Investigation of Acid-Neutralizing Property of Bacillus cereus GUF8

Extreme pHs, especially acidic pHs, are among the environmental stresses that some bacteria face. The most important strategies that bacteria employ for acid adaptation include either production of acidophilic proteins, or raising the pH of the microenvironment by secretion of basic compounds including ammonia produced by the action of urease. Considering the importance of acid-neutralizing bacteria, we previously isolated Bacillus sp. GUF8 from acidic soil of a tea plantation and identified it as Bacillus cereus using standard bacterial identification methods and 16S rDNA sequencing. Tea plantation soil is intrinsically acidic and so allows survival for only acidophilic or acid-tolerant bacteria. In the light of this fact, we investigated acid tolerance and/or adaptation property of B. cereus GUF8 in the present study. Our results showed that the isolate is an acid-tolerant and not acidophilic strain which neutralizes the acidic microenvironment by secreting urease. Urease production increases until the pH reaches to about 8.0-9.0, whilst the isolate grows optimally at around pHs 6.0-7.0 and there is a lag period of about two days prior to active growth on media at pH 4.0. The results suggest that the isolate has potential for use as a neutralizing agent in acidified environments.