一株茁芽短梗霉的分离鉴定及产多糖研究

Isolation and identification of a strain of Aureobasidium pullulans and its production of polysaccharide

【目的】筛选具有产普鲁兰多糖能力的茁芽短梗霉(Aureobacidium pullulans)菌种,为普鲁兰行业提供菌种资源。【方法】从鄱阳湖国家湿地公园的草地上采集9份土壤样品,采用稀释平板涂布法,结合对菌落和菌株形态特征观察及18SrDNA序列对比分析筛选茁芽短杆霉野生菌株。发酵培养测定菌株的普鲁兰产量和颜色,并运用红外光谱(FT-IR)法分析普鲁兰多糖的分子结构。【结果】从9份土样中分离得到5株菌株,其中只有菌株AP23具有酵母、菌丝体等多态性,该菌株的18SrDNA序列与已知序列DQ242509(A.pullulans)、DQ278883(A.pullulans)的同源性均达100%,可确定为茁芽短梗霉。发酵培养测定菌株AP23的普鲁兰产量为6.72g/L,糖转化率达22.4%。FT-IR分析表明茁芽短梗霉多糖是由α-糖苷键连接的D-吡喃葡萄糖残基组成的普鲁兰。【结论】茁芽短梗霉AP23具有良好的生长特性,可作为诱变高产普鲁兰多糖的出发菌株加以利用。

【Objective】An Aureobacidium pullulans strain able to produce pullulans was screened to provide strains for pullulans fermentation industry. 【Method】Nine soil samples were taken from the grassland of Poyang lake national wetland park. Plate dilution method was used to separate fungus. The colony morphology and cell morphology of fungus were observed, and the sequence of 18 s rDNA of fungus was analyzed. Then, a new strain of Aureobasidium pullulans was isolated. Fermental cultivation was also conducted for measuring colour and yield of pulluans, and the structure of polysaccharide was determined by infrared spectroscopy（FT-IR）. 【Result】Five candidate fungus were isolated from the nine soil samples. After purified and cultured, it was found that only Strain AP23 had morphological diversity, such as yeast and mycelium. It was considered that strain AP23 was Aureobasidium pullulans. The yield of pullulans was 6.72 g/L and sugar conversion rate was 22.4%. Infrared spectrum（FT-IR） verified that pullulans were consisted of Alpha glycosidic bond connection of D- pyran glucose residues. 【 Conclusion 】 Aureobasidium pullulans AP23 has good growth characteristics, hence it can be utilized for pullulan fermentation industry.