Changes in physicochemical properties and microbial community succession during leaf stacking fermentation

Abstract

Leaf stacking fermentation involves enzymatic actions of many microorganisms and is an efficient and environmentally benign process for degrading macromolecular organic compounds. We investigated the dynamics of metabolite profiles, bacterial and fungal communities and their interactions during fermentation using cigar leaves from three geographic regions. The results showed that the contents of total sugar, reducing sugar, starch, cellulose, lignin, pectin, polyphenol and protein in cigar tobacco leaves was significantly decreased during fermentation. Notably, the furfural, neophytadiene, pyridine, benzyl alcohol, geranyl acetone, 2-butanone, 3-hydroxy-, N-hexanal, isoamylalcohol and 2,3-pentanedione were important features volatile aroma compounds during fermentation. The α-diversity of fungi and bacteria initially increased and then decreased during fermentation. The microbial diversity was influenced by fermentation stages and growing locations, in which the fermentation stages had greater impacts on the microbial diversity than locations. Microbiome profiling had identified several core bacteria including Sphingomonas, Bacillus, Staphylococcus, Pseudomonas, Ralstonia, Massilia and Fibrobacter. Fungal biomarkers included Aspergillus, Penicillium, Fusarium, Cladosporium and Trichomonascus. Interestingly, the molecular ecological networks showed that the core taxa had significant correlations with metabolic enzymes and physicochemical properties; bacteria and fungi jointly participated in the carbohydrate and nitrogen compound degrading and volatile aroma compound chemosynthesis processes during fermentation. These studies provide insights into the coupling of material conversion and microbial community succession during leaf fermentation.

Research on the Composting Technology of Cattle and Sheep Manure Based on Intelligent and Efficient Composting Equipment and the Evaluation Standard of Decomposition Degree

“…For instance, in the Inner Mongolia region, there are 1.3 billion mu of natural grassland and 30 million mu of artificial grassland, along with around 95,000 large-scale cattle and sheep farms [4][5][6][7]. Over the past few decades, the cattle and sheep populations in Inner Mongolia have significantly increased; however, improper management of the resulting manure can lead to severe environmental pollution [8][9][10][11]. Furthermore, the excessive use of chemical fertilizers in China has resulted in irreversible damage to the soil [12][13][14].…”