Temporal Variations in Cigarette Tobacco Bacterial Community Composition and Tobacco-Specific Nitrosamine Content Are Influenced by Brand and Storage Conditions

Microbial community and functions involved in smokeless tobacco product: a metagenomic approach

Smokeless tobacco products (STPs) are attributed to oral cancer and oral pathologies in their users. STP-associated cancer induction is driven by carcinogenic compounds including tobacco-specific nitrosamines (TSNAs). The TSNAs synthesis could enhanced due to the metabolic activity (nitrate metabolism) of the microbial populations residing in STPs, but identifying microbial functions linked to the TSNAs synthesis remains unexplored. Here, we rendered the first report of shotgun metagenomic sequencing to comprehensively determine the genes of all microorganisms residing in the Indian STPs belonging to two commercial (Moist-snuff and Qiwam) and three loose (Mainpuri Kapoori, Dohra, and Gudakhu) STPs, specifically consumed in India. Further, the level of nicotine, TSNAs, mycotoxins, and toxic metals were determined to relate their presence with microbial activity. The microbial population majorly belongs to bacteria with three dominant phyla including Actinobacteria, Proteobacteria, and Firmicutes. Furthermore, the STP-linked microbiome displayed several functional genes associated with nitrogen metabolism and antibiotic resistance. The chemical analysis revealed that the Mainpuri Kapoori product contained a high concentration of ochratoxins-A whereas TSNAs and Zink (Zn) quantities were high in the Moist-snuff, Mainpuri Kapoori, and Gudakhu products. Hence, our observations will help in attributing the functional potential of STP-associated microbiome and in the implementation of cessation strategies against STPs. KEY POINTS: •Smokeless tobacco contains microbes that can assist TSNA synthesis. •Antibiotic resistance genes present in smokeless tobacco-associated bacteria. •Pathogens in STPs can cause infections in smokeless tobacco users.

Analyzing microbial community and volatile compound profiles in the fermentation of cigar tobacco leaves

Variations in industrial fermentation techniques have a significant impact on the fermentation of cigar tobacco leaves (CTLs), consequently influencing the aromatic attributes of the resulting cigars. The entire fermentation process of CTLs can be categorized into three distinct phases: phase 1 (CTLs prior to moisture regain), phase 2 (CTLs post-moisture regain and pile fermentation), and phase 3 (CTLs after fermentation and drying). These phases were determined based on the dynamic changes in microbial community diversity. During phase 2, there was a rapid increase in moisture and total acid content, which facilitated the proliferation of Aerococcus, a bacterial genus capable of utilizing reducing sugars, malic acid, and citric acid present in tobacco leaves. In contrast, fungal microorganisms exhibited a relatively stable response to changes in moisture and total acid, with Aspergillus, Alternaria, and Cladosporium being the dominant fungal groups throughout the fermentation stages. Bacterial genera were found to be more closely associated with variations in volatile compounds during fermentation compared to fungal microorganisms. This association ultimately resulted in higher levels of aroma components in CTLs, thereby improving the overall quality of the cigars. These findings reinforce the significance of industrial fermentation in shaping CTL quality and provide valuable insights for future efforts in the artificial regulation of secondary fermentation in CTLs. KEY POINTS: • Industrial fermentation processes impact CTLs microbial communities. • Moisture and total acid content influence microbial community succession in fermentation. • Bacterial microorganisms strongly influence CTLs' aldehyde and ketone flavors over fungi.

Enrichment of polycyclic aromatic hydrocarbon metabolizing microorganisms on the oral mucosa of tobacco users

Certain soil microbes resist and metabolize polycyclic aromatic hydrocarbons (PAHs). The same is true for a subset of skin microbes. In the human mouth, oral microbes have the potential to oxidize tobacco PAHs, thereby increasing these chemicals' ability to cause cancer of adjacent epithelium. We hypothesized that we could identify, in smokers, the oral mucosal microbes that can metabolize PAH. We isolated bacteria and fungi that survived long-term in minimal media with PAHs as the sole carbon source, under aerobic conditions, from the oral mucosa in 17 of 26 smokers and two of 14 nonsmokers. Of bacteria genera that survived harsh PAH exposure in vitro, most were found at trace levels, except for Staphylococcus, Actinomyces, and Kingella, which were more abundant. Two PAH-resistant strains of Candida albicans (C. albicans) were isolated from smokers. C. albicans was a prime candidate to contribute to carcinogenesis in tobacco users as it is found orally at high levels in tobacco users on the mucosa, and some Candida species can metabolize PAHs. However, when C. albicans isolates were tested for metabolism of two model PAH substrates, pyrene and phenanthrene, they were not capable, suggesting they cannot metabolize PAH under the conditions used. In conclusion, evidence for large scale microbial degradation of tobacco PAHs under aerobic conditions on the oral mucosa remains lacking, though nonabundant PAH metabolizers are certainly present.

From cultivation to cancer: formation of N-nitrosamines and other carcinogens in smokeless tobacco and their mutagenic implications

Tobacco use is a major cause of preventable morbidity and mortality globally. Tobacco products, including smokeless tobacco (ST), generally contain tobacco-specific N-nitrosamines (TSNAs), such as N'-nitrosonornicotine (NNN) and 4-(methylnitrosamino)-1-(3-pyridyl)-butanone (NNK), which are potent carcinogens that cause mutations in critical genes in human DNA. This review covers the series of biochemical and chemical transformations, related to TSNAs, leading from tobacco cultivation to cancer initiation. A key aim of this review is to provide a greater understanding of TSNAs: their precursors, the microbial and chemical mechanisms that contribute to their formation in ST, their mutagenicity leading to cancer due to ST use, and potential means of lowering TSNA levels in tobacco products. TSNAs are not present in harvested tobacco but can form due to nitrosating agents reacting with tobacco alkaloids present in tobacco during certain types of curing. TSNAs can also form during or following ST production when certain microorganisms perform nitrate metabolism, with dissimilatory nitrate reductases converting nitrate to nitrite that is then released into tobacco and reacts chemically with tobacco alkaloids. When ST usage occurs, TSNAs are absorbed and metabolized to reactive compounds that form DNA adducts leading to mutations in critical target genes, including the RAS oncogenes and the p53 tumor suppressor gene. DNA repair mechanisms remove most adducts induced by carcinogens, thus preventing many but not all mutations. Lastly, because TSNAs and other agents cause cancer, previously documented strategies for lowering their levels in ST products are discussed, including using tobacco with lower nornicotine levels, pasteurization and other means of eliminating microorganisms, omitting fermentation and fire-curing, refrigerating ST products, and including nitrite scavenging chemicals as ST ingredients.

Effects of fermentation chamber temperature on microbes and quality of cigar wrapper tobacco leaves

The natural fermentation of cigar tobacco leaves usually utilizes natural temperature and humidity for fermentation. Cigars produced in China are often fermented in winter, and the low environmental temperatures can lead to slow heating of the tobacco stack, affecting the cigar tobacco leaves quality. This study aimed to determine the minimum chamber temperature required to initiate the process of fermentation for cigar tobacco leaves and to explore the impact of temperature on the microbial community of tobacco leaves. Here, the cigar variety "Dexue 1" were subjected to stacking fermentation under three temperature parameters (20 ℃, 27 ℃, 34 ℃). With an increase in environmental temperature, the temperature inside the stack of cigar leaves increased significantly, the protein, total sugar, starch, and total alkaloid content in fermented tobacco leaves decreased, and the aroma components and amino acid content increased. Microbial richness and community diversity associated with fermented tobacco were highest at chamber temperatures of above 27 ℃. The relative abundance of Chryseobacterium and Rhodococcus was significantly negatively correlated with protein, alkaloids, total sugar, and starch, and positively correlated with amino acids and aroma components. Chryseobacterium and Rhodococcus may be responsible for the degradation of macromolecular substances and the conversion of favorable aromatic substances, thus improving the tobacco leaves quality. This study demonstrated that increasing the fermentation chamber temperature above 27 ℃ was conductive to raising the inner-stack temperature, increased microbial diversity and aromatic quality, reduced the strength and irritation, and extremely enhanced the overall quality of fermented cigar tobacco leaves. KEY POINTS: • The environmental temperature of the fermentation chamber has a significant impact on the quality of tobacco • Temperature > 27 ℃ can initiate the process of cigar tobacco leaves fermentation and increase inner-stack temperature and microbial diversity and abundance • Chryseobacterium and Rhodococcus may be related to the degradation of macromolecular substances and the transformation of aromatic substances, thereby improving the quality of tobacco leaves.

