Non-specific amplification of human DNA is a major challenge for 16S rRNA gene sequence analysis

Abstract The targeted sequencing of the 16S rRNA gene is one of the most frequently employed techniques in the field of microbial ecology, with the bacterial communities of a wide variety of niches in the human body have been characterised in this way. This is performed by targeting one or more hypervariable (V) regions within the 16S rRNA gene in order to produce an amplicon suitable in size for next generation sequencing. To date, all technical research has focused on the ability of different V regions to accurately resolve the composition of bacterial communities. We present here an underreported artefact associated with 16S rRNA gene sequencing, namely the off-target amplification of human DNA. By analysing 16S rRNA gene sequencing data from a selection of human sites we highlighted samples susceptible to this off-target amplification when using the popular primer pair targeting the V3–V4 region of the gene. The most severely affected sample type identified (breast tumour samples) were then re-analysed using the V1–V2 primer set, showing considerable reduction in off target amplification. Our data indicate that human biopsy samples should preferably be amplified using primers targeting the V1–V2 region. It is shown here that these primers result in on average 80% less human genome aligning reads, allowing for more statistically significant analysis of the bacterial communities residing in these samples.

Download Full-text

Analysis of Bacterial Communities by 16S rRNA Gene Sequencing in a Melon-Producing Agro-environment

Microbial Ecology ◽

10.1007/s00248-021-01709-8 ◽

2021 ◽

Author(s):

Eduardo Franco-Frías ◽

Victor Mercado-Guajardo ◽

Angel Merino-Mascorro ◽

Janeth Pérez-Garza ◽

Norma Heredia ◽

...

Keyword(s):

16S Rrna ◽

16S Rrna Gene ◽

Bacterial Communities ◽

Gene Sequencing ◽

16S Rrna Gene Sequencing ◽

Rrna Gene ◽

Rrna Gene Sequencing

Download Full-text

1207. Combining standard bacterial vaginosis treatment with cystine uptake inhibitors to block growth of Lactobacillus iners is a potential a target for shifting the cervicovaginal microbiota towards health-associated Lactobacillus crispatus-dominant communities

Open Forum Infectious Diseases ◽

10.1093/ofid/ofaa439.1392 ◽

2020 ◽

Vol 7 (Supplement_1) ◽

pp. S625-S626

Author(s):

Seth M Bloom ◽

Nomfuneko A Mafunda ◽

Benjamin M Woolston ◽

Matthew R Hayward ◽

Josephine F Frempong ◽

...

Keyword(s):

16S Rrna ◽

16S Rrna Gene ◽

Bacterial Communities ◽

Gene Sequencing ◽

16S Rrna Gene Sequencing ◽

Lactobacillus Species ◽

Rrna Gene ◽

Rrna Gene Sequencing ◽

Media Condition ◽

Mrs Broth

Abstract Background Cervicovaginal microbiota domination by Lactobacillus crispatus is associated with beneficial health outcomes, whereas L. iners dominance has more adverse associations. However bacterial vaginosis (BV) treatment with metronidazole (MTZ) typically leads to domination by L. iners rather than L. crispatus. L. iners differs from other lactobacilli by its inability to grow in MRS media. We hypothesized that exploring this growth difference would identify targets for selective L. iners inhibition. Methods Bacteria were grown anaerobically. Nutrient uptake and metabolism were assessed using UPLC-MS/MS and isotopically labeled substrates. Bacterial genome annotation employed Prodigal, Roary, and EggNOG. Competition experiments with mock mixed communities were analyzed by 16S rRNA gene sequencing. We confirmed result generalizability using a diverse collection of South African and North American strains and genomes. Results Supplementing MRS broth with L-cysteine (Cys) or L-cystine permitted robust L. iners growth, while L. crispatus grew without Cys supplementation. Despite their different growth requirements, neither species could synthesize Cys via canonical pathways. Adding the cystine uptake inhibitors S-methyl-L-cysteine (SMC, Fig 1) or seleno-DL-cystine (SDLC) blocked growth of L. iners but not other lactobacilli, suggesting L. iners lacks mechanisms other lactobacilli use to exploit complex exogenous Cys sources. Notably, cydABCD, an operon with Cys/glutathione transport and redox homeostasis activities, is absent from L. iners but present in non-iners Lactobacillus species. Consistent with possible roles for cydABCD in explaining the observed phenotypes, (1) L. iners failed to take up exogenous glutathione and (2) supplementing MRS with reducing agents permitted L. iners growth, which could be blocked by SMC or SDLC. In growth competitions testing L. iners and L. crispatus within mock BV-like communities, SMC plus MTZ outperformed MTZ alone in promoting L. crispatus dominance (Figs 2&3). Figure 1: S-methyl-L-cysteine (SMC) selectively blocks growth of L. iners but not other cervicovaginal Lactobacillus species in cysteine-supplemented MRS broth. Growth was measured by optical density and inhibition calculated relative to Cys-supplemented no-inhibitor control during exponential growth. Values displayed are median (+/- maximum/minimum) for 3 replicates from a single experiment. In all panels, representative data are shown from 1 of >=2 independent experiments for each bacterial strain and media condition. Results are representative of multiple strains for L. iners (n = 16), L. crispatus (n = 7), and L. jensenii (n = 2). Figure 2: Relative abundance of L. crispatus, L. iners, or various BV-associated bacteria in mock bacterial communities grown in rich, non-selective media with or without metronidazole (MTZ) and/or SMC. Relative abundance was determined by bacterial 16S rRNA gene sequencing. Data are shown for three representative mock communities with 5 replicates per media condition. Figure 3: Ratio of L. crispatus to other species in the mock bacterial communities depicted in Figure 2. Statistical significance determined via 1-way ANOVA of log10-transformed ratios with post-hoc Tukey test; selected pairwise comparisons are shown (***, p < 0.001). Conclusion L. iners has unique requirements for exogenous cysteine/cystine or a reduced environment for growth. Targeting cystine uptake to inhibit L. iners is a potential strategy for shifting cervicovaginal microbiota towards L. crispatus-dominant communities. Disclosures Douglas S. Kwon, MD, PhD, Day Zero Diagnostics (Consultant, Shareholder, Other Financial or Material Support, co-founder)

