Isolation of a thermophilic Anoxybacillus flavithermus sp nov and production of thermostable ?-amylase under solid-state fermentation (SSF)

Abstract

A new bacteria was isolated from hot-spring water of Gazligol, Afyonkarahisar in Turkey. Based on morphological and biochemical tests and 16S rRNA gene sequence analysis, the isolate belonged to the Anoxybacillus flavithermus species which has 99% similarity with the bacterium DNA. The production of alpha-amylase by thermophilic Anoxybacillus flavithermus was investigated under solid-state fermentation by using some agricultural waste as substrates. Solid substrates such as rice husk, banana husk, millet, water melon husk, lentil bran, wheat bran and maize oil cake were studied for enzyme production. Of these, rice husk was proved as the best substrate for alpha-amylase production (1,271 U/mg). The maximum alpha-amylase production was observed as 1,803 U/mg at 72 h, 1,000 mu m particle size, 70% initial moisture content (w/v), and 40% inoculum level (v/w). Among the various nitrogen sources tested, 1% peptone (3,170 U/mg) was found to be the best nitrogen source for alpha-amylase production. As additional carbon sources, 1% starch (2,364 U/mg) enhanced alpha-amylase production. The optimum temperature for the activity of alpha-amylase was found to be 70A degrees C. The enzyme was optimally active at pH 6.0 and stable in the pH range of 6.0-8.0.