Optimized culturing conditions for an algicidal bacterium Pseudoalteromonas sp. SP48 on harmful algal blooms caused by Alexandrium tamarense

MicrobiologyOpen

Jin Zhou¹  Yue‐Xia Zhou²  Yi‐Xiao Xu³  Yi Li⁴  Yi‐Hua Lyu⁵ 

[1] Division of Ocean Science and Technology Graduate School at Shenzhen Tsinghua University Shenzhen Guangdong Province P.R. China;Food and Drug Administration Linqing Shandong Province P.R. China;Key Laboratory of Environment Change and Resources Use in Beibu Gulf Ministry of Education Guangxi Teachers Education University Nanning P.R. China;School of life Science Henan Normal University Xinxiang Henan P.R. China;South China Sea Environmental Monitoring Center State Oceanic Administration Guangzhou P.R. China;

关键词: Alexandrium tamarense;    growth medium optimization;    HABs control;    optimum fermentation conditions;    Pseudoalteromonas SP48;   

DOI  :  10.1002/mbo3.803

来源: DOAJ

【 摘 要 】

Abstract 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.

【 授权许可】

Unknown