Sulphate Reducing Bacteria in California Oil Waters.

Abstract

Edson S. Bastin has recently pointed out 1 that certain bacteria are responsible for the fact that oil well waters are low in sulphates and high in carbonates when compared with the sources from which these waters are presumably derived. He was able to isolate bacteria producing such chemical reactions from Illinois oil field waters. He also sampled oil-well waters originating from the Sunset-Midway and Coalinga districts in California. The samples were cultured by us and we were able to isolate from them sulphate reducing anaerobic bacteria of the same type as had been found in the Illinois oil field waters. Not all the wells, however, showed evidence of these organisms. The methods used for culturing will be described in another paper.

As the temperature and salt concentration range at which the organisms metabolize have been used by former investigators 2 , 3 , 4 to differentiate between various types, these influences were studied. All the organisms cultured were found to grow at room temperature and up to 37° C. Only some of them (4 out of 12) grew at 50° C. According to their preferences for certain salt concentrations the following groups were distinguished:

Type 1. Growth only in media without or with less than one per cent NaCl. Represented by 2 cultures only.

Type 2. Growth only in media containing NaCl. The organisms of this type seem also to be sensitive to high concentrations of salt, 3 per cent being the upper limit at which growth was obtained. This type is represented by 2 cultures only.

Type 3. Growth both in media with and without NaC1. Some of the cultures grew in all concentrations between 0 and 3 per cent salt, one culture between 0 and 5 per cent. In no case was the upper salt limit below 3 per cent. This is the most common type which we encountered.