Characterization of physiochemical parameters & their effect on microbial content of smokeless tobacco products marketed in north India

BACKGROUND OBJECTIVES

Smokeless tobacco (SLT) product consumption has profound public health implications for its users. The p H and moisture of SLTs determine the bioavailability of nicotine, the microbial structure dynamics and the amount of microbial conversion of tobacco alkaloids to carcinogenic tobacco-specific nitrosamines. This study aimed to characterize and compare the p H, moisture and alkaloid content of various SLT products.

METHODS

Thirty-seven SLT samples including khaini , snus, moist snuff, gul , pan masala , zarda , Mainpuri kapoori and qiwam were collected from the retail market around the National Capital Region in north India and their p H, moisture, nicotine and alkaloid content were measured. The p H and total nicotine were used to calculate the amount of free nicotine, the readily absorbed form, for each product by applying the Henderson-Hasselbalch equation.

RESULTS

The investigation showed that the SLTs varied drastically in their p H (5.36 to 10.27), moisture content (4.7 to 51.7%) and alkaloid content (0.82 to 35.87 mg/g). The p H and free nicotine levels of a product were found to be positively correlated, and the highest free nicotine content was reported in snus samples. Further, the moisture content was seen to impact the bacterial and fungal diversity in these samples.

INTERPRETATION CONCLUSIONS

Studies to detect the presence of pathogenic microbiological genera as well as potentially toxic constituents are warranted. The use of SLTs as an alternative to cigarette smoking should be discouraged, and cessation programmes must call attention to their detrimental effects and emphasize on benefits of quitting SLT consumption.

Study on the effect of enzymatic treatment of tobacco on HnB cigarettes and microbial succession during fermentation

Starch and cellulose are the fundamental components of tobacco, while their excessive content will affect the quality of tobacco. Enzymatic treatment with different enzymes is a promising method to modulate the chemical composition and improve the sensory quality of tobacco leaves. In this study, enzymatic treatments, such as amylase, cellulase, and their mixed enzymes, were used to improve tobacco quality, which could alter the content of total sugar, reducing sugar, starch, and cellulose in tobacco leaves. The amylase treatment changed surface structure of tobacco leaves, increased the content of neophytadiene in tobacco by 16.48%, and improved the total smoking score of heat-not-burn (HnB) cigarette products by 5.0 points compared with the control. The Bacillus, Rubrobacter, Brevundimonas, Methylobacterium, Stenotrophomonas, Acinetobacter, Pseudosagedia-chlorotica, and Sclerophora-peronella were found to be significant biomarkers in the fermentation process by LEfSe analysis. The Basidiomycota and Agaricomycetes were significantly correlated with aroma and flavor, taste, and total score of HnB. The results showed that microbial community succession occurred due to amylase treatment, which promoted the formation of aroma compounds, and regulated the chemical composition of tobacco, and improved tobacco quality during tobacco fermentation. This study provides a method for enzymatic treatment to upgrade the quality of tobacco raw materials, thereby improving the quality of HnB cigarettes, and the potential mechanism is also revealed by chemical composition and microbial community analysis. KEY POINTS: Enzymatic treatment can change the chemical composition of tobacco leaves. The microbial community was significantly affected by enzymatic treatment. The quality of HnB cigarettes was significantly improved by amylase treatment.

Tobacco microbial screening and application in improving the quality of tobacco in different physical states

The first-cured tobacco contains macromolecular substances with negative impacts on tobacco products quality, and must be aged and fermented to mitigate their effects on the tobacco products quality. However, the natural fermentation takes a longer cycle with large coverage area and low economic efficiency. Microbial fermentation is a method to improve tobacco quality. The change of chemical composition of tobacco during the fermentation is often correlated with shapes of tobacco. This study aimed to investigate the effects of tobacco microorganisms on the quality of different shapes of tobacco. Specifically, Bacillus subtilis B1 and Cytobacillus oceanisediminis C4 with high protease, amylase, and cellulase were isolated from the first-cured tobacco, followed by using them for solid-state fermentation of tobacco powder (TP) and tobacco leaves (TL). Results showed that strains B1 and C4 could significantly improve the sensory quality of TP, enabling it to outperform TL in overall texture and skeleton of tobacco products during cigarette smoking. Compared with the control, microbial fermentation could increase reducing sugar; regulate protein, starch, and cellulose, reduce nicotine, improve total aroma substances, and enable the surface of fermented TP and TL to be more loose, wrinkled, and porous. Microbial community analysis indicated that strains B1 and C4 could change the native structure of microbial community in TP and TL. LEfSe analysis revealed that the potential key biomarkers in TP and TL were Bacilli, Pseudonocardia, Pantoea, and Jeotgalicoccus, which may have cooperative effects with other microbial taxa in improving tobacco quality. This study provides a theoretical basis for improving tobacco fermentation process for better cigarettes quality.

Multiomics provides insights into the succession of microbiota and metabolite during plant leaf fermentation

The quality of fermented plant products is closely related to microbial metabolism. Here, the associations of bacterial communities, metabolites, and functional genes were explored using multi-omics techniques based on plant leaf fermentation systems. The results showed significant changes in the structure of the microbial community, with a significant decrease in Firmicutes and a significant increase in Proteobacteria. In addition, the concentration of metabolites with antibacterial, antioxidant and aroma properties increased significantly, enhancing the quality of the fermented plant leaves. Integrated macrogenomic and metabolomic analyses indicated that amino acid metabolism could be key metabolic pathway affecting fermentation quality. Actinobacteria, Proteobacteria, Firmicutes were actively involved in tyrosine metabolism (ko00350) and phenylalanine metabolism (ko00360), and are presumed to be the major groups responsible for synthesizing growth and flavor compounds. This study emphasized the important role of microorganisms in the changes of metabolites during the fermentation of plant leaves.

Fungal Community Composition and Function Associated with Loose Smokeless Tobacco Products

Smokeless tobacco products (STPs) contain several microbial communities which are responsible for the formation of carcinogens, like tobacco-specific nitrosamine (TSNAs). A majority of STPs are sold in loose/unpackaged form which can be loaded with a diverse microbial population. Here, the fungal population and mycotoxins level of three popular Indian loose STPs, Dohra, Mainpuri Kapoori (MK), and loose leaf-chewing tobacco (LCT) was examined using metagenomic sequencing of ITS1 DNA segment of the fungal genome and LC-MS/MS, respectively. We observed that Ascomycota was the most abundant phylum and Sterigmatomyces and Pichia were the predominant fungal genera in loose STPs. MK displayed the highest α-diversity being enriched with pathogenic fungi Apiotrichum, Aspergillus, Candida, Fusarium, Trichosporon, and Wallemia. Further, FUNGuild analysis revealed an abundance of saprotrophs in MK, while pathogen-saprotroph-symbiotroph were abundant in Dohra and LCT. The level of a fungal toxin (ochratoxins A) was high in the MK product. This study caution that loose STPs harbor various harmful fungi that can infect their users and deliver fungal toxins or disrupt the oral microbiome of SLT users which can contribute to several oral pathologies.

