Effect of the environmental factors on diketopiperazine cyclo(Pro-Phe) production and antifungal activity of Bacillus amyloliquefaciens Q-426

Bacillus amyloliquefaciens Q-426 with strong antifungal activity was isolated from the compost samples in Dalian of China. Four kinds diketopiperazines were extracted strain including cyclo(Pro-Phe) (cPP), which had cyclo(L-Pro-L-Phe), cyclo(D-Phe-L-Pro), cyclo(D-Pro-D-Phe) and cyclo(L-Pro-D-Phe) isomers. Results showed that (1) cPP production reached maximum at 12 h then maintained constant yield; (2) a stable wide temperature range 31–42°C; (3) quite different for various carbon sources because growth rate strain; (4) higher level yield neutral weakly alkaline environment (pH 6–10) than acid 3–5) environment. Moreover, played negative effect on synthesis substance when bacteria good growth, previous studies found positive response to biosensors used detect signal molecules. Based these studies, suspected as molecule B. Q-426.