Microbial community change and quality improve via endophytic colonization of tobacco by Saccharomyces cerevisiae

Abstract

Microbial fermentation can be used to solve the problems of deficient aroma and uncoordinated chemical composition in tobacco. Despite this, the pertinent mechanisms underlying microorganism colonization and indigenous microbial response remain poorly documented. Here, a previously screened strain of Saccharomyces cerevisiae (Z2) was selected as the fermentation strain. Upper tobacco leaves of GZ36, K326, and Yunyan 87 (Y87) were inoculated with Z2 before curing under the best inoculation conditions. The microbial community and quality of tobacco leaves were measured after curing. Colonization of Z2 was observed by scanning electron microscope before and after curing. It was observed that cells mainly colonized around stomata, base of glandular hair and hollow of leaf surface, and began to enter stomata in large numbers after 24 h. After inoculation, the richness and diversity of tobacco bacterial community increased, while the diversity of fungi increased and richness decreased. The aroma quality of tobacco leaves was improved and the impurity was reduced. After treatment with S. cerevisiae, the contents of total nitrogen, starch, and potassium/chlorine ratio of GZ36 tobacco were significantly reduced by 0.39 %, 0.71 %, and 8.36 %, respectively, the chlorine content was significantly increased by 0.39 % (P < 0.05). The total alkaloid and starch contents of K326 were decreased by 0.12 % and 0.50 %, respectively. The contents of total sugar, reducing sugar, and starch of Y87 were reduced by 0.53 %, 3.33 % and 0.44 %, respectively. The contents of total alkaloid and total nitrogen of Y87 were significantly reduced by 0.69 % and 0.41 %, respectively (P < 0.05). The internal chemical coordination of tobacco GZ36 and Y87 significantly improved. The aroma quantity, aftertaste, nicotine, and reducing sugars were the most significant factors correlated with microbial communities. This study showed that S. cerevisiae can be introduced into tobacco leaves as endophytes, changing the microbial community and occupying a dominant position, resulting in promotion of quality.