Dong Hailiang, Rothmel Randi, Onstott Tullis C, Fuller Mark E, DeFlaun Mary F, Streger Sheryl H, Dunlap Robb, Fletcher Madilyn
Department of Geosciences, Princeton University, Princeton, New Jersey 08544, USA.
Appl Environ Microbiol. 2002 May;68(5):2120-32. doi: 10.1128/AEM.68.5.2120-2132.2002.
The transport characteristics of two adhesion-deficient, indigenous groundwater strains, Comamonas sp. strain DA001 and Erwinia herbicola OYS2-A, were studied by using intact sediment cores (7 by 50 cm) from Oyster, Va. Both strains are gram-negative rods (1.10 by 0.56 and 1.56 by 0.46 microm, respectively) with strongly hydrophilic membranes and a slightly negative surface charge. The two strains exhibited markedly different behaviors when they were transported through granular porous sediment. To eliminate any effects of physical and chemical heterogeneity on bacterial transport and thus isolate the biological effect, the two strains were simultaneously injected into the same core. DA001 cells were metabolically labeled with (35)S and tagged with a vital fluorescent stain, while OYS2-A cells were metabolically labeled with (14)C. The fast decay of (35)S allowed deconvolution of the two isotopes (and therefore the two strains). Dramatic differences in the transport behaviors were observed. The breakthrough of DA001 and the breakthrough of OYS2-A both occurred before the breakthrough of a conservative tracer (termed differential advection), with effluent recoveries of 55 and 30%, respectively. The retained bacterial concentration of OYS2-A in the sediment was twofold higher than that of DA001. Among the cell properties analyzed, the statistically significant differences between the two strains were cell length and diameter. The shorter, larger-diameter DA001 cells displayed a higher effluent recovery than the longer, smaller-diameter OYS2-A cells. CXTFIT modeling results indicated that compared to the DA001 cells, the OYS2-A cells experienced lower pore velocity, higher porosity, a higher attachment rate, and a lower detachment rate. All these factors may contribute to the observed differences in transport.
利用弗吉尼亚州牡蛎市的完整沉积物岩芯（7×50厘米），研究了两种缺乏黏附能力的本地地下菌株，即食酸丛毛单胞菌属菌株DA001和草生欧文氏菌OYS2 - A的传输特性。这两种菌株均为革兰氏阴性杆菌（分别为1.10×0.56微米和1.56×0.46微米），具有强亲水性膜和略带负电荷的表面。当它们通过颗粒状多孔沉积物传输时，这两种菌株表现出明显不同的行为。为消除物理和化学异质性对细菌传输的任何影响，从而分离出生物效应，将这两种菌株同时注入同一岩芯。DA001细胞用³⁵S进行代谢标记并用一种活体荧光染料标记，而OYS2 - A细胞用¹⁴C进行代谢标记。³⁵S的快速衰变使得能够对这两种同位素（进而对这两种菌株）进行反褶积分析。观察到传输行为存在显著差异。DA001和OYS2 - A的突破均发生在保守示踪剂突破之前（称为差异平流），流出物回收率分别为55%和30%。沉积物中OYS2 - A的保留细菌浓度比DA001高两倍。在所分析的细胞特性中，这两种菌株之间具有统计学显著差异的是细胞长度和直径。较短、直径较大的DA001细胞比较长、直径较小的OYS2 - A细胞表现出更高的流出物回收率。CXTFIT建模结果表明，与DA001细胞相比，OYS2 - A细胞经历的孔隙流速更低、孔隙率更高、附着率更高且脱离率更低。所有这些因素可能导致了观察到的传输差异。
