Scanning electron microscopy coupled with energydispersive X-ray spectrometry for quick detection of sulfuroxidizing bacteria in environmental water samples

• Published in: 中国海洋湖沼学报：英文版 2017, Vol.35 (1), p.185-191
• Main Author: 孙承君 蒋凤华 高伟 李小云 于延珍 尹晓斐 王勇 丁海兵
• Format: Article
• Language: English
• Subjects: X射线光谱法; 基因测序技术; 快速检测; 扫描电子显微镜; 环境样品分析; 环境水样; 硫氧化细菌; 能量色散
• ISSN: 0254-4059; 1993-5005

Detection of sulfur-oxidizing bacteria has largely been dependent on targeted gene sequencing technology or traditional cell cultivation, which usually takes from days to months to carry out. This clearly does not meet the requirements of analysis for time-sensitive samples and/or complicated environmental samples. Since energy-dispersive X-ray spectrometry（EDS） can be used to simultaneously detect multiple elements in a sample, including sulfur, with minimal sample treatment, this technology was applied to detect sulfur-oxidizing bacteria using their high sulfur content within the cell. This article describes the application of scanning electron microscopy imaging coupled with EDS mapping for quick detection of sulfur oxidizers in contaminated environmental water samples, with minimal sample handling. Scanning electron microscopy imaging revealed the existence of dense granules within the bacterial cells, while EDS identified large amounts of sulfur within them. EDS mapping localized the sulfur to these granules. Subsequent 16S rRNA gene sequencing showed that the bacteria detected in our samples belonged to the genus Chromatium, which are sulfur oxidizers. Thus, EDS mapping made it possible to identify sulfur oxidizers in environmental samples based on localized sulfur within their cells, within a short time（within 24 h of sampling）. This technique has wide ranging applications for detection of sulfur bacteria in environmental water samples.