The R,R isomer in bacteria is supposed to increase in abundance with increasing culturing temperature.12 To confirm this hypothesis, seven thermotolerant bacteria were cultured from Karlovy Vary springs at two different temperatures. As shown in Table and Fig. , the abundance of other isomers of PG, i.e., R,R, S,R, and S,S increases with increasing cultivation temperature (see also Fig. , Fig. , and Fig. ). In particular, the relative abundance of R,R-PG increased by more than 80% in Bacillus tequilensis (isolate M10) when the cultivation temperature was changed from 15 °C to 50 °C. The ratio of S,R and S,S isomers also increased in favor of S,R, which is even more than twice the amount of the "natural" R,S-PG.