Uronen Pauliina, Kuuppo Pirjo, Legrand Catherine, Tamminen Timo
Tvärminne Zoological Station, University of Helsinki, 10900 Hanko, Finland.
Microb Ecol. 2007 Jul;54(1):183-93. doi: 10.1007/s00248-006-9188-8. Epub 2007 Mar 8.
The haptophyte Prymnesium parvum has lytic properties, and it affects coexisting phytoplankton species through allelopathy. We studied the effect of P. parvum allelochemicals on the lysis of the nontoxic and nonaxenic cryptomonad Rhodomonas salina and the consequent release of dissolved organic carbon (DOC). Changes in production, cell density, and biomass of associated bacteria were measured over 12 h. Six different combinations of P. parvum and R. salina cultures, their cell- and bacteria-free filtrates, and growth media as controls were used in the experiments. When P. parvum and R. salina cells were mixed, a significant increase in DOC concentration was measured within 30 min. Bacterial biomass increased significantly during the next 6 to 12 h when R. salina was mixed either with the P. parvum culture or the cell-free P. parvum filtrates (allelochemicals only). In contrast, bacterial biomass did not change in the treatments without the allelopathic action (without R. salina cells). Blooms of P. parvum alter the functioning of the planktonic food web by increasing carbon transfer through the microbial loop. In addition, P. parvum may indirectly benefit from the release of DOC as a result of its ability to ingest bacteria, by which it can acquire nutrients during limiting conditions.
定鞭藻微小原甲藻具有溶解特性，它通过化感作用影响共存的浮游植物物种。我们研究了微小原甲藻化感物质对无毒且非无菌的隐藻盐生红胞藻溶解的影响以及随之而来的溶解有机碳（DOC）的释放。在12小时内测量了相关细菌的产量、细胞密度和生物量的变化。实验中使用了微小原甲藻和盐生红胞藻培养物、它们的无细胞滤液以及作为对照的生长培养基的六种不同组合。当微小原甲藻和盐生红胞藻细胞混合时，在30分钟内测量到DOC浓度显著增加。当盐生红胞藻与微小原甲藻培养物或无细胞微小原甲藻滤液（仅化感物质）混合时，细菌生物量在接下来的6至12小时内显著增加。相比之下，在没有化感作用的处理（没有盐生红胞藻细胞）中细菌生物量没有变化。微小原甲藻水华通过增加通过微生物环的碳转移改变了浮游食物网的功能。此外，微小原甲藻可能因其摄取细菌的能力而间接受益于DOC的释放，通过这种方式它可以在限制条件下获取营养物质。
