Genomic Characteristics and Evolutionary Analysis of a Rare GI.1 Norovirus Isolate From Beijing, China

Noroviruses are one of the main pathogens of acute gastroenteritis, causing frequent outbreaks worldwide every year that seriously affect human health. The GII.4 genotype causes most norovirus (NoV) infections and large-scale outbreaks. By contrast, the GI genotype is relatively rare. In this study, the whole genome sequence of a newly isolated ZD strain from a patient in Beijing, China, was sequenced and analyzed. The ZD strain genome consisted of 7,597 nucleotides and contained three open reading frames. Whole-genomic analysis indicated the strain was a GI.1 genotype, and no recombination site was detected in the genome. The histo-blood group antigen (HBGA)binding site associated with invasion of the GI genotype did not change, implying relatively conservative evolution. Phylogenetic analysis indicated the VP1 sequence of GI.1 strains could be divided into three clusters according to time of appearance: older (1968-2011), earlier (2011-2015), and new (2017-2018). Each cluster showed distinctive amino acid substitution characteristics, and the number of substitutions increased with time. The isolated ZD strain was in the new cluster. This study is the first to conduct a phylogenetic analysis of a GI genotype NoV isolated from Beijing. The results improve understanding of NoV diversity in China and can be a reference for further study of nondominant epidemic strains of NoVs as well as epidemic prevention and control.

Genome Mining of Secondary Metabolites From a Marine-derived Aspergillus Terreus B12

As an important saprophytic filamentous fungus, Aspergillus terreus is ubiquitously distributed, including soil rhizospheres and marine environments. Due to the prominent capabilities of bioconversion and biosynthesis, A. terreus has become attractive in biotechnical and pharmaceutical industry. In this work, an A. terreus strain, B12, was isolated from sponge in South China Sea, which demonstrated broad bacteriostatic effects against a variety of pathogenic bacteria. The whole genome was sequenced, showing a genetic richness of BGCs, which might underpin the metabolic plasticity and adaptive resilience for the strain. Genome mining identified 67 biosynthetic gene clusters (BGCs), among which, 6 gene clusters could allocate to known BGCs (100% identity), corresponding to diverse metabolites like clavaric acid, dihydroisoflavipucine /isoflavipucine, dimethylcoprogen, alternariol, aspterric acid and pyranonigrin E. However, instead of the putative compounds, several other products were obtained from the B12 fermentation, including terrein, butyrolactone I, terretonin A&E, acoapetaline B and epi-aszonalenins A. Of note, acoapetaline B and epi-aszonalenins A, discovered natural products recently with little information, unexpectedly were reported in this A. terreus strain. The genomic and heterogeneity observed in strain B12, should be at least partially attributed to the genetic variability and biochemical diversity of A. terreus , which could be an interesting issue open to future efforts.

Selection and characterization of twoBacillus thuringiensisstrains showing nematicidal activity againstCaenorhabditis elegansandMeloidogyne incognita

Bacillus thuringiensis has been widely used as a biological control agent against insect pests. Additionally, nematicidal strains have been under investigation. In this report, 310 native strains of B. thuringiensis against Caenorhabditis elegans were tested. Only the LBIT-596 and LBIT-107 strains showed significant mortality. LC50s of spore-crystal complexes were estimated at 37.18 and 31.89 μg/mL for LBIT-596 and LBIT-107 strains, respectively, while LC50s of partially purified crystals was estimated at 23.76 and 20.25 μg/mL for LBIT-596 and LBIT-107, respectively. The flagellin gene sequence and plasmid patterns indicated that LBIT-596 and LBIT-107 are not related to each other. Sequences from internal regions of a cry5B and a cyt1A genes were found in the LBIT-596 strain, while a cry21A, a cry14A and a cyt1A genes were found in the LBIT-107 strain. Genome sequence of the LBIT-107 strain showed new cry genes, along with other virulence factors, hence, total nematicidal activity of the LBIT-107 strain may be the result of a multifactorial effect. The highlight of this contribution is that translocation of spore-crystal suspensions of LBIT-107 into tomato plants inoculated at their rhizosphere decreased up to 90% the number of galls of Meloidogyne incognita, perhaps the most important nematode pest in the world.

StrainGE: A toolkit to track and characterize low-abundance strains in complex microbial communities

Human-associated microbial communities comprise not only complex mixtures of bacterial species, but also mixtures of conspecific strains, the implications of which are mostly unknown since strain level dynamics are underexplored due to the difficulties of studying them. We introduce the Strain Genome Explorer (StrainGE) toolkit, which deconvolves strain mixtures and characterizes component strains at the nucleotide level from short-read metagenomic sequencing with higher sensitivity and resolution than other tools. StrainGE is able to identify nearest known references and find variants for multiple conspecific strains within a sample at relative abundances below 0.1% in typical metagenomic datasets.

