In the manganese (Mn) mines, Mn-oxidizing microbes have been isolated frequently. Mn oxidizes formed by microbes would play important roles ecophysiologically; 1) the protection of microbes from biotic or abiotic stress, such as UV light, heat and predation, etc., 2) the reduction of the toxicities of Mn and other metals via the adsorption. Our study site, a Mn mine in Japan, and the mine water contained high concentrations of Mn and low nutrients. The temperature and pH of the mine water were stable to be around 25°C and pH 6.0, respectively, through the year. On the contrary, the mine water contained high concentration of HCO₃^- (730 mg/L) and CO₂ concentration (14%) was high at the water surface. Such environmental factors would influence microbial growth and Mn-oxidizing abilities of microbes in the mine water. Therefore, the objective of this study was to investigate how environmental factors, such as temperature, pH, nutrients, HCO₃^-, and CO₂, influence microbial growth and the ability of Mn-oxidizing fungus, Sarocladium strictum isolated from the mine water.
 The effects of temperature or pH on S. strictum were evaluated to grow this fungus at different temperatures (5, 10, 15, 20, 25, and 30°C) or pH values (pH was adjusted to be 5.5, 6.0, 6.5, 7.0, 7.5, and 8.0) on Hay medium. In the results, the optimal growth of S. strictum was detected at 25°C and at the pH between 5.5 and 8.0; the results suggest that the water temperature and pH at our study site would be suitable for the mycelial growth. Additionally, the same concentration of HCO₃^- at our study site, high CO₂ concentration, or high nutrients enhanced the mycelial growth of S. strictum on Hay medium. Now, Mn-oxidizing areas under each treatment (temperature, pH, high nutrients, HCO₃^- and CO₂) are measuring via scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS) followed by image analysis with ImageJ software. These findings would clarify the influences of environmental factors on the growth and Mn-oxidizing ability of S. strictum at the mine site.