Bacteria play an important role in preventing algal blooms and reducing their harm to the environment. To improve the algicidal activity of Pseudoalteromonas SP48 which had an inhibition effect on dinoflagellate Alexandrium tamarense, its growth medium and fermentation conditions were optimized for this bacterium. In this study, we used two steps to establish the optimum conditions. First, the proper proportion of medium was selected based on an orthogonal design. Then, the fermentation conditions were further optimized through uniform design in an enlarged 5L bioreactor. To test the algicidal ability of Pseudoalteromonas SP48 under the optimum conditions, algal cell morphology was observed by transmission electron microscopy (TEM). After the orthogonal design, we found that the optimum medium was [0.7% (m/v) tryptone, 0.2% (m/v) soluble starch, 0.2% (m/v) sucrose, 0.1% (m/v) FeSO4, and 1.2% (m/v) K2HPO4] for Pseudoalteromonas SP48 growth. Based on these results, optimum fermentation conditions were further explored in a 5L fermentation cylinder using a uniform design; the influence of variables such as incubation time, carbon type, and rotation speed were tested. The optimal fermentation conditions were fermentation time (42 hr), tryptone (1.1%), seeding volume (1.4 × 1013 cells), and rotation speed (250 r/min). Under these established optimum conditions, the biomass of strain SP48 increased by 79.2% and its lethal dose 50% (LD50) decreased by 54.0%, respectively. The TEM results showed that compared with the control group, the cell wall and cell membrane of A. tamarense were significantly damaged, and the structure and shape of the organelles were destroyed by algicidal bacteria of Pseudoalteromonas SP48. Overall, our results demonstrate that the optimized culture conditions could significantly enhance the algicidal activity of Pseudoalteromonas SP48 against a harmful dinoflagellate, such as A. tamarense. It will effectively provide a scientific foundation for both production of algicidal substances and HABs control.

Because the time of traffic signal lights when vehicles are released is the same, it is easy to cause vehicle accumulation, traffic congestion and other problems. Therefore, a coordinated control method of intelligent traffic lights based on YOLOv3 and DQN is proposed. Obtain the basic parameters of intelligent traffic, set the green signal ratio of each phase in a balanced manner, define the reward of coordinated control as the change in cumulative waiting time between two adjacent cycles, set the intersection control domain decision sequence based on YOLOv3 and DQN, calculate the intersection cycle correlation, and design the signal coordination control method. Experimental results: The average queue waiting time of the intelligent traffic signal coordination control method in this paper is 648.37 s, which is 64.22 s and 41.05 s lower than the other two intelligent traffic signal coordination control methods respectively, indicating that the designed intelligent traffic signal coordination control method is better after combining YOLOv3 and DQN algorithms.