Microbial communities in the tropical air ecosystem follow a precise diel cycle.

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.

The dynamics of the midgut microbiome in Aedes aegypti during digestion reveal putative symbionts.

Blood-feeding is crucial for the reproductive cycle of the mosquito Aedes aegypti, as well as for the transmission of arboviruses to hosts. It is postulated that blood meals may influence the mosquito microbiome but shifts in microbial diversity and function during digestion remain elusive. We used whole-genome shotgun metagenomics to monitor the midgut microbiome in 60 individual females of A. aegypti throughout digestion, after 12, 24, and 48 h following blood or sugar meals. Additionally, ten individual larvae were sequenced, showing microbiomes dominated by Microbacterium sp. The high metagenomic coverage allowed for microbial assignments at the species taxonomic level, also providing functional profiling. Females in the post-digestive period and larvae displayed low microbiome diversities. A striking proliferation of Enterobacterales was observed during digestion in blood-fed mosquitoes. The compositional shift was concomitant with enrichment in genes associated with carbohydrate and protein metabolism, as well as virulence factors for antimicrobial resistance and scavenging. The bacterium Elizabethkingia anophelis (Flavobacteriales), a known human pathogen, was the dominant species at the end of blood digestion. Phylogenomics suggests that its association with hematophagous mosquitoes occurred several times. We consider evidence of mutually beneficial host-microbe interactions raised from this association, potentially pivotal for the mosquito's resistance to arbovirus infection. After digestion, the observed shifts in blood-fed females' midguts shifted to a sugar-fed-like microbial profile. This study provides insights into how the microbiome of A. aegypti is modulated to fulfil digestive roles following blood meals, emphasizing proliferation of potential symbionts in response to the dynamic midgut environment.

The genomic characterisation and comparison of Bacillus cereus strains isolated from indoor air.

BACKGROUND: Bacillus cereus is ubiquitous in nature, found in environments such as soil, plants, air, and part of the insect and human gut microbiome. The ability to produce endospores and biofilms contribute to their pathogenicity, classified in two types of food poisoning: diarrheal and emetic syndromes. Here we report gap-free, whole-genome sequences of two B. cereus strains isolated from air samples and analyse their emetic and diarrheal potential. RESULTS: Genome assemblies of the B. cereus strains consist of one chromosome and seven plasmids each. The genome size of strain SGAir0260 is 6.30-Mb with 6590 predicted coding sequences (CDS) and strain SGAir0263 is 6.47-Mb with 6811 predicted CDS. Macrosynteny analysis showed 99% collinearity between the strains isolated from air and 90.2% with the reference genome. Comparative genomics with 57 complete B. cereus genomes suggests these strains from air are closely associated with strains isolated from foodborne illnesses outbreaks. Due to virulence potential of B. cereus and its reported involvement in nosocomial infections, antibiotic resistance analyses were performed and confirmed resistance to ampicillin and fosfomycin, with susceptibility to ciprofloxacin, tetracycline and vancomycin in both strains. CONCLUSION: Phylogenetic analysis combined with detection of haemolytic (hblA, hblC, and hblD) and non-haemolytic (nheA, nheB, and nheC) enterotoxin genes in both air-isolated strains point to the diarrheic potential of the air isolates, though not emetic. Characterization of these airborne strains and investigation of their potential disease-causing genes could facilitate identification of environmental sources of contamination leading to foodborne illnesses and nosocomial infections transported by air.

Complete genome of Enterobacter sichuanensis strain SGAir0282 isolated from air in Singapore.

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.

Deciphering the transcriptomic insight during organogenesis in Castor (Ricinus communis L.), Jatropha (Jatropha curcas L.) and Sunflower (Helianthus annuus L.).

