Reynolds P J, Sharma P, Jenneman G E, McInerney M J
Department of Botany and Microbiology, University of Oklahoma, Norman 73019.
Appl Environ Microbiol. 1989 Sep;55(9):2280-6. doi: 10.1128/aem.55.9.2280-2286.1989.
The biological factors important in the penetration of Escherichia coli through anaerobic, nutrient-saturated, Ottawa sand-packed cores were studied under static conditions. In cores saturated with galactose-peptone medium, motile strains of E. coli penetrated four times faster than mutants defective only in flagellar synthesis. Motile, nonchemotactic mutants penetrated the cores faster than did the chemotactic parental strain. This, plus the fact that a chemotactic galactose mutant penetrated cores saturated with peptone medium at the same rate with or without a galactose gradient, indicates that chemotaxis may not be required for bacterial penetration through unconsolidated porous media. The effect of gas production on bacterial penetration was studied by using motile and nonmotile E. coli strains together with their respective isogenic non-gas-producing mutants. No differences were observed between the penetration rates of the two motile strains through cores saturated with peptone medium with or without galactose. However, penetration of both nonmotile strains was detected only with galactose. The nonmotile, gas-producing strain penetrated cores saturated with galactose-peptone medium five to six times faster than did the nonmotile, non-gas-producing mutant, which indicates that gas production is an important mechanism for the movement of nonmotile bacteria through unconsolidated porous media. For motile strains, the penetration rate decreased with increasing galactose concentrations in the core and with decreasing inoculum sizes. Also, motile strains with the faster growth rates had faster penetration rates. These results imply that, for motile bacteria, the penetration rate is regulated by the in situ bacterial growth rate.(ABSTRACT TRUNCATED AT 250 WORDS)
在静态条件下，研究了大肠杆菌穿透厌氧、营养饱和的渥太华砂填充岩芯过程中重要的生物学因素。在半乳糖 - 蛋白胨培养基饱和的岩芯中，运动型大肠杆菌菌株的穿透速度比仅在鞭毛合成方面有缺陷的突变体快四倍。运动型、无趋化性的突变体比趋化性亲本菌株更快地穿透岩芯。此外，趋化性半乳糖突变体在有或没有半乳糖梯度的情况下，以相同速率穿透蛋白胨培养基饱和的岩芯，这表明细菌穿透未固结多孔介质可能不需要趋化作用。通过使用运动型和非运动型大肠杆菌菌株及其各自的同基因不产气突变体，研究了气体产生对细菌穿透的影响。在有或没有半乳糖的蛋白胨培养基饱和岩芯中，两种运动型菌株的穿透速率之间未观察到差异。然而，仅在有半乳糖的情况下检测到两种非运动型菌株的穿透。非运动型产气菌株穿透半乳糖 - 蛋白胨培养基饱和岩芯的速度比非运动型不产气突变体快五到六倍，这表明气体产生是非运动型细菌通过未固结多孔介质移动的重要机制。对于运动型菌株，穿透速率随着岩芯中半乳糖浓度的增加和接种量的减少而降低。此外，生长速率较快的运动型菌株具有更快 的穿透速率。这些结果表明，对于运动型细菌，穿透速率受原位细菌生长速率的调节。（摘要截断于250字）
