de Goffau Marcus C, Yang Xiaomei, van Dijl Jan Maarten, Harmsen Hermie J M
Department of Medical Microbiology, University Medical Center Groningen and University of Groningen, Hanzeplein 1, PO Box 30001, 9700 RB Groningen, the Netherlands.
Environ Microbiol. 2009 Apr;11(4):809-22. doi: 10.1111/j.1462-2920.2008.01802.x. Epub 2008 Nov 26.
The response of different bacterial species to reduced water availability was studied using a simple relative humidity gradient technique. Interestingly, distinct differences in morphology and growth patterns were observed between populations of the same species growing at different relative humidity. Gram-positive cocci increased in cell size as they approached humidity growth limits and staphylococcal species started growing in tetrad/cubical formations instead of their normal grape-like structures. Gram-negative rods displayed wave-like patterns, forming larger waves as they became increasingly filamentous at low humidity. In contrast, cells of the Gram-positive bacterium Bacillus subtilis became shorter, curved, and eventually almost coccoid. Moreover, B. subtilis started to sporulate at low humidity. The altered morphology and/or growth patterns of bacteria growing at low humidity might be more ecologically relevant than their textbook appearance at high humidity since their natural habitats are often dry. Transmission electron microscopic analyses revealed that staphylococci grown at low humidity have significantly thickened cell walls, which may explain why these cells displayed increased resistance to vancomycin. We conclude that our relative humidity gradient technique is widely applicable for investigating effects of relative humidity on microbial survival, growth and competitive success at solid-air interfaces, making it a versatile tool in microbial ecology.
使用一种简单的相对湿度梯度技术研究了不同细菌种类对水分可利用性降低的反应。有趣的是，在不同相对湿度下生长的同一种细菌群体之间，在形态和生长模式上观察到了明显差异。革兰氏阳性球菌在接近湿度生长极限时细胞大小增加，葡萄球菌属物种开始以四联/立方体形式生长，而不是其正常的葡萄状结构。革兰氏阴性杆菌呈现出波浪状模式，在低湿度下变得越来越丝状时形成更大的波浪。相比之下，革兰氏阳性细菌枯草芽孢杆菌的细胞变得更短、弯曲，最终几乎呈球菌状。此外，枯草芽孢杆菌在低湿度下开始形成芽孢。在低湿度下生长的细菌形态和/或生长模式的改变可能比它们在高湿度下的教科书外观在生态上更具相关性，因为它们的自然栖息地通常是干燥的。透射电子显微镜分析表明，在低湿度下生长的葡萄球菌细胞壁显著增厚，这可能解释了为什么这些细胞对万古霉素的抗性增加。我们得出结论，我们的相对湿度梯度技术广泛适用于研究相对湿度对固体-空气界面微生物存活、生长和竞争成功的影响，使其成为微生物生态学中的一种通用工具。