Streptomyces tsukubensis VKM Aс-2618D - an Effective Producer of Tacrolimus

The identification of the Streptomyces sp. VKM Ac-2618D strain had been carried out and its morphological and physiological features have been studied in relation to the immunosuppressant tacrolimus production. The phenotypic variability of the strain was analyzed and the dissociant with a high level of tacrolimus production was identified. Based on a comprehensive study of morphological, physiological and chemotaxonomic properties, as well as phylogenetic analysis, the strain was named Streptomyces tsukubensis VKM Ac-2618D. The strain genome contains the full version of the tacrolimus biosynthetic gene cluster. The advantages of fed-batch cultivation mode for tacrolimus biosynthesis were shown. The results obtained expand the understanding of the peculiarities of polyketide biosynthesis and can be used in the development of a tacrolimus production technology. Key words: Streptomyces tsukubensis, tacrolimus, FK-506, dissociant, genome, biosynthesis The research was carried out within the framework of the state assignment АААА-А16-116062110077-6.

Generation and molecular characteristics of a highly attenuated GPV strain through adaptation in GEF cells

Background Goose parvoviruses (GPVs) spread globally and cause a huge economic loss to the poultry industry. Although the attenuated GPV vaccines play a key role in preventing the disease caused by GPV, the molecular basis for the attenuation of GPV is barely known. Results A highly attenuated GPV strain, GPV-CZM-142, was generated through blindly passaging of the highly pathogenic strain, GPV-CZM, in goose embryonic fibroblasts (GEF) for 142 generations. The GEF-adapted GPV strain’s virulence was 10,000 times weaker than its wild type counterpart, GPV-CZM, based on the ELD50 (50% Embryo Lethal Dose). By comparing with the wild type strain, genome sequencing analysis identified adapted mutations either in ITR or in NS and VP1 of GPV-CZM-142. Conclusions The highly attenuated GPV strain, GPV-CZM-142, provides a GPV vaccine candidate, and the identified virulence-related mutations give a novel insight into the molecular determinants of GPV virulence.

gcType: a high-quality type strain genome database for microbial phylogenetic and functional research

Taxonomic and functional research of microorganisms has increasingly relied upon genome-based data and methods. As the depository of the Global Catalogue of Microorganisms (GCM) 10K prokaryotic type strain sequencing project, Global Catalogue of Type Strain (gcType) has published 1049 type strain genomes sequenced by the GCM 10K project which are preserved in global culture collections with a valid published status. Additionally, the information provided through gcType includes >12 000 publicly available type strain genome sequences from GenBank incorporated using quality control criteria and standard data annotation pipelines to form a high-quality reference database. This database integrates type strain sequences with their phenotypic information to facilitate phenotypic and genotypic analyses. Multiple formats of cross-genome searches and interactive interfaces have allowed extensive exploration of the database's resources. In this study, we describe web-based data analysis pipelines for genomic analyses and genome-based taxonomy, which could serve as a one-stop platform for the identification of prokaryotic species. The number of type strain genomes that are published will continue to increase as the GCM 10K project increases its collaboration with culture collections worldwide. Data of this project is shared with the International Nucleotide Sequence Database Collaboration. Access to gcType is free at http://gctype.wdcm.org/.

Generation and molecular characteristics of a highly attenuated GPV strain through adaptation in GEF cells

Background: Goose parvoviruses (GPVs) spread globally and cause a huge economic loss to the poultry industry. Although the attenuated GPV vaccines play a key role in preventing the disease caused by GPV, the molecular basis for the attenuation of GPV is barely known. Results: A highly attenuated GPV strain, GPV-CZM-142, was generated through blindly passaging of the highly pathogenic strain, GPV-CZM, in goose embryonic fibroblasts (GEF) for 142 generations. The GEF-adapted GPV strain's virulence was 10,000 times weaker than its wild type counterpart, GPV-CZM, based on the ELD50 (50% Embryo Lethal Dose). By comparing with the wild type strain, genome sequencing analysis identified adapted mutations either in ITR or in NS and VP1 of GPV-CZM-142.Conclusions: The highly attenuated GPV strain, GPV-CZM-142, provides a GPV vaccine candidate, and the identified virulence-related mutations give a novel insight into the molecular determinants of GPV virulence.

Generation and molecular characteristics of a highly attenuated GPV strain through adaptation in GEF cells

Background: Goose parvoviruses (GPVs) spread globally and cause a huge economic loss to poultry industry. Although the attenuated GPV vaccines play a key role in preventing the disease caused by GPV, the molecular basis for the attenuation of GPV is barely known. Results: A highly attenuated GPV strain, GPV-CZM-142, was generated through blindly passaging of the highly pathogenic strain, GPV-CZM, in goose embryonic fibroblasts (GEF) for 142 generations. The virulence of the GEF-adapted GPV strain was 10000 times weaker than that of its wild type counterpart, GPV-CZM, based on the ELD50. By comparing with the wild type strain, genome sequencing analysis identified a novel insertion in ITR and several other mutations in both NS and VP1 of GPV-CZM-142.Conclusions: The highly attenuated GPV strain, GPV-CZM-142, provides a GPV vaccine candidate, and the identified virulence-related insertion/mutations give a novel insight into the molecular determinants of GPV virulence.