Optimization by the Response Surface Method (RSM) was done via two carbon sources, glucose and molasses.
In the present study, 21 of 63 strains isolated from the refinery oil sludge produced PHB, seven of which were over producers. Poly-β-hydroxybutyrate production was analyzed by Sudan Black B staining, spectrophotometric and gas chromatography (GC) methods. The strain with the highest rate of PHB production was used to optimize the culture medium. Fifteen factors were analyzed in PHB production by the Plackett-Burman method to find the most effective factors. Five important factors were optimized by RSM. Molasses were used as a cheap source of carbon. The maximum PHB obtained from molasses was 6.62 g/L. The phenotypic and 16S rRNA biotyping tests led to the identification of the isolate as Bacillus coagulans.
The results suggest that B. coagulans is a good candidate for the fermentative production of PHB.
可生物降解聚酯是开发环保塑料的候选材料。聚-β-羟基丁酸酯(PHB)是羟基链烷酸酯家族中的一种聚酯,由细菌合成作为细胞内物质,并以颗粒形式积累在细胞质中。
本研究旨在分离出高产聚-β-羟基丁酸酯的细菌并优化生产培养基。
从伊朗克尔曼沙阿炼油厂污泥中分离出多种积累PHB的细菌菌株。通过气相色谱法确认产聚-β-羟基丁酸酯的细菌菌株。选择PHB产量最高的菌株。研究了制糖工业副产品甘蔗废蜜用于生产PHB的情况。采用Plackett-Burman统计方法获得细胞生长和PHB生产的影响因素。通过响应面法(RSM)对葡萄糖和废蜜这两种碳源进行优化。
在本研究中,从炼油厂污泥中分离出的63株菌株中有21株产生PHB,其中7株为高产菌株。通过苏丹黑B染色、分光光度法和气相色谱(GC)法分析聚-β-羟基丁酸酯的产量。使用PHB产量最高的菌株来优化培养基。通过Plackett-Burman方法分析了PHB生产中的15个因素,以找出最有效的因素。通过RSM对5个重要因素进行了优化。废蜜被用作廉价的碳源。从废蜜中获得的最大PHB为6.62 g/L。表型和16S rRNA生物分型测试确定该分离株为凝结芽孢杆菌。
结果表明凝结芽孢杆菌是发酵生产PHB的良好候选菌株。