Optimization of fermentation conditions, enzymatic properties and sugar metabolic pathways of agarase-producing strain

To determine the optimal fermentation conditions and culture conditions of FG12, an agarase-producing strain was taken from the tropical marine environment for improving its enzyme activity, 3,5-Dinitrosalicylic acid (DNS) method was used to determine the enzyme activity and study its enzymatic properties, and the high-throughput sequencing was applied to obtain enzymes involved in glucose metabolism. By the test of single factors and multiple factor, the optimal agarase-producing medium was as follows: 0.8% agar, 1% peptone, 0.02% K2HPO4, 28 and pH 7.5; the optimal culture medium was as follows: 0.8% agar, 0.5% peptone and pH 6.8. The activity reached the highest value of 739.58 U/mL which was 273.49% times higher than that under the original conditions. Enzymatic properties showed that its optimal temperature and pH were 36 and 7.5, respectively, it was stable at 36~55 and pH 6.5~7.5. Analysis on KEGG metabolism pathways showed that a variety of different enzymes from FG12 were involved in glucose metabolism, which could improve the enzyme production through genetic modification. The results indicate that FG12, an efficient agarase-producing strain, might act as a potential candidate for the industrial application.