Microbial enzymes can be exploited to improve the sensory quality and reduce the harmful effects of tobacco-originated compounds in tobacco-derived products. In this study, a novel oligogalacturonide lyase (OGL) gene from Klebsiella variicola GB3 was cloned and heterologously expressed in Escherichia coli BL21(DE3). The recombinant enzyme was purified to a protein concentration of 18.63 mg/mL. OGL exhibited the highest activity toward tetragalacturonic acid (GalA4), with kinetic parameters of Km = 3.89 ± 0.18 mM and Vmax = 36.41 ± 1.20 μmol/min/mg, and optimal catalytic activity at 45 °C and pH 6.0. The enzyme remained stable over a moderate temperature range (30–40 °C) and a broad pH range (6.0–8.0), while Ca2+ significantly enhanced its catalytic activity. The treatment with 1% OGL degraded approximately 32.18% of tobacco pectin, accompanied by significant increases in galacturonic acid (39.86%) and oligogalacturonides (403.85%). Sensory evaluation indicated improved aroma quality, increased smoothness, and reduced irritation in OGL-treated tobacco strands. GC-MS analysis confirmed that OGL treatment significantly enhanced the production of key aroma compounds, including norisoprenoids, furans, and terpenoids, while reducing undesirable off-flavor compounds. Collectively, these results indicate that OGL efficiently degrades tobacco pectin, promotes the release of aroma precursors, and the formation of key flavor compounds. This study highlights the potential of OGL as a promising biocatalyst for improving aroma quality and enabling the value-added bioconversion of tobacco resources.

Sugars are one of the important chemical components in tobacco. They serve as key precursor substances for various aromatic compounds in tobacco. Furthermore， they also have a significant impact on the taste and burning characteristics of tobacco. Thus， obtaining accurate information on the composition and content of soluble sugars in tobacco can provide a scientific basis for quality assessment of tobacco leaves. Moreover， it offers critical data support for quality control and process optimization. Traditional techniques for soluble sugar analysis include continuous flow analysis， ion chromatography， gas chromatography， and liquid chromatography， etc. However， these methods still have limitations such as tedious sample pretreatment， poor detection sensitivity， and low analysis efficiency. In contrast， ultra performance liquid chromatography-quadrupole-time of flight mass spectrometry （UPLC-Q-TOF-MS） is a highly effective analytical technology. It integrates the excellent separation capability of UPLC and the superior sensitivity of MS. This combination offers great potential for qualitative and quantitative analysis of target compounds. Nonetheless， the types of soluble sugars detectable in tobacco by UPLC-Q-TOF-MS remain limited. This defect restricts the comprehensive evaluation of sugar components in tobacco. Herein， a rapid and accurate analysis method was established for high-throughput screening and quantification of 26 soluble sugars in tobacco leaves. The tobacco leaf samples were ultrasonically extracted with 30 mL 40% acetonitrile aqueous solution at 120 W for 30 min. Soluble sugar extract solution was prepared using a Waters Sep-Pak C18 solid-phase extraction cartridge. With the help of self-built sugar library， the tobacco leaf samples were screened by UPLC-Q-TOF-MS. Then matrix-matched standard calibration curves were employed to accurately quantify the target analytes. The established method was verified. The 26 soluble sugars exhibited good linear relationships with correlation coefficients （R2） ranging from 0.999 1 to 0.999 9. The limits of quantification （LOQs） were in the range of 0.03-20 mg/L. The spiked recoveries ranged from 92.39% to 111.75%， and relative standard deviations （RSDs） were ≤4.65%. Finally， this method was applied to analyze 59 tobacco leaf samples from different origins， grades and years. Six soluble sugars including erythritol， fructose， sorbitol， glucose， sucrose and inositol were successfully identified. The content of each soluble sugar varied significantly among samples from different origins， grades， and years. Even among samples from the same origin， grade， and year， the soluble sugar contents showed certain fluctuations. This is speculated to be related to factors such as the growth environment， maturity， processing， and harvest time of the tobacco leaves. Among them， the contents of fructose and glucose were at relatively high levels in all tobacco leaf samples. The soluble sugar content from Heilongjiang was generally higher than that from Guizhou， Hunan， and other regions. Additionally， the overall soluble sugar content in samples from 2021 and 2022 was higher than that from 2020. Principal component analysis （PCA） and hierarchical cluster analysis （HCA） were conducted on tobacco leaf samples from different positions， respectively. These analyses demonstrated significant differences in soluble sugar contents among tobacco leaves from different positions. It confirmed that soluble sugars could serve as effective indicators for distinguishing positions of tobacco leaves. In summary， the established method enables the qualitative and quantitative detection of the 26 soluble sugars without relying on standard substances. Moreover， the method exhibits high throughput， simplicity， rapidity， and accuracy. Meanwhile， it is suitable for the qualitative and quantitative detection of soluble sugars in tobacco leaf samples. It provides robust technical support for in-depth research on tobacco chemical components and the digital formulation design of cigarette products.

