AUTHOR=Fang Yujie , Wang Yonglu , Li Zhenpeng , Liu Zongdong , Li Xinyue , Diao Baowei , Kan Biao , Wang Duochun 

TITLE=Distribution and Genetic Characteristics of SXT/R391 Integrative Conjugative Elements in Shewanella spp. From China

JOURNAL=Frontiers in Microbiology

VOLUME=9

YEAR=2018

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2018.00920

DOI=10.3389/fmicb.2018.00920

ISSN=1664-302X

ABSTRACT=<p>The genus <italic>Shewanella</italic> consists of facultatively anaerobic Gram-negative bacteria, which are regarded as potential agents of food contamination and opportunistic human pathogens. Information about the distribution and genetic characteristics of SXT/R391 integrative conjugative elements (ICEs) in <italic>Shewanella</italic> species is limited. Here, 91 <italic>Shewanella</italic> strains collected from diverse samples in China were studied for the presence of SXT/R391 ICEs. Three positive strains, classified as <italic>Shewanella upenei</italic>, were obtained from patients and water from a local mill. In light of their close clonal relationships and high sequence similarity, a representative ICE was selected and designated ICE<italic>Sup</italic>CHN110003. The BLASTn searches against GenBank showed that ICE<italic>Vch</italic>Ban5 was most closely related to ICE<italic>Sup</italic>CHN110003, with the coverage of 76% and identity of 99%. The phylogenetic tree of concatenated core genes demonstrated that ICE<italic>Sup</italic>CHN110003 formed a distinct branch outside the cluster comprising ICE<italic>Val</italic>A056-1, ICE<italic>Pmi</italic>CHN2410, and ICE<italic>Pmi</italic>Chn1. Comparison of the genetic structures revealed that ICE<italic>Sup</italic>CHN110003 encoded uncommon genes in hotspots, such as specific type III restriction-modification system, conferring adaptive functions to the host. Based on the low coverage in the sequence analysis, independent clade in the phylogenetic tree, and unique inserted fragments in hotspots, ICE<italic>Sup</italic>CHN110003 represented a novel SXT/R391 element, which widened the list of ICEs. Furthermore, the antibiotic resistance genes <italic>floR</italic>, <italic>strA</italic>, <italic>strB</italic>, and <italic>sul2</italic> in ICE<italic>Sup</italic>CHN110003 and resistance to multiple drugs of the positive isolates were detected. A cross-species transfer capability of the SXT/R391 ICEs was also discovered. In summary, it is necessary to reinforce continuous surveillance of SXT/R391 ICEs in the genus <italic>Shewanella</italic>.</p>