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The atmosphere is vastly underexplored as a habitable ecosystem for microbial organisms. In this study, we investigated 795 time-resolved metagenomes from tropical air, generating 2.27 terabases of data. Despite only 9 to 17% of the generated sequence data currently being assignable to taxa, the air harbored a microbial diversity that rivals the complexity of other planetary ecosystems. The airborne microbial organisms followed a clear diel cycle, possibly driven by environmental factors. Interday taxonomic diversity exceeded day-to-day and month-to-month variation. Environmental time series revealed the existence of a large core of microbial taxa that remained invariable over 13 mo, thereby underlining the long-term robustness of the airborne community structure. Unlike terrestrial or aquatic environments, where prokaryotes are prevalent, the tropical airborne biomass was dominated by DNA from eukaryotic phyla. Specific fungal and bacterial species were strongly correlated with temperature, humidity, and CO2 concentration, making them suitable biomarkers for studying the bioaerosol dynamics of the atmosphere.
Assuntos
Microbiologia do Ar , Microbiota , Clima Tropical , Poluentes Atmosféricos/análise , Ritmo Circadiano , Ecossistema , Metagenoma , Modelos Biológicos , SingapuraRESUMO
BACKGROUND: Enterobacter cloacae complex (ECC) bacteria, such as E. cloacae, E. sichuanensis, E. kobei, and E. roggenkampii, have been emerging as nosocomial pathogens. Many strains isolated from medical clinics were found to be resistant to antibiotics, and in the worst cases, acquired multidrug resistance. We present the whole genome sequence of SGAir0282, isolated from the outdoor air in Singapore, and its relevance to other ECC bacteria by in silico genomic analysis. RESULTS: Complete genome assembly of E. sichuanensis strain SGAir0282 was generated using PacBio RSII and Illumina MiSeq platforms, and the datasets were used for de novo assembly using Hierarchical Genome Assembly Process (HGAP) and error corrected with Pilon. The genome assembly consisted of a single contig of 4.71 Mb and with a G+C content of 55.5%. No plasmid was detected in the assembly. The genome contained 4371 coding genes, 83 tRNA and 25 rRNA genes, as predicted by NCBI's Prokaryotic Genome Annotation Pipeline (PGAP). Among the genes, the antibiotic resistance related genes were included: Streptothricin acetdyltransferase (SatA), fosfomycin resistance protein (FosA) and metal-dependent hydrolases of the beta-lactamase superfamily I (BLI). CONCLUSION: Based on whole genome alignment and phylogenetic analysis, the strain SGAir0282 was identified to be Enterobacter sichuanensis. The strain possesses gene clusters for virulence, disease and defence, that can also be found in other multidrug resistant ECC type strains.
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Brevundimonas sp. strain SGAir0440 was isolated from indoor air samples collected in Singapore. Its genome was assembled using single-molecule real-time sequencing data, resulting in one circular chromosome with a length of 3.1 Mbp. The genome consists of 3,033 protein-coding genes, 48 tRNAs, and 6 rRNA operons.
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Enterococcus faecalis strain SGAir0397 was isolated from a tropical air sample collected in Singapore. Its genome was assembled using single-molecule real-time sequencing data and comprises one circular chromosome with a length of 2.69 Mbp. The genome contains 2,595 protein-coding genes, 59 tRNAs, and 12 rRNAs.
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The Pontibacter bacterial genus has been detected in marine and soil environments. Here, we report the genome sequence of Pontibacter sp. strain SGAir0037, which was isolated from outdoor air samples collected in Singapore. The genome comprises one chromosome of 5.26 Mb and one plasmid of 127 kb.
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Nissabacter sp. strain SGAir0207 was isolated from a tropical air sample collected in Singapore. Its genome was assembled using a hybrid approach with long and short reads, resulting in one chromosome of 3.9 Mb and 7 plasmids. The complete genome consists of 4,403 protein-coding, 84 tRNA, and 22 rRNA genes.
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Brachybacterium sp. strain SGAir0954 was isolated from tropical air collected in Singapore, and its genome was sequenced and assembled using long reads generated by single-molecule real-time (SMRT) sequencing. The complete genome has a size of 3.41 Mb and consists of 2,955 protein coding genes, 50 tRNAs, and 9 rRNAs.