In this study, the effects of microbial fermentation on the nutrient composition, antioxidant activity, and volatile compounds of sugarcane juice were investigated using different strains of Monascus purpureus(M. purpureus) and Aspergillus niger (A. niger), both individually and as a co-culture. The results indicated a significant decline in the soluble sugar content of sugarcane juice after fermentation, with 50 % reduction observed after 48 h (p<0.05), suggesting that these strains utilized the soluble sugar for fermentation. The pH increased from 5.3 to 6.4 after 144 h of fermentation in the M. purpureus group, while decreasing from 5.3 to 4.4 in the A. niger and co-culture groups. The fermentation broth contained 17 types of free amino acids. The content of free amino acids decreased notably from 0 to 96 h (p<0.05), and then it exhibited slight changs (a little) from 98 to144 h in the M. purpureus and co-culture groups. In contrast, free amino acids were almost completely depleted in the A. niger group. Phenol concentrations increased significantly in the A. niger and co-culture groups (p<0.05). Notably, fermentation broths demonstrated excellent antioxidant activity. The types and concentration of flavor components in the sugarcane juice were enhanced by microbial fermentation, which improved its flavor and flavor profile. Alcohol levels, particularly the content of isobutanol and isoamylol increased significantly in the co-culture group (p<0.05). These results showed that an M. purpureus and A. niger co-culture is suitable for sugarcane juice fermentation with a process time of 48-96 h.

The abuse of fluoroquinolone antibiotics (FQs) has caused negative impact on ecological environment and public health. However, due to complex matrix interference from environmental samples and low content, developing a sensitive and accurate strategy for detecting residual FQs remains a challenge. Herein, amino-functionalized inverse opal photonic crystals (NH2-IOPCs) were successfully fabricated and employed as novel adsorbents for enrichment of FQs. The outstanding enrichment ability was ascribed to the special structure of IOPCs and the interaction of FQs with NH2 groups, as confirmed by theoretical calculation. Combined with the powerful qualitative and quantitative capabilities of ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS), the proposed detection strategy was established for six FQs. Satisfactory analytical performance was obtained with low detection limits (0.01-0.15 µg L-1), a wide linearity range (0.03-2000 µg L-1) with correlation coefficient (R2) ≥0.9967, and excellent reproducibility with relative standard deviations (RSDs) ≤5.2%. The strategy was successfully applied to detect FQs in the medical wastewater, the lake water and the pharmaceutical wastewater with recoveries ranging from 80.7% to 121.2%, confirming the reliability of the strategy. This work not only provides a feasible strategy for monitoring FQs in environmental samples, but also further indicates the potential of photonic crystal materials as adsorbents.

Menthyl carbonates based on malic acid and tartaric acid were designed and synthesized to reduce menthol volatilization at room temperature while enabling controlled release through thermo pyrolysis. The synthesis involves two key steps: reaction of dimethyl malate or dibenzyl tartrate with menthyl chloroformate, followed by enzymatic hydrolysis or hydrogenolysis to deprotect the carboxyl moieties, yielding the target menthyl carbonates. Thermogravimetry analysis (TG-DTG) demonstrated that menthyl carbonate exhibits significant weight loss starting at around 150 °C within a narrow temperature range. Online pyrolysis gas chromatography mass spectroscopy (Py-GC-MS) confirmed efficient menthol release at 150–300 °C, with menthol as the dominant product. The proposed pyrolysis mechanism involves preferential elimination of the hydroxy acid moiety, triggering rapid monocarbonate decomposition into menthol due to its inherent instability. Compared to free menthol, these carbonates demonstrated superior storage stability for heat-not-burn (HNB) products applications while maintaining controlled menthol release at typical HNB operating temperatures. Parallel studies with phenylethanol, benzyl alcohol, and leaf alcohol carbonates revealed similar thermal behavior, with corresponding flavor compounds as primary pyrolysis products. This collective evidence suggests that hydroxy acid based carbonates constitute promising precursor structures for fragrance delivery systems.

