A large diversity of lactic acid bacteria species is involved in the fermentation of wheat used for the manufacture of lemzeiet

Abstract

Algerian couscous named lemzeiet is manufactured from fermented wheat. Historically performed in underground silos called matmor, the fermentation of wheat is now generally carried out in plastic jerrycans with or without addition of vinegar at the beginning of the fermentation. Culture-dependent and culture-independent methods (PCR-TTGE) were used to characterize lactic acid bacteria and to determine their dynamic and diversity over a two-year period, with and without the addition of vinegar. Fungi, physicochemical characteristics, and volatile compound profiles were also monitored. The isolates obtained from different stages of fermentation and from both processes were characterized by coupling different molecular methods (16SrRNA/pheS/rpoA gene sequencing, species-specific PCR, RAPD and PFGE). PCR-TTGE revealed very similar profiles for both processes. Sixty-nine isolates were identified as belonging to six genera of 16 species (Enterococcus, Lactobacillus, Leuconostoc, Pediococcus, Weissella, and Streptococcus). The profiles of volatile aroma compounds showed a marked effect of the fermentation process, compared to non-fermented wheat, with 35 of the 40 volatiles detected at amounts 20- to 30-fold higher in fermented wheat samples. This study gives the first insight into lactic acid bacteria population diversity and activity in fermented wheat and will contribute to a better control of the fermentation process.