Nicotine concentration and mentholation affect bacterial community diversity in SPECTRUM research cigarettes

Abstract

Previous studies have characterized bacterial communities in menthol versus non-menthol cigarettes. However, these studies evaluated commercial cigarettes, for which levels of chemical constituents are largely unknown, and therefore, could not assess the impact of varying nicotine and menthol concentrations on tobacco bacterial communities. To address this knowledge gap, we performed time-series experiments using SPECTRUM research cigarettes with varying nicotine and menthol levels. Cigarettes were incubated under three storage conditions for 14 days. Cigarette tobacco was then sub-sampled (n = 288), DNA extracted, and subjected to PCR amplification of the V3V4 region of the 16S rRNA gene, followed by Illumina HiSeq sequencing. Sequences were analyzed using QIIME and R. Incubation under varying conditions did not affect bacterial diversity. However, significant differences in bacterial communities were observed across varying nicotine concentrations in menthol and non-menthol products. For example, Pseudomonas spp. was negatively correlated with nicotine concentrations in menthol cigarettes. A significantly higher relative abundance of P. veronii and P. viridiflava was observed in menthols versus nonmenthols, while a significantly higher relative abundance of Bacillus foraminis and B. coagulans was found in non-menthols versus menthols. Additional bacteria (e.g., Staphylococcus spp., Jeotgalicoccus psychrophilus, and B. flexus) significantly changed in relative abundance between days 0 and 14. Our findings demonstrate that nicotine and menthol levels have a significant impact on the relative abundance of potential bacterial pathogens present in cigarettes. Future work is needed to demonstrate whether these tobacco-associated bacteria could be transferred to users while smoking, ultimately contributing to adverse respiratory impacts. Key points• Varying nicotine levels changes bacterial composition of research cigarettes.• Mentholation affects the tobacco bacterial microbiome.• SPECTRUM research cigarettes are dominated by Pseudomonas and Bacillus.

Bacterial communities of hookah tobacco products are diverse and differ across brands and flavors

“…However, we did not observe significant changes in bacterial community diversity when storage conditions were altered. This observation corroborates previous studies that investigated the effect of different storage conditions on the microbial diversity of commercial cigarettes (Chopyk et al 2017b ), little cigars (Smyth et al 2019 ), and research cigarettes (Chattopadhyay et al 2021 ). Previous studies have also shown that, unlike other tobacco products, hookah products contain higher levels of humectants like glycerol and honey (Khater et al 2008 ; Uebelacker et al 2019 ), both of which also exhibit bacteriostatic and bactericidal activities, which could help explain the lack of effect of incubation temperatures or humidity levels on hookah tobacco alpha-diversity.…”

Heterogeneity of Harmful Constituent Profiles in Smokeless Tobacco Products from Five African Countries

“…Consumer and vendor education about the product preparation practices that result in high levels of TSNA could potentially lead to changes in such practices and the eventual reduction in exposures to these potent carcinogens in users of custom-made products. For manufactured SLT products, the governments in African countries may consider a mandated reduction of TSNA, as has been proposed by the WHO and the U.S. FDA. , We also note that the trend in nitrate and nitrite content between menthol and nonmenthol varieties of manufactured products from South Africa is an interesting observation (Figure A) and can be potentially explained by the effect of menthol on the bacterial profile of tobacco, which may alter the abundance of nitrate-reducing bacteria. , Future studies could provide insights into the potential associations between product mentholation and TSNA levels.…”

“…44,45 We also note that the trend in nitrate and nitrite content between menthol and nonmenthol varieties of manufactured products from South Africa is an interesting observation (Figure 3A) and can be potentially explained by the effect of menthol on the bacterial profile of tobacco, which may alter the abundance of nitrate-reducing bacteria. 46,47 Future studies could provide insights into the potential associations between product mentholation and TSNA levels. The variability of other constituents measured in this study, namely, metals and metalloids and PAH, can also be addressed, at least in part, by modifying product manufacturing practices.…”