Conventional tobacco products harbor unique and heterogenous microbiomes

While an increasing number of studies have evaluated tobacco microbiomes, comparative microbiome analyses across diverse tobacco products are non-existent. Moreover, to our knowledge, no previous studies have characterized the metabolically-active (live) fraction of tobacco bacterial communities and compared them across products. To address these knowledge gaps, we compared bacterial communities across four commercial products (cigarettes, little cigars, cigarillos and hookah) and one research cigarette product. After total DNA extraction (n = 414) from all samples, the V3V4 region of the 16S rRNA gene was sequenced on the Illumina HiSeq platform. To identify metabolically-active bacterial communities within these products, we applied a coupled 5-bromo-2'-deoxyuridine labeling and sequencing approach to a subset of samples (n = 56). Each tobacco product was characterized by its signature microbiome, along with a shared microbiome across all tobacco products consisting of Pseudomonas aeruginosa, P. putida, P. alcaligenes, Bacillus subtilis, and Klebsiella pneumoniae. Comparing across products (using Linear discriminant analysis Effect Size (LEfSe)), a significantly higher (p < 0.05) relative abundance of Klebsiella and Acinetobacter was observed in commercial cigarettes, while a higher relative abundance of Pseudomonas and Pantoea was observed in research cigarettes. Methylorubrum and Paenibacillus were higher in hookah, and Brevibacillus, Lactobacillus, Bacillus, Lysinibacillus, and Staphylococcus were higher in little cigars and cigarillos. Across all products, the majority of the metabolically-active bacterial communities belonged to the genus Pseudomonas, followed by several genera within the Firmicutes phylum (Bacillus, Terribacillus, and Oceanobacillus). Identification of some metabolically-active pathogens such as Bacillus cereus and Haemophilus parainfluenzae in commercial products is of concern because of the potential for these microorganisms to be transferred to users' respiratory tracts via mainstream smoke. Future work is warranted to evaluate the potential impact of these tobacco bacterial communities on users' oral and lung microbiomes, which play such an important role on the spectrum from health to disease.

Towards Healthy Adolescents: A Review of Smoking Impact According to Dental Perspectives

Nowadays, tobacco companies target to recruit new smokers among adolescents due to this age group was easy to be influenced by smoking behaviours. This narrative review aimed to explore the possible impact of smoking among adolescents. Knowing the negative impacts of smoking might result in avoiding continuing the habit or preventing from initiation of the habit. The literature search on PubMed, SCOPUS, and Epistemonikos database with related search terms of “adolescents”, “smoking” and “impact”. Only papers published within the year 2017 to 2021 and in the English language were included. However, articles without full text were excluded from this review. Fourteen articles were selected and divided impacts into three categories which are effect on oral health, effect on general health and other impacts. Possible impacts of smoking among adolescents were identified, and it could be beneficial in the development of customized smoking prevention or smoking cessation intervention for adolescents.

Phyllosphere microbial community of cigar tobacco and its corresponding metabolites

Cigar is made of a typical fermented tobacco where the microbiota inhabits within an alkaline environment. Our current understanding on cigar fermentation is far from thorough. This work employed both high-throughput sequencing and chromatography-mass spectrometric technologies to provide new scientific reference for this specific fermented system. Typical cigar samples from different regions (the Caribbeans, South America, East Asia, and Southeast Asia) were investigated. The results show that Firmicutes, Actinobacteria, Proteobacteria, Ascomycota, and Basidiomycota were the predominant phyla in the cigar samples. Rather than the fungal community, it was the bacterial community structures that played vital roles to differentiate the cigar from different regions: Staphylococcus was the dominant genus in the Americas; Bacillus was the dominant genus in Southeast Asia; while in East Asia, there was no dominant genus. Such differences in community structure then affected the microflora metabolism. The correlation between microbiota and metabolites revealed that Aspergillaceae, Cercospora, and Staphylococcus were significantly correlated with sclareolide; Bacillus were positively associated with isophorone. Alcaligenaceae was significantly and positively correlated with L-nicotine and hexadecanoic acid, methyl ester. GRAPHICAL ABSTRACT.

Variations in Bacterial Communities and Antibiotic Resistance Genes Across Diverse Recycled and Surface Water Irrigation Sources in the Mid-Atlantic and Southwest United States: A CONSERVE Two-Year Field Study

Reduced availability of agricultural water has spurred increased interest in using recycled irrigation water for U.S. food crop production. However, there are significant knowledge gaps concerning the microbiological quality of these water sources. To address these gaps, we used 16S rRNA gene and metagenomic sequencing to characterize taxonomic and functional variations (e.g., antimicrobial resistance) in bacterial communities across diverse recycled and surface water irrigation sources. We collected 1 L water samples (n = 410) between 2016 and 2018 from the Mid-Atlantic (12 sites) and Southwest (10 sites) U.S. Samples were filtered, and DNA was extracted. The V3-V4 regions of the 16S rRNA gene were then PCR amplified and sequenced. Metagenomic sequencing was also performed to characterize antibiotic, metal, and biocide resistance genes. Bacterial alpha and beta diversities were significantly different (p < 0.001) across water types and seasons. Pathogenic bacteria, such as Salmonella enterica, Staphylococcus aureus, and Aeromonas hydrophilia were observed across sample types. The most common antibiotic resistance genes identified coded against macrolides/lincosamides/streptogramins, aminoglycosides, rifampin and elfamycins, and their read counts fluctuated across seasons. We also observed multi-metal and multi-biocide resistance across all water types. To our knowledge, this is the most comprehensive longitudinal study to date of U.S. recycled water and surface water used for irrigation. Our findings improve understanding of the potential differences in the risk of exposure to bacterial pathogens and antibiotic resistance genes originating from diverse irrigation water sources across seasons and U.S. regions.

Metagenomic insight into the microbial degradation of organic compounds in fermented plant leaves

Microbial degradation of organic compounds is an environmentally benign and energy efficient part in product processing. Fermentation of plant leaves involves enzymatic actions of many microorganisms. However, microbes and enzymes discovered from natural degradation communities were still limited by cultural methods. In this study, we used a metagenomics sequence-guided strategy to identify the microbes and enzymes involved in compound degradation and explore the potential synergy among community members in fermented tobacco leaves. The results showed that contents of protein, starch, pectin, lignin, and cellulose varied in fermented leaves from different growing sites. The different compound contents were closely related to taxonomic composition and functional profiles of foliar microbial communities. Microbial communities showed significant correlations with protein, lignin, and cellulose. Vital species for degradations of protein (Bacillus cereus and Terribacillus aidingensis), lignin (Klebsiella pneumoniae and Pantoea ananatis) and cellulose (Pseudomonas putida and Sphingomonas sp. Leaf20) were identified and relating hydrolytic enzymes were annotated. Further, twenty-two metagenome-assembled genomes (MAGs) were assembled from metagenomes and six potential cellulolytic genomes were used to reconstruct the cellulose-degrading process, revealing the potential metabolic cooperation related to cellulose degradation. Our work should deepen the understanding of microbial roles in plant fermentation and provide a new viewpoint for applying microbial consortia to convert plant organic components to small molecules.