Cultivation of the castor crop is hindered by various factors and one of the approaches for genetic improvement of the crop is through exploitation of biotechnological tools. Response of castor tissues to in vitro culture is poor which necessitated this study on understanding the molecular basis of organogenesis in cultured tissues of castor, through de novo transcriptome analysis and by comparing with jatropha and sunflower having good regeneration ability. Transcriptome profiling analysis was carried out with hypocotyl explants from castor, jatropha and cotyledons from sunflower cultured on MS media supplemented with different concentrations of hormones. Differentially expressed genes during dedifferentiation and organogenic differentiation stages of callus included components of auxin and cytokinin signaling, secondary metabolite synthesis, genes encoding transcription factors, receptor kinases and protein kinases. In castor, many genes involved in auxin biosynthesis and homeostasis like WAT1, vacuolar transporter genes, transcription factors like short root like protein were down-regulated while genes like DELLA were up-regulated accounting for regeneration recalcitrance. Validation of 62 DEGs through qRT-PCR showed a consensus of 77.4% of the genes expressed. Overall study provides set of genes involved in the process of organogenesis in three oilseed crops which forms a basis for understanding and improving the efficiency of plant regeneration and genetic transformation in castor.

Complete Genome Sequence of Enterococcus faecalis Strain SGAir0397, Isolated from a Tropical Air Sample Collected in Singapore.

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.

Complete Genome Sequence of Brevundimonas sp. Strain SGAir0440, Isolated from Indoor Air in Singapore.

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.

Complete Genome Sequence of Citricoccus sp. Strain SGAir0253, Isolated from Indoor Air in Singapore.

Citricoccus sp. strain SGAir0253 was isolated from indoor air collected in Singapore. Its genome sequence was assembled using single-molecule real-time sequencing. It comprises one chromosome of 3.32 Mb and two plasmids of 137 kb and 99 kb. The genome consists of 2,950 protein-coding genes, 49 tRNAs, and 9 rRNAs.

Complete Genome Sequence of Rhodococcus sp. Strain SGAir0479, Isolated from Indoor Air Collected in Singapore.

The complete genome sequence of Rhodococcus sp. strain SGAir0479 is presented here. This organism was isolated from an air sample collected in an indoor location in Singapore. The consensus assembly generated one chromosome of 4.86 Mb (G+C content of 69.8%) and one plasmid of 104,493 bp.

Complete Genome Sequence of Streptomyces sp. Strain SGAir0924, an Actinobacterium Isolated from Outdoor Air in Singapore.

Streptomyces sp. strain SGAir0924 was isolated from outdoor air collected in Singapore. Its genome was assembled using long reads generated by single-molecule real-time sequencing. The final assembly had one chromosome of 7.65 Mb and three plasmids with an average length of 142 kb. The genome contained 6,825 protein-coding genes, 68 tRNAs, and 18 rRNAs.

Complete Genome Sequence of Micrococcus luteus Strain SGAir0127, Isolated from Indoor Air Samples from Singapore.

Micrococcus luteus strain SGAir0127 was isolated from indoor air samples collected in Singapore. The assembly, based on single-molecule real-time sequencing reads, resulted in two contigs, one chromosomal contig with a length of 2.57 Mbp and one nonchromosomal contig of 8.68 kbp. The genome has a total of 2,564 genes.

Complete Genome Sequence of Nissabacter sp. Strain SGAir0207, Isolated from an Air Sample Collected in Singapore.

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.

Complete Genome Sequence of Curtobacterium sp. Strain SGAir0471, Isolated from Singapore Air Samples.

Curtobacterium sp. strain SGAir0471 was isolated from tropical air samples collected in Singapore. The genome was assembled using PacBio RS II long reads and Illumina MiSeq short paired-end reads. The complete genome measures 3.53 Mb and consists of 3,151 protein-coding genes, 49 tRNAs, and 12 rRNAs.

Complete Genome Sequence of Microbacterium sp. Strain SGAir0570, Isolated from Tropical Air Collected in Singapore.

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.

Complete Genome Sequence of Pseudomonas sp. Strain SGAir0191, Isolated from Tropical Air Collected in Singapore.

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.

Genome Sequence of the Tropical Atmosphere Bacterium Pontibacter sp. Strain SGAir0037.

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.

Complete Genome Sequence of Lysinibacillus sp. Strain SGAir0095, Isolated from Tropical Air Samples Collected in Singapore.

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.

Whole-Genome Sequence of Bacillus megaterium Strain SGAir0080, Isolated from an Indoor Air Sample.

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.

Complete Genome Sequence of Staphylococcus haemolyticus Type Strain SGAir0252.

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.

Complete Genome Sequence of Lelliottia nimipressuralis Type Strain SGAir0187, Isolated from Tropical Air Collected in Singapore.

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.