Phan Joann, Meinardi Simone, Barletta Barbara, Blake Donald R, Whiteson Katrine
Department of Molecular Biology and Biochemistry, University of California, Irvine, CA, United States.
J Breath Res. 2017 Feb 6;11(1):017101. doi: 10.1088/1752-7163/aa5833.
Volatile organic compounds (VOCs) measured from exhaled breath have great promise for the diagnosis of bacterial infections. However, determining human or microbial origin of VOCs detected in breath remains a great challenge. For example, the microbial fermentation product 2,3-butanedione was recently found in the breath of Cystic Fibrosis (CF) patients; parallel culture-independent metagenomic sequencing of the same samples revealed that Streptococcus and Rothia spp. have the genetic capacity to produce 2,3-butanedione. To investigate whether the genetic capacity found in metagenomes translates to bacterial production of a VOC of interest such as 2,3-butanedione, we fed stable isotopes to three bacterial strains isolated from patients: two gram-positive bacteria, Rothia mucilaginosa and Streptococcus salivarius, and a dominant opportunistic gram-negative pathogen, Pseudomonas aeruginosa. Culture headspaces were collected and analyzed using a gas chromatographic system to quantify the abundance of VOCs of interest; mass spectroscopy was used to determine whether the stable isotope label had been incorporated. Our results show that R. mucilaginosa and S. salivarius consumed D-Glucose-C to produce labeled 2,3-butanedione. R. mucilaginosa and S. salivarius also produced labeled acetaldehyde and ethanol when grown with HO. Additionally, we find that P. aeruginosa growth and dimethyl sulfide production are increased when exposed to lactic acid in culture. These results highlight the importance VOCs produced by P. aeruginosa, R. mucilaginosa, and S. salivarius as nutrients and signals in microbial communities, and as potential biomarkers in a CF infection.
呼出气体中检测到的挥发性有机化合物（VOCs）在细菌感染诊断方面具有巨大潜力。然而，确定呼出气体中检测到的VOCs的人类或微生物来源仍然是一项巨大挑战。例如，最近在囊性纤维化（CF）患者的呼出气体中发现了微生物发酵产物2,3 - 丁二酮；对相同样本进行的平行非培养宏基因组测序显示，链球菌属和罗氏菌属具有产生2,3 - 丁二酮的遗传能力。为了研究宏基因组中发现的遗传能力是否转化为细菌产生感兴趣的VOC（如2,3 - 丁二酮），我们给从患者分离出的三种细菌菌株投喂稳定同位素：两种革兰氏阳性菌，粘液罗氏菌和唾液链球菌，以及一种主要的机会性革兰氏阴性病原体铜绿假单胞菌。收集培养顶空气体并使用气相色谱系统进行分析，以量化感兴趣的VOCs的丰度；使用质谱法确定稳定同位素标记是否已被纳入。我们的结果表明，粘液罗氏菌和唾液链球菌消耗D - 葡萄糖 - C以产生标记的2,3 - 丁二酮。粘液罗氏菌和唾液链球菌在与HO一起生长时还产生了标记的乙醛和乙醇。此外，我们发现铜绿假单胞菌在培养中暴露于乳酸时生长和二甲基硫醚产量增加。这些结果突出了铜绿假单胞菌、粘液罗氏菌和唾液链球菌产生的VOCs作为微生物群落中的营养物质和信号以及作为CF感染中潜在生物标志物的重要性。