Viable bacteria abundant in cigarettes are aerosolized in mainstream smoke

Multiple studies have demonstrated that cigarettes harbor bacterial pathogens. Yet, to our knowledge, there are no published data to date on whether or not these microorganisms can be aerosolized and transmitted to the respiratory tract of users. To address this knowledge gap, we characterized cigarette bacterial communities and evaluated whether or not they could be aerosolized in mainstream smoke. Filtered and unfiltered cigarettes were tested. Non-smoked tobacco leaf, enriched non-smoked tobacco leaf extract and enriched mainstream smoke extract samples (n = 144) were incubated on trypticase soy agar, and resulting bacterial colonies were sequenced. Total DNA was also extracted, followed by PCR amplification of the 16S rRNA gene, sequencing and analysis using UCHIME, QIIME and R packages. The predominant bacterial genera cultured from the mainstream smoke of unfiltered cigarettes were Bacillus, Terribacillus, Paenibacillus and Desulfotomaculum. Culturable bacteria were not recovered from the smoke of filtered products. However, sequencing data demonstrated no significant differences in bacterial community diversity in the smoke of filtered versus unfiltered cigarettes, suggesting that other non-culturable bacteria may be aerosolized in mainstream smoke as well. Our study provides novel evidence that tobacco-associated bacterial communities are viable, can be aerosolized in mainstream smoke, and could potentially be transferred to the oral cavity and respiratory tract of smokers.

Composition and Ecological Functionality of Fungal Communities Associated with Smokeless Tobacco Products Mainly Consumed in India

The microbial communities present in smokeless tobacco products (STPs) perform critical steps in the synthesis of carcinogens, mainly tobacco-specific nitrosamines (TSNAs). Most studies emphasize the bacterial component, and the mycobiome of STPs has not been well characterized. In this study, we investigated the fungal communities in the different categories of STPs by sequencing the internal transcribed spacer (ITS) rRNA region of the fungal genome. The ecological character of the fungal community associated with STPs was determined by using FUNGuild. Our results indicated that Ascomycota and Basidiomycota were the most abundant fungal phyla across all STPs. The predominant fungal genera in STPs were Pichia, Sterigmatomyces, and Mortierella. The α-diversity varied significantly across the STPs based on observed, Fisher, and Shannon indices. Using SparCC cooccurrence network analysis, significant positive correlations of 58.5% and negative connections of 41.5% were obtained among fungal genera identified in STPs. Furthermore, the functional predictions by FUNGuild determined that STPs possessed high abundances of saprotroph and pathotroph-saprotroph-symbiotroph fungal trophic groups. At the functional guild level, the qiwam samples contained high abundances of soil saprotrophs, while plant pathogens were prevalent in pan-masala samples. These results suggest that various fungal populations reside in STPs and interrelate with each other and can contribute to the synthesis of TSNAs. This study has established the basis for future large-scale investigations of STP-associated mycobiota and the impact of such mycobiota in oral carcinogenesis in STP users via inflammation and carcinogens (TSNAs and mycotoxins). IMPORTANCE Smokeless tobacco products (STPs) contain complex microbial communities that influence the synthesis of carcinogens, such as tobacco-specific nitrosamines (TSNAs). Research on STP-associated bacterial populations revealed connections between bacterial metabolism and TSNA synthesis. The abundance of the fungal population may also have an impact on the production of TSNAs. This study examined STPs popularly used in India, and diverse fungal communities were identified in these STPs. Pichia, Sterigmatomyces, and Mortierella were the predominant fungal genera in the STPs. High abundances of saprotroph and pathotroph-saprotroph-symbiotroph trophic groups in STPs could affect the degradation of tobacco products and the synthesis of TSNAs.

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

Abstract

Young adults are increasingly using non-cigarette products, such as hookahs, since they are perceived as healthier alternatives to cigarette smoking. However, hookah users are exposed to not only carcinogenic compounds but also microorganisms that may play an active role in the development of both infectious and chronic diseases among users. Nevertheless, existing hookah research in this area has focused only on microorganisms that may be transferred to users through the smoking apparatus and not on bacterial communities associated with hookah tobacco. To address this knowledge gap, we conducted time-series experiments on commercially available hookah brands (Al Fakher (flavors: two apple, mint, and watermelon) and Fumari (flavors: white gummy bear, ambrosia, and mint chocolate chill)) stored under three different temperature and relative humidity conditions over 14 days. To characterize bacterial communities, the total DNA was extracted on days 0, 5, 9, and 14, PCR-amplified for the V3V4 region of the bacterial 16S rRNA gene, sequenced on the Illumina HiSeq platform, and analyzed using R. Diversity (alpha and beta) analyses revealed that the microbiotas of Fumari and Al Fakher products differed significantly and that flavor had a significant effect on the hookah microbiota. Overall, Pseudomonas, Bacillus, Sphingomonas, and Methylobacterium were the predominant bacterial taxa across all products. Additionally, we observed compositional differences between hookah brands across the 14-day incubation. These data suggest that the bacterial communities of hookah tobacco are diverse and differ across brands and flavors, which may have critical implications regarding exposures to specific bacteria among hookah users.

Key points

• Commercial hookah products harbor diverse bacterial communities.

• Brands and flavors impact the diversity of these communities.

• Research on their viability and transmission to users’ respiratory tracts is needed.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s00253-022-12079-7.

Analysis of Microbial Community, Volatile Flavor Compounds, and Flavor of Cigar Tobacco Leaves From Different Regions

Despite the booming international trade in cigar tobacco leaves (CTLs), the main characteristics of tobacco leaves from different producing areas are rarely reported. This study aimed to characterize the microbial community, volatile flavor compounds (VFCs), and flavor of CTLs from four famous cigar-producing areas, including Dominica, Brazil, Indonesia, and China. High-throughput sequencing results showed that the dominant genera in CTLs were Staphylococcus, Pseudomonas, Aspergillus, Sampaiozyma, and Alternaria. Sensory analysis revealed that Indonesian and Chinese CTLs were characterized by leathery, peppery, and baked aroma. Brazilian CTLs were dominated by caramel and herb aroma. Dominican CTLs had aromas of milk, fruity, sour, cream, flower, nutty, and honey. Supplemented with the determination of volatile flavor compounds (VFCs), the flavor of CTLs could be scientifically quantified. Most of these VFCs were aldehydes and ketones, and 20 VFCs showed significant differences in CTLs from different regions. The microbial community, VFCs, and flavor of CTLs vary widely due to geographic differences. Network analysis revealed the microbial community was closely related to most VFCs, but the relationships between the fungal community and VFCs were less than the bacterial community, and most of them were negative. Furthermore, it also found that the bacterial community had a greater contribution to the flavor of CTLs than the fungal community. This study obtained essential information on CTLs, which laid a foundation for deeply excavating the relationship between microbes and VFCs and flavor, and establishing a tobacco information database.

Comparative and analytical characterization of the oral bacteriome of smokeless tobacco users with oral squamous cell carcinoma

Oral cavity squamous cell carcinoma (OSCC) is the most common type of head and neck cancer worldwide. Smokeless tobacco (SLT) has been well proven for its role in oral carcinogenesis due to the abundance of several carcinogens. However, the role of inhabitant microorganisms in the oral cavity of smokeless tobacco users has not yet been well explored in the context of OSCC. Therefore, the present investigation was conceived to analyze the oral bacteriome of smokeless tobacco users having OSCC (CP group). With the assistance of illumina-based sequencing of bacterial-specific V3 hypervariable region of 16S rDNA gene, 71,969 OTUs (operational taxonomic units) were categorized into 18 phyla and 166 genera. The overall analysis revealed that the oral bacteriome of the patients with OSCC, who were smokeless tobacco users, was significantly different compared to the healthy smokeless tobacco users (HTC group) and non-users (HI users). The appearance of 14 significantly abundant genera [FDR (false discovery rate) adjusted probability value of significance (p value) < 0.05] among the CP group showed the prevalence of tobacco-specific nitrosamines forming bacteria (Staphylococcus, Fusobacterium, and Campylobacter). The functional attributes of the oral bacteriome of the CP group can also be correlated with the genes involved in oncogenesis. This study is the first report on the oral bacteriome of Indian patients with OSCC who were chronic tobacco chewers. The results of the present study will pave the way to understand the influence of smokeless tobacco on the oral bacteriome of OSCC patients. KEY POINTS: • Oral bacteriome of OSCC patients differ from healthy smokeless tobacco (SLT) users and SLT non-users. • Smokeless tobacco influences the oral bacteriome of OSCC group. • Oral bacteriome specific diagnostics may be developed for pre-diagnosis of oral cancer.

