A study of the properties of oligotrophic bacteria

用双向电泳法分析了寡营养细菌的膜蛋白。寡营养细菌即使在极差的营养肉汤中也能生长，用蒸馏水稀释(1/10000)。然而，它们也可以在丰富的介质中生长。我们推测，当它们生长在较差的介质中时，它们具有通过膜高效吸收外界营养的能力。它们可能会改变膜蛋白的组成，以便在较差的介质中有效地吸收营养。然后，我们分析了从同一细菌中分离出的膜蛋白，分别在富培养基和差培养基中生长。对三种寡营养细菌的膜蛋白进行了研究。它们都被鉴定为洋葱假单胞菌。在不同的生长条件下，膜蛋白的双向电泳图谱存在明显的差异。尤其是能在贫菌群中生长的洋葱假单胞菌I，在富菌群向贫菌群过渡的过程中，总溶菌模式发生了较大的变化，好像它们是不同的菌株一样。在低浓度条件下生长的细菌，在蛋白质总量减少的情况下，膜上还出现了几种新的富含蛋白质的蛋白质。随着培养基中营养物质的去除，这种模式的变化也在增加。特别是，当营养稀释到1/100时，这种模式发生了很大的变化。在其他菌株中，总的电泳谱没有改变，也没有发现新的蛋白，但在较差的培养基中，几种膜蛋白的浓度增加了。这些结果表明，寡营养细菌产生更多的膜蛋白，为营养的有效吸收提供运输通道。

Membrane proteins of oligotrophic bacteria were analyzed by two -dimensional electropholysis. Oligortrophic bacteria could grow even in extremely poor medium, diluted nutrient broth, that was diluted with distillled water (1/10,000). However, they also could grow in rich medium. We speculated that had ability to uptake nutrition outside efficiently through membrane when they grow in poor medium. They may change the membrane proteins composition for efficient uptake of nutrition in poor medium. Then we analyzed membrane proteins isolated from the same bacteria growing in rich medium and poor medium respectively. Membrane proteins of three species of oligotrophic bacteria were investigated. They were all identified as Pseudomonas cepacia.Considerable differences in two-dimensional electropholysis patterns of membrane proteins were found between growing conditions. Especially in P.cepacia I that could grow in poor medium weel, during the transition from rich medium to poor medium total elctrophlysis pattern changed fairly as if they had been different strains. In spite of the decrease of the total number of proteins, several new proteins of rich amount appeared in membrane of bacteria growing in poor medium. The change of the pattern was increasing as nutrition in medium was removed. Especially, as the nutrition was diluted to 1/100, the pattern was changed considerably. In other strains, total elctropholysis patterns were not changed and new proteins were not found, but the concentration of several membrane proteins increased in poor medium. These results suggest that oligotrophic bacteria produce some membrane proteins much more to make transport channel for efficientl uptake of nutrition.