Department of Marine Science and Engineering, North Carolina State University, Raleigh, North Carolina 27607; National Marine Fisheries Service, Southeast Fisheries Center, Beaufort Laboratory, Beaufort, North Carolina 28516 ; and Biology Department, Whitman College, Walla Walla, Washington 99362.
Appl Environ Microbiol. 1984 Jul;48(1):157-64. doi: 10.1128/aem.48.1.157-164.1984.
The size of bacteria and the size distribution of heterotrophic activity were examined in estuarine, neritic, and coastal waters. The data indicated the small size of suspended marine bacteria and the predominance of free-living cells in numerical abundance and in the incorporation of dissolved amino acids. The average per-cell volume of suspended marine bacteria in all environments was less than 0.1 mum. Cell volume ranged from 0.072 to 0.096 mum at salinities of 0 to 34.3 per thousand in the Newport River estuary, N.C., and from 0.078 to 0.096 mum in diverse areas of the Gulf of Mexico. Thus, the free-living bacteria were too small to be susceptible to predation by copepods. In the Newport River estuary, ca. 93 to 99% of the total number of cells and 75 to 97% of incorporated tritium (from H-labeled mixed amino acids) retained by a 0.2-mum-pore-size filter passed through a 3.0-mum-pore-size filter. Although the amino acid turnover rate per cell was higher for the bacteria in the >3.0-mum size fraction than in the <3.0-mum size fraction, the small number of bacteria associated with the >3.0-mum size particles resulted in the low relative contribution of attached bacteria to total heterotrophic activity in the estuary. For coastal and neritic samples, collected off the coast of Georgia and northeast Florida and in the plume of the Mississippi River, 56 to 98% of incorporated label passed through a 3.0-mum-pore-size filter. The greatest activity in the >3.0-mum fraction in the Georgia Bight was at nearshore stations and in the bottom samples. Our data were consistent with the hypothesis that resuspension of bottom material is an important factor in influencing the proportion of heterotrophic activity attributable to particle-associated bacteria.
对河口、近岸和沿海水域中的细菌大小和异养活性的大小分布进行了研究。数据表明，悬浮海洋细菌的体积较小，并且在数量丰度和溶解氨基酸的摄取方面，自由生活的细胞占主导地位。所有环境中悬浮海洋细菌的平均单个细胞体积均小于 0.1 微米。在北卡罗来纳州纽波特河河口，盐度为 0 至 34.3/千的环境中，悬浮海洋细菌的细胞体积范围为 0.072 至 0.096 微米，在墨西哥湾的不同地区，细胞体积范围为 0.078 至 0.096 微米。因此，自由生活的细菌体积太小，无法成为桡足类捕食的对象。在纽波特河河口，通过 0.2 微米孔径的过滤器截留的总细胞数的 93%至 99%和氚（来自 H 标记的混合氨基酸）的 75%至 97%都可以通过 3.0 微米孔径的过滤器。尽管 >3.0 微米大小部分的细菌的氨基酸周转率高于 <3.0 微米大小部分的细菌，但与 >3.0 微米大小颗粒相关的细菌数量较少，导致附着细菌对河口总异养活性的相对贡献较低。对于在佐治亚州和佛罗里达州东北部沿海以及密西西比河羽流采集的沿海和近岸样本，56%至 98%的标记被通过 3.0 微米孔径的过滤器。在佐治亚湾，>3.0 微米部分的最大活性出现在近岸站和底部样本中。我们的数据与以下假设一致，即底部物质的再悬浮是影响归因于颗粒相关细菌的异养活性比例的重要因素。
