Shewanella cyperi sp. nov., a facultative anaerobic bacterium isolated from mangrove sediment

Isolation and genomics of ten novel Shewanella species from mangrove wetland

Mangrove bacteria largely compose the microbial community of the coastal ecosystem and are directly associated with nutrient cycling. In the present study, 12 Gram-negative and motile strains were isolated from a mangrove wetland in Zhangzhou, China. Pairwise comparisons (based on 16S rRNA gene sequences) and phylogenetic analysis indicated that these 12 strains belong to the genus Shewanella. The 16S rRNA gene sequence similarities among the 12 Shewanella strains and their related type strains ranged from 98.8 to 99.8 %, but they still could not be considered as known species. The digital DNA-DNA hybridization (dDDH) and average nucleotide identity (ANI) values between the 12 strains and their related type strains were below the cut-off values (ANI 95-96% and dDDH 70 %) for prokaryotic species delineation. The DNA G+C contents of the present study strains ranged from 44.4 to 53.8 %. The predominant menaquinone present in all strains was MK-7. The present study strains (except FJAT-53532^T) also contained ubiquinones (Q-8 and Q-7). The polar lipid phosphatidylglycerol and fatty acid iso-C_15 : 0 was noticed in all strains. Based on phenotypic, chemotaxonomic, phylogenetic and genomic comparisons, we propose that these 12 strains represent 10 novel species within the genus Shewanella, with the names Shewanella psychrotolerans sp. nov. (FJAT-53749^T=GDMCC 1.2398^T=KCTC 82649^T), Shewanella zhangzhouensis sp. nov. (FJAT-52072^T=MCCC 1K05363^T=KCTC 82447^T), Shewanella rhizosphaerae sp. nov. (FJAT-53764^T=GDMCC 1.2349^T=KCTC 82648^T), Shewanella mesophila sp. nov. (FJAT-53870^T=GDMCC 1.2346^T= KCTC 82640^T), Shewanella halotolerans sp. nov. (FJAT-53555^T=GDMCC 1.2344^T=KCTC 82645^T), Shewanella aegiceratis sp. nov. (FJAT-53532^T=GDMCC 1.2343^T=KCTC 82644^T), Shewanella alkalitolerans sp. nov. (FJAT-54031^T=GDMCC 1.2347^T=KCTC 82642^T), Shewanella spartinae sp. nov. (FJAT-53681^T=GDMCC 1.2345^T=KCTC 82641^T), Shewanella acanthi sp. nov. (FJAT-51860^T=GDMCC 1.2342^T=KCTC 82650^T) and Shewanella mangrovisoli sp. nov. (FJAT-51754^T=GDMCC 1.2341^T= KCTC 82647^T).

Shewanella subflava sp. nov., a novel multi-resistant bacterium, isolated from the estuary of the Fenhe River into the Yellow River

A aerobic, gram-negative, rod-shaped and polar-flagellum bacterial strain, designated as FYR11-62^T, was isolated from the estuary of the Fenhe River into the Yellow River in Shanxi Province, China. The isolate was able to grow at 4-37 °C (optimum, 25 °C), pH 5.5-9.5 (optimum, pH 7.5) and in the presence of 0-7.0% (w/v) NaCl (optimum, 1.0% NaCl). Phylogenetic analyses based on 16S rRNA genes and 1597 single-copy orthologous clusters indicated that strain FYR11-62^T affiliated with the genus Shewanella and shared the highest 16S rRNA gene sequence similarity to Shewanella aestuarii SC18^T (98.3%) and Shewanella gaetbuli TF-27^T (97.3%), respectively. The major fatty acids were summed feature 3 (C_16:1 ω7c and/or C_16:1 ω6c), C_16:0 and iso-C_15:0. The major polar lipids were phosphatidylethanolamine and phosphatidylglycerol. The main quinones were Q-7 and Q-8. The genomic DNA G + C content was 41.6%. Gene annotation showed that strain FYR11-62^T possessed 30 antibiotic resistance genes, implying its multiple antidrug resistance. The average nucleotide identity and digital DNA-DNA hybridization values between strain FYR11-62^T and its closely related species were all below the thresholds for species delineation. The phylogenetic position together with the results of the analysis of morphological, physiological and genomic features support the classification of strain FYR11-62^T (= MCCC 1K07242^T = KCTC 92244^T) as a novel species of the genus Shewanella, for which the name Shewanella subflava sp. nov. is proposed.

