Experiments in Deep-Sea Biology

[9415371] Jannasch该项目的主要目标是研究那些在深海中积极生长和矿化有机碳的微生物的主要生长特征。该项目将测试深海细菌对原位温度和压力（嗜冷性和嗜湿性）的适应是否随营养不变的假设。更具体地说，在深海微生物菌群中，营养不良（适应在极低营养水平下生长）和嗜盐性是否在代谢方面存在联系。在上一个研究期间，对不同压力下的分批培养研究和1atm下的连续培养研究进行了早期观察，得出的数据清楚地表明底物浓度对嗜氧活性的影响。数据还表明，需要在低于批量培养固有的底物浓度的情况下使用典型的寡营养细菌，并且需要在压力下的稳态培养中进行生长实验。为此，设计并制造了一种新型的可加压式恒化器。该项目将采用现有的压力设备，并结合加压恒化器在低底物水平下富集深海细菌的新能力。可加压的恒化器将用于在没有减压的情况下获得深海样品，以分离真正的低营养嗜压菌。这项工作的意义在于，生物圈中溶解有机碳的最大部分，即海洋部分的微生物周转是未知的。阐明适应深海细菌代谢策略的数据将对全球碳循环的计算具有重要价值。* * *

9415371 Jannasch The principal objective of this project is to study the major growth characteristics of those microorganisms that are actively growing and mineralizing organic carbon in the deep-sea. The project will test the hypothesis whether adaptation to in situ temperature and pressure (psychrophily and barophily) of deep-sea bacteria are invariant with nutrition. More specifically, whether oligotrophy (adaptation to growth at extremely low nutrient levels) and barophily are metabolically linked in the microbial deep-sea flora. Earlier observations during the last research period with batch culture studies at various pressures and with continuos culture studies at 1 Atm, resulted in data that clearly indicated an effect of substrate concentration on barophilic activity. The data also demonstrated the need for working with typical oligotrophic bacteria in the presence of substrate concentrations lower than those inherent to batch culture and the need to carry out growth experiments in steady state cultures under pressure. To this end a new pressurizable chemostat has been designed and constructed. This project will employ existing pressure equipment in combination with the new capability to enrich for deep-sea bacteria at low substrate levels in the pressurized chemostat. The pressurizable chemostat will be used to obtain deep-sea samples in the absence of decompression for the isolation of truly oligotrophic barophiles. The significance of this work lies in the fact that the microbial turnover of the largest portion of dissolved organic carbon in the biosphere, the oceanic portion, is unknown. Data clarifying the metabolic strategies of the adapted deep-sea bacteria will be of great value for calculation of the global carbon cycle. ***