| The sea cucumber culture is a big industry in the marine economy and the distribution of resistant bacteria in the sea cucumber culture environment is concerned by the people. Passage of antimicrobials into the environment can select for resistant bacteria and increase horizontal gene transfer (HGT) and antimicrobial resistance genes (ARG) recombination. There appears to be an unimpeded flow of ARG among the resistome of bacteria from environment, animal and human, resuting in the ARG into the resistomes of pathogens, which will do harm to human health. Samples from two sea cucumber culture ponds in Rongcheng (122° 14’34" E 36° 54’36" N) and the Shuangdao Bay (121° 57’52" E 37° 28’16" N) that were not under the direct influence of human contamination were used as the research objects (SS1, WS1, SS2, WS2, WS3). Samples were serially diluted and plated on different agars for reckoning the number of culturable bacteria. And the results show that the number were 54.4xl04,3.6x104,40xl04,20.5x104 and 4.2x104 per gram or mL in the samples SS1, WS1, SS2, WS2 and WS3. It is shown that bacteria resistant to tetracycline and clindamycin were in high proportion. Disk diffusion method was used to detect phenotypic resistance. MAR index calculation was used to compare similarities and differences among the five groups of samples resistant bacteria population. Through statistical analysis, we found that the resistant bacteria in the sediment samples were greater than that in water samples. The drug-resistant frequency to aminoglycosides, tetracyclines and lincosamides were remarkably greater than that to β-lactam antibiotics, rifampicin, chloramphenicols, macrolides and quinolones. The drug-resistance bacteria were distributed both in sea cucumber culture ponds environment and non-aquacultural environment which were not under the direct influence of human contamination. Among the isolated drug-resistance bacteria, 43.28% were Proteobacteria,28.36% were Firmicutes,25.37% were Bacteroides and 2.99% were Actinobacteria. Based on 16S rDNA sequence,105 isolates were analysed and stored at -80 ℃. There were 53 strains in phylum Proteobacteria,26 strains in phylum Firmicutes,24 strains in phylum Bacteroidetes and 2 strains in phylum Actinobacteria. And 32 potential novel strains were isolated. Besides analyzing the distribution of durg-resistance bacteria, we have isolated five novel strains from the samples. Polyphasic taxonomy method was performed in this study for identifying their taxonomic status.Strain 435T, a catalase- and oxidase-positive, beige-pigmented, facultatively anaerobic and Gram-stain-negative marine bacterium, was isolated from marine sediment collected in the Arctic (8°21’629" E 72°8’827" N). The cells of the type species are short-rod to curve-rod and able to grow at 4-25 ℃, pH 6.0-9.0 and in the presence of 0.5-6.0% (w/v) NaCl. The predominant isoprenoid quinone was identified as Q-8 and the polar lipids are comprised phosphatidylethanolamine (PE) and phosphatidylglycerol (PG). The DNA G+C content is 38.7 mol%. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain 435T belongs to the genus Colwellia. Strain 435T was found to exhibit 92.1-95.6% of the 16S rRNA gene sequence similarities with other species of the genus Colwellia. The differential phenotypic properties, together with the phylogenetic and genetic distinctiveness indicated that strain 435T can be considered to represent a novel species, Colwellia arctica sp. nov., of genus Colwellia. The type strain is 435T (= CICC 10860T= ATCC BAA-2609T).A novel bacterial strain, designated SY21T, was isolated from the coastal area in Weihai, China (122° 0’37" E 37° 31’33" N). Strain SY21T grew optimally at 33-37 ℃, pH 7.0-7.5, and in the presence of 2-3%(w/v) NaCl. The major respiratory quinone is MK-7, and dominant fatty acids are iso-C15:0, iso-C17:03-OH and anteiso-C15:0.The major polar lipids are phosphatidylethanolamine (PE), aminolipid (AL) and an unidentified lipid (L), and the G+C content is 37.9 