The phototrophic euglenophyte Eutreptiella eupharyngea often causes blooms in the coastal waters of many countries, but its mode of nutrition has not been assessed. This species has previously been considered as exclusively auxotrophic. To explore whether E. eupharyngea is a mixotrophic species, the protoplasm of E. eupharyngea cells were examined using light, epifluorescence, and transmission electron microscopy after eubacteria, the cyanobacterium Synechococcus sp., and diverse algal species were provided as potential prey. Furthermore, the ingestion rates of E. eupharyngea KR on eubacteria or Synechococcus sp. as a function of prey concentration were measured. In addition, grazing by natural populations of euglenophytes on natural populations of eubacteria in Masan Bay was investigated. This study is the first to report that E. eupharyngea is a mixotrophic species. Among the potential prey organisms offered, E. eupharyngea fed only on eubacteria and Synechococcus sp., and the maximum ingestion rates of these two organisms measured in the laboratory were 5.7 and 0.7 cells predator⁻¹ h⁻¹, respectively. During the field experiments, the maximum ingestion rates and grazing impacts of euglenophytes, including E. eupharyngea, on natural populations of eubacteria were 11.8 cells predator⁻¹ h⁻¹ and 1.228 d⁻¹, respectively. Therefore, euglenophytes could potentially have a considerable grazing impact on marine bacterial populations.

在许多国家的沿海地区，光养的真绿藻类植物常绿芽孢杆菌常引起花开，但其营养方式尚未得到评估。该物种以前被认为是唯一的营养缺陷型。为了探索真核大肠杆菌是否为混合营养物种，在真细菌，蓝细菌Synecoococcus sp。和各种藻类作为潜在的猎物之后，使用光，落射荧光和透射电子显微镜检查了真核大肠杆菌细胞的原生质。此外，摄入率E. eupharyngea KR的真细菌或聚球藻sp。测量作为猎物浓度的函数。此外，还研究了马山湾自然裸藻类种群对真细菌自然种群的放牧。这项研究是第一个报告真核大肠杆菌是一种混合营养物种。在所提供的潜在猎物生物中，仅以真细菌和Synechococcus sp。为食的真核大肠杆菌，在实验室中测得的这两种生物的最大摄食率分别为捕食者^-1  h ^-1和5.7细胞。在田间实验中，包括真核肠杆菌在内的真核生物对自然细菌的最大摄入率和放牧影响为11.8个细胞捕食者^-1  h ^-1和1.228 d ^-1。因此，裸藻植物可能会对海洋细菌种群产生相当大的放牧影响。