Serrato Rodrigo V, Sassaki Guilherme L, Cruz Leonardo M, Pedrosa Fábio O, Gorin Philip A J, Iacomini Marcello
Department of Biochemistry and Molecular Biology, Universidade Federal do Paraná, Curitiba, Brazil.
Can J Microbiol. 2006 May;52(5):489-93. doi: 10.1139/w05-155.
The endophytic diazotrophic bacterium Burkholderia tropica, strain Ppe8, produced copious amounts of exopolysaccharide (EPS) on batch growth in liquid synthetic media containing mannitol and glutamate as carbon and nitrogen sources. The effect of various aeration regimes and carbon source concentrations on EPS production was determined, as well as the effects of temperature and time of growth. The degree of aeration had a great influence on the yield of EPS, in contrast with the C:N ratio of the medium. Growth temperature also affected the EPS yield after the first 24 h of culture but seemed to be irrelevant after that. After isolation and purification, the EPS was analyzed by high-performance size exclusion chromatography and multiangle laser light scattering (HPSEC-MALLS), revealing a molecular mass of 300 kDa. The acid hydrolyzate of EPS was examined by HPLC and found to contain Glc, Rha, GlcA, and an aldobiouronic acid. The latter was found to have a GlcA and a Rha unit. Carboxy-reduced EPS contained Glc and Rha (3:2). The monosaccharide composition of the native acidic EPS was calculated as GlcA, Glc, and Rha in a molar ratio of 1:2:2.
内生固氮细菌热带伯克霍尔德氏菌（Burkholderia tropica）菌株Ppe8，在以甘露醇和谷氨酸作为碳源和氮源的液体合成培养基中分批生长时，会产生大量胞外多糖（EPS）。测定了不同通气方式和碳源浓度对EPS产量的影响，以及生长温度和时间的影响。与培养基的碳氮比相比，通气程度对EPS产量有很大影响。培养温度在培养的前24小时也会影响EPS产量，但之后似乎无关紧要。经过分离和纯化后，通过高效尺寸排阻色谱和多角度激光光散射（HPSEC-MALLS）对EPS进行分析，结果显示其分子量为300 kDa。通过HPLC对EPS的酸水解产物进行检测，发现含有葡萄糖（Glc）、鼠李糖（Rha）、葡萄糖醛酸（GlcA）和一种二糖醛酸。发现后者含有一个GlcA和一个Rha单元。羧基还原的EPS含有Glc和Rha（3:2）。天然酸性EPS的单糖组成经计算为GlcA、Glc和Rha的摩尔比为1:2:2。
