MALDI-TOF MS as a supportive tool for the evaluation of bacterial diversity in soils from Africa and the Americas

Identification and characterization of viable culturable bacteria (VCB) associated with soils from Africa and the Americas are significant for environmental and battlefield security. Such analyses are scarce, and their evaluation using traditional microbiological methods does not fully elucidate the structure and chemotaxonomic characteristics of the microbial community. In this study, matrix-assisted laser desorption time of flight mass spectrometry (MALDI-TOF MS), spectrometry in addition to 16S rRNA sequencing, and diversity indices were employed to characterize VCB and their associated biomarkers. Nineteen genera were identified across all sample locations, but only four (, , and ) confirmed by ClustalW2 as being 98–99 % similar among locations. Further evaluation of soils showed bacterial diversity () of (1.0–8.4), evenness ( ), (0.14–0.72), similarity (), (0.0–0.38), and cfu/g soil (2.5 × 10–2.2 × 10). Analysis of representative bacteria using MALDI-TOF MS identified biomarkers for the genera at m/z 6,778 (75 %), 9,437 (100 %); , m/z 7,381 (86 %); , 5,473 (63 %); and , 4,517, 6,532, 7,574 (67 %). Peptide mass fingerprinting of biomarkers identified partial peptide maps for several potential virulence factors such as hemagglutinin from a spp. The data indicate an east (Sudan) to west (Jamaica; Mexico; Washington, DC; Baltimore) trend of potentially pathogenic endospore-forming bacteria.