放射形土壤杆菌生物变型IS-1231产丁二酸型多糖的研究

Studies on the Extracellular Polysaccharide from Agrobacterium radiobadter biovar IS-1231

从北京地区土样中分离到一株革兰氏阴性、无芽胞、稀周毛及运动的菌株S-1231。它能以糖类为底物产丁二酸型胞外多糖,不能利用淀粉和纤维素。该菌发酵葡萄糖产酸,生长12—24小时,细胞杆状0.7—0.8×1.3—1.5μm,圆端,单个或成对。在营养洋菜平板上菌落圆形、低凸、表面光滑、润泽、边缘整齐。该菌产生3-酮基乳糖,接种向日葵不致瘤,DNA中G+C含量62.8—63.4克分子％。该菌氧化酶阳性,接触酶阳性,产生H_2S,35C生长,2％NaCl生长,及石蕊牛奶产碱,该菌定为放射形土壤杆菌生物变型Ⅰ。组分分析表明,该菌株产生的胞外多糖(简称Agran-S)由D-葡萄糖(69.1％),D-半乳糖(8.6％),丙酮酸(9.5％)和丁二酸(10.8％)组成。甲基化分析表明,多糖Agran-S含有下列主要结构单位(均为β-糖苷键):(1→3)-连接的D-葡萄糖(21.2％);(1→3)-连接的D-半乳糖(11.4％);(1-6)-连接的D-葡萄糖(10.5％);(1→4)-连接的D-葡萄糖(30.4％)。(1→4,1→6)-连接的D-葡萄糖(22.2％)和末端D-葡萄糖(4.3％)。

A strain S-1231 isolated from specimen of soil around Beijing area is gram-negative, non-sporing, motile by peritrichous flagella. It produces exopolysaccharide suc-cinoglycan from carbohydrates as its carbon source but not starch and cellulose. Acid is produced during fermentation of glucose. Growing for 12 - 24 h,the cells are rods 0. 7 -0. 8×1.3-1. 5 um,round end,singly or in pairs. Colonies on nutrient agar plate are non-pigmented, circular, raised, smooth and moist - glistening, edge entire. The organism produces 3 -ketolactose and lacks ability to invade sunflower tissue,The G+C content of DNA is 62. 8 -63. 4 mol % ,The organism is referred to as Agrobacterium radiobacter. Moreover,the strain is oxidase-positive,catalase-positive,H2S-produce. And it can grow at 35 Cand 2% NaCl also. Litmus milk is alkalified. Thus,the organism was named as Agrobacterium radiobacter biovar I , Component analyses showed that/the exopolysaccharide (Agran-S) from Agrobacterm.m radiobacter biovar I S-1231 consisted of D-glu-cose(69.1%), D-galactose (8-6%) , pyruvic acid (9. 5%) and succinic acid(10.8%). Methylation analyses revealed that the polyasccharide AgranA -S contained following main structural units: (1 → 3)-linked D-glucose (21.2%) , (1→ 3)-linked D-galactose (11.4%),(1-6)-inked D-glucose(10.5%),(1→ 4)-linked D-glucose(30.4%), (1→ 4, 1→ 6)-linked D-glucose(22.2%)and terminal D-glucose(4.3%). The 1H-N. M. R. spectrum of the polysaccharide indicated that the linkages in the polymer are all B-glycosidic. The IR spectra of the polysaccharide revealed the presence of ester linkage in polysaccharide Agran-s.