Identification of amesophilic α-amylase-producing strain isolated from the deep-sea sediment and enzymatic characteristics

The strains that can degrade starch were screened from the deep-sea sediment by using oligotrophic medium with high salinity. The single colonies were obtained by streak cultivation,identified by Gram dyeing method and scanning electron micrograph. The phylogenetic analysis of the strain with producing α-amylase with the maximum activity was performed by sequencing the gyrB genes. The optimal growth temperature and pH of the strain were also determined. The α-amylase activity produced by the strain was examined using the 3,5-dinitrosalicylic acid(DNS)method. Effects of different starch contents,growth temperature of the strain,and in different growth stages of the strain on the α-amylase activity were also explored. The results showed that a strain of Gram positive bacteria,which could effectively degrade starch,was obtained and identified as Bacillusamyloliquefaciens TVG11-1.The optimal growth temperature and pH of the strain TVG11-1 were 45 ℃ and 7.0,respectively. The α-amylase produced by the strain TVG11-1 was an extracelluar and mesophilic enzyme independent of starch substrate. The optimal reaction temperature and pH of the α-amylase of the strain TVG11-1 were 60 ℃and pH6.5,respectively. This study will provide the strain resources for starch saccharification and other food processing.