Department of Microbiology, University of Maryland, College Park, Maryland 20742.
Appl Environ Microbiol. 1985 Oct;50(4):1002-6. doi: 10.1128/aem.50.4.1002-1006.1985.
To better understand the ecological significance of pressure effects on bacteria in the abyssobenthic boundary layer, experimental suspensions of sediments and sinking particulates were prepared from samples collected in boxcore and bottom-moored sediment traps at two stations (depth, 4,470 and 4,850m) in the Demerara abyssal plain off the coast of Brazil. Replicate samples were incubated shipboard at 3 degrees C and at both atmospheric and deep-sea pressures (440 or 480 atm [4.46 x 10 or 4.86 x 10 kPa]) following the addition of [C]glutamic acid (<10 mug liter) or yeast extract (0.025%) and the antibiotic nalidixic acid (0.002%). In seven of the eight samples supplemented with isotope, a barophilic microbial response was detected, i.e., substrate incorporation and respiration were greater under in situ pressure than at 1 atm (101.3 kPa). In the remaining sample, prepared from a sediment trap warmed to 24 degrees C before recovery, pressure was observed to inhibit substrate utilization. Total bacterial counts by epifluorescence microscopy decreased with depth in each sediment core, as did utilization of glutamic acid. Significant percentages of the total bacterial populations in cold sediment trap samples (but not the prewarmed one or any boxcore sample) were abnormally enlarged and orange fluorescing after incubation with yeast extract and nalidixic acid under deep-sea conditions. Results indicated that in the deep sea, barophilic bacteria play a predominant role in the turnover of naturally low levels of glutamic acid, and the potential for intense microbial activity upon nutrient enrichment is more likely to occur in association with recently settled particulates, especially fecal pellets, than in buried sediments.
为了更好地理解压力对深渊边界层细菌的生态意义，从巴西海岸德默拉拉深渊平原两个站位（深度分别为 4470 米和 4850 米）的箱式沉积物采集器和海底沉积物捕获器中采集的沉积物和下沉颗粒的实验悬浮液。将复制的样品在船上培养，在添加 [C]谷氨酸（<10 微克/升）或酵母提取物（0.025%）和抗生素萘啶酸（0.002%）后，在 3°C 和大气压力和深海压力（440 或 480 大气压 [4.46 x 10 或 4.86 x 10 kPa]）下进行。在添加同位素的八个样本中的七个样本中，检测到嗜压微生物的反应，即在原位压力下，基质的掺入和呼吸作用大于 1 大气压（101.3 kPa）。在其余样本中，从在回收前加热到 24°C 的沉积物捕获器中制备，发现压力抑制了基质的利用。每个沉积物岩芯中的细菌总数通过荧光显微镜随深度而减少，谷氨酸的利用也随之减少。在冷沉积物捕获器样品中（但不是预热的样品或任何箱式样品），在深海条件下用酵母提取物和萘啶酸孵育后，总细菌种群的显著比例异常增大并呈橙色荧光。结果表明，在深海中，嗜压细菌在自然低水平谷氨酸的转化中起主要作用，在营养丰富时，微生物活性增强的可能性更有可能与最近沉降的颗粒，特别是粪便颗粒有关，而不是与埋藏的沉积物有关。
