Microscopic examination of acidic hot springs of Waiotapu, North Island, New Zealand

Abstract

Microorganisms other than Sulfolobus are reported for the first time in the low pH high temperature springs of Waiotapu, North Island, New Zealand. In one spring of the tourist reserve, rod‐shaped organisms with a toga‐like wall were observed, in addition to Sulfolobus‐like spheres. In another acid hot spring, microbial cells were small and intermingled with mineral crystals, making their presence difficult to detect, even by scanning electron microscopy (SEM). Evidence for the existence of microorganisms included: (1) phase contrast microscopic observation; (2) DNA‐specific staining with UV microscopy; and (3) SEM examination of natural samples. At pH 2, the highest temperature at which microbes were observed was 77°C and at pH 4.5, it was 87°C. Cells at pH 2, 77°C were small rods encrusted with mineral crystals shown by X‐ray microanalysis to consist mainly of silicon and aluminum. At pH 4.5, spherical, rod‐shaped, and filamentous cells were seen. Attempts to culture the observed microbes were unsuccessful. PCR, cloning, sequencing, and BLAST analysis identified Thermofilum pendens in Champagne Pool, and Sulfobacillus, Thiobacillus, and several unknown bacteria in Frying Pan Flat pools.

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