Microbial Community Structure and Dynamics of Dark Fire-Cured Tobacco Fermentation

Abstract

The Italian Toscano cigar production includes a fermentation step that starts when dark fire-cured tobacco leaves are moistened and mixed with ca. 20% prefermented tobacco to form a 500-kg bulk. The dynamics of the process, lasting ca. 18 days, has never been investigated in detail, and limited information is available on microbiota involved. Here we show that Toscano fermentation is invariably associated with the following: (i) an increase in temperature, pH, and total microbial population; (ii) a decrease in reducing sugars, citric and malic acids, and nitrate content; and (iii) an increase in oxalic acid, nitrite, and tobacco-specific nitrosamine content. The microbial community structure and dynamics were investigated by culture-based and cultureindependent approaches, including denaturing gradient gel electrophoresis and single-strand conformational polymorphism. Results demonstrate that fermentation is assisted by a complex microbial community, changing in structure and composition during the process. During the early phase, the moderately acidic and mesophilic environment supports the rapid growth of a yeast population predominated by Debaryomyces hansenii. At this stage, Staphylococcaceae (Jeotgalicoccus and Staphylococcus) and Lactobacillales (Aerococcus, Lactobacillus, and Weissella) are the most commonly detected bacteria. When temperature and pH increase, endospore-forming low-G؉C content gram-positive bacilli (Bacillus spp.) become evident. This leads to a further pH increase and promotes growth of moderately halotolerant and alkaliphilic Actinomycetales (Corynebacterium and Yania) during the late phase. To postulate a functional role for individual microbial species assisting the fermentation process, a preliminary physiological and biochemical characterization of representative isolates was performed.

Smokeless tobacco products harbor diverse bacterial microbiota that differ across products and brands

“…These studies identified several specific bacterial species present in tobacco products including Actinomycetes spp. (Di Giacomo et al 2007), Bacteriovox sp. (Zhao et al 2007), Kurthia spp., Bacillus spp.…”

Temporal Variations in Cigarette Tobacco Bacterial Community Composition and Tobacco-Specific Nitrosamine Content Are Influenced by Brand and Storage Conditions

“…These comprise species from the families Pseudomonadaceae, Staphylococcaceae , Lactobacillaceae , Enterobacteriaceae , Enterococcaceae , Aerococcaceae , Corynebacteriaceae , among others, and include potential human and respiratory pathogens (Di Giacomo et al, 2007; Huang et al, 2010; Sapkota et al, 2010; Su et al, 2011). Furthermore, tobacco and tobacco smoke have been shown to harbor microbial derived toxins and secondary metabolites (Hasday et al, 1999).…”

Production of Primary Biomolecules in Different Varieties of Oriental Tobacco (Nicotiana Tabacum L.)

“…It's high activity inhibits the activity of certain microorganisms that are essential for fermentation (Di Giacomo et al, 2007). During fermentation the content of catalase is reduced, and in the context of these data and the results of this study, where the highest activity of catalase show leaves harvested in 2012 for all tested varieties.…”