Cross talk occurs between the human gut and the lung through a gut-lung axis involving the gut microbiota. However, the signatures of the human gut microbiota after active Mycobacterium tuberculosis infection have not been fully understood. Here, we investigated changes in the gut microbiota in tuberculosis (TB) patients by shotgun sequencing the gut microbiomes of 31 healthy controls and 46 patients. We observed a dramatic changes in gut microbiota in tuberculosis patients as reflected by significant decreases in species number and microbial diversity. The gut microbiota of TB patients were mostly featured by the striking decrease of short-chain fatty acids (SCFAs)-producingbacteria as well as associated metabolic pathways. A classification model based on the abundance of three species, Haemophilus parainfluenzae, Roseburia inulinivorans , and Roseburia hominis , performed well for discriminating between healthy and diseased patients. Additionally, the healthy and diseased states can be distinguished by SNPs in the species of B. vulgatus . We present a comprehensive profile of changes in the microbiota in clinical TB patients. Our findings will shed light on the design of future diagnoses and treatments for M. tuberculosis infections.

Minerals, natural organic matter (NOM), and divalent manganese (Mn(II)) often coexist in suboxic/oxic environment. Multiple adsorption and oxidation processes occur in this ternary system, which are coupled to affect the fate of both OM and Mn therein and alter their chemical reactivity toward metals and other pollutants. However, the details about the coupling are poorly known although much has been gained for the binary systems. We determined the mutual influence of surfacecatalyzed Mn(II) oxidation and humic acid (HA) adsorption and oxidation in a Fe(III) oxide (goethite)-HA-Mn(II) system at pH 5−8. The presence of Mn(II) substantially increased HA adsorption whereas HA greatly impaired the extent and rate of Mn(II) oxidation by O 2 on goethite surfaces. The impacts were more pronounced at higher pH. Mn(II) oxidation produced β-MnOOH, γ-MnOOH, and Mn 3 O 4 which in turn oxidized HA, producing small organic acids. The presence of HA markedly altered the composition of Mn(II) oxidation products by inhibiting the formation of β-MnOOH while favoring the production of γ-MnOOH and Mn(II) adsorbed on the HA-mineral assemblage. Nonconducting γ-Al 2 O 3 exhibited similar but weaker effects than semiconducting goethite in the above processes. Our results suggest that similar to Mn-oxidizing microorganisms, mineral surfaces can drive the coupling of the Mn redox cycle with NOM oxidative degradation under suboxic/oxic and circumneutral/alkaline conditions.

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