Analyzing the Effect of Microbial Consortia Fermentation on the Quality of HnB by Untargeted Metabolomics.

Fermentation has been identified as an effective strategy to alter the chemical makeup of tobacco, thereby enhancing its quality. The deliberate introduction of microorganisms can hasten the fermentation process. In this research, microbial consortia harvested from the tobacco surface were utilized to enhance the tobacco quality. This enhancement also elevated several sensory attributes of HnB cigarettes, such as aroma richness, moisture, strength, and reduced irritation, achieving a sensory quality rating of 84.5. This marks a notable improvement compared to the 82 rating of the original, unfermented cigarettes. Untargeted metabolomics analysis revealed a decrease in total polyphenols and unsaturated fatty acids, while the levels of polyacids, alcohols, ketones, furans, and other compounds increased in the fermented tobacco. Additionally, KEGG pathway enrichment analysis indicated that the enhancement in tobacco quality through microbial consortia fermentation is linked to various biological pathways, with pathways related to fatty acid and amino acid degradation playing pivotal roles. The findings of this study will serve as a reference for the commercial production of HnB cigarettes, and the elucidated mechanism offers a theoretical basis for exploring microbial fermentation as a means to improve tobacco quality.

Evaluating the Transition State Stabilization/Destabilization Effects of the Electric Fields from Scaffold Residues by a QM/MM Approach.

The protein scaffolds of enzymes not only provide structural support for the catalytic center but also exert preorganized electric fields for electrostatic catalysis. In recent years, uniform oriented external electric fields (OEEFs) have been widely applied to enzymatic reactions to mimic the electrostatic effects of the environment. However, the electric fields exerted by individual residues in proteins may be quite heterogeneous across the active site, with varying directions and strengths at different positions of the active site. Here, we propose a QM/MM-based approach to evaluate the effects of the electric fields exerted by individual residues in the protein scaffold. In particular, the heterogeneity of the residue electric fields and the effect of the native protein environment can be properly accounted for by this QM/MM approach. A case study of the O-O heterolysis reaction in the catalytic cycle of TyrH shows that (1) for scaffold residues that are relatively far from the active site, the heterogeneity of the residue electric field in the active site is not very significant and the electrostatic stabilization/destabilization due to each residue can be well approximated with the interaction energy between a uniform electric field and the QM region dipole; (2) for scaffold residues near the active site, the residue electric fields can be highly heterogeneous along the breaking O-O bond. In such a case, approximating the residue electric fields as uniform fields may misrepresent the overall electrostatic effect of the residue. The present QM/MM approach can be applied to evaluate the residues' electrostatic impact on enzymatic reactions, which also can be useful in computational optimization of electric fields to boost the enzyme catalysis.

Assessing the thermal efficiency and emission reduction potential of alcohol-based fuel curing equipment in tobacco-curing.

So far, coal, petroleum, and natural gas are still the most widely used fuels, and the emissions of SO2, NOX and particulate matter produced from their combustion have a serious influence on the air. Therefore, it is necessary to develop a clean fuel. In this study, the bulk curing barns were equipped with different fuel equipment, Barn A used traditional coal heating equipment; Barn B used biomass briquettes fuel (BBF) integrated heating equipment; Barn C equipped with alcohol-based fuel (ABF) heating equipment. The temperature of the outer surface of the heating equipment, the exhaust gas of the chimney, and the curing heat efficiency and energy consumption were analyzed. Compared with the barn BBF and barn coal, the barn ABF can meet the flue-cured tobacco curing highest temperature requirements of 68 °C, the accuracy of the target dry bulb temperature (DBT) curve during the curing of flue-cured tobacco was 93.4%. At the same time, during ABF combustion, the emissions of CO2 and CO were 40.82% and 0.19%, respectively. However, no emissions of NOX, SO2, and H2S were detected in the chimney exhaust. Compared with the barn BBF and barn coal, the thermal efficiency of barn ABF heating equipment in the barn was increased by 44.78% and 86.28%, respectively. Additionally, the coast per kilogram of dry tobacco was reduced by 19.44% and 45.28%, respectively. Therefore, compared to barn coal and barn BBF, the barn ABF can control temperature changes more accurately, and shows an obvious advantage in environmental protection and heat utilization efficiency.