Johnston C G, Vestal J R
Department of Biological Sciences, University of Cincinnati, OH 45221-0006, USA.
Geomicrobiol J. 1989;7:137-53. doi: 10.1080/01490458909377858.
Chemical differences were noted between two Antarctic cryptoendolithic (hidden within rock) microenvironments colonized by different microbial communities. Microenvironments dominated by cyanobacteria (BPC) had a higher pH (pH 7-8) than those dominated by lichen (LTL) (pH 4.5-5.5). In order to understand the interactions between the microbiota and the inorganic environment, the inorganic environment was characterized. Water-soluble, carbonate-bound, metal-oxide, organically bound, and residual inorganic species were sequentially extracted from rock samples by chemical means. Each fraction was then quantified using inductively coupled plasma atomic emission spectrometry. BPC contained much more water-soluble and carbonate-bound Ca and Mg than LTL. Metal-oxide species of Al, Fe, and Mn were more abundant in LTL than BPC. Metal oxides appeared to be mobilized (in the order Mn > Fe > Al) from the LTL lichen zone but remained immobile in BPC sandstone. The distribution of K and P bound to metal oxide reflected the distribution of iron oxide in LTL, an indication of the importance of iron in controlling the availability of nutrients in this ecosystem. Metal oxides in turn were likely controlled or influenced by organic matter associated with the lichen community. Despite overall depletion of Fe, Al, and K in the lichen zone, SEM X-ray analysis showed that they were enriched in fungal hyphae. Water-soluble P was present despite the presence of metal oxides, which sequester phosphate. This has biological relevance since P is an essential nutrient.
在由不同微生物群落定殖的两个南极隐生岩内（隐藏在岩石内部）微环境之间，发现了化学差异。以蓝细菌为主导的微环境（BPC）的pH值（pH 7 - 8）高于以地衣为主导的微环境（LTL）（pH 4.5 - 5.5）。为了了解微生物群与无机环境之间的相互作用，对无机环境进行了表征。通过化学方法从岩石样品中依次提取水溶性、碳酸盐结合态、金属氧化物态、有机结合态和残余无机物种。然后使用电感耦合等离子体原子发射光谱法对每个组分进行定量。BPC中水溶性和碳酸盐结合态的钙和镁比LTL多得多。LTL中铝、铁和锰的金属氧化物态比BPC中更丰富。金属氧化物似乎从LTL地衣区被 mobilized（顺序为锰>铁>铝），但在BPC砂岩中保持不动。与金属氧化物结合的钾和磷的分布反映了LTL中氧化铁的分布，这表明铁在控制该生态系统中养分有效性方面的重要性。金属氧化物反过来可能受与地衣群落相关的有机物控制或影响。尽管地衣区中铁、铝和钾总体上有所消耗，但扫描电子显微镜X射线分析表明它们在真菌菌丝中富集。尽管存在会螯合磷酸盐的金属氧化物，但仍存在水溶性磷。这具有生物学相关性，因为磷是一种必需营养素。
