Transmission Dynamics of an Outbreak of the COVID-19 Delta Variant B.1.617.2——Guangdong Province,China,May-June 2021

On May 21,2021,a local case of coronavirus disease 2019(COVID-19)was confirmed in a 75-year-old woman(experienced onset of symptoms on May 18)in Liwan District,Guangzhou City,Guangdong Province,China.The number of infections has increased in the following 10 days and led to 5 generations of transmission.

Diverse Asgard archaea including the novel phylum Gerdarchaeota participate in organic matter degradation

Asgard is an archaeal superphylum that might hold the key to understand the origin of eukaryotes, but its diversity and ecological roles remain poorly understood. Here, we reconstructed 15 metagenomic-assembled genomes from coastal sediments covering most known Asgard archaea and a novel group, which is proposed as a new Asgard phylum named as the "Gerdarchaeota".Genomic analyses predict that Gerdarchaeota are facultative anaerobes in utilizing both organic and inorganic carbon. Unlike their closest relatives Heimdallarchaeota, Gerdarchaeota have genes encoding for cellulase and enzymes involved in the tetrahydromethanopterin-based Wood–Ljungdahl pathway. Transcriptomics showed that most of our identified Asgard archaea are capable of degrading organic matter, including peptides, amino acids and fatty acids, occupying ecological niches in different depths of layers of the sediments. Overall, this study broadens the diversity of the mysterious Asgard archaea and provides evidence for their ecological roles in coastal sediments.

Genomic insights into versatile lifestyle of three new bacterial candidate phyla

Metagenomic explorations of the Earth's biosphere enable the discovery of previously unknown bacterial lineages of phylogenetic and ecological significance.Here,we retrieved 11 metagenomic-assembled genomes(MAGs)affiliated to three new monophyletic bacterial lineages from the seawater of the Yap Trench.Phylogenomic analysis revealed that each lineage is a new bacterial candidate phylum,subsequently named Candidatus Qinglongiota,Candidatus Heilongiota,and Candidatus Canglongiota.Metabolic reconstruction of genomes from the three phyla suggested that they adopt a versatile lifestyle,with the potential to utilize various types of sugars,proteins,and/or short-chain fatty acids through anaerobic pathways.This was further confirmed by a global distribution map of the three phyla,indicating a preference for oxygen-limited or particle-attached niches,such as anoxic sedimentary environments.Of note,Candidatus Canglongiota genomes harbor genes for the complete WoodLjungdahl pathway and sulfate reduction that are similar to those identified in some sulfate-reducing bacteria.Evolutionary analysis indicated that gene gain and loss events,and horizontal gene transfer(HGT)play important roles in shaping the genomic and metabolic features of the three new phyla.This study presents the genomic insight into the ecology,metabolism,and evolution of three new phyla,which broadens the phylum-level diversity within the domain Bacteria.

Genomic and transcriptomic dissection of Theionarchaea in marine ecosystem

Theionarchaea is a recently described archaeal class within the Euryarchaeota.While it is widely distributed in sediment ecosystems,little is known about its metabolic potential and ecological features.Here,we used metagenomics and metatranscriptomics to characterize 12 theionarchaeal metagenome-assembled genomes,which were further divided into two subgroups,from coastal mangrove sediments of China and seawater columns of the Yap Trench.Genomic analysis revealed that apart from the canonical sulfhydrogenase,Theionarchaea harbor genes encoding heliorhodopsin,group 4[NiFe]-hydrogenase,and flagellin,in which genes for heliorhodopsin and group 4[NiFe]-hydrogenase were transcribed in mangrove sediment.Further,the theionarchaeal substrate spectrum may be broader than previously reported as revealed by metagenomics and metatranscriptomics,and the potential carbon substrates include detrital proteins,hemicellulose,ethanol,and CO_(2).The genes for organic substrate metabolism(mainly detrital protein and amino acid metabolism genes)have relatively higher transcripts in the top sediment layers in mangrove wetlands.In addition,co-occurrence analysis suggested that the degradation of these organic compounds by Theionarchaea might be processed in syntrophy with fermenters(e.g.,Chloroflexi)and methanogens.Collectively,these observations expand the current knowledge of the metabolic potential of Theionarchaea,and shed light on the metabolic strategies and roles of these archaea in the marine ecosystems.