High-throughput identification of the microbial biodiversity of cocoa bean fermentation by MALDI-TOF MS
Miescher Schwenninger, Susanne; Freimüller Leischtfeld, Susette; Gantenbein-Demarchi, Corinne (2016). High-throughput identification of the microbial biodiversity of cocoa bean fermentation by MALDI-TOF MS. Letters in Applied Microbiology, doi:10.1111/lam.12621 Peer reviewed.
Matrix-assisted laser desorption ionization time-of-ﬂight mass spectrometry(MALDI-TOF MS) is a powerful biotyping tool increasingly used for high-
throughput identiﬁcation of clinical microbial isolates, however, in food fermentation research this approach is still not well established. This study
examines the microbial biodiversity of cocoa bean fermentation based on the
isolation of micro-organisms in cocoa-producing regions, followed by MALDI-
TOF MS in Switzerland. A preceding 6-week storage test to mimic lengthy
transport of microbial samples from cocoa-producing regions to Switzerland
was performed with strains of Lactobacillus plantarum, Acetobacter pasteurianus and Saccharomyces cerevisiae. Weekly MALDI-TOF MS analysis was able to successfully identify microbiota to the species level after storing live cultures on slant agar at mild temperatures (7°C) and/or in 75% aqueous ethanol at differing temperatures (20, 7 and 30°C). The efﬁcacy of this method was conﬁrmed by on-site recording of the microbial biodiversity in cocoa bean
fermentation in Bolivia and Brazil, with a total of 1126 randomly selected
isolates. MALDI-TOF MS analyses revealed known dominant cocoa bean
fermentation species with Lact. plantarum and Lactobacillus fermentum in the
lactic acid bacteria taxon, Hanseniaspora opuntiae and S. cerevisiae in the yeast taxon, and Acet. pasteurianus, Acetobacter fabarum, Acetobacter ghanensis and Acetobacter senegalensis in the acetic acid bacteria taxon.