Microbial population dynamics during spontaneous fermentation of Asparagus officinalis L. young sprouts

Abstract

The aim of the present study was to assess the spontaneous fermentation of Asparagus officinalis L. young sprouts. For this purpose, asparagus fermentation was performed according to a traditional procedure originating from northern Greece. Young asparagus sprouts were cut, submerged in a brine solution (8 % NaCl) and placed in room temperature for fermentation to occur. Fermentation was monitored by measuring pH and total titratable acidity values as well as by qualitative and quantitative assessment of the microbiota dynamics. The latter was performed by classical microbiological techniques; clustering was performed by SDS-PAGE of whole cell proteins and rep-PCR and identification by sequencing of the 16S-rRNA gene. A culture-independent approach [PCR-denaturing gradient gel electrophoresis (DGGE)] was also applied in order to obtain a more integrated view of the microbiota dynamics. Lactic acid bacteria prevailed the fermentation forming a microbial consortium that was stable at species level; Lactobacillus sakei and Enterococcus faecium dominated until the 5th day while Weissella viridescens and W. cibaria dominated from the 7th day until the end of fermentation. Combination of SDS-PAGE with rep-PCR resulted in a very efficient clustering and differentiation also at sub-species level, revealing a succession at that level of all species throughout fermentation. On the other hand, application of PCR-DGGE was of limited usefulness.