微小卡罗藻(Karlodinium micrum)共附生微生物抗菌与细胞毒活性

【目的】本文对微小卡罗藻共附生微生物进行分离并对其抗菌和细胞毒活性进行初步研究,以期望获得既具有抗菌又具有细胞毒的高活性菌株,为从共附生微生物的角度去研究微小卡罗藻毒素的合成途径以及真正来源提供研究材料。【方法】利用琼脂扩散法和MTT法对细菌培养液的乙酸乙酯提取物进行抗菌和细胞毒活性筛选,并对具有细胞毒活性的细菌菌株进行了16S rRNA系统发生学分析。【结果】在分离到的38株海洋细菌中,25株细菌具有抗菌活性,5株细菌(W-14-2、W-2-2、W-12、E-8-2和W-4)具有细胞毒活性。对这5株具有细胞毒活性的细菌菌株进行16S rRNA系统发生学分析显示它们分别与Alteromonas alvinellae、Stappia aggregata、Pelagibaca bermudensis、Marinobacter kribbensis和Maribacter dokdonensis的16S rRNA基因序列具有较高的相似性。【结论】在分离到的微小卡罗藻共附生微生物中含有较为丰富的活性菌株,且获得5株具有抗菌活性又具有细胞毒的高活性菌株。

Screening and characterization of antibacterial and cytotoxic marine bacteria associated with Karlodinium micrum

Abstract: Objective] Antibacterial and cytotoxic activities were screened for marine bacteria which have been isolated from Karlodinium micrum, in order to obtain potential strains with antibacterial and cytotoxic activities. Methods] In total 38 bacteria isolated from Karlodinium micrum were screened by agar-screening and MTT methods. The 16S rRNA genes were amplified from the genome DNA of those bacteria positive for both antibacterial and cytotoxic activities, which were cloned into pMD18-T vector for sequencing analysis. Results] Twenty-five isolates had antimicrobial activity and 5 isolates (W-14-2, W-2-2, W-12, E-8-2 and W-4) had cytotoxicity. Molecular phylogenetic analysis of marine bacteria with cytotoxicity based on 16S rRNA sequences indicated that they exhibited the highest similarity (98%, 99%, 99%, 98% and 99%, respectively) to the 16S rRNA fragments of Alteromonas alvinellae, Stappia aggregata, Pelagibaca bermudensis, Marinobacter kribbensis and Maribacter dokdonensis. Conclusion] The bacteria with bioactivity in Karlodinium micrum were abundant. We obtained five strains positive for both antibacterial and cytotoxic activities, which provide a clue to understanding the mechanism of toxin biosynthesis in Karlodinium micrum based on epiphytic and endophytic bacteria.