一株岩石放线菌对碳酸钙形貌的影响

Effect on calcium carbonate morphology by a strain of rock actinomycete

摘要:

[目的] 微生物诱导成矿是近年来地质微生物学领域研究中的热点之一。采用一株分离自喀斯特地区的岩生放线菌DHS C013^T菌株,研究该菌株及其代谢产物在由NaHCO₃、Ca(NO₃)₂·4H₂O组成的成矿体系中对CaCO₃生成及形貌的影响。[方法] 将在葡萄糖麦芽酵母提取物(MGYP)培养液中培养的放线菌上清液、菌丝球、发酵液以及无菌的MGYP培养液和超纯水分别加入成矿体系,SEM观察不同处理成矿体系中的底部沉淀物。[结果] 在超纯水成矿体系中只形成标准菱面体方解石,而在添加放线菌及其代谢产物甚至含有机质的培养液则可形成形态各异的CaCO₃晶体,如球形、哑铃以及表面具有鳞片状的柱形。这些特殊形态的CaCO₃晶体的形成,可能是在放线菌的菌丝球和菌丝片段以及胞外分泌物上成核和逐渐生长的结果。[结论] 放线菌菌丝体及代谢产物对调控和影响CaCO₃的晶体形貌有重要作用。研究结果对进一步认识放线菌及其代谢产物诱导生物成矿提供了新的证据。

Abstract:

[Objective] Microbes-induced mineralization is one of the hottest issues in the field of geomicrobiology. Strain DHS C013^T isolated from the surfaces of rocks in the Karst region was used to investigate microbial influence on the formation of carbonate and its morphology in the metallogenic system consisting NaHCO₃ and Ca(NO₃)₂·4H₂O. [Methods] Strain DHS C013^T was inoculated into malt extract-glucose-yeast extract peptone (MGYP) liquid medium. After cultivation we put the fermented solution, supernatant, hypha pellets, sterile MGYP liquid medium and ultrapure water into the metallogenic system separately. Scanning electronic microscope was applied to observe the crystals at the bottom of the petri dishes. [Results] In the metallogenic system with ultrapure water, only standard calcite of rhombohedron was found. However, special morphology of CaCO₃, such as dumbbelllike, spherulite and scaly cylindrical shapes, were found in the metallogenic system with actinomycetes, hyphae fragment and their cell metabolism products. These calcium carbonates of special morphology might be resulted from their nucleation on smaller hypha pellets, hyphae fragment or extracellular secretion. [Conclusion] Actinomycetes can induce the formation of CaCO₃, and the mycelium and metabolites have important effects on regulating and influencing CaCO₃ morphology. Our data provide new evidence for further understanding of the biological mineralization mediated by actinomycete and its metabolic products.