包装箱内片烟醇化过程中不同空间点位的微生物群落结构和基础生化指标分析

Microbial community structures and basic biochemical indexes of different spatial sites in the packaging box of strips during mellowing

摘要:

背景 片烟醇化是烤烟生产中将农艺成熟度转化为工业可用性的关键一环。目的 揭示醇化过程中包装箱内不同空间点位片烟的微生物群落特征和基础生化指标差异。方法 以醇化期20个月的‘K326’片烟包装箱内的9个空间点位样品为材料，进行宏基因组测序和功能酶活性、常规化学成分含量与中性致香成分含量的测定。结果 在9个片烟样品的微生物群落中，假单胞菌门(Pseudomonadota)为优势菌门，假单胞菌属(Pseudomonas)为优势菌属；上层样品的共有基因数目最多，微生物群落结构差异较小；下层样品的特有基因数目最多，微生物群落多样性与丰富度相对较高；中层和下层样品内微生物群落结构差异较大。新陈代谢、氨基酸转运和代谢、糖苷水解酶和糖基转移酶的功能丰度排前3；下层中心样品的α-淀粉酶活性最高，中层中心样品的β-半乳糖苷酶和超氧化物歧化酶活性最高；下层中心样品的常规化学成分协调性最好，中层样品对中性致香成分的富集效果最明显；空间点位与大部分基础生化指标呈现出弱相关，与6-甲基-3,5-庚二烯-2-酮、2-己烯醛和苯乙酮呈现出强相关。结论 醇化期包装箱片烟的不同空间点位对其微生物群落结构、基因功能丰度以及部分基础生化指标呈现出显著影响，研究结果为片烟醇化过程的精准控制提供了理论支持。

Abstract:

Background The mellowing of strips is a key step in flue-cured tobacco production, converting agricultural maturity into industrial usability.Objective To compare the microbial community characteristics and basic biochemical indexes of strips at different spatial sites within the packaging box during mellowing.Methods Sampling was conducted at nine spatial sites of the packaging box of ‘K326’ strips mellowed for 20 months, followed by metagenomic sequencing and determination of functional enzyme activities, conventional chemical components, and neutral aroma components.Results Among the microbial communities in the nine samples, Pseudomonadota was the dominant phylum and Pseudomonas was the dominant genus. The upper-layer samples had the largest number of shared genes, which indicated small structural differences of microbial communities. The lower-layer samples had the largest number of unique genes, demonstrating higher microbial diversity and richness. The microbial community structure differed greatly between the middle-layer and lower-layer samples. The top three functions in terms of abundance were metabolism, amino acid transport and metabolism, and glycoside hydrolases and glycosyl transferases. The α-amylase activity was the highest in the sample from the center of the lower layer, and the β-galactosidase and superoxide dismutase activities were the highest in the sample from the center of the middle layer. The coordination of conventional chemical components was the best in the sample from the center of the lower layer, while the enrichment of neutral aroma components was the most significant in the sample from the middle layer. The spatial sites demonstrated weak correlations with the majority of basic biochemical indexes and strong correlations with 6-methyl-3,5-heptadien-2-one, 2-hexenal, and acetophenone.Conclusion There were significant differences in microbial community structure, functional gene abundance, and partial basic biochemical indexes among different spatial sites in the packaging box of strips during mellowing. The findings provide theoretical support for the precise regulation of the strip mellowing process.