Effects of prey abundance and light intensity on the mixotrophic chrysophyte Poterioochromonas malhamensis from a mesotrophic lake
Effects of prey abundance and light intensity on the mixotrophic chrysophyte Poterioochromonas malhamensis from a mesotrophic lake
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DOI：
10.1046/j.1365-2427.1999.00476.x
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发表时间：
1999-11-01
影响因子：
2.7
通讯作者：
Holen, DA
中科院分区：
文献类型：
--
作者：
Holen, DA
1. 先前对鞭毛类 Poterioochromonas malhamensis（金藻纲）混合营养的研究是在培养超过 30 年的菌株上进行的。本研究旨在将培养菌株的混合营养性与最近从美国宾夕法尼亚州中营养湖（拉卡瓦克）分离的菌株进行比较2。湖中的 P. malhamensis 表现出与培养菌株相似的营养灵活性，其光养生长但与其他营养模式相比效率较低（生长速率（mu）= 0.015 h(-1)）。在无机盐培养基中添加1 mM 葡萄糖后，在光照和黑暗条件下，mu 分别加倍至0.035 h(-1) 和0.033 h(-1)。在无机盐培养基中添加藻类猎物微绿藻，可以增加生长速度，其生长速度与使用葡萄糖观察到的速度相似。当细菌作为食物提供时，湖菌株的最大生长时间为 0.095 h(-1)。在细菌生长过程中，无论在光照还是黑暗条件下培养，细胞叶绿素 a (Chl a) 在 22 小时内从 140 fg cell(-1) 减少到 10 fg cell(-1)。在光照培养物中，细菌受到限制后，细胞特异性叶绿素a浓度恢复至185 fg cell(-1)。3．然而，与培养菌株相反，湖分离株表现出光强度和摄取率之间的反比关系。根据荧光标记细菌的摄入量计算出的放牧率，对于在高光、低光和黑暗中培养的马尔哈门氏菌来说分别为 3.2、5.2 和 9.4 个细菌鞭毛(-1) h(-1)。因此，在这种以异养为主的混合营养体中，吞噬营养受到光照状况的影响。
1. Previous studies of mixotrophy in the flagellate Poterioochromonas malhamensis (Chrysophyceae) were performed on strains that had been in culture for > 30 years. This study aims to compare mixotrophy in a cultured strain with one recently isolated from a mesotrophic lake (Lacawac) in Pennsylvania, U.S.A.2. P. malhamensis from the lake exhibited a nutritional flexibility similar to that of the culture strain, growing phototrophically but inefficiently in comparison to other nutritional modes (growth rate (mu) = 0.015 h(-1)). Supplementing an inorganic salts medium with 1 mM glucose resulted in a doubling of mu to 0.035 h(-1) and 0.033 h(-1) in the light and the dark, respectively. Addition of an algal prey, Nannochloris, to the inorganic salts medium increased growth to rates similar to those observed with glucose. Maximum growth of the lake strain, 0.095 h(-1), was achieved when bacteria was supplied as food. During growth on bacteria, cellular chlorophyll a (Chl a) decreased from 140 fg cell(-1) to 10 fg cell(-1) over 22 h when cultured either in the light or dark. In illuminated cultures, cell-specific Chl a concentration recovered to 185 fg cell(-1) after bacteria became limiting.3. In contrast to the cultured strain, however, the lake isolate exhibited an inverse relationship between light intensity and ingestion rate. Calculated grazing rates, based upon the ingestion of fluorescently labeled bacteria, were 3.2, 5.2 and 9.4 bacteria flagellate(-1) h(-1), for P. malhamensis incubated in high light, low Light and darkness, respectively. Phagotrophy is thus influenced by a light regime in this predominately heterotrophic mixotroph.