The microbiota of fresh unfermented date palm sap: a culturomics and metagenomics investigation

ABSTRACT Palm sap is an artisanal fermented beverage, the consumption of which has been historically attested for millennia. Despite this, the underlying fermentative microbiota is poorly known. Here, three date palm sap samples collected and bought in Tunisia were investigated for bacteria, methanogenic archaea, and fungi using culturomics and molecular detection techniques, including metagenomics. Metagenomics yielded 250 bacteria, two fungi, and no archaea. Culturomics yielded 36 bacteria, eight fungi, and no archaea. Taken together, these approaches detected 250 bacteria and nine fungi, including 28 bacteria and eight fungi which had been previously unreported in date palm sap, in addition to three potentially new bacteria. Specifically, the bacteria Zymomonas mobilis and Leuconostoc mesenteroides and the fungus Saccharomyces cerevisiae were the most abundant, fermentative species found in the three samples, by culturomics and metagenomics. While determining the source of these microbes of interest was beyond the scope of the study, the data reported here may pave the way for a better understanding of the organic and organoleptic qualities of date palm sap in productive countries. IMPORTANCE This study provides valuable insights into the microbial composition of date palm sap, a traditional fermented beverage with deep historical roots. Despite its widespread consumption and cultural importance, the microbes driving its fermentation remain largely unexplored. Using advanced methods like metagenomics and culturomics, we uncovered a diverse array of bacteria and fungi, including species crucial for fermentation, such as Zymomonas mobilis, Leuconostoc mesenteroides , and Saccharomyces cerevisiae . Moreover, the discovery of previously unreported microbes highlights the potential for further research into their roles in sap fermentation and quality. Improving our understanding of the microbial communities involved in the fermentation of date palm sap underscores its importance to the field of applied and environmental microbiology.