Dodds K L, Perry M B, McDonald I J
Can J Microbiol. 1987 May;33(5):452-8. doi: 10.1139/m87-075.
Escherichia coli O157:H7 was grown in chemostats as continuous cultures at different controlled growth rates and under different nutrient limitations to determine the effects on lipopolysaccharide (LPS) structure. LPS from whole cells and extracted using the hot aqueous phenol method was examined by sodium dodecyl sulfate--polyacrylamide gel electrophoresis (SDS-PAGE) and by gel filtration after hydrolysis with acetic acid. At low growth rates under glucose limitation (D = 0.1 h-1, doubling time (td), approx. 416 min; or D = 0.4 h-1, td, approx. 104 min), E. coli O157 produced high molecular weight LPS identical to that previously characterized from cells grown in batch culture. At a high growth rate (D = 0.8 h-1, td, approx. 52 min), the ratio of high molecular weight LPS to low molecular weight LPS produced greatly decreased. A small amount of high molecular weight LPS, containing O-polysaccharide which lacked amino sugars, and which thus was chemically different from that previously characterized, was produced by the cells at high growth rates. The predominant form of LPS from these cells was of slightly higher molecular weight than rough LPS, probably S-R LPS, and it consistently formed aggregates on SDS-PAGE. This form of LPS was also predominant when E. coli O157 was grown under Mg2+ limitation at an intermediate growth rate (D = 0.4 h-1, td, approx. 104 min).
大肠杆菌O157:H7在恒化器中作为连续培养物，在不同的受控生长速率下以及不同的营养限制条件下培养，以确定对脂多糖（LPS）结构的影响。通过十二烷基硫酸钠-聚丙烯酰胺凝胶电泳（SDS-PAGE）以及用乙酸水解后的凝胶过滤，对采用热酚水法从全细胞中提取的LPS进行了检测。在葡萄糖限制下的低生长速率（稀释率（D）=0.1 h-1，倍增时间（td）约为416分钟；或D = 0.4 h-1，td约为104分钟）时，大肠杆菌O157产生的高分子量LPS与先前分批培养的细胞中所鉴定的LPS相同。在高生长速率（D = 0.8 h-1，td约为52分钟）时，产生的高分子量LPS与低分子量LPS的比例大幅下降。细胞在高生长速率下产生了少量的高分子量LPS，其含有缺乏氨基糖的O-多糖，因此在化学性质上与先前鉴定的不同。这些细胞产生的LPS的主要形式分子量略高于粗糙型LPS，可能是S-R LPS，并且在SDS-PAGE上始终形成聚集体。当大肠杆菌O157在Mg2+限制下以中等生长速率（D = 0.4 h-1，td约为104分钟）生长时，这种形式的LPS也是主要的。
