抄録
Bluish green Zn-S-and yellowish brown Fe-microbial mats were found on outer surfaces of well riser pipes on Kakuma campus of Kanazawa University, Ishikawa Prefecture. The microscopic observation and XRF chemical analysis revealed that the formative conditions of microbial mats differ in depth due to stationary and pumping groundwater levels. Bluish green microbial mats formed in 61.6-75.6 m depth were characterized by high content of Zn and S. The microbial mats mainly consist of spherical fifine particles of several Am in size. A small amount of coccoid-and bacilli-form bacteria were found in the aggregation. While, yellowish brown microbial mats formed in 30.8-61.6 m depth and were characterized by high content of Fe, Ca, P, Si and Zn. The microbial mats mainly consist of spiral materials that were metabolized from an iron oxidizing bacterium, Gallionella ferruginea. Harp-like materials metabolized from another iron oxidizing bacteria, Toxothirixspp. were also found below 56 m in depth. A large amount of coccoid-, bacilli-and filamentous-form bacteria were found in the assemblage of the metabolic materials and the number of filamentous-form bacteria increased with depth.
TEM observations and FE-TEM-EDX elemental maps revealed that some spherical particles on the cell surface of bacteria in the bluish green microbial mats are rich in Zn and S stick, suggesting that Zn exist as sulfide. The other adhesion materials consisted of Fe, Si, 0, and Zn were also formed around cell wall. The bacteria inthe bluish green microbial mats might be tolerant to heavy metal Zn.
