Microbes and Environments
Online ISSN : 1347-4405
Print ISSN : 1342-6311
ISSN-L : 1342-6311
Research Articles
Application of a Portable Spectrophotometer to Microbial Mat studies: Temperature Dependence of the Distribution of Cyanobacteria and Photosynthetic Bacteria in Hot Spring Water
Miwa SugiuraMasao TakanoShin-ichi KawakamiKatsumi TodaSatoshi Hanada
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2001 Volume 16 Issue 4 Pages 255-261


We developed a simple method for absorbance spectrophotometry to identify photosynthetic pigments of microbial mats using a portable spectrophotometer in the field. This method was very efficient for the identification of mat-forming phototrophs and estimations of their mixing ratios in the field. It was also applied to describe the structure of hot spring microbial mats developed at the Nakabusa Hot Spring, Nagano Prefecture. The microbial mats consisted of cyanobacteria and Chloroflexus, and their distribution depended on the water temperature. The ratio of these two bacteria determined by absorbance spectra was constant at temperatures ranging from 45 to 60°C, and the spectral mixing ratios of Chloroflexus were about 40%. That ratio increased with temperatures in the range of 60 to 70°C; above 70°C, only Chloroflexus was observed. The spectrophotometry also found a pink bacterial mat which had distinctive absorption peaks at 801 and 878 nm. These peaks strongly suggested that the organism was a novel phototrophic bacterium of a new taxon.

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