Species Interactions in Microbial Mat Communities: VerticalMigration and Tactic Responses

滑翔和游泳细菌（光养型和化养型）的光感觉和化学感觉运动反应被认为是原始的“神经感觉”类似物，被认为是增强自然界生物体生存潜力的适应性。在本提案中，微生物的昼夜垂直迁移模式将在各种微生物垫群落中进行研究，这些微生物垫群落代表了优化白天和夜间微环境的高度有利策略。目标将是：量化在温泉和其他垫子上运动的日常时间表；通过实验确定生物体对其作出反应的物理和化学线索；并评估在迁移模式或微环境发生改变时的存活率或相对增长率。在24小时内垂直向上/向下迁移发生在短距离内（几毫米），这代表了光强、氧张力、硫化物浓度和其他化学因素的急剧梯度。这些结果将把策略行为置于自然栖息地的背景下，这在生态学研究中是不确定的，并将为理解微生物定向运动进化中涉及的“选择力”提供数据。

Photosensory and chemosensory motility responses in both gliding and swimming bacteria (phototrophic and chemotrophic types) are regarded as primitive "neurosensory" analogs and are presumed to be adaptations that enhance the survival potential of the organism in nature. In this proposal, diel vertical migration patterns of microorganisms will be examined in a variety of microbial mat communities representing highly advantageous strategies that optimize both the day and night microenvironments. The objective will be to: quantify the diel schedule of movements in hot spring and other mats; to experimentally determine the physical and chemical cues to which organisms respond; and to assess survival rate or comparative growth when migration patterns or microenvironments are altered. The vertical up/down migrations over a 24 hr period occur over short distances (a few mm) that represent sharp gradients in light intensity, oxygen tension, sulfide concentration, and other chemical factors. The results will place tactic behavior in the context of the natural habitat, previously undetermined in ecological studies and will provide data for understanding the "selective forces" involved in the evolution of oriented motility in microorganisms.