Associations between microbial communities and key chemical constituents in U.S. domestic moist snuff

BACKGROUND

Smokeless tobacco (ST) products are widely used throughout the world and contribute to morbidity and mortality in users through an increased risk of cancers and oral diseases. Bacterial populations in ST contribute to taste, but their presence can also create carcinogenic, Tobacco-Specific N-nitrosamines (TSNAs). Previous studies of microbial communities in tobacco products lacked chemistry data (e.g. nicotine, TSNAs) to characterize the products and identify associations between carcinogen levels and taxonomic groups. This study uses statistical analysis to identify potential associations between microbial and chemical constituents in moist snuff products.

METHODS

We quantitatively analyzed 38 smokeless tobacco products for TSNAs using liquid chromatography with tandem mass spectrometry (LC-MS/MS), and nicotine using gas chromatography with mass spectrometry (GC-MS). Moisture content determinations (by weight loss on drying), and pH measurements were also performed. We used 16S rRNA gene sequencing to characterize the microbial composition, and additionally measured total 16S bacterial counts using a quantitative PCR assay.

RESULTS

Our findings link chemical constituents to their associated bacterial populations. We found core taxonomic groups often varied between manufacturers. When manufacturer and flavor were controlled for as confounding variables, the genus Lactobacillus was found to be positively associated with TSNAs. while the genera Enteractinococcus and Brevibacterium were negatively associated. Three genera (Corynebacterium, Brachybacterium, and Xanthomonas) were found to be negatively associated with nicotine concentrations. Associations were also investigated separately for products from each manufacturer. Products from one manufacturer had a positive association between TSNAs and bacteria in the genus Marinilactibacillus. Additionally, we found that TSNA levels in many products were lower compared with previously published chemical surveys. Finally, we observed consistent results when either relative or absolute abundance data were analyzed, while results from analyses of log-ratio-transformed abundances were divergent.

Bacteriome of Moist Smokeless Tobacco Products Consumed in India With Emphasis on the Predictive Functional Potential

Smokeless tobacco products (STPs) carry assorted microbial population that contributes to carcinogens synthesis like tobacco-specific nitrosamines (TSNAs). Extensive exploration of microbiota-harboring STPs is required to understand their full carcinogenic potential. Here, we applied 16S rRNA gene sequencing to investigate bacteriome present in moist STPs immensely consumed in India (Khaini, Moist-snuff, Qiwam, and Snus). Further, the functional metagenome was speculated by PICRUSt (Phylogenetic Investigation of Communities by Reconstruction of Unobserved States) to assign the abundance of genes related to nitrogen metabolism, bacterial toxins, antibiotic drug resistance and other pro-inflammatory molecules. Highly diverse bacterial communities were observed in all moist STPs. Taxonomic analysis revealed a total of 549 genera belonging to four major phyla Proteobacteria, Firmicutes, Bacteroidetes and Actinobacteria. Overall, the core bacterial genera Acinetobacter, Bacillus, Prevotella, Acetobacter, Lactobacillus, Paracoccus, Flavobacterium, and Bacteroides were significantly abundant in moist STPs. Elevated moisture-holding products like Moist-snuff and Qiwam harbor rich bacterial species diversity and showed similar bacteriome composition. Furthermore, Qiwam products showed the highest level of genes associated with nitrogen metabolism, antibiotic resistance, toxins, and pro-inflammation (predicted by PICRUSt) which can contribute to the synthesis of TSNAs and induction of oral cancer. The present broad investigation of moist STPs-associated bacteriome prevalence and their detailed metabolic potential will provide novel insight into the oral carcinogenesis induced by STPs.

Effects of ecological environment and host genotype on the phyllosphere bacterial communities of cigar tobacco (Nicotiana tabacum L.)

Microorganisms of plant phyllosphere play an important role in plant health and productivity and are influenced by abiotic and biotic factors. In this study, we investigated the phyllosphere bacterial communities of three cigar tobacco varieties cultivated in Guangcun (GC) and Wuzhishan (WZS), Hainan, China. Metagenomic DNA was extracted from tobacco leaf samples and sequenced by 16S rDNA amplicon sequencing. Our results showed that bacterial communities of cigar tobacco phyllosphere in GC exhibited remarkably higher alpha diversity than that in WZS. There was slight effect of tobacco genotype variations on the alpha diversity in both cultivation sites, and beta diversity and structure of bacterial community were not influenced significantly by the cultivation sites and tobacco varieties. Statistical analyses of species diversity unraveled that the dominant species in bacterial communities of cigar tobacco phyllosphere among all these samples were phylogenetically affiliated to Proteobacteria and Cyanobacteria. At the genus level, the most abundant microorganism was Limnobacter, followed by Brevundimonas, unidentified_Cyanobacteria, and Pseudomonas. Additionally, environmental conditions except for humidity were negatively correlated with the relative abundance of bacterial genera. Further analyses revealed that influence of site-specific factors on tobacco bacterial community was relatively higher than genotype-specific factors. In short, this study may contribute to the knowledge base of practical applications of bacterial inoculants for tobacco leaf production.

Response of Root-Associated Bacterial Communities to Different Degrees of Soft Rot Damage in Amorphophallus konjac Under a Robinia pseudoacacia Plantation

Bacterial soft rot is a destructive disease that restricts the development of the konjac (Amorphophallus konjac K. Koch ex N.E.Br) industry. The objective of this study was to investigate how soft rot disease affects bacterial communities associated with the roots of konjac plants growing under a pure Robinia pseudoacacia plantation. Three sampling sites affected by different degrees of soft rot damage were selected based on the disease incidence [0%, non-diseased (ND); 4.2%, moderately diseased (MD); and 18.6%, highly diseased (HD)]. The variation in soil and root bacterial diversity and community composition among the sampling sites was determined by Illumina HiSeq sequencing of the V3-V4 hypervariable regions of the bacterial 16S rRNA gene. The results showed that the contents of soil organic matter and available nutrients (N, P, and K) increased with increasing damage degree, whereas higher damage degree resulted in lower soil pH and enzymatic activity (sucrase, urease, catalase, and polyphenol oxidase). The composition of root-associated bacterial communities differed among the three sampling sites. Proteobacteria was the most dominant bacterial phylum in all soil and root samples. Pseudomonas, Bacillus, Rhizobium, and Streptomyces were the most abundant in all samples from the ND sites, whereas Pectobacterium carotovorum and Serratia were predominant in the samples from the MD and HD sites. The abundance and alpha diversity of root-associated bacteria were significantly higher (p < 0.05) in the ND sites than in the diseased sites. The results suggested pronounced differences in the abundance, alpha diversity, and community composition of bacteria associated with the roots of konjac plants affected by different degrees of soft rot damage. Such differences in bacterial community structure were related to dynamic changes in soil variables, especially soil available potassium content, sucrase activity, and urease activity. Analysis of the dominant root-associated bacterial taxa offers an approach to predict the damage degree due to soft rot in konjac and provides evidence for the prevention of this soil-borne disease via microecological regulation.

