Identification and feeding characteristics of the mixotrophic flagellate Poterioochromonas malhamensis, a microalgal predator isolated from outdoor massive Chlorella culture
Identification and feeding characteristics of the mixotrophic flagellate Poterioochromonas malhamensis, a microalgal predator isolated from outdoor massive Chlorella culture
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DOI：
10.1016/j.algal.2017.11.024
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发表时间：
2018-01-01
影响因子：
5.1
通讯作者：
Hu, Qiang
中科院分区：
文献类型：
--
作者：
Ma, Mingyang;Gong, Yingchun;Hu, Qiang
小球藻是未来生物燃料和其他藻类衍生产品的潜在生产生物体的有力候选者，但放牧原生动物的污染是其大规模商业生产的主要制约因素。在这项研究中，一个兼养鞭毛虫金藻，针对小球藻在大量培养观察到的样品从室外大规模光生物反应器系统。来自现场研究的数据表明，一旦在藻类培养物中观察到捕食性鞭毛虫，则小球藻细胞浓度急剧降低。根据形态学和18 S rDNA基因序列的分子条形码，将食草动物鉴定为Poterioochromonas malhamensis。透射电子显微镜显示，P. malhamensis消化的小球藻sorokiniana细胞内的食物泡，与残留的细胞壁从猎物被观察到在最后阶段。结果表明，在消化过程中，C.在sorokiniana细胞中，Malhamensis的叶绿体体积减小，而线粒体的数量和体积增加。当猎物被完全消化后，Malhamensis的叶绿体和线粒体恢复到摄食前的状态。实验室饲养试验表明，C. sorokiniana和P. malhamensis之间呈负相关。此外，当马拉汉逊青霉达到5 × 10 ~（5）cells mL ~（-1）时，C. sorokiniana与P. malhamensis的细胞浓度在15：1 ~ 30：1之间; sorokiniana文化急剧下降。结果表明，马缨丹在草地上放牧的最适温度为100 ℃。结果表明，在25 ℃时，马蹄莲的采食能力较弱，光照条件下马蹄莲的采食能力高于黑暗条件，马蹄莲喜弱酸性环境。此外，研究还表明，该鞭毛虫还可以捕食其他具有商业价值的常见微藻。根据其摄取广泛浮游植物的能力，以及其广泛的环境范围和全球分布，这种污染物有可能成为微藻大量培养中的一个常见问题，值得进一步研究。
Chlorella is a strong candidate as a potential production organism for future biofuels and other algal-derived products, but contamination by grazing protozoa is a major constraint to its commercial production on a large scale. In this study, a mixotrophic flagellate chrysophyte that targeted Chlorella in mass culture was observed in samples from outdoor massive photobioreactor systems. Data from field studies demonstrated that once the predatory flagellate was observed in the algal culture, there was a dramatic reduction in Chlorella cell concentration. The grazer was identified as Poterioochromonas malhamensis, based on both morphology and molecular barcoding employing 18S rDNA gene sequences. Transmission electron microscopy revealed that P. malhamensis digested the ingested Chlorella sorokiniana cells within a food vacuole, with residual cell wall from the prey being observed in the final phase. It was noted that during the process of ingesting and digesting the C. sorokiniana cells, the chloroplast of P. malhamensis reduced in size, whereas the number and volume of mitochondria increased. After the prey had been completely digested, the chloroplast and mitochondria of P. malhamensis returned to their pre-feeding status. Feeding experiments in the laboratory demonstrated that cell concentrations of C. sorokiniana and P. malhamensis were negatively correlated. Furthermore, once P. malhamensis reached 5 x 10(5) cells mL(-1) and the ratio of C. sorokiniana to P. malhamensis was in the range 15: 1 to 30: 1, the cell concentration of the C. sorokiniana culture decreased dramatically. The optimal temperature for P. malhamensis grazing on C. sorokiniana was 25 degrees C; the grazing ability of P. malhamensis in light conditions was higher than that in dark conditions; and P. malhamensis preferred weakly acidic conditions. In addition, it was demonstrated that this flagellate could graze on other common microalgae of commercial value. On the basis of its capacity to ingest a wide spectrum of phytoplankton, and its wide environmental range and global distribution, this contaminant has the potential to be a common problem in microalgal mass cultures and warrants further study.