Interspecific diversity reduces and functionally substitutes for intraspecific variation in biofilm communities
Interspecific diversity reduces and functionally substitutes for intraspecific variation in biofilm communities
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DOI：
10.1038/ismej.2015.159
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发表时间：
2016-04-01
期刊：
影响因子：
11
通讯作者：
Rice, Scott A.
中科院分区：
文献类型：
--
作者：
Lee, Kai Wei Kelvin;Yam, Joey Kuok Hoong;Rice, Scott A.
多样性在群落的动态和恢复力中起着关键作用，种间（物种）和种内（基因型）多样性对群落结构和功能都有重要影响。然而，了解群落生态学的一个关键和未解决的问题是，这两个层次的多样性在多大程度上是功能可替代的？在这里，我们发现，对于由铜绿假单胞菌、P. protegens和肺炎克雷伯菌组成的混合物种生物膜群落，种间多样性的增加减少了种内多样性，并在功能上替代了种内多样性，从而介导了对胁迫的耐受性。生物膜群体产生了高比例的基因型变异，而这些变异在生物膜群落中基本不存在。具有高种内或种间多样性的生物膜比没有或低多样性的生物膜更能耐受SDS胁迫。出乎意料的是，当实验引入生物膜群落时，基因型变异降低了群落的耐受性。例如，在生物膜群落中，将P. protegens的野生型替换为其基因型变体，使SDS耐受性降低了两倍，这显然是由于种间相互作用的干扰。当生物膜群体暴露于另一物种的无细胞流出物时，也观察到变异频率的减少，这表明细胞外因素在选择中对种内变异的出现起作用。这项工作证明了种间和种内多样性对生物膜的紧急特性的功能替代。这也为微生物学中一个长期存在的悖论提供了一个潜在的解释，即形态变异在实验室生长的生物膜群体中很常见，但在不同的环境生物膜群落中却很少见。
Diversity has a key role in the dynamics and resilience of communities and both interspecific (species) and intraspecific (genotypic) diversity can have important effects on community structure and function. However, a critical and unresolved question for understanding the ecology of a community is to what extent these two levels of diversity are functionally substitutable? Here we show, for a mixed-species biofilm community composed of Pseudomonas aeruginosa, P. protegens and Klebsiella pneumoniae, that increased interspecific diversity reduces and functionally substitutes for intraspecific diversity in mediating tolerance to stress. Biofilm populations generated high percentages of genotypic variants, which were largely absent in biofilm communities. Biofilms with either high intra- or interspecific diversity were more tolerant to SDS stress than biofilms with no or low diversity. Unexpectedly, genotypic variants decreased the tolerance of biofilm communities when experimentally introduced into the communities. For example, substituting P. protegens wild type with its genotypic variant within biofilm communities decreased SDS tolerance by twofold, apparently due to perturbation of interspecific interactions. A decrease in variant frequency was also observed when biofilm populations were exposed to cell-free effluents from another species, suggesting that extracellular factors have a role in selection against the appearance of intraspecific variants. This work demonstrates the functional substitution of inter- and intraspecific diversity for an emergent property of biofilms. It also provides a potential explanation for a long-standing paradox in microbiology, in which morphotypic variants are common in laboratory grown biofilm populations, but are rare in diverse, environmental biofilm communities.