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Agrococcus sp. strain SGAir0287 was isolated from tropical air samples collected in Singapore. Assembled using single-molecule real-time (SMRT) sequencing and MiSeq reads, the genome consists of one circular chromosome of 3,084,767 bp. The entire genome has 2,870 protein-coding genes, 45 tRNAs, and 3 rRNAs.
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Microbacterium sp. strain SGAir0570 was isolated from air samples collected in Singapore. Its genome was assembled using single-molecule real-time sequencing and MiSeq short reads. It has one chromosome with a length of 3.38 Mb and one 59.2-kb plasmid. It contains 3,170 protein-coding genes, 48 tRNAs, and 6 rRNAs.
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Pseudomonas sp. strain SGAir0191 was isolated from an air sample collected in Singapore, and its genome was sequenced using a combination of long and short reads to generate a high-quality genome assembly. The complete genome is approximately 5.07 Mb with 4,370 protein-coding genes, 19 rRNAs, and 73 tRNAs.
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Bacillus megaterium strain SGAir0080 was isolated from a tropical air sample in Singapore. Its genome was assembled using single-molecule real-time (SMRT) sequencing and MiSeq reads. It has one chromosome of 5.06 Mbp and seven plasmids (average length, 62.8 kbp). It possesses 5,339 protein-coding genes, 130 tRNAs, and 35 rRNAs.
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Lysinibacillus sp. strain SGAir0095 was isolated from tropical air samples collected in Singapore, and its complete genome was sequenced with a hybrid strategy using single-molecule real-time sequencing and short reads. The genome consists of one chromosome of 4.14 Mbp and encompasses 3,885 protein-coding genes, 39 rRNAs, and 101 tRNAs.
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Serratia marcescens strain SGAir0764 was isolated from a tropical air sample collected in Singapore. The complete genome, sequenced on the PacBio RS II platform, consists of one chromosome with 5.1 Mb and one plasmid with 76.4 kb. Genome annotation predicts 4,723 protein-coding genes, 89 tRNAs, and 22 rRNAs.
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Bacillus velezensis strain SGAir0473 (Firmicutes) was isolated from tropical air collected in Singapore. Its genome was assembled using short reads and single-molecule real-time sequencing and comprises one chromosome with 4.18 Mb. The genome consists of 3,937 protein-coding genes, 86 tRNAs, and 27 rRNAs.
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Pantoea ananatis SGAir0210 was isolated from outdoor air collected in Singapore. The genome was assembled from long reads generated by single-molecule real-time sequencing complemented with short reads. The genome size was approximately 4.81 Mb, with 4,303 protein-coding genes, 80 tRNAs, and 22 rRNAs identified.
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Lelliottia nimipressuralis type strain SGAir0187 was isolated from tropical air samples collected in Singapore. The genome was assembled with an average coverage of 180-fold using Pacific Biosciences long reads and Illumina MiSeq paired-end reads. The genome measures 4.8 Mb and contains 4,424 protein-coding genes, 83 tRNAs, and 25 rRNAs.
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Acinetobacter indicus (Gammaproteobacteria) is a strict aerobic nonmotile bacterium. The strain SGAir0564 was isolated from air samples collected in Singapore. The complete genome is 3.1 Mb and was assembled using a combination of short and long reads. The genome contains 2,808 protein-coding genes, 80 tRNAs, and 21 rRNA subunits.
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Acinetobacter schindleri strain SGAir0122 was isolated from tropical air samples collected in Singapore. The prevalence of nosocomial infection caused by this Gram-negative bacterium indicates its clinical significance as an opportunistic human pathogen. Its complete genome consists of one chromosome of 3.105 Mb and a plasmid of 181 kb.
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Pseudomonas stutzeri strain SGAir0442 was isolated from tropical air samples collected in Singapore. It is a Gram-negative denitrifying bacterium and an opportunistic human pathogen. Its complete genome consists of one chromosome of 4.52 Mb, containing 4,129 protein-coding genes, 12 rRNA subunits, and 62 tRNAs.
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Staphylococcus haemolyticus is a coagulase-negative staphylococcal species that is part of the skin microbiome and an opportunistic human pathogen. The strain SGAir0252 was isolated from tropical air samples collected in Singapore, and its complete genome comprises one chromosome of 2.63 Mb and one plasmid of 41.6 kb.