Objective: The genus Phrynium has medicinal value and is effective in relieving sore throat and mouth ulcers. However, the extraction and chemical analysis of essential oils from Phrynium tonkinense Gagnep, have not yet been reported. The present study aimed to extract, chemically characterize, and evaluate the antimicrobial properties of volatile oils from Phrynium tonkinense Gagnep ( P. tonkinense). Methods: In the present study, essential oil was extracted from the leaves of P. tonkinense for the first time by the hydrodistillation method, and its chemical composition was determined by gas chromatography-flame ionization detection (GC-FID) and gas chromatography-mass spectrometry (GC-MS). The area normalization method was used to calculate the relative percentage content of each chemical constituent in the essential oil. Additionally, the antibacterial efficacy of the essential oil was tested against six pathogenic microorganisms by the agar diffusion method and the microdilution method. Result: The yield of essential oil obtained by hydrodistillation was 0.499%. Ninety volatile components were identified from the essential oil, with fatty acid compounds (47.36%) accounting for the largest proportion of these components. The main compounds were hexadecanoic acid (25.20%), ( Z)-3-hexen-1-ol (10.31%), pentadecanoic acid (8.09%), and myristic acid (3.99%). The results of the in vitro antimicrobial assay showed that essential oils from P. tonkinense had a good inhibitory effect on the six selected pathogenic microorganisms and showed good bactericidal activity, with the minimum inhibitory concentration (MIC) value ranging from 31.3 to 250 μg/mL and the minimum bactericidal concentration (MBC) value ranging from 62.5 to 500 μg/mL. Notably, the essential oil exhibited the highest antibacterial activity against Staphylococcus aureus, with the MIC of 31.3 μg/mL and the MBC of 62.5 μg/mL. Conclusion: The findings of this study provided new insights into the medicinal functions of P. tonkinense and offered a scientific basis for the development and utilization of P. tonkinense as a natural antibacterial agent.

K326 has excellent botanical and economic properties, good smoke appearance quality, orange color, moderate and strong gloss, medium and more oil content, loose leaf structure, moderate and thin leaf thickness, suitable nitrogen to base ratio, and high industrial availability. The quality of flue-cured tobacco depends on the types of chemicals produced in its leaves. In one tobacco plant, the total amount of furans, aldehydes and organic acids in middle tobacco leaves was significantly higher than that in upper tobacco leaves, but there was no significant difference between middle tobacco leaves and lower tobacco leaves. The total amount of phenols and organic acids in the pyrolysis products of the lower tobacco leaves was the highest and significantly higher than that of the upper tobacco leaves, but the difference was not significant compared with the middle tobacco leaves. There was significant negative correlation between total alkaloids, total nitrogen, total sugars and reducing sugars in all three parts. The different habitats effectively regulate the production of chemicals in tobacco by controlling the composition of the microbiome of its leaves. Nicotine content is different in different growing environments, for example, altitude and nicotine content are negatively correlated. Therefore, the effect of seven different habitats, including Sichuan, Hunan, Yunnan, Henan, Fujian, and Guizhou, on the composition of the K326 tobacco microbiome was investigated in this study using high throughput 16S rRNA Illumina MiSeq sequencing technology in this study. The results demonstrated that the abovementioned growth habitats strongly regulated the composition of the microbiome of K326 tobacco, which resultantly affected the production of chemicals. The following bacterial genera, such as Allorhizobium, Neorhizobium, Pararhizobium, and Rhizobium, displayed significantly positive correlations with the potassium and nitrogen-nicotine contents of K326 tobacco leaves. Methylobacterium influenced the production of 5-Methylfuranaldehyde and furfural. Halomonas positively correlated with the production of key neutral aroma compounds (NACs) in K326 tobacco leaves, such as geraniol, 4-Oxyisofluorone,Phenyl ethanol and Damascusone. Our findings show that the aroma of K326 tobacco can be engineered by controlling the microbiome composition by growing tobacco in selective habitats.

