Shi, Yijing; Shu, Longfei; He, Zhenzhen; Guan, Xiaotong; Yang, Xueqin; Tian, Yuehui; Zhang, Siyi; Wu, Chenyuan; He, Zhili; Yan, Qingyun; Wang, Cheng
When you think about top predators, you may picture big cats like lions and tigers, or crocodiles and the great white shark. In the microbial world, bacteria are the most abundant prey. For them, protists, a group of single-cell eukaryotic microbes, are their top predators. Like gray wolves in the Yellowstone National Park, protists can affect bacterial communities through predation and significantly impact aquatic and terrestrial ecosystems.
When the top predators hunt, they will not play fair and often prey on weak, sick, or young individuals. For instance, mountain lions prefer to hunt deer that have a chronic wasting disease. However, in the microbial world, we know very little about the hunting preference and strategy of microbial predators.
In this study, we used a soil amoeba species, an efficient bacterial killer, to investigate how microbial predators sense, recognize and prey on different soil bacteria. We find that discrimination and sensing of prey in soil amoebae start as early as dormant spores, a period in the amoeba’s life cycle when growth, development and physical activity are temporarily stopped. These amoebae prefer specific types of bacteria, such as gram-negative and non-motile bacteria. They also prefer bacterial prey with high nutritional values. In addition, they are also capable of avoiding harmful pathogenic bacteria. This study suggests that, like other top predators, these microbial predators are smarter than we thought, even without a brain.