What a pickle—a metagenomic perspective on the cucumber fermentation

Food fermentation involves an interplay between multiple strains and species. This delicate composition during fermentation has been investigated so far using both classical and molecular methods; however, the results remain difficult to interpret. In this perspective article, we discuss the spontaneous fermentation of cucumber from organic and commercial cultivation (from 1st day to 90th day) based on our preliminary data from a nanopore sequencing study. The present study is the first to report the occurrence of coagulase-negative cocci in cucumber fermentation [ Staphylococcus saprophyticus (0.01%) and Staphylococcus schleiferi (0.03%)]. Furthermore, we conclude that own-cultivation cucumbers may exhibit a lower incidence and diversity of phages, which have practical implications for designing future studies as well as for direct consumers. Our data also show that, even in the absence of phages (own-cultivation cucumbers <1%), lactic acid bacteria dominance occurs, which contrasts with previous conclusions and contributes to the discussion on the role of phages in maintaining the balance between Enterobacteriaceae and lactic acid bacteria in plant fermentation. The powerful metagenomic approach provides a broader understanding of the day-to-day and sample-to-sample diversity within microbiome communities. The maturity of the fermentation product may play a significant role in exerting specific biological actions. This should be accounted for before planning an intervention study.