MALDI-TOF MS insight into the biodiversity of Staka, the artisanal Cretan soured cream

Abstract

Staka is a naturally fermented cream produced from sheep or mixtures of sheep and goat milk in the island of Crete, Greece. This work is the first report on Staka cream microbiota. Initially, counts of various bacterial groups were enumerated using selective media and growth conditions. All isolates (101) were subjected to matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF MS) analysis; the spectra obtained were compared with those of an in-house reference database. While 70 isolates were considered identified at the species level, the remaining 31 were not, probably due to a lack of, or an insufficient number of, reference spectra in the MALDI-TOF MS database. Strains representative of the observed diversity among the unidentified MALDI-TOF MS spectra were therefore subjected to pheS and 16S rRNA gene sequencing analysis for further identification. The identification results revealed the presence of Lactobacillus spp., Enterococcus spp., Streptococcus thermophilus and Aerococcus viridans.