Alpha-cembratriene-4,6-diol (α-CBT-diol) is a complex diterpenoid primarily found in Solanaceae (i.e., tobacco leaves), Pinaceae, and marine corals. Due to its intricate chemical structure, it serves as a precursor for several aroma compounds, including farnesal. Farnesal and its derivatives have applications across various fields, such as the fragrance and flavor industry, pharmaceuticals, agriculture, and cosmetics. In this study, Stenotrophomonas maltophilia H3-1, a strain capable of efficiently biodegrading α-CBT-diol into farnesal, was isolated from soil and identified through 16S rDNA sequence analysis. S. maltophilia H3-1 biodegraded 93.3% of α-CBT-diol (300 mg/L) within 36 h when grown under optimized culture conditions, including a temperature of 40 °C, pH of 8, 2 g/L maltose, and 2 g/L ammonium sulfate. Theoretically, this strain can produce 201 mg/L of farnesal during the biotransformation of α-CBT-diol. The putative α-CBT-diol bioconversion pathway expressed in S. maltophilia H3-1 is also proposed. This is the first study to report the bioconversion of α-CBT-diol into the high-value compound farnesal using a novel S. maltophilia H3-1 strain. It highlights that other compounds found in tobacco can also be bioconverted into valuable products.

Over the past 20 years, researchers have used multi-omics techniques to study microbial diversity and metabolic function on tobacco leaves. The unique metabolic function of tobacco microorganisms has attracted extensive attention from researchers, which is an important research field in tobacco industry to improve the intrinsic quality of tobacco leaf with microbial agents. The microorganisms are particularly rich on the surface of tobacco leaf, and their metabolic function is closely related to the change of tobacco leaf chemical composition. Some microorganisms have important metabolic functions, such as: degrading macromolecular and harmful substances in tobacco leaves, and they have different degradation rates and pathways for the substances. At present, many functions of tobacco leaf microorganisms have not been fully verified and analyzed. In the future, more novel culture methods are needed to screen and isolate microorganisms on the surface of tobacco leaves, deeply tap their metabolic potential, explore the application value of microorganisms in the tobacco industry, and further promote the innovation and development of the industry.

Microbial fermentation shapes the reconstituted tobacco leaf concentrate’s (RTLC) chemical composition and sensory quality. This study employed macrotranscriptomic analysis to investigate how the aroma-enhancing bacterium Klebsiella variicola H8 modulates RTLC fermentation. High-throughput second-generation RNA sequencing revealed that the transcript abundance of K. variicola H8 increased from 5.92% at the start of fermentation to 14.78% at 16 h, accompanied by the enrichment of other key genera such as Lactobacillus and Citrobacter. Differential gene expression analysis showed that K. variicola H8 transcription correlated strongly (R2 = 0.85) with water-soluble sugar degradation, while nitrogen and potassium correlations were weaker (R2 = 0.47 and 0.41, respectively). Notably, the upregulation of glycoside hydrolases-particularly GH78, GH13_25, GH31, and GH28-was associated with the release of key non-volatile aroma-enhancing compounds (NAECs), such as β-damascenone (13.24 μg/g), phenylethanol (7.12 μg/g), solanone (5.89 μg/g), dihydrokiwi lactone (6.03 μg/g), and benzyl alcohol (5.15 μg/g). Furthermore, expression levels of apoptosis-related genes increased at 36 h, coinciding with a decline in sensory quality and aroma compound accumulation. These findings reveal the dynamic microbial and enzymatic processes underpinning NAEC production and provide a mechanistic basis for optimizing microbial fermentation in tobacco processing.

