坛紫菜叶状体的抗生素联合除菌效果

为研究坛紫菜及其外生菌群对氯霉素、竹桃霉素和头孢噻肟3种抗生素的敏感性,通过将其与氨苄青霉素、卡那霉素和庆大霉素的组合,优化坛紫菜叶状体的除菌方法,并利用涂布平板、qRT-PCR及16S rRNA测序分析其除菌效果。结果显示,当坛紫菜先以氨苄青霉素(300 mg/L)、卡那霉素(100 mg/L)和庆大霉素(100 mg/L)混合处理18 h,再以氯霉素(50 mg/L)、头孢噻肟(200 mg/L)和竹桃霉素(50 mg/L)混合处理4 d,叶状体的健康率保持在96.3%以上,而对可培养细菌的抑制率达到99.9%。根据qRT-PCR和16S rRNA的结果可知,该种组合方法较前3种抗生素的组合,其菌总数下降41.5%,微生物的丰度和多样性指数明显下降。其中,假单胞菌、交替赤杆菌、交替单胞菌以及海杆菌等得到针对性的抑制。研究表明,多种抗生素的优化组合能够对坛紫菜叶片的菌群结构产生显著影响,使其受到抑制,但仍无法达到绝对除菌的效果。

Antibacterial effect of antibiotics combination in Pyropia haitanensis

The susceptibility of Pyropia haitanensis and its bacteria to chloramphenicol, oleandomycin and cefotaxime was studied. They were combined with ampicillin, kanamycin and gentamicin to optimize the sterilization effect of P. haitanensis thalli. The effects were evaluated by plate count, qRT-PCR and 16S rRNA sequencing analysis. The results show that when P. haitanensis thalli was treated with ampicillin (300 mg/L), kanamycin (100 mg/L) and gentamicin (100 mg/L) mixture for 18 h, and then treated with chloramphenicol (50 mg/L), cefotaxime (200 mg/L) and oleandomycin (50 mg/L) mixture for 4 days, the health rate of the thalli is above 96.3%, and the inhibition rate of bacteria reached 99.9%. According to the results of qRT-PCR and 16S rRNA, the number of bacteria in this antibiotic combination was nearly reduced by half as compared with the first three antibiotic combination, and the bacteria abundance and diversity index were also significantly decreased. Among them, Pseudoalteromonas, Altererythrobacter, Salinimonas and Marinobacter were specifically inhibited. These results indicated that the optimal combination of multiple antibiotics could significantly affect the community structure of epiphytes on the thalli, which could be inhibited to the minimum, but still could not achieve the absolute sterilization.