Bacteria regulate the life histories of diverse eukaryotes, but relatively little is known about how eukaryotes interpret and respond to multiple bacterial cues encountered simultaneously. To explore how a eukaryote might respond to a combination of bioactive molecules from multiple bacteria, we treated the choanoflagellate Salpingoeca rosetta with two sets of bacterial cues, one that induces mating and the other that induces multicellular development. We found that simultaneous exposure to both sets of cues enhanced multicellular development in S. rosetta, eliciting both larger multicellular colonies and an increase in the number of colonies. Thus, rather than conveying conflicting sets of information, these distinct bacterial cues synergize to augment multicellular development. This study demonstrates how a eukaryote can integrate and modulate its response to cues from diverse bacteria, underscoring the potential impact of complex microbial communities on eukaryotic life histories.

Importance Eukaryotic biology is profoundly influenced by interactions with diverse environmental and host-associated bacteria. However, it is not well understood how eukaryotes interpret multiple bacterial cues encountered simultaneously. This question has been challenging to address because of the complexity of many eukaryotic model systems and their associated bacterial communities. Here, we studied a close relative of animals, the choanoflagellate Salpingoeca rosetta, to explore how eukaryotes respond to diverse bacterial cues. We found that a bacterial chondroitinase that induces mating on its own can also synergize with bacterial lipids that induce multicellular "rosette" development. When encountered together, these cues enhance rosette development, resulting in the formation of both larger rosettes and an increase in the number of rosettes, compared to rosette development in the absence of the chondroitinase. These findings highlight how synergistic interactions among bacterial cues can influence the biology of eukaryotes.

细菌调节着各种真核生物的生活史，但对真核生物如何解释和响应同时遇到的多种细菌线索的了解相对较少。为了探索真核生物如何响应多种细菌的生物活性分子的结合，我们用两套细菌线索处理了鞭毛鞭毛藻（Salpingoeca rosetta），这两种细菌线索可以诱导交配，而另一种则可以诱导多细胞发育。我们发现，同时暴露于这两组线索可以增强玫瑰茄中的多细胞发育。，会引起更大的多细胞菌落和菌落数量的增加。因此，这些独特的细菌线索协同作用以增强多细胞发育，而不是传达冲突的信息集。这项研究证明了真核生物如何整合和调节其对来自多种细菌的线索的反应，强调了复杂的微生物群落对真核生物生活史的潜在​​影响。

重要性真核生物受到与各种环境细菌和宿主相关细菌相互作用的深刻影响。然而，人们还不太了解真核生物如何解释同时遇到的多种细菌线索。由于许多真核模型系统及其相关细菌群落的复杂性，这个问题很难解决。在这里，我们研究了动物的近亲，即鞭毛鞭毛虫Salpingoeca rosetta，以探索真核生物如何响应各种细菌线索。我们发现，一种细菌软骨素酶自身诱导交配也可以与诱导多细胞“玫瑰红”发育的细菌脂质协同作用。与缺少软骨素酶的玫瑰花发育相比，这些线索在一起时会增强玫瑰花结的发育，导致形成更大的玫瑰花结并增加玫瑰花结的数量。这些发现凸显了细菌线索之间的协同相互作用如何影响真核生物的生物学。