Vallentyne: Environmental Biophysics & Microbial Ubiquity 345 



supply of H2S()4 can contain concentrations up to 2.08 n H2SO4 at the end of 

 growth (Starkey, 1925). 



Several molds are capable of growth at a pH of 1.7 (Johnson, 1923). The 

 most acid tolerant fungi known are Acontiuni velatum and fungus D (an un- 

 identified member of the Dermatiaceae), originally isolated from strong acid 



B 



H 



J K L 



Figure 1. Eh-pH characteristics of diverse microorganisms. A, green algae and diatoms; 

 B, DunalieUa; C, Enteromorpha; D, blue-green algae; E, photosynthetic ])urple bacteria; 

 F, photosynthetic green bacteria; G, sulfate reducing bacteria; //, thiobacteria; /, iron bac- 

 teria; J, denitrifying bacteria; A', three species of heterotrophic bacteria; L, methane producing 

 bacteria. Redrawn from Baas Becking el al. (1960). Eh is expressed in millivolts. 



