Isolation and identification of a bacterium MA-B22 producing agarase and the optimal cultivation of enzyme production

Agarase plays a key role in degrading many complex polysaccharides.The screening of agar-degrading bacteria from marine environment and organisms becomes an important means. A gram-negative bacterial strain, MA-B22 with high agarase activity was isolated from small abalone Haliotis diversicolor. By 16S rRNA analysis, this strain has 99% homology to Tamlana agarivorans sp. nov., it was named Tamlana sp. in this report. Under 2216E medium, the optimal temperature, pH value and culture time are 25 ℃, 6.0 and 60 h respectively. With one-factor-at-a-time method and orthogonal designed experiment, the optimal compositions of the ferment medium were confirmed. It contained 2.5‰ agar, 6.0‰ beef extract based on the salinity of 25. The highest enzyme activity of agarase was detected by DNS method at 1021.79 U/mL, which is 8.82 times higher than before. MA-B22 demonstrated high-performance characteristics of enzyme production. This is the first report on the agar degrading Tamlana sp. and optimal cultivation to enhance its enzyme activity. The results provide a basis for constructing engineering bacterium for expression agarase genes and potential probiotics of abalone aquaculture in the future.