螺旋鱼腥藻土嗅素的产生和分布规律

在12L玻璃瓶中,对富营养底泥培养条件下螺旋鱼腥藻生长时土嗅素的产生情况进行了研究.结果表明,随着螺旋鱼腥藻生物量增加,土嗅素产生量增大,最大浓度可达626ng/L,远超出人体可感知浓度(10ng/L).嗅味物质在螺旋鱼腥藻生物量出现最大值前76h达到最高浓度.生长过程中,土嗅素主要分布在螺旋鱼腥藻细胞内,占总含量的85%~95%,远高于胞外含量.培养初期底泥刚向水体中释放氮时,藻细胞更倾向利用类异戊二烯合成土嗅素,导致土嗅素与叶绿素含量比值增大;随着水体中的氮含量逐渐充足,土嗅素与叶绿素含量比值趋于稳定,维持在0.0015左右.因此,当野外水体的氮含量充分时,螺旋鱼腥藻土嗅素产生量的变化可通过叶绿素含量的变化得到反映.

Geosmin production and distribution of Anabaena sp

12L pyrex bottle experiments were applied to investigate the geosmin production and distribution of Anabaena sp. under eutrophic condition. Geosmin produced by Anabaena sp. increased with the increasing Anabaena sp. cells numbers and the highest concentration recorded was 626ng/L,which was significantly above the perceptive concentration of human with about 10ng/L. Geosmin production was not synchronous with cells growth, and the highest concentration of geosmin was observed 76h earlier before the biomass of Anabaena sp. cells reached the highest point.Geosmin was found to be enriched in cell matrix rather than in medium that about 85%~95% of total geosmin was concentrated in cell. The mud began to release nitrogen since the beginning of culturing and lower nitrogen concentration would induce the synthesis of geosmin using the isoprenoid precursors rather than the demand of chlorophyll accumulation. When the nitrogen concentration was sufficient in medium, the geosmin concentration could be calculated by monitoring the chlorophyll concentration since the geosmin/chlorophyll ratio would reach a stable value at 0.0015.