Coupled DNA-labeling and sequencing approach enables the detection of viable-but-non-culturable Vibrio spp. in irrigation water sources in the Chesapeake Bay watershed

Nontraditional irrigation water sources (e.g., recycled water, brackish water) may harbor human pathogens, including Vibrio spp., that could be present in a viable-but-nonculturable (VBNC) state, stymieing current culture-based detection methods. To overcome this challenge, we coupled 5-bromo-2'-deoxyuridine (BrdU) labeling, enrichment techniques, and 16S rRNA sequencing to identify metabolically-active Vibrio spp. in nontraditional irrigation water (recycled water, pond water, non-tidal freshwater, and tidal brackish water). Our coupled BrdU-labeling and sequencing approach revealed the presence of metabolically-active Vibrio spp. at all sampling sites. Whereas, the culture-based method only detected vibrios at three of the four sites. We observed the presence of V. cholerae, V. vulnificus, and V. parahaemolyticus using both methods, while V. aesturianus and V. shilonii were detected only through our labeling/sequencing approach. Multiple other pathogens of concern to human health were also identified through our labeling/sequencing approach including P. shigelloides, B. cereus and E. cloacae. Most importantly, 16S rRNA sequencing of BrdU-labeled samples resulted in Vibrio spp. detection even when our culture-based methods resulted in negative detection. This suggests that our novel approach can effectively detect metabolically-active Vibrio spp. that may have been present in a VBNC state, refining our understanding of the prevalence of vibrios in nontraditional irrigation waters.

Microbiology of the American Smokeless Tobacco

Smokeless tobacco products (STP) contain diverse microbial communities that contribute to the formation of harmful chemical byproducts. This is concerning since 300 million individuals around the globe are users of smokeless tobacco. Significant evidence has shown that microbial metabolic activities mediate the formation of carcinogens during manufacturing. In recent years, studies have revealed a series of additional health impacts that include lesions and inflammation of the oral mucosa and the gastrointestinal tract, as well as alterations of the endogenous microbiota. These findings are due to recent developments in molecular technologies that allowed researchers to better examine the microbial component of these products. This new information illustrates the scale of the STP microbiota and its diversity in the finished product that is sold for consumption. Additionally, the application of metagenomics and metatranscriptomics has provided the tools to look at phylogenies across bacterial, viral, and eukaryotic groups, their functional capacities, and viability. Here we present key examples of tobacco microbiology research that utilizes newer approaches and strategies to define the microbial component of smokeless tobacco products. We also highlight challenges in these approaches, the knowledge gaps being filled, and those gaps that warrant further study. A better understanding of the microbiology of STP brings vast public health benefits. It will provide important information for the product consumer, impact manufacturing practices, and provide support for the development of attainable and more meaningful regulatory goals. KEY POINTS: Newer technologies allowed quicker and more comprehensive identification of microbes in tobacco samples, encapsulating microorganisms difficult or impossible to culture. Current research in smokeless tobacco microbiology is filling knowledge gaps previously unfilled due to the lack of suitable approaches. The microbial ecology of smokeless tobacco presents a clearer picture of diversity and variability not considered before.

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

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 non-menthols, 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.

A roadmap from unknowns to knowns: Advancing our understanding of the microbiomes of commercially available tobacco products

Tobacco smoking is still the leading cause of preventable diseases and death in the USA and throughout the globe. Under Section 904(a)(3) of the US Federal Food, Drug, and Cosmetic Act, tobacco manufacturing companies need to report on quantities of harmful and potentially harmful constituents (HPHCs) in all tobacco products. While the extensive HPHC list of 2012 includes 93 chemicals, which are categorized as carcinogenic, respiratory, cardiovascular, or reproductive toxicants or addictive compounds, it fails to include microorganisms (bacteria and fungi) that have been shown to contribute to adverse health outcomes among tobacco users. Nevertheless, over the last 50 years, researchers have studied microorganisms in a variety of tobacco products using both culture-based and culture-independent techniques. In this mini-review, we provide an overview of this body of research, detailing the bacterial and fungal microbiomes residing in commercial tobacco products. Overall, studies have characterized over 89 unique bacterial genera and 19 fungal genera in cigarettes, cigars, cigarillos, hookah, and smokeless tobacco. The most predominant bacterial genera are Bacillus, Pseudomonas, and Staphylococcus. Fungal genera identified have included Aspergillus, Penicillium, Mucor, Alternaria, Cladosporium, Streptomyces, and Candida, to name a few. While some of the identified microorganisms are known human pathogens, others are potential opportunistic pathogens. Given the vast array of microorganisms that are present across diverse types of tobacco products, future research should be focused on the viability of these microorganisms, as well as their ability to transfer to the user's respiratory tract, potentially contributing to adverse health outcomes. KEY POINTS: • Commercial tobacco products harbor diverse bacterial and fungal communities. • Some of these microorganisms are known or opportunistic human pathogens. • Research on their viability and transmission to users' respiratory tracts is needed.

Potential role of the skin and gut microbiota in premenarchal vulvar lichen sclerosus: A pilot case-control study

The etiology of vulvar lichen sclerosus (LS) remains unclear; however, alterations in cutaneous and gut microbiota may be contributing to the pathogenesis of this inflammatory condition. To explore this hypothesis, we conducted a pilot case-control study, obtaining dermal swab and stool samples from prepubertal girls with vulvar LS (n = 5), girls with nonspecific vulvovaginitis (n = 5), and healthy controls (n = 3). Samples (n = 56) were subjected to total DNA extractions. Resulting DNA was purified, subjected to PCR (targeting the V3V4 region of the 16S rRNA gene), sequenced, and analyzed using QIIME, MetagenomeSeq, and DESeq2 software packages. Our findings showed that there were significant differences in the cutaneous and gut microbiotas of girls with LS compared to controls. On the skin, girls with LS had a statistically significantly higher relative abundance of Porphyromonas spp., Parvimonas spp., Peptoniphilus spp., Prevotella spp., Dialister spp., and Peptostreptococcus spp., but a lower relative abundance of Cornyebacterium compared to the control group. In the gut samples, girls with LS had a significantly higher relative abundance of Dialister spp., Clostridiales spp., Paraprevotella spp., Escherichia coli, Bifidobacterium adolescentis, and Akkermansia muciniphila, and a lower relative abundance of Roseburia faecis and Ruminococcus bromii compared to controls. These results suggest a potential association between cutaneous and gut dysbiosis and pediatric vulvar LS. Future studies involving larger samples sizes are warranted to further evaluate this association.

Metabolically-active bacteria in reclaimed water and ponds revealed using bromodeoxyuridine DNA labeling coupled with 16S rRNA and shotgun sequencing

Understanding the complex microbiota of agricultural irrigation water is vital to multiple sectors of sustainable agriculture and public health. To date, microbiome characterization methods have provided comprehensive profiles of aquatic microbiotas, but have not described which taxa are likely metabolically-active. Here, we combined 5‑bromo‑2'-deoxyuridine (BrdU) labeling with 16S rRNA and shotgun sequencing to identify metabolically-active bacteria in reclaimed and agricultural pond water samples (n = 28) recovered from the Mid-Atlantic United States between March 2017 and January 2018. BrdU-treated samples were significantly less diverse (alpha diversity) compared to non-BrdU-treated samples. The most abundant taxa in the metabolically-active fraction of water samples (BrdU-treated samples) were unclassified Actinobacteria, Flavobacterium spp., Pseudomonas spp. and Aeromonas spp. Interestingly, we also observed that antimicrobial resistance and virulence gene profiles seemed to be more diverse and more abundant in non-BrdU-treated water samples compared to BrdU-treated samples. These findings raise the possibility that these genes may be associated more with relic (inactive) DNA present in the tested water types rather than viable, metabolically-active microorganisms. Our study demonstrates that the coupled use of BrdU labeling and sequencing can enhance understanding of the metabolically-active fraction of bacterial communities in alternative irrigation water sources. Agricultural pond and reclaimed waters are vital to the future of sustainable agriculture, and thus, the full understanding of the pathogenic potential of these waters is important to guide mitigation strategies that ensure appropriate water quality for intended purposes.