A total of 12 megastigmane glycosides (1 - 12), including four undescribed ones, were extracted from the leaf tissues of Nicotiana tabacum. The molecular frameworks of all isolates could be indicated by 1D and 2D-NMR analysis and mass spectrometry along with comparison with those previously reported. Absolute configuration from four new metabolites (1 - 4) was established through ECD and empirical rules of 13C-NMR chemical shift. Additionally, a hydrogen peroxide-induced SH-SY5Y cell model was used to assess the isolates' in vitro neuroprotective activity, and the bioassay results demonstrated compounds 2, 3, 6, and 7 displayed moderate protective effects against H2O2-induced neurotoxicity at 10 μM in comparison to the positive control, edaravone.

Structural isomers are critical analytes in the biological and chemical arenas. Despite the ability of tandem mass spectrometry to provide fragment ion information, their high structural similarity impedes confident identification. To address this, we developed a novel method leveraging energy-resolved mass spectrometry (ER-MS) of fragment ions generated by electron activation dissociation (EAD). EAD initiated rapid radical chain dissociation via electron excitation and removal mechanisms, delivering superior isomer discrimination compared to conventional collision-induced dissociation (CID). Subsequent energy-resolved analysis further enhanced the distinction by integrating these dissociation mechanisms. Our strategy employed a cosine-based multidimensional spectral similarity algorithm to visualize and quantify subtle spectral differences across multiple energies. This method successfully distinguished many types of isomers, such as linkage, composition, and conformation isomers in disaccharides and flavonoid glycosides and achieved 93.8% top-1 identification accuracy against an in-house library. When applied to pomelo peel and commercial beverages for key metabolite characterization, it provided 44.4-50.0% top-1 annotation accuracy across all detected interest features. These results demonstrate that the multidimensional similarity algorithm that combines EAD and ER-MS significantly advances the depth and accuracy of compound annotation.

Microorganisms, particularly those contributing to aroma development, play a vital role in the aging of flue -cured tobacco. In this study, heat release by five aroma -enhancing bacteria were measured during their growth in reconstituted tobacco extracts using isothermal microcalorimetry (IMC). The growth of the strains H4 ( Pantoea ), H8 (Klebsiella ), H9 ( Acinetobacter ), H11 ( Staphylococcus ), and H12( Enterobacter ) was detected under the conditions of 3%(v/v) inoculations, temperature of 26, 30, 34 and 37 degrees C , pH 6 and 2.6 baume degree. Additionally, the growth of H8 was analyzed under the conditions of 30 degrees C , pH of 4, 5, 6, 7, 8, baume degrees of 2.6, 5.2, 10.4, 15.6, 20.8 and 26. The number and contents of aroma components in reconstituted tobacco extracts significantly increased compared to the control groups after fermentation by H8, with resulting in significant enhancement of aroma. Specifically, the total content of aroma components in the reconstituted tobacco extracts was 9.245 mg/mL. Further, important aroma components significantly increased compared to controls, with 4,7,9-megastigmatrien-3-one increasing by 0.43 mg/mL, (Z)-6,10-Dimethyl-5, 9-undecadien-2-one by 0.144 mg/mL, (E)6,10-Dimethylundeca-5, 9-dien-2-one by 0.072 mg/mL, (E)-5-isopropyl-8-methylnona-6,8-dien-2-one by 0.059 mg/mL, and (2, 6, 6-Trimethyl-2-hydroxycyclohexylidene) acetic acid lactone by 0.044 mg/mL. The content of Benzyl alcohol changed the most, increased by 943.86%, Benzaldehyde increased by 93.75%, and (E)-5-isopropyl-8-methylnona-6,8-dien-2-one increased by 84.29%. These findings lay the groundwork for optimizing aroma enhancement through H8 and comprehending the underlying mechanisms. Furthermore, they serve as a foundation for optimizing microbial growth characteristics within opaque reconstituted tobacco extracts.

