Abstract
In situ liquid time-of-flight secondary ion mass spectrometry (ToF-SIMS) is a powerful technique to study surface characterization of living biofilms in hydrated conditions. However, ToF-SIMS data analysis is still a great challenge in complicated bacterial biofilms, because many interference peaks from the medium may result in inaccurate interpretation. In this study, two syntrophic Geobacter populations are investigated using in situ liquid ToF-SIMS to reveal the biofilm surface changes between them due to direct interspecies electron transfer. By comparing spectral principal component analysis (PCA) results of all peaks and selected peaks, the authors find that spectral peak overlay is an effective strategy to reduce the matrix effect in handling complex ToF-SIMS data. Additionally, the spectral PCA results of high intensity and high resolution data obtained from liquid ToF-SIMS are compared. Selected peaks, amino acid peaks, and water cluster peaks spectral PCA produce nice separation among samples in both high intensity and high resolution data sets. However, the high resolution data show better separation between coculture planktonic and coculture aggregates, confirming that the higher mass accuracy is useful in the analysis of microbial samples. In conclusion, the results show that peak selection is critical for acquiring effective microbial information and interpretation of syntrophic Geobacter using spectral data from in situ liquid ToF-SIMS.
| Original language | English |
|---|---|
| Article number | 051004 |
| Journal | Biointerphases |
| Volume | 14 |
| Issue number | 5 |
| DOIs | |
| State | Published - Sep 1 2019 |
| Externally published | Yes |
Funding
The authors are grateful for the support from Pacific Northwest National Laboratory (PNNL) with the funding from Earth and Biological Sciences Directorate (EBSD) mission seed Laboratory Directed Research and Development (LDRD) and the China National Scholarship. The ToF-SIMS measurement was performed at W. R. Wiley Environmental Molecular Sciences Laboratory (EMSL), a Department of Energy (DOE) Office of Science User Facility sponsored by the Office of Biological and Environmental Research, through a general user proposal (Nos. 49694 and 50569). The sample preparation was conducted in the Biological Sciences Facility (BSF). The authors are also grateful to Derek Lovley for providing Geobacter metallireducens and Geobacter sulfurreducens strains. They thank Andy Plymale for helping with a biofilm cultivation setup. Cuiyun Yang and Wenchao Wei thank for the support from the PNNL Alternate Sponsored Fellowship.
| Funders | Funder number |
|---|---|
| China National Scholarship | |
| Office of Biological and Environmental Research | 49694, 50569 |
| Office of Science User Facility | |
| U.S. Department of Energy | |
| Directorate for Biological Sciences | |
| Laboratory Directed Research and Development | |
| Pacific Northwest National Laboratory | PNNL |