Download Full-text

Diversity of bacterial communities on the facial skin of different age-group Thai males

PeerJ ◽

10.7717/peerj.4084 ◽

2017 ◽

Vol 5 ◽

pp. e4084 ◽

Cited By ~ 11

Author(s):

Alisa Wilantho ◽

Pamornya Deekaew ◽

Chutika Srisuttiyakorn ◽

Sissades Tongsima ◽

Naraporn Somboonna

Keyword(s):

Young Adults ◽

16S Rrna ◽

16S Rrna Gene ◽

Gene Sequencing ◽

16S Rrna Gene Sequencing ◽

Rrna Gene ◽

Skin Microbiome ◽

The Us ◽

Rrna Gene Sequencing ◽

The 16S Rrna Gene

BackgroundSkin microbiome varies from person to person due to a combination of various factors, including age, biogeography, sex, cosmetics and genetics. Many skin disorders appear to be related to the resident microflora, yet databases of facial skin microbiome of many biogeographies, including Thai, are limited.MethodsMetagenomics derived B-RISA and 16S rRNA gene sequencing was utilized to identify the culture-independent bacterial diversity on Thai male faces (cheek and forehead areas). Skin samples were categorized (grouped) into (i) normal (teenage.hea) and (ii) acne-prone (teenage.acn) young adults, and normal (iii) middle-aged (middle.hea) and (iv) elderly (elderly.hea) adults.ResultsThe 16S rRNA gene sequencing was successful as the sequencing depth had an estimated >98% genus coverage of the true community. The major diversity was found between the young and elderly adults in both cheek and forehead areas, followed by that between normal and acne young adults. Detection of representative characteristics indicated that bacteria from the order Rhizobiales, generaSphingomonasandPseudoalteromonas, distinguished theelderly.heamicrobiota, along the clinical features of wrinkles and pores. Prediction of the metabolic potential revealed reduced metabolic pathways involved in replication and repair, nucleotide metabolism and genetic translation in theelderly.heacompared with that in theteenage.hea. For young adults, some unique compositions such as abundance ofPropionibacterium acnesandStaphylococcus epidermidis, with a minor diversity between normal and acne skins, were detected. The metabolic potentials of the acne vs. normal young adults showed thatteenage.acnwas low in many cellular processes (e.g., cell motility and environmental adaptation), but high in carbohydrate metabolism, which could support acne growth. Moreover, comparison with the age-matched males from the US (Boulder, Colorado) to gain insight into the diversity across national biogeography, revealed differences in the distribution pattern of species, although common bacteria were present in both biogeographical samples. Furthermore, B-RISA served as a crosscheck result to the 16S rRNA gene sequencing (i.e., differences between teenage and elderly microbiota).ConclusionsThis study revealed and compared the microbial diversity on different aged Thai male faces, and included analyses for representing the bacterial flora, the clinical skin characteristics, and comparison with the US age-matched. The results represent the first skin microbiota of Thai males, and helps the design of a large-scale skin microbiome study of Thais. The findings of the diversity among ages, skin type and national biogeography supported the importance of these traits in the skin microbiome and in developing a safe and sustainable treatment for acne and aging skin diseases.

Download Full-text

Chemotaxis Away from 4-Chloro-2-nitrophenol, 4-Nitrophenol, and 2,6-Dichloro-4-nitrophenol byBacillus subtilisPA-2

Journal of Chemistry ◽

10.1155/2015/296231 ◽

2015 ◽

Vol 2015 ◽

pp. 1-4 ◽

Cited By ~ 2

Author(s):

Pankaj Kumar Arora ◽

Mi-Jeong Jeong ◽

Hanhong Bae

Keyword(s):

Bacillus Subtilis ◽

16S Rrna ◽

16S Rrna Gene ◽

Gene Sequencing ◽

16S Rrna Gene Sequencing ◽

Rrna Gene ◽

Rrna Gene Sequencing ◽

The 16S Rrna Gene ◽

Drop Plate ◽

Chemotactic Behavior

Bacterial strain PA-2 exhibits chemotaxis away from 4-chloro-2-nitrophenol, 4-nitrophenol, and 2,6-dichloro-4-nitrophenol. This strain was identified asBacillus subtilison the basis of the 16S rRNA gene sequencing. The drop plate assay and the chemical-in-plug method were used to demonstrate negative chemotactic behavior of strain PA-2. The growth studies showed that strain PA-2 did not utilize 4-chloro-2-nitrophenol, 4-nitrophenol, and 2,6-dichloro-4-nitrophenol as its sole sources of carbon and energy. This is the first report of negative chemotaxis of 4-chloro-2-nitrophenol, 4-nitrophenol, and 2,6-dichloro-4-nitrophenol by any bacterium.

Download Full-text