Bogosian G, Sammons L E, Morris P J, O'Neil J P, Heitkamp M A, Weber D B
Protiva, Monsanto Company, Chesterfield, Missouri 63198, USA.
Appl Environ Microbiol. 1996 Nov;62(11):4114-20. doi: 10.1128/aem.62.11.4114-4120.1996.
Whether Escherichia coli K-12 strain W3110 can enter the "viable but nonculturable" state was studied with sterile and nonsterile water and soil at various temperatures. In nonsterile river water, the plate counts of added E. coli cells dropped to less than 10 CFU/ml in less than 10 days. Acridine orange direct counts, direct viable counts, most-probable-number estimates, and PCR analyses indicated that the added E. coli cells were disappearing from the water in parallel with the number of CFU. Similar results were obtained with nonsterile soil, although the decline of the added E. coli was slower. In sterile water or soil, the added E. coli persisted for much longer, often without any decline in the plate counts even after 50 days. In sterile river water at 37 degrees C and sterile artificial seawater at 20 and 37 degrees C, the plate counts declined by 3 to 5 orders of magnitude, while the acridine orange direct counts remained unchanged. However, direct viable counts and various resuscitation studies all indicated that the nonculturable cells were nonviable. Thus, in either sterile or nonsterile water and soil, the decline in plate counts of E. coli K-12 strain W3110 is not due to the cells entering the viable but nonculturable state, but is simply due to their death.
研究了大肠杆菌K-12菌株W3110在不同温度下于无菌和非无菌水及土壤中是否能进入“活的但不可培养”状态。在非无菌河水中，添加的大肠杆菌细胞平板计数在不到10天内降至低于10 CFU/ml。吖啶橙直接计数、直接活菌计数、最大可能数估计和PCR分析表明，添加的大肠杆菌细胞与CFU数量平行地从水中消失。在非无菌土壤中也得到了类似结果，尽管添加的大肠杆菌数量下降较慢。在无菌水或土壤中，添加的大肠杆菌持续时间长得多，即使在50天后平板计数通常也没有任何下降。在37℃的无菌河水中以及20℃和37℃的无菌人工海水中，平板计数下降了3至5个数量级，而吖啶橙直接计数保持不变。然而，直接活菌计数和各种复苏研究均表明，不可培养的细胞是没有活力的。因此，在无菌或非无菌水及土壤中，大肠杆菌K-12菌株W3110平板计数的下降并非由于细胞进入活的但不可培养状态，而仅仅是由于它们的死亡。
