海洋溶藻菌假交替单胞菌(Pseudoalteromonas sp.) J75的分离鉴定及溶藻作用

Isolation, identification, and algicidal characterization of the marine algicidal strain Pseudoalteromonas sp. J75

摘要:

目的 从温州东海海域分离获得溶藻细菌，对其进行鉴定并研究其溶藻特性及溶藻机制，以期为赤潮的微生物治理提供坚实的科学基础。方法 通过形态学分析、生理生化特征鉴定以及16S rRNA基因序列分析对菌株进行初步鉴定。测定菌株的溶藻活性、环境因子对溶藻活性的影响，以及溶藻特异性等溶藻特性。通过电镜观察、光合参数测定、藻细胞内活性氧和丙二醛含量测定以及抗氧化酶活性检测等方法，初步探究其溶藻机制。结果 溶藻菌株J75被鉴定为假交替单胞菌(Pseudoalteromonas sp.)，36 h内对中肋骨条藻的溶藻率可达95.97%。菌株J75通过分泌胞外溶藻物质实现间接溶藻，溶藻物质在-20-80 ℃、pH 5.0-9.0条件下均能保持良好的溶藻效果。菌株J75对米氏凯伦藻、微小原甲藻和球形棕囊藻均表现出溶藻活性。在J75无菌滤液的胁迫下，藻细胞的形态结构发生破坏，光合活性严重下降，活性氧含量升高，膜脂过氧化损伤加剧，超氧化物歧化酶、过氧化氢酶、过氧化物酶的活性均有所升高，谷胱甘肽含量也明显升高，表明溶藻细菌引起了藻细胞的氧化损伤，最终导致藻死亡。结论 海洋溶藻假交替单胞菌J75通过分泌溶藻物质能够有效抑制多种赤潮微藻生长，在赤潮防治方面具有广阔的应用前景，对其溶藻特性和溶藻机制的探究为赤潮的治理提供了重要的理论依据。

关键词:中肋骨条藻;溶藻细菌;分离鉴定;溶藻特性;溶藻机制

Abstract:

Objective This study isolated and identified an algicidal bacterium from the East China Sea near Wenzhou and investigated its algicidal characteristics and mechanisms, aiming to contribute a solid scientific basis to the microbial control against red tides.Methods The strain was identified by morphological observation, physiological and biochemical tests, and 16S rRNA gene sequence analysis. The algicidal characteristics such as algicidal activity, influences of environmental factors on the algicidal activity, and algicidal specificity were assessed. The algicidal mechanism was explored by electron microscopy, measurements of photosynthetic parameters, and determination of reactive oxygen species (ROS) and malondialdehyde levels and antioxidant enzyme activities.Results The algicidal strain J75 was identified as Pseudoalteromonas sp. The algicidal rate of strain J75 against Skeletonema costatum reached 95.97% within 36 h. Strain J75 induced lysis of algal cells indirectly by secreting extracellular algicidal substances, maintaining the algicidal activity across broad ranges of temperatures (-20 °C to 80 °C) and pH levels (5.0 to 9.0). In addition, strain J75 demonstrated algicidal activities against other harmful microalgae, including Karenia mikimotoi, Prorocentrum minimum, and Phaeocystis globosa. Under the stress of J75 cell-free supernatant, the algal cells showed morphological structure damage, a significant decrease in the photosynthetic activity, elevations in the levels of ROS, membrane lipid peroxidation, activities of superoxide dismutase, catalase, and peroxidase, and the level of glutathione. These results indicated that strain J75 caused oxidative damage to algal cells, ultimately leading to algal death.Conclusion The marine algicidal bacterium Pseudoalteromonas sp. J75, which holds significant potential for the control of red tides, demonstrates its efficacy by secreting algicidal compounds that inhibit the growth of diverse red tide microalgae. The exploration of the algicidal characteristics and mechanisms of this strain provides a theoretical basis for advancing red tide management strategies.

Key words:Skeletonema costatum;algicidal bacteria;isolation and identification;algicidal characteristics;algicidal mechanism