Mentholation triggers brand-specific shifts in the bacterial microbiota of commercial cigarette products

Bacterial communities are integral constituents of tobacco products. They originate from tobacco plants and are acquired during manufacturing processes, where they play a role in the production of tobacco-specific nitrosamines. In addition, tobacco bacterial constituents may play an important role in the development of infectious and chronic diseases among users. Nevertheless, tobacco bacterial communities have been largely unexplored, and the influence of tobacco flavor additives such as menthol (a natural antimicrobial) on tobacco bacterial communities is unclear. To bridge this knowledge gap, time series experiments including 5 mentholated and non-mentholated commercially available cigarettes-Marlboro red (non-menthol), Marlboro menthol, Newport menthol box, Newport menthol gold, and Newport non-menthol-were conducted. Each brand was stored under three different temperature and relative humidity conditions. To characterize bacterial communities, total DNA was extracted on days 0 and 14. Resulting DNA was purified and subjected to PCR of the V3V4 region of the 16S rRNA gene, followed by sequencing on the Illumina HiSeq platform and analysis using the QIIME, phyloseq, metagenomeSeq, and DESeq software packages. Ordination analyses showed that the bacterial community composition of Marlboro cigarettes was different from that of Newport cigarettes. Additionally, bacterial profiles significantly differed between mentholated and non-mentholated Newports. Independently of storage conditions, tobacco brands were dominated by Proteobacteria, with the most dominant bacterial genera being Pseudomonas, unclassified Enterobacteriaceae, Bacillus, Erwinia, Sphingomonas, Acinetobacter, Agrobacterium, Staphylococcus, and Terribacillus. These data suggest that the bacterial communities of tobacco products differ across brands and that mentholation of tobacco can alter bacterial community composition of select brands. KEY POINTS: • Bacterial composition differed between the two brands of cigarettes. • Mentholation impacts cigarette microbiota. • Pseudomonas and Bacillus dominated the commercial cigarettes. Graphical abstract.

Smokeless Tobacco Products (STPs) Harbour Bacterial Populations with Potential for Oral Carcinogenicity

INTRODUCTION

Smokeless Tobacco Products (STPs) vary significantly in their carcinogenicity, a feature accredited to the variation in the concentrations of carcinogenic chemicals. Tobacco associated bacteria are known to produce Tobacco-specific N-nitrosamines (TSNAs) and hence are determinants of TSNA levels in Tobacco. The primary objective of this study was to conduct a microbiological survey of STPs and to provide a baseline information of the bacterial communities present in the STPs.

MATERIALS AND METHODS

The present study analyzed the constituency of microbial communities in 7 different smokeless Tobacco products including four chewable (T1_CW to T4_CW), two snus (T5_Snus and T6_Snus) and one snuff sample (T7_Snuff) using high-throughput sequencing of the 16S rRNA based next generation sequencing. The Tobacco samples were also analyzed for pH and moisture content. Statistical analysis of the data obtained was done using SPSS software version 20. Pearson's Correlation was done to analyze the correlation between pH and moisture content of the Tobacco samples.

RESULTS

A total of 11 phyla were identified in all smokeless Tobacco products. A total of 36 classes were identified across all smokeless Tobacco products and bacilli was the predominant class in all the products followed by Actinobacteria and Bacteroidia. In species level, a total of 2369 species were identified across all smokeless Tobacco products. In T1 chewable Tobacco products, predominant species was staphylococcus whereas in T2 and T3, Bacillus subtilis and pumilus were predominant. In T4 chewable Tobacco product, Virgibacillus was predominant followed by halodentrificans, staphylococcus epidermidis. In snus 1 and 2, Bacillus pumilus and subtilis were predominant. In snuff, Bacillus cereus was predominant. Snus products had the highest moisture content (15.4% and 14.3%) compared to the chewable Tobacco and snuff products. The snus products analyzed had alkaline values (pH 8.50 and 8.15) and snuff and chewable Tobacco had acidic values ranging from 5.62 to 6.09.

CONCLUSION

The current study demonstrates that ST products differ qualitatively, quantitatively, and in their bacterial composition. There is a possibility that some of these species may contribute to oral carcinogenesis, either by influencing levels of TSNAs or directly inducing chronic inflammation.

Characterization of the core microbiome in tobacco leaves during aging

Microbiome plays an important role during the tobacco aging process which was an indispensable link in the production and processing of cigarettes. However, the structure and functions of microbiome have not been clarified during the tobacco aging process. In this study, 16S rDNA and ITS amplicon sequencing techniques were used to analyze the core microbiome of 15 tobacco samples from five different aging stages. The whole bacterial microbiome was classified into 29 microbial phyla and 132 orders. Enterobacteriales (63%), Pseudomonadales (16%), Sphingomonadales (8%), Xanthomonadales (4%), Burkholderiales (4%), Rhizobiales (3%), and Bacillales (2%) comprised the core bacterial microbiome. The whole fungal microbiome was classified into five microbial phyla and 52 orders. Incertae_sedis_Eurotiomycetes (27%), Wallemiales (25%), Sporidiobolales (17%), Capnodiales (5%), Eurotiales (2%), an unclassified Ascomycota (12%), and an unidentified Eurotiomycetes (4%) comprised the core fungal microbiome. FAPROTAX function prediction suggested that the core microbiome has a substantial potential for the carbon cycle, nitrate metabolism, aromatic compound degradation, chitinolysis, cellulolysis, and xylanolysis, but simultaneously, the core microbiome is also a source of human pathogens. The dynamics of the bacterial community were primarily determined by the total nitrogen in tobacco leaves during the aging process, while those of the fungal microbiome were primarily determined by total organic carbon. This study indicated that the core microbiome activities may play an important role in regulating the loss of carbon organic compounds and enhancing the secondary metabolites during tobacco leaves aging process.

The Bacterial Communities of Little Cigars and Cigarillos Are Dynamic Over Time and Varying Storage Conditions

Despite their potential importance with regard to tobacco-related health outcomes, as well as their hypothesized role in the production of tobacco-specific N-nitrosamines, bacterial constituents of tobacco products lack characterization. Specifically, to our knowledge, there has been no comprehensive characterization of the effects of storage conditions on the bacterial communities associated with little cigars and cigarillos. To address this knowledge gap, we characterized the bacterial community composition of the tobacco and wrapper components of the following four products: Swisher Sweets Original; Swisher Sweets, Sweet Cherry; Cheyenne Cigars Full Flavor 100's; and Cheyenne Menthol Box. Each product was stored under three different conditions of temperature and relative humidity to mimic different user storage conditions: room (20°C 50% RH), refrigerator (5°C 18% RH) and pocket (25°C 30% RH). On days 0, 5, 9 and 14, subsamples were collected, the wrapper and tobacco were separated, and their total DNA was extracted separately and purified. Resulting DNA was then used in PCR assays targeting the V3 V4 region of the bacterial 16S rRNA gene, followed by sequencing using Illumina HiSeq 300bp PE. Resulting sequences were processed using the Quantitative Insights Into Microbial Ecology (QIIME) software package, followed by analyses in R using the Phyloseq and Vegan packages. A single bacterial phylum, Firmicutes, dominated in the wrapper subsamples whereas the tobacco subsamples were dominated by Proteobacteria. Cheyenne Menthol Box (CMB) samples were characterized by significant differential abundances for 23 bacterial operational taxonomic units (OTUs) in tobacco subsamples and 27 OTUs in the wrapper subsamples between day 0 and day 14 under all conditions. OTUs from the genera Acinetobacter and Bacillus significantly increased in the CMB tobacco subsamples, and OTUs from Bacillus, Streptococcus, Lactobacillus, and Enterococcus significantly increased in the CMB wrapper subsamples over time. These initial results suggest that the bacterial communities of little cigars and cigarillos are dynamic over time and varying storage conditions.

