可得然多糖生产菌株的筛选、鉴定及其培养条件的研究

Screening and Identification of a Bacterial Strain Produced by Curdlan and Research on Its Culture Conditions

可得然多糖是一种可溶性多糖,是由葡萄糖残基以β-1,3糖苷键连接组成的直链无分支葡聚糖。这种多糖被广泛应用在食品行业中。聚合度的不同导致这种多糖具有不同的理化性质。因此发现具有合成可得然多糖的不同微生物资源是非常重要的,但到目前为止,只报道了粪产碱杆菌和农杆菌具有合成这种多糖的能力。研究从土壤中筛选到一株能合成可得然多糖的细菌,通过16SrDNA扩增、序列比对,发现该菌株(Cur-4)是革兰氏阳性的假单胞菌属(Pseudomonas sp.)。通过对影响该菌株合成可得然多糖的因素研究,发现葡萄糖是最适碳源,酵母粉是最适氮源,培养基初始最适pH为7.0。文章首次报道了Pseudomonas sp.也能合成可得然多糖。

Curdlan is a soluble polysaccharide, composed of β-1,3-1inked glucose residues. Curdlan and its derivatives have potential application value in food industries. Hence, polymer has different physi- cochemical properties with different degrees of polymerization. It is important to find different micro- bial resources which can synthetize curdlan polysaccharide. However, so far only Alcaligenes and Agrobacterium species have been reported to produce curdlan. In this study, a bacterium which can produce extracellular curdlan is isolated from soil samples on the basis of 16S rDNA gene sequencing. The strain Cur-4 is a gram-positive Pseudomonas sp. In addition, the factors affecting the systhesis of curdlan ar investigated. It is observed that glucose is the most suitable carbon source for curdlan pro- duction by Cur-4 strain. The maximum curdlan production is achieved when yeast extract is used as nitrogen source. Furthermore, it is also found that maximum curdlan production is obtained when ini- tial pH is at 7. 0. To the best of our knowledge, this is the first report on curdlan production by P seudomonas sp..