Analysis of differences in tobacco leaf microbial communities after redrying in Chinese provinces and from abroad.

Microorganisms play an important role in the tobacco aging process. Before the aging process, raw tobacco leaves must be threshed and redried. In order to explore the differences of microbial community structure of threshed and redried tobacco leaves from different origins at home and abroad, 14 groups of tobacco leaves from 8 different countries were tested by high-throughput DNA sequencing and microbiology analysis. Then, through amplicon sequence variants (ASV) cluster analysis, Venn diagram and species labeling and other microbial diversity analysis, the dominant bacteria and fungi on the surface of threshed and redried tobacco leaves were obtained. The results showed that there were significant differences in the composition of tobacco bacteria and fungi after threshing and redrying from different geographical areas. The relative abundance of Microbacterium and Sphingomonas in domestic tobacco leaves was significantly higher than that of foreign tobacco leaves. The relative abundance of Pseudomonas in foreign tobacco bacterial colonies was significantly higher than that of domestic tobacco leaves. In terms of fungi, the relative abundance of Aspergillus and Alternaria in domestic tobacco leaves was significantly higher than that of foreign tobacco leaves. Septoria, Sampaiozyma, Cladosporium and Phoma account for significantly higher proportions of foreign tobacco leaves. These microorganisms may be indispensable in aging process to form different flavors of tobacco leaves. It provides an important theoretical basis for the further use of microorganisms to promote tobacco leaf aging.

Characterization of bacterial community in tobacco leaves at flue-curing and redrying processing stages.

During the processing of tobacco leaves, flue-curing and redrying can affect the structure of bacterial community, having an effect on the aging quality of tobacco leaves. In order to characterize the effects of flue-curing and redrying on the bacterial community of tobacco leaves, the bacterial community of samples at different processing stages (before flue-curing, after flue-curing, before redrying and after redrying) was analyzed using Illumina sequencing. A total of 33 phyla, 79 classes, 195 orders, 344 families, 826 genera and 7922 ASVs were obtained from 36 samples. There was no significant difference in the core bacterial groups of tobacco leaf at four processing stages. Proteobacteria dominated at the phylum level. Sphingomonas, Pseudomonas and Methylobacterium were the main genera shared by all samples. The functional prediction by PICRUSt showed an increase in the relative abundance of pathway related to metabolism after flue-curing and pathway related to environmental information processing after redrying. This study, we analyzed the changes of bacterial community and structural composition of tobacco leaves from flue-curing to redrying, and found that flue-curing had a greater effect on the microbial community than redrying. This is conducive for the exploration of microbial resources and improvement of tobacco leaf quality.

Homotypic Cancer Cell Membranes Camouflaged Nanoparticles for Targeting Drug Delivery and Enhanced Chemo-Photothermal Therapy of Glioma.

Glioma is among the deadliest types of brain cancer, for which there currently is no effective treatment. Chemotherapy is mainstay in the treatment of glioma. However, drug tolerance, non-targeting, and poor blood-brain barrier penetrance severely inhibits the efficacy of chemotherapeutics. An improved treatment method is thus urgently needed. Herein, a multifunctional biomimetic nanoplatform was developed by encapsulating graphene quantum dots (GQDs) and doxorubicin (DOX) inside a homotypic cancer cell membrane (CCM) for targeted chemo-photothermal therapy of glioma. The GQDs with stable fluorescence and a superior light-to-heat conversion property were synthesized as photothermal therapeutic agents and co-encapsulated with DOX in CCM. The as-prepared nanoplatform exhibited a high DOX loading efficiency. The cell membrane coating protected drugs from leakage. Upon an external laser stimuli, the membrane could be destroyed, resulting in rapid DOX release. By taking advantage of the homologous targeting of the cancer cell membrane, the GQDs/DOX@CCM were found to actively target tumor cells, resulting in significantly enhanced cellular uptake. Moreover, a superior suppression efficiency of GQDs/DOX@CCM to cancer cells through chemo-photothermal treatment was also observed. The results suggest that this biomimetic nanoplatform holds potential for efficient targeting of drug delivery and synergistic chemo-photothermal therapy of glioma.