Department of Marine Science, University of South Florida, St. Petersburg, Florida 33701.
Appl Environ Microbiol. 1986 Jan;51(1):150-6. doi: 10.1128/aem.51.1.150-156.1986.
Three independent techniques, [H]thymidine incorporation, the reduction rate of p-iodonitrotetrazolium violet (INT) to INT formazan normalized to DNA, and the ratio of ATP to DNA, were adapted to measure the activity of attached and unattached estuarine bacteria. In experiments employing the estuarine isolate Vibrio proteolytica, nutrient concentrations were manipulated by varying the concentration of peptone-yeast extract. In the presence of exogenous nutrients, the activity of free-living cells was greater than that of attached cells as measured by [H]thymidine incorporation and ATP/DNA ratios. In the absence of peptone-yeast extract, however, the activity of attached cells surpassed that of free-living cells as determined by [H]thymidine incorporation and INT formazan normalized to DNA. Of the three techniques, [H]thymidine incorporation was deemed most sensitive for detecting changes in activity resulting from slight differences in nutrient concentration. By this technique, attached cells were much less sensitive to changing nutrient concentrations than were free-living cells. Below a threshold concentration, attached cell activity remained constant, while the activity of unattached cells decreased as a function of decreasing nutrient concentration. The results suggest that loss of cell surface area available for substrate uptake due to attachment may be an important factor in determining the relative activities of attached and free-living cells.
三种独立的技术，即[H]胸苷掺入、碘化硝基四唑紫（INT）还原为 INT 甲臜并归一化为 DNA，以及 ATP 与 DNA 的比值，被用于测量附着和非附着河口细菌的活性。在使用河口分离物蛋白酶的实验中，通过改变蛋白胨-酵母提取物的浓度来操纵营养物浓度。在存在外源营养物的情况下，游离细胞的活性大于附着细胞的活性，如通过[H]胸苷掺入和 ATP/DNA 比值测量。然而，在没有蛋白胨-酵母提取物的情况下，附着细胞的活性超过了游离细胞的活性，如通过[H]胸苷掺入和 INT 甲臜归一化为 DNA 测量。在这三种技术中，[H]胸苷掺入被认为是最敏感的技术，可用于检测由于营养物浓度的微小差异而导致的活性变化。通过该技术，附着细胞对营养物浓度变化的敏感性远低于游离细胞。在阈值浓度以下，附着细胞的活性保持不变，而游离细胞的活性随着营养物浓度的降低而降低。结果表明，由于附着而导致用于底物摄取的细胞表面积的损失可能是决定附着和自由生活细胞相对活性的重要因素。
