光合细菌的色素分析及蛋白质测定研究

光合细菌含有丰富的营养成分和生物活性物质,对其色素及蛋白质含量的分析,为其在食品领域应用奠定基础.研究采用平板画线法与液体培养法从某养殖池塘底泥中分离、纯化出5株光合细菌,进行了形态观察及菌种16S rDNA鉴定.采用Varian Cary 50紫外光谱分析仪进行色素分析与蛋白质的测定,并对类胡萝卜素稳定性进行了分析.结果表明分离纯化的光合细菌革兰氏反应为阴性,菌落为棕红色,光照厌氧和黑暗好氧条件下均可生长.16S rDNA基因的分子系统学分析表明,菌株与GenBank中的沼泽红假单胞菌菌株的同源性为99%,初步确定筛选出的菌株为沼泽红假单胞菌(Rhodopseudomonas palustris).菌株含有的色素主要是类胡萝卜素和细菌叶绿素a,类胡萝卜素在低温或低光照条件下,具有一定的稳定性,但在高温、加热时间过长或太阳光直射时色素迅速分解褪色.此外,菌株的蛋白质含量相对较高,是一种优质的蛋白源.光合细菌富含类胡萝卜素,并且可以作为一种高效的蛋白源,在食品及其他行业上的应用前景十分广阔.

Pigment Analysis and Protein Determination of Photosynthetic Bacteria

Nutrients and bioactive substances found from photosynthetic bacteria were abundant. The position in the field of food applications was established by analyzing its pigments and protein content. Five photosynthetic bacteria were isolated from bottom sludge in aquaculture pond using flat line drawing and liquid culture method, and then the primary identification and identification of 16S rDNA of these strains were performed. The pigment and protein of photosynthetic bacteria were analyzed by Varian Cary 50 ultraviolet spectrum analyzer. The strains screened from bottom sludge in aquaculture pond were Gram-negative bacterium. PSB were red, they could grow both under anaerobic condition in the light and aerobic in the dark. Phylogenetic tree of 16S rDNA indicated that the similarity of PSB and standard bacterium of Rhodopseudomonas palustris in GenBank was 99% and the photosynthetic bacteria were identified as R. palustris. The pigment of PSB was analyzed. The result indicated that bacteria contained major pigments being chlorophyll a and carotenoids. Carotenoid had intense stability in low temperature or low illumination intensity. Reversely, carotenoid would decompose in high temperature, heating up too long or high illumination intensity. The application of carotenoid was restricted with temperature and illumination intensity. Strains were a high quality source of protein containing relatively high protein content. Photosynthetic bacteria contained affluent carotenoids and could be used as highly efficient protein source, as the same time its applications in the food and other industries were very broad.