mol%. According to phylogenetic analysis based on 16S rRNA sequences, strain SY21T exhibited 94.7% similarity with Mariniphaga anaerophila JCM 18693T and was affiliated with the genus Mariniphaga. The distinct phylogenetic position and phenotypic traits distinguished the novel isolate from other closely related species. The collective findings suggest that strain SY21T represents a novel species of the genus Mariniphaga, for which the name Mariniphaga sediminis sp. nov. is proposed. The type strain is SY21T (= KCTC 42260T= MCCC 1H00107T).A yellow-pigmented, Gram-stain-negative and facultatively anaerobic bacterium, designated FB218T, was isolated from a sediment sample collected from sea cucumber culture pond in Rongcheng, China (122°14’34" E 36° 54’36" N). Phylogenetic analysis based on 16S rRNA gene sequence showed that strain FB218T belonged to the genus Carboxylicivirga, family Marinilabiliaceae. The predominant fatty acid was iso-C15:0 and anteiso-C15:0. MK-7 was the main respiratory quinone. The major polar lipids of strain FB218T were two unidentified lipids and phospholipid (PL).The genomic DNA G+C content was 40.0 mol%. Based on the distinct phylogenetic position and the combination of physiological and phenotypic characteristics, strain FB218T is presented as a novel species for which the name Carboxylicivirga linearis sp. nov. is proposed. The type strain of Carboxylicivirga linearis is FB218T(= KCTC 42254T= MCCC 1H00106T).A yellow-pigmented, Gram-stain-negative and facultatively anaerobic bacterium, designated MF326T, was isolated from a sample of sediment collected from sea cucumber culture pond in Rongcheng, China (122°14’34" E 36°54’36" N). Cells of strain MF326T were catalase-negative and oxidase-positive. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain MF326T exhibited the highest sequence similarity (94.3%) with the type strain of Mesonia ostreae, followed by Mesonia algae (93.9%), which indicated that the new isolate represents a novel species of the genus Mesonia. The predominant fatty acid of strain MF326T was iso-C15:0, unknown fatty acid with an equivalent chain-length of 13.565 and anteiso-C15:0.The major polar lipids were two unknown lipids and phosphatidylethanolamine. The major respiratory quinone was MK-6 and the genomic DNA G+C content was 40.7 mol%. On the basis of the phylogenetic distinctions and differential phenotypic characteristics, it is suggested that strain MF326T (=KCTC 42255T= MCCC 1H00125T) should be assigned to the genus Mesonia as the type strain of a novel species, for which the name Mesonia sediminis sp. nov. is proposed.A Gram-stain-negative, facultatively anaerobic, orange-pigmented bacterium, designated HQYD1T, was isolated from a styela clava and was characterized taxonomically by using a polyphasic approach. Cells of strain HQYD1T were rods with gliding motility. The novel isolate grew optimally at 28 ℃ and in the presence of 2-3% NaCl. The highest level of 16S rRNA gene sequence similarity was with [Saccharicrinis] marina Y11T (94.83%) followed by Saccharicrinis fermentans DSM 9555T (92.28%). The dominant fatty acids of strain HQYD1T were identified as C16:0, C18:0 and iso-C15:0.Major polar lipids are unidentified lipids and phospholipid. The major respiratory quinone was found to be MK-7. Based on evidence from this polyphasic taxonomic study, a novel genus, Labilibacter gen. nov., is proposed in the family Marinilabiliaceae with one novel species, Labilibacter aurantiaca gen. nov. sp. nov. with type strain HQYD1T (= MCCC 1K02304T= KCTC 42583T). [Saccharicrinis] marina Y11T is reclassified as Labilibacter marina comb. nov. (= CICC10837T= KCTC42400T), as a member of the genus Labilibacter.It can offer a theoretical basis for the relevant departments of supervision and management through the analysis of the distribution of resistant bacteria. Study of five novel strains can enrich the marine microorganism and reserve the resource of research on novel gene. |
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