The bacterial communities of the small intestine and stool in children with short bowel syndrome

Short bowel syndrome (SBS) presents an increasing problem in pediatrics. SBS often results from surgical resection of necrotic bowel following necrotizing enterocolitis or treatment of anatomic gastrointestinal defects. SBS is associated with significant morbidity and mortality, and creates substantial burdens for patients, families, and the health system. Recent reports have demonstrated that the fecal microbiome of children with SBS is significantly different from healthy control and severe intestinal microbial imbalances is associated with poor growth. We hypothesized that children with SBS and adverse clinical features such as PN dependent, shorter bowel length and lack of ileocecal valve would demonstrate more gut dysbiosis compare with the SBS non-PN dependent. An improved understanding of SBS pathogenesis would enhance management and potentially suggest new interventions. We studied microbial communities of SBS and control non-SBS patients from the jejunum, obtained endoscopically or by ostomy aspiration, and stool. We enrolled SBS patients who did and did not require parenteral nutrition (PN), as a surrogate marker for the seriousness of their disease. We studied the microbiota using high-throughput DNA sequencing of 16S rRNA genes and statistical analyses. We found that microbial diversity was significantly greater in jejunal aspirate than in stool samples in SBS patients, unlike non-SBS patients; that SBS patients receiving enteral feeds had greater diversity, and that SBS patients on PN and enteral feeds had lower differences in diversity in jejunal vs. stool samples. We found a trend toward increased diversity in patients with an intact ileocecal valve, and found that certain taxa were more abundant in the certain sample types, and in SBS patients vs. non-SBS patients. SBS patients have lower microbial diversity, especially patients with more severe disease, patients requiring PN, and those lacking an ileocecal valve. SBS patients, particularly those with more complex characteristics, exhibit differences in their intestinal microbiota. Particular individual taxa were over- and under-represented in patients with more unfavorable disease. While diminished diversity and alterations in microbiota composition are likely consequences of SBS, future efforts aimed at increasing microbial diversity and interventions targeting specific microbiota characteristics might constitute a testable approach to ameliorate some clinical SBS clinical consequences.

Little cigars and cigarillos harbor diverse bacterial communities that differ between the tobacco and the wrapper

Despite their potential importance with regard to infectious and chronic diseases among tobacco users, microbial constituents of tobacco products lack characterization. Specifically, to our knowledge, there are no data describing the bacterial diversity of little cigars or cigarillos. To address this knowledge gap, we tested four brands of little cigars and cigarillos. Tobacco and wrapper subsamples (n = 132) were separately subjected to DNA extraction, followed by PCR amplification of the V3V4 hypervariable region of the 16S rRNA gene, and sequencing using Illumina HiSeq. Sequences were analyzed using QIIME and Phyloseq implemented in R. We identified 2,681 operational taxonomic units across all products. Significant differences in alpha and beta diversity were observed between Swisher Sweets and Cheyenne products. Alpha and beta diversity was also significantly different between tobacco and wrapper subsamples within the same product. Beta diversity analyses of only tobacco samples identified no significant differences in the bacterial microbiota of different lots of the same products; however, the microbiota in the wrapper differed significantly across lots for all brands. Overall, Firmicutes were found to dominate in the wrapper, whereas Proteobacteria were most abundant in the tobacco. At the genus level, Bacillus and Lactobacillus dominated in the wrappers, and Staphylococcus and Pseudomonas dominated in the tobacco. Our findings suggest that the bacterial microbiota of little cigars and cigarillos is diverse and differs significantly between the tobacco and the wrapper, and across brands. Future work is necessary to evaluate the potential public health implications of these findings.

Agricultural Freshwater Pond Supports Diverse and Dynamic Bacterial and Viral Populations

Agricultural ponds have a great potential as a means of capture and storage of water for irrigation. However, pond topography (small size, shallow depth) leaves them susceptible to environmental, agricultural, and anthropogenic exposures that may influence microbial dynamics. Therefore, the aim of this project was to characterize the bacterial and viral communities of pond water in the Mid-Atlantic United States with a focus on the late season (October-December), where decreasing temperature and nutrient levels can affect the composition of microbial communities. Ten liters of freshwater from an agricultural pond were sampled monthly, and filtered sequentially through 1 and 0.2 μm filter membranes. Total DNA was then extracted from each filter, and the bacterial communities were characterized using 16S rRNA gene sequencing. The remaining filtrate was chemically concentrated for viruses, DNA-extracted, and shotgun sequenced. Bacterial community profiling showed significant fluctuations over the sampling period, corresponding to changes in the condition of the pond freshwater (e.g., pH, nutrient load). In addition, there were significant differences in the alpha-diversity and core bacterial operational taxonomic units (OTUs) between water fractions filtered through different pore sizes. The viral fraction was dominated by tailed bacteriophage of the order Caudovirales, largely those of the Siphoviridae family. Moreover, while present, genes involved in virulence/antimicrobial resistance were not enriched within the viral fraction during the study period. Instead, the viral functional profile was dominated by phage associated proteins, as well as those related to nucleotide production. Overall, these data suggest that agricultural pond water harbors a diverse core of bacterial and bacteriophage species whose abundance and composition are influenced by environmental variables characteristic of pond topology and the late season.

Insights into the human oral microbiome

Human oral cavity harbors the second most abundant microbiota after the gastrointestinal tract. The expanded Human Oral Microbiome Database (eHOMD) that was last updated on November 22, 2017, contains the information of approximately 772 prokaryotic species, where 70% is cultivable, and 30% belong to the uncultivable class of microorganisms along with whole genome sequences of 482 taxa. Out of 70% culturable species, 57% have already been assigned to their names. The 16S rDNA profiling of the healthy oral cavity categorized the inhabitant bacteria into six broad phyla, viz. Firmicutes, Actinobacteria, Proteobacteria, Fusobacteria, Bacteroidetes and Spirochaetes constituting 96% of total oral bacteria. These hidden oral micro-inhabitants exhibit a direct influence on human health, from host's metabolism to immune responses. Altered oral microflora has been observed in several diseases such as diabetes, bacteremia, endocarditis, cancer, autoimmune disease and preterm births. Therefore, it becomes crucial to understand the oral microbial diversity and how it fluctuates under diseased/perturbed conditions. Advances in metagenomics and next-generation sequencing techniques generate rapid sequences and provide extensive information of inhabitant microorganisms of a niche. Thus, the retrieved information can be utilized for developing microbiome-based biomarkers for their use in early diagnosis of oral and associated diseases. Besides, several apex companies have shown keen interest in oral microbiome for its diagnostic and therapeutic potential indicating a vast market opportunity. This review gives an insight of various associated aspects of the human oral microbiome.