Background Viral-encoded auxiliary metabolic genes (AMGs) are important toolkits for modulating their hosts’ metabolisms and the microbial-driven biogeochemical cycles. Although the functions of AMGs have been extensively reported in numerous environments, we still know little about the drivers that shape the viral community-wide AMG compositions in natural ecosystems. Exploring the drivers of viral community-wide AMG compositions is critical for a deeper understanding of the complex interplays among viruses, hosts, and the environments. Results Here, we investigated the impact of viral lifestyles (i.e., lytic and lysogenic), habitats (i.e., water, particle, and sediment), and prokaryotic hosts on viral AMG profiles by utilizing metagenomic and metatranscriptomic techniques. We found that viral lifestyles were the most important drivers, followed by habitats and host identities. Specifically, irrespective of what habitats viruses came from, lytic viruses exhibited greater AMG diversity and tended to encode AMGs for chaperone biosynthesis, signaling proteins, and lipid metabolism, which could boost progeny reproduction, whereas temperate viruses were apt to encode AMGs for host survivability. Moreover, the lytic and temperate viral communities tended to mediate the microbial-driven biogeochemical cycles, especially nitrogen metabolism, in different manners via AMGs. When focusing on each lifestyle, we further found clear dissimilarity in AMG compositions between water and sediment, as well the divergent AMGs encoded by viruses infecting different host orders. Conclusions Overall, our study provides a first systematic characterization of the drivers of viral community-wide AMG compositions and further expands our knowledge of the distinct interactions of lytic and temperate viruses with their prokaryotic hosts from an AMG perspective, which is critical for understanding virus-host-environment interactions in natural conditions.

Background: Metagenomic next-generation sequencing (mNGS) is an effective diagnostic method for infectious diseases, however, its clinical utility for tuberculosis (TB) diagnosis remains to be demonstrated. Methods: A total of 322 bronchoalveolar lavage fluid (BALF) samples were collected from 311 suspected and confirmed pulmonary TB patients and tested by mNGS, acid-fast bacillus (AFB) smear by microscopy, Xpert 1 MTB/RIF (Xpert), mycobacterium culture and bacterial/fungal culture. Diagnostic performance of mNGS was compared with conventional methods for detection of Mycobacterium tuberculosis complex (MTBC) and other pathogens in BALF. Underlying factors associated with positive detection in pulmonary TB patients were investigated. Results: mNGS, Xpert and culture presented a high proportion of complete matching for MTBC detection (244/322, 75.8%). In pulmonary TB patients pre-treatment the sensitivity of MTBC detection by mNGS, Xpert, culture and smear was 59.9% (85/142), 69.0% (98/142), 59.9% (85/142) and 24.6% (35/142), respectively, and 79.6% overall; MTBC was detected by mNGS in 33.2% (5/34) Xpert and culture negative samples. Positive MTBC detection by mNGS was affected by Vitamin D, erythrocyte sedimentation rate, TB initial treatment/ retreatment, and cavity in chest imaging (χ 2 = 37.42, P < 0.001), but not by prior anti-TB therapy within 3 months. mNGS was able to detect new potential pathogens in 8.7% (28/322) of samples. Conclusions: Combining mNGS with conventional detection methods could increase the detection rate for MTBC. Additionally, mNGS could identify pathogens in a non-targeted approach for better diagnosis of coinfection.

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1. Microbial biogeography has predominantly been studied through a taxonomic lens. However, functional properties of microbial communities are often decoupled from their taxonomic compositions, emphasizing the need to study the biogeography of microbial functional genes directly.2. Here, using the Pearl River Estuary (PRE) sediments as a study system, we characterized the biogeographical patterns of the diversities and abundances of key microbial nitrogen-cycling genes using metagenomic techniques.3. We found that functional genes involved in denitrification and dissimilatory nitrate reduction to ammonium pathways were more diverse and abundant than genes involved in other processes (i.e. nitrogen fixation, nitrification, assimilatory nitrite reduction). The diversities and abundances of certain nitrogen-cycling genes were, to some extent, spatially decoupled. Specifically, the diversities of narG, napA, nirK and nrfA were greater adjacent to the river outlet, whereas the abundances of narG, napA and norB were greater in the downstream of the PRE. These spatial variations were mainly driven by water depth, C/N and NH + 4 . 4. Moreover, nitrogen-cycling genes involved in the same pathways (e.g. denitrification) showed no consistent responses to environmental changes and the main taxa involved in different nitrogen-cycling steps were diverse, providing important clues for explaining why the abundance of single functional gene often seems not to be a reliable proxy for the specific process rate. Overall, our results demonstrate that studying the biogeography of microbial functional genes can help expand our knowledge of the nitrogen cycle from a biogeographical perspective.

Understanding the dynamics of lung microbiota in tuberculosis patients, especially those who cannot be confirmed bacteriologically in clinical practice, is imperative for accurate diagnosis and effective treatment. This study aims to characterize the distinct lung microbial features between bacteriologically confirmed and negative tuberculosis patients to understand the influence of microbiota on tuberculosis patients. We collected specimens of bronchoalveolar lavage fluid from 123 tuberculosis patients. Samples were subjected to metagenomic next-generation sequencing to reveal the lung microbial signatures. By combining conventional bacterial detection and metagenomic sequencing, 101/123 (82%) tuberculosis patients were bacteriologically confirmed. In addition to Mycobacterium tuberculosis, Staphylococcus aureus, Kluyveromyces lactis, and Pyricularia pennisetigena were also enriched in the bacteriological confirmation group. In contrast, Haemophilus parainfluenzae was enriched in the bacteriologically negative group. Besides, microbial interaction exhibits a different state between bacteriologically confirmed and negative tuberculosis patients. Mycobacterium tuberculosis was confirmed correlated with clinical characteristics such as albumin and chest cavities. Our study comprehensively demonstrates the correlation between unique features of lung microbial dynamics and the clinical characteristics of tuberculosis patients, suggesting the importance of studying the pulmonary microbiome in tuberculosis disease and providing new insights for future precision diagnosis and treatment.