Jenull Sabrina, Bauer Tobias, Silbermayr Katja, Dreer Maximilian, Stark Timo D, Ehling-Schulz Monika
Institute of Microbiology, Department of Pathobiology, University of Veterinary Medicine Vienna, Vienna, Austria.
Institute of Parasitology, Department of Pathobiology, University of Veterinary Medicine Vienna, Vienna, Austria.
Environ Microbiol. 2023 Nov;25(11):2231-2249. doi: 10.1111/1462-2920.16454. Epub 2023 Jun 24.
Most microbes share their environmental niches with very different forms of life thereby engaging in specialised relationships to enable their persistence. The bacterium Bacillus cereus occurs ubiquitously in the environment with certain strain backgrounds causing foodborne and opportunistic infections in humans. The emetic lineage of B. cereus is capable of producing the toxin cereulide, which evokes emetic illnesses. Although food products favouring the accumulation of cereulide are known, the ecological role of cereulide and the environmental niche of emetic B. cereus remain elusive. To better understand the ecology of cereulide-producing B. cereus, we systematically assayed the toxicological spectrum of cereulide on a variety of organisms belonging to different kingdoms. As cereulide is a potassium ionophore, we further tested the effect of environmental potassium levels on the action of cereulide. We found that adverse effects of cereulide exposure are species-specific, which can be exacerbated with increased environmental potassium. Additionally, we demonstrate that cereulide is produced within an insect cadaver indicating its potential ecological function for a saprophytic lifestyle. Collectively, distinct cereulide susceptibilities of other organisms may reflect its role in enabling competitive niche specialization of emetic B. cereus.
大多数微生物与截然不同的生命形式共享其环境生态位，从而建立特殊关系以维持自身生存。蜡样芽孢杆菌在环境中普遍存在，某些菌株背景会导致人类食源性感染和机会性感染。蜡样芽孢杆菌的呕吐型菌株能够产生呕吐毒素，引发呕吐性疾病。尽管已知有利于呕吐毒素积累的食品，但呕吐毒素的生态作用以及呕吐型蜡样芽孢杆菌的环境生态位仍不清楚。为了更好地了解产呕吐毒素蜡样芽孢杆菌的生态学，我们系统地测定了呕吐毒素对不同界的多种生物的毒理学谱。由于呕吐毒素是一种钾离子载体，我们进一步测试了环境钾水平对呕吐毒素作用的影响。我们发现，接触呕吐毒素的不良影响具有物种特异性，环境钾含量增加会加剧这种影响。此外，我们证明呕吐毒素是在昆虫尸体中产生的，这表明它对腐生生活方式具有潜在的生态功能。总的来说，其他生物对呕吐毒素的不同敏感性可能反映了它在使呕吐型蜡样芽孢杆菌实现竞争性生态位特化方面的作用。
