Biology Department, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, and Institute of Ecology and Genetics, Aarhus University, Ny Munkegade, DK-8000 Aarhus C, Denmark.
Appl Environ Microbiol. 1986 Aug;52(2):225-33. doi: 10.1128/aem.52.2.225-233.1986.
Recently developed techniques involving opposed, gel-stabilized gradients of O(2) and H(2)S permit cultivation of a marine Beggiatoa strain as a chemolithoautotroph which uses gliding motility to precisely track the interface between H(2)S and O(2). In the current study with microelectrodes, vertical profiles of H(2), O(2), and pH were measured in replicate cultures grown for various intervals. After an initial period of exponential biomass increase (doubling time, 11 h), linear growth prevailed throughout much of the time course. This H(2)S-limited growth was followed by a transition to stationary phase when the declining H(2)S flux was sufficient only to supply maintenance energy. During late-exponential and linear growth phases, the Beggiatoa sp. consumed a constant 0.6 mol of H(2)S for each 1.0 mol of O(2), the ratio anticipated for balanced lithoautotrophic growth at the expense of complete oxidation of H(2)S to SO(4). Over the entire range of conditions studied, this consumption ratio varied by approximately twofold. By measuring the extent to which the presence of the bacterial plate diminished the overlap of O(2) and H(2)S, we demonstrated that oxidation of H(2)S by Beggiatoa sp. is approximately 3 orders of magnitude faster than spontaneous chemical oxidation. By integrating sulfide profiles and comparing sulfide consumed with biomass produced, a growth yield of 8.4 g (dry weight) mol of H(2)S was computed. This is higher than that found for sulfide-grown thiobacilli, indicating very efficient growth of Beggiatoa sp. as a chemoautotroph. The methods used here offer a unique opportunity to determine the yield of H(2)S-oxidizing chemolithoautotrophs while avoiding several problems inherent in the use of homogeneous liquid culture. Finally, by monitoring time-dependent formation of H(2)S profiles under anoxic conditions, we demonstrate a method for calculating the molecular diffusion coefficient of soluble substrates in gel-stabilized media.
最近开发的技术涉及到氧（O(2)）和硫化氢（H(2)S）的凝胶稳定梯度的相反方向，允许培养一种海洋贝氏硫菌菌株作为化能自养生物，该菌株利用滑行运动精确跟踪 H(2)S 和 O(2)之间的界面。在目前的微电极研究中，在不同时间间隔下生长的重复培养物中测量了 H(2)、O(2)和 pH 的垂直分布。在最初的指数生物量增加期（倍增时间为 11 小时）之后，线性生长在整个时间过程中占主导地位。当下降的 H(2)S 通量仅足以供应维持能量时，这种 H(2)S 限制的生长随后过渡到静止期。在晚指数和线性生长阶段，贝氏硫菌消耗每 1.0 摩尔 O(2)时消耗恒定的 0.6 摩尔 H(2)S，这是在完全氧化 H(2)S 以消耗 H(2)S 的情况下预期的平衡化能自养生长的比例。在研究的整个条件范围内，这种消耗比变化了大约两倍。通过测量细菌板的存在程度，减少了 O(2)和 H(2)S 的重叠，我们证明了贝氏硫菌对 H(2)S 的氧化速度大约比自发化学氧化快 3 个数量级。通过整合硫化物分布并将消耗的硫化物与产生的生物量进行比较，计算出 H(2)S 的生长产率为 8.4 克（干重）摩尔。这高于用硫化物生长的硫杆菌的发现，表明贝氏硫菌作为化能自养生物的生长效率非常高。这里使用的方法为确定 H(2)S 氧化化能自养生物的产率提供了一个独特的机会，同时避免了使用均相液体培养所固有的几个问题。最后，通过在缺氧条件下监测 H(2)S 分布随时间的形成，我们证明了一种用于计算凝胶稳定介质中可溶性基质分子扩散系数的方法。