Shewanella shenzhenensis sp. nov., a novel Fe(III)-reducing bacterium with abundant possible cytochrome genes, isolated from mangrove sediment

A facultative anaerobic bacterium, designated as A25^T, was isolated from a mangrove sediment sample collected in Shenzhen, China. Cells of strain A25^T were found to be Gram-staining negative, rod-shaped, flagella-harboring, and oxidase- and catalase-positive. The isolate was able to grow at 4-40 °C (optimum 28 °C) and pH 5.0-9.0 (optimum pH 6.0), and in 0-10% NaCl concentration (w/v) (optimum 1%). Strain A25^T was capable of reducing Fe(III) citrate under anaerobic conditions. The major fatty acids of this strain was C_16:1ω7c/C_16:1ω6c (summed feature 3), C_17:1ω8c and iso-C_15:0. Results of phylogenetic analyses based on 16S rRNA gene sequences indicated that strain A25^T is affiliated with the genus Shewanella, showing the highest similarity to Shewanella seohaensis S7-3^T (98.4% similarity). The average nucleotide identity and digital DNA-DNA hybridization values between the genomes of strain A25^T and its closely related strains were ≤ 79.0% and ≤ 22.8%, respectively. Based on its phenotypic, phylogenetic properties and physiological and biochemical characteristics, strain A25^T (= JCM 34900^T = GDMCC 1.2731^T) was designated as the type strain of a novel species of the genus Shewanella, for which the name Shewanella shenzhenensis sp. nov. was proposed.

Stress response mechanisms and description of three novel species Shewanella avicenniae sp. nov., Shewanella sedimentimangrovi sp. nov. and Shewanella yunxiaonensis sp. nov., isolated from mangrove ecosystem

Three Gram-staining negative, facultatively anaerobic, rod-shaped and motile strains, FJAT-51800^T, FJAT-52962^T and FJAT-54481^T were isolated from the sediment samples of Zhangjiang Estuary Mangrove National Nature Reserve in Fujian Province, China. The 16S rRNA gene sequencing results indicated they could be novel members of the genus Shewanella. The optimum temperature for growth was 30 °C. The respiratory quinones of the strains were ubiquinone Q-7 or Q-8, and menaquinone MK-7. Polar lipids of the strains FJAT-52962^T and FJAT-51800^T were phosphatidyl glycerol, phosphatidyl ethanolamine, and unidentified aminophospholipids while strain FJAT-54481 consist of phosphatidylglycerol, phosphatidylethanolamine, unidentified aminophospholipids, two unidentified aminolipids and four unidentified lipids. The major fatty acid of the three strains was iso-C_15:0. The genomic DNA G + C contents of strains FJAT-51800^T, FJAT-52962^T and FJAT-54481^T were 48.2, 55.3 and 48.1%, respectively. The average nucleotide identity and digital DNA-DNA hybridization values between strains FJAT-51800^T, FJAT-52962^T and FJAT-54481^T and other closely related Shewanella members were below the cut-off level (95-96%) for species identification. Genome analysis showed that these strains encode genes for osmo-regulation. Based on the results of phenotypic, chemotaxonomic and genome analyses, strains FJAT-51800^T, FJAT-52962^T and FJAT-54481^T represent three novel species of the genus Shewanella, for which the names Shewanella avicenniae sp. nov., Shewanella sedimentimangrovi sp. nov., and Shewanella yunxiaonensis sp. nov., are proposed. The type strains are FJAT-51800^T (= GDMCC 1.2204^T = KCTC 82448^T), FJAT-52962^T (= MCCC 1K05496^T = KCTC 82445^T) and FJAT-54481^T (= GDMCC 1.2348^T = KCTC 82646^T).