Key points are not available for this paper at this time.
Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) is widely employed for rapid bacterial identification; however, the influence of cultivation conditions on spectral variability and downstream multivariate analyses remains insufficiently characterized, particularly for environmental isolates relevant to bioprocessing systems. In this study, MALDI-TOF MS combined with principal component analysis (PCA) was used to differentiate 16 bacterial strains cultivated on three media (LB, MD1, and urea medium, UM). Species-level identification was largely consistent across media for most taxa, indicating preservation of core spectral features required for reliable assignment. In contrast, protein fingerprint profiles and PCA clustering patterns varied substantially with growth conditions. LB-grown cultures produced clustering patterns most consistent with 16S rRNA gene–based phylogeny, whereas MD1 and UM resulted in progressively greater dispersion and reorganization of strain relationships, reflecting condition-dependent proteomic responses. Environmental Virgibacillus isolates generated reproducible spectra but yielded low identification scores, suggesting limitations of current reference databases rather than analytical instability. Overall, the findings demonstrate that growth medium selection strongly influences MALDI-TOF MS–derived protein fingerprints and multivariate interpretations while preserving identification capability. These results underscore the importance of standardized cultivation protocols and expanded spectral libraries for reliable strain differentiation, monitoring, and comparative analyses in environmental and bioprocess engineering contexts.
Disi et al. (Mon,) studied this question.