In nature, microorganisms often exhibit competitive behavior for nutrients and limited space, allowing them to alter the virulence determinants of pathogens. The human pathogenic yeast Cryptococcus neoformans can be found organized in biofilms, a complex community composed of an extracellular matrix which confers protection against predation. The aim of this study was to evaluate and characterize antagonistic interactions between two cohabiting microorganisms: C. neoformans and the bacteria Serratia marcescens. The interaction of S. marcescens with C. neoformans expressed a negative effect on biofilm formation, polysaccharide capsule, production of urease, and melanization of the yeast. These findings evidence that competition in mixed communities can result in dominance by one species, with direct impact on the physiological modulation of virulence determinants. Such an approach is key for understating the response of communities to the presence of competitors and, ultimately, rationally designing communities to prevent and treat certain diseases.

中文翻译：

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微生物邻居的比赛：粘质沙雷氏菌与人类病原体新型隐球菌的种间竞争

在自然界中，微生物通常表现出对营养物质的竞争行为和有限的空间，使它们能够改变病原体的毒力决定因素。人类致病性酵母新型隐球菌可以在生物膜中发现，生物膜是一个复杂的群落，由细胞外基质组成，可以防止捕食。本研究的目的是评估和表征两种共存微生物之间的拮抗相互作用：新型 C.neoformans 和细菌粘质沙雷氏菌。S. marcescens 与 C. neoformans 的相互作用对生物膜形成、多糖荚膜、脲酶的产生和酵母的黑化产生负面影响。这些发现证明混合群落中的竞争可能导致一个物种的优势，直接影响毒力决定因素的生理调节。这种方法对于低估社区对存在竞争者的反应以及最终合理设计社区以预防和治疗某些疾病至关重要。