An aerobic, Gram-stain-negative, yellowish, rod-shaped bacterium, designated DJ1R-1T, was isolated from water sample from a volcanic lake, located on Da Hinggan Ling Mountain, PR China. Growth of DJ1R-1T optimally occurred at pH 7.0, at 22–25 °C and with 0–0.5 % (w/v) NaCl concentration. Phylogenetic analysis of 16S rRNA gene sequences indicated that DJ1R-1T was clustered into the genus Polymorphobacter, and showed 96.5 %, 95.9 % and 95.6 % similarities to Polymorphobacter fuscus D40PT, Polymorphobacter multimanifer 262-7T and Polymorphobacter glacialis B555-2T, respectively. The predominant polar lipids were phosphatidylethanolamine, phosphatidylglycerol, one unidentified aminophospholipid, three unidentified aminolipids and one unidentified phospholipid. The major fatty acids were summed feature 8 (C18 : 1ω7c / C18 : 1ω6c, 40.0 %), summed feature 3 (C16 : 1ω7c / C16 : 1ω6c, 25.6 %) and C16 : 0 (13.7 %). The respiratory quinone was ubiquinone-10. The DNA G+C content was 65.0 % according to the genomic sequencing results. On the basis of the results of the phylogenetic analysis, physiological and biochemical properties comparisons, DJ1R-1T was proposed to represent a novel species of the genus Polymorphobacter , with the name Polymorphobacter arshaanensis. The type strain is DJ1R-1T (=CGMCC 1.13788T=KCTC 72014T).

As the COVID-19 pandemic continues, there is growing concordance and persisting conflicts on the virus and the disease process. We discuss limited transmissibility of the virus by asymptomatic and mild cases of COVID-19 patients in Bhutan. We followed up the secondary transmission of SARS-CoV-2 in the contacts of asymptomatic and mild COVID-19 patients in Bhutan. Bhutan had 33 confirmed COVID-19 cases in the country as of May 29, 2020. Of these, 22 (67%) were females. Except the first two cases (American tourists), the rest were Bhutanese living outside the country. The mean age of the Bhutanese patients was 26.3 (range 16–33) years. Close contacts of 27 of the 33 cases were followed up for signs and symptoms and COVID-19 positivity. The first two cases had 73 and 97 primary contacts, respectively, and equal number of secondary contacts (224). From the third case, a mandatory 21-day facility quarantine was instituted, all primary contacts were facility quarantined, and there were no secondary contacts. In total, the 27 cases had 1,095 primary contacts and 448 secondary contacts. Of these, 75 individuals were categorized as definite high-risk contacts. Secondary transmission occurred in seven high-risk contacts. Therefore, the overall secondary transmission was 9.0% (7/75) and 0.6% (7/1,095) among the high-risk and primary contacts, respectively. No transmission occurred in the secondary contacts. In contrast to several reports indicating high transmissibility of SARS-CoV-2 in contacts of confirmed cases, the mostly young, asymptomatic, and mild cases of COVID-19 in Bhutan showed limited secondary transmission.

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A Gram-stain-negative, aerobic, flagellated, non-spore-forming, rod-shaped bacterium, named B2R-29T, was isolated from water collected from a crater lake on Da Hinggan mountain, PR China. Strain B2R-29T was oxidase- and catalase-positive. On the basis of the results of 16S rRNA gene sequence analyses, strain B2R-29T clearly belonged to the family Oxalobacteraceae , class Betaproteobacteria and showed the highest similarity to Undibacterium oligocarboniphilum EM1T (97.4 %) and to the other species of Undibacterium (less than 96.8 %). In the phylogenetic tree, strain B2R-29T formed a clade with U. oligocarboniphilum EM1T and Undibacterium squillarum CMJ-9T, indicating that is a member of the genus Undibacterium . Digital DNA–DNA hybridization and average nucleotide identity analyses were performed and the values between strain B2R-29T and its closely related Undibacterium species were less than 75.1 % and 16.9 %, respectively. The chemotaxonomic data of B2R-29T were as follows: major uniquinone, Q-8; predominant polar lipids, phosphatidylethanolamine, diphosphatidylglycerol and phosphatidylglycerol; major fatty acids, C16 : 0 and summed feature 3 (C16 : 1  ω7c / C16 : 1  ω6c); predominant polyamines, putrescine, 2-hydroxyputrescine and spermidine. The DNA G+C content was 51.7 mol% from the genomic sequencing data. In accordance with the phenotypic, physiological and chemotaxonomic properties mentioned above, strain B2R-29T represents a novel species of the genus Undibacterium for which the name Undibacterium crateris sp. nov. is proposed. The type strain is B2R-29T (=CGMCC 1.13792T=KCTC 72018T).

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