罗汉果内生菌及其周边土壤中产α-淀粉酶菌株的筛选

Screening of α-Amylase Producing Strains from Endophytic Bacteria in Siraitia grosvenorii and Its Surrounding Soil

对罗汉果内生菌及其种植区土壤中的微生物进行分离,筛选淀粉酶产生菌,并研究其发酵条件,结果得到15株内生菌和8株微生物,从中筛选到2株产淀粉酶高的菌株2-1(土壤)和R-4(根部内生菌)。经初步鉴定,菌株2-1为球菌,菌株R-4为芽孢杆菌,均为革兰氏阳性菌。研究显示,菌株2-1产酶条件为1.0%氯化铵、0.5%酵母粉、1.0%可溶性淀粉、0.4%氯化钠,发酵温度为40℃,发酵3 d,其产酶量为127.65 U/m L;R-4菌株产酶条件为0.5%酵母粉、1.0%氯化铵、0.05%氯化钠、2.0%可溶性淀粉,发酵温度为40℃,发酵3 d,其产酶量为197.21 U/m L。

In this study, the screening of α -amylase producing strains from endophytic bacteria in Siraitia grosvenorii and surrounding soil were preformed, and the optimum fermentation conditions for α -amylase producing strains were performed. Our results showed that 15 strains were isolated from the Siraitia gros- venori and 8 strains from surrounding soil. High amylase producing strains 2-1 （ surrounding soil） and R-4（root endophytic bacteria） were isolated. The identification results showed that 2-1 strain was staphy-lococcus and R- 4 strain was bacillus, which were gram positive bacteria. The appropriate condition of enzyme production for strains 2-1 and R-4 were determined. For strain 2-1, the appropriate conditions were 1.0% ammonium chloride, 0. 5% yeast powder, 1. 0 % soluble starch, 0. 4 % sodium chloride, fer-mentation temperature 40 益,and fermentation time 3 days and the enzyme production was 127.65 U/mL under these conditions. For strain R-4, the appropriate conditions were 0. 5 % yeast powder, 1.0% ammonium chloride, 0.05% sodium chloride, 2.0% soluble starch, fermentation temperature 40 ℃, and fermentation time 3 days, and the enzyme production was 197. 21 U/mL under these conditions.