Oxygen limitation within a bacterial aggregate.
Oxygen limitation within a bacterial aggregate.
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DOI：
10.1128/mbio.00992-14
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发表时间：
2014-04-15
期刊：
影响因子：
6.4
通讯作者：
Whiteley M
中科院分区：
文献类型：
--
作者：
Wessel AK;Arshad TA;Fitzpatrick M;Connell JL;Bonnecaze RT;Shear JB;Whiteley M
生物膜内的细胞表现出生理异质性，部分原因是这些空间结构的社区内存在的化学梯度。以前的工作已经研究了化学梯度如何在包含>108个细胞的大型生物膜中发展。然而，自然界中的许多细菌群落由小的、密集的细胞聚集体（≤105个细菌）组成。使用基于明胶的三维（3D）打印策略，我们将细菌铜绿假单胞菌限制在皮升大小的3D“微陷阱”中，这些微陷阱可渗透营养素，废物和其他生物活性小分子。我们表明，作为一个单一的细菌生长到一个最大密度（1012个细胞ml−1）的克隆人口，氧气的发展，当它达到一个临界聚集体大小约55 pl的局部耗尽。总的来说，这些数据表明，化学和表型异质性存在于微米尺度上的小聚集人口。在发展成大型复杂的群落之前，微生物最初聚集成聚集体，目前还不清楚这些无处不在的微米级聚集体中是否存在化学异质性。我们选择检查聚集体中的氧可用性，因为氧浓度影响许多重要的细菌过程，包括代谢，社会行为，毒力和抗生素耐药性。通过确定含≤105个细菌的聚集体中的氧可用性可能不同，我们确定铜绿假单胞菌聚集体中存在生理异质性，这表明这种异质性经常存在于许多天然存在的小种群中。
Cells within biofilms exhibit physiological heterogeneity, in part because of chemical gradients existing within these spatially structured communities. Previous work has examined how chemical gradients develop in large biofilms containing >108 cells. However, many bacterial communities in nature are composed of small, densely packed aggregates of cells (≤105 bacteria). Using a gelatin-based three-dimensional (3D) printing strategy, we confined the bacterium Pseudomonas aeruginosa within picoliter-sized 3D “microtraps” that are permeable to nutrients, waste products, and other bioactive small molecules. We show that as a single bacterium grows into a maximally dense (1012 cells ml−1) clonal population, a localized depletion of oxygen develops when it reaches a critical aggregate size of ~55 pl. Collectively, these data demonstrate that chemical and phenotypic heterogeneity exists on the micrometer scale within small aggregate populations. Before developing into large, complex communities, microbes initially cluster into aggregates, and it is unclear if chemical heterogeneity exists in these ubiquitous micrometer-scale aggregates. We chose to examine oxygen availability within an aggregate since oxygen concentration impacts a number of important bacterial processes, including metabolism, social behaviors, virulence, and antibiotic resistance. By determining that oxygen availability can vary within aggregates containing ≤105 bacteria, we establish that physiological heterogeneity exists within P. aeruginosa aggregates, suggesting that such heterogeneity frequently exists in many naturally occurring small populations.