Two new megastigmane glycosides, (6 R,7E,9R)-3-oxo-alpha-ionyl-9-O-alpha-L-rhamnopyranosyl-(1 ''-> 4 ')-beta-D-glucopyranoside (1) and (6 R,7E,9R)-3-oxo-alpha-ionyl-9-O-beta-D-glucopyranosyl-(1 ''-> 6 ')-beta-D-glucopyranoside (2), together with six known analogues (3-8) were isolated from the leaves of Nicotiana tabacum. The structures of all metabolites were determined by comprehensive analysis of NMR and MS spectroscopic data as well as by comparison with those of previously reported. The in vitro anti-inflammatory activity of all isolates was evaluated using a lipopolysaccharide (LPS)-induced RAW264.7 cell inflammatory model, and the compounds 1, 3, 7, and 8 exhibited inhibition of LPS-induced NO production in RAW264.7 macrophage cells with IC50 values of 42.3-61.7 mu M (positive control, dexamethasone, IC50 = 21.3 +/- 1.2 mu M).

Sensory attributes strongly influence consumers’ preferences for products. The inoculation of the Klebsiella variicola H8 strain in a reconstituted tobacco leaf concentrate (RTLC) solution increased neutral aroma-enhancing compound (NAEC) production by 45%, decreased the nicotine level by 25%, decreased the water-soluble total sugar content by ~36%, and improved the sensory quality by 5.71%. The production of NAECs such as dihydrokiwi lactone (DHKL: 192.86%), 1,2,3,4-tetrahydro-1,1,6-trimethylnaphthalene (THTMN: 177.77%), 2,4-di-tert-butylphenol (DTBP: 25%), 4-oxoisofolkone (OIFK: 116.66%,) 1,9-heptadecadiene-4,6-diyn-3-ol (HDD: 116.67%), β-damastrone (BDS: 116.67), and megastigmatrienone A (MSTA: 116.67%) was increased. A metagenomics analysis of the microbial community in the fermented RTLC (FRTLC) was performed to elucidate the mechanism by which NAECs were produced. As a result, 24 groups of functional genes were identified, and among them, five families of carbohydrate-active enzymes, (i) glycoside hydrolase (GH), (ii) glycosyltransferase (GT), (iii) polysaccharide lyase (PL), (iv) carbohydrate esterase (CE), and (v) auxiliary active enzyme (AA), were found to be positively correlated with the production of NAECs. However, among the GHs, the GHs annotated from the H8 strain chromosome displayed the highest relative abundance and a positive correlation with the production of NAECs. Specifically, the GH13-14, GH13-20, GH13-38, GH13-25, GH13-10, GH42, and GH28 genes of the H8 strain were relatively more abundant and were key contributors to the production of NAECs. The correlation analyses revealed that the H8 strain plays a leading role among all the microorganisms in FRTLC in the production of NAECs. Our findings support the application of Klebsiella variicola in NAEC production and a reduction in nicotine content in tobacco products.

基于生物酶处理对烟草及其制品品质变化的显著影响,综述了近年来生物酶处理在烟草提质、产香和减害等方面的研究成果,分析了生物酶在研究中存在的薄弱环节及问题.认为:烟叶中淀粉和果胶的酶催化降解相关研究取得较大进展,其中复合酶的作用效果多优于单一酶;漆酶与蛋白酶搭配处理梗丝效果较单一酶处理更好,同时,对烟梗进行酸处理、碱处理和汽爆处理可显著提高酶解效果;在烟草薄片制备原料再造烟叶浓缩液中,生物酶更容易发挥作用,具有处理时间短、效率高和作用效果显著等优点;在产香方面,生物酶主要通过产生参与美拉德反应的物质或催化香味前体物产香实现;在减害方面,生物酶主要通过降低烟草特有亚硝胺和烟气自由基等有害物质含量来实现.未来可从烟草生物大分子结构表征和特性研究、烟用酶制剂创制和催化机制解析两方面进行深入研究,以进一步推进生物酶在烟草增香、提质和减害等方面的研究及应用.

