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首页> 外文期刊>Applied and Environmental Microbiology >Measurement and Significance of Specific Activity in the Heterotrophic Bacteria of Natural Waters
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Measurement and Significance of Specific Activity in the Heterotrophic Bacteria of Natural Waters

机译：天然水的异养细菌中比活的测定及其意义

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It is now possible to obtain accurate total counts of the bacteria of natural waters with the use of acridine orange staining and epifluorescence microscopy. This approach can be coupled to highly sensitive measurements of heterotrophic activity using radioisotopes. To accomplish this, three variations of a “specific activity index” are suggested, based on different approaches to measuring heterotrophic activity with radiolabeled organic solutes. The denominator of each index is the direct count of bacteria from a given natural sample. Three numerators are presented, each of which has been shown to vary directly with heterotrophic bacterial activity: Vmax, turnover rate, and direct uptake (at high substrate concentrations). Each approach is illustrated with data from estuarine and coastal waters of northeastern Massachusetts. The data show major differences in specific activity that accompany such habitat differences as distances within or offshore from an estuary and vertical location in the water column. These and other data suggest that specific activity is a valid indicator of the physiological state and metabolic role of the bacteria. Some evidence is presented in support of the hypothesis that the natural bacteria are adapted to conditions of nutrient starvation by becoming “dormant,” existing for an unknown period of time in a reversible physiological state that reflects the availability of organic nutrients.
机译：现在，可以通过使用orange啶橙染色和落射荧光显微镜获得准确的自然水细菌总数。这种方法可以与使用放射性同位素的异养活性的高灵敏度测量相结合。为实现这一目标，建议采用“比活度指数”的三种变化形式，这是基于使用放射性标记的有机溶质测量异养活性的不同方法。每个指数的分母是来自给定天然样品的细菌的直接计数。提出了三种分子，每种分子随异养细菌的活性而直接变化：Vmax，周转率和直接摄取（在高底物浓度下）。每种方法都有马萨诸塞州东北部河口和沿海水域的数据进行说明。数据显示，特定活动的主要差异伴随着栖息地差异，例如水柱内河口和垂直位置之间或离海口的距离。这些和其他数据表明，比活是细菌的生理状态和代谢作用的有效指标。提出了一些证据支持以下假设：天然细菌通过变为“休眠”而适应营养不足的条件，该休眠在未知时间段内以可逆的生理状态存在，反映了有机营养的可利用性。

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