以烟叶中重要致香成分巨豆三烯酮前体物(3-氧代-α-紫罗兰醇-β-D-吡喃葡萄糖苷)两种同分异构体,即(6R,9R)-3-氧代-α-紫罗兰醇-β-D-吡喃葡萄糖苷(rrOIPG)和(6R,9S)-3-氧代-α-紫罗兰醇-β-D-吡喃葡萄糖苷(rsOIPG)为研究对象,建立超声辅助萃取-超高效液相色谱法对rrOIPG和rsOIPG进行定量分析,并利用该方法考查国内外 7 个产地烟叶中两种同分异构体的分布情况.结果表明:rrOIPG 和rsOIPG分别在25.85～258.50 μg/mL(R2=0.999 1)和6.28～62.75 μg/mL(R2=0.999 0)内具有良好的线性关系,检出限分别为2.5 μg/mL和2.9 μg/mL,仪器精密度较高,样品的稳定性和重复性较好,加标回收率分别为83.94%和105.90%,RSD分别为1.22%和1.93%;根据rrOIPG和rsOIPG含量分布可较好地区分国内外产地烟叶,国外产地烟叶中rsOIPG含量明显高于国内产地烟叶,且国内外产地烟叶中rrOIPG的含量均高于rsOIPG.该方法可行性较好,前处理步骤简单,适用于烟叶中rrOIPG和rsOIPG的定量分析.

采用肠杆菌(Enterobacter cloacae F8-2)和不动杆菌(Acinetobacter nosocomialis 7S-2)混菌发酵山东烟叶,对发酵前后烟叶的感官品质与化学成分、烟气化学成分及烟叶表面微生物群落变化进行研究.结果表明:肠杆菌和不动杆菌按照体积比1:1混合发酵24 h时,烟叶香气增加、杂气降低最为明显;发酵后烟叶中甲基庚烯酮、二氢大马酮、5-甲基糠醛分别增加了89.22％、35.67％、33.93％,烟气中橙花醇、茄酮、金合欢醇分别增加了78.01％、46.83％和45.95％;混菌发酵对烟叶表面细菌群落有较大影响,微生物间协同发酵、互利共生,同时肠杆菌和不动杆菌可能与苯甲醛、甲基庚烯酮等香气物质的生成有关.

以乙酰溴-α-D-葡萄糖(Ⅰ)为糖基供体和酱油酮(Ⅱ)进行反应,分别合成了酱油酮-2,3,4,6-四-O-乙酰基-β-D-葡萄糖苷(Ⅲ)和酱油酮-β-D-葡萄糖苷(Ⅳ).在合成中间体Ⅲ的过程中探索了Koenigs-Knorr法和相转移催化法.中间体及产物结构经1HNMR、13CNMR、FTIR和HRMS确证.将产物Ⅳ加入卷烟中,测定了其在主流烟气粒相中的转移率.结果表明,两种方法均可得到中间体Ⅲ,相转移催化法优于Koenigs-Knorr法.最优的相转移催化法的反应条件为:0.10 g四丁基溴化铵为催化剂、10 mL二氯甲烷为溶剂、n(Ⅰ)=1.2 mmol、1.60 g无水K2CO3为缚酸剂、n(Ⅰ):n(Ⅱ)=1.2:1.0,室温反应8 h.在上述条件下中间体Ⅲ的收率为44.5％.中间体Ⅲ在甲醇钠/甲醇体系中脱去乙酰基,得到目标产物Ⅳ,收率88.0％.卷烟燃吸过程中,产物Ⅳ热裂解为酱油酮后,其在主流烟气粒相中的转移率为3.11％.

Abstract Cembranoids compounds are mainly distributed in higher plants of the Pinaceae and Solanaceae families, as well as soft corals, and serve as important aroma precursors. Their degradation products are widely used in various aspects of life, such as farnesal, which finds extensive applications in the pharmaceutical industry. In this study, a strain (Stenotrophomonas maltophilia H3-1) was isolated from soil, which can efficiently degrade α-cedriene-4,6-diol.Based on GC-MS detection of α-cembratriene-4,6-diol degradation efficiency of the H3-1 strain, it was determined that the optimal culture conditions for H3-1 are 40°C, pH 8, maltose concentration of 2 g/L, and ammonium sulfate concentration of 2 g/L. Under the optimum culture conditions, the degradation rate of 1 mg/mL α-cembratriene-4,6-diol by H3-1 strain within 36 h was as high as 85.86%. This indicates the strong biodegradation ability of the H3-1 strain towards α-cembratriene-4,6-diol. Through GC-MS analysis, we identified the biodegradation products of α-cembratriene-4,6-diol, including farnesal. This provides a theoretical basis and microbial resources for further study on the degradation products and applications of α-cembratriene-4,6-diol.