Phylogenetic and genome characterization
The nearly complete the 16S rRNA gene sequence of CAU 1569T (1,511 bp) was investigated for similarity among sequences of related bacterial strains in the GenBank databases (access May 2021) and submitted to the GenBank/EMBL/DDBJ under the accession number MN544292. The 16S rRNA gene sequence analysis revealed that strain CAU 1569T was a novel strain belonging to the genus Snuella with 95.8%, 95.5%, and 95.4% pairwise similarities to S. lapsa JC2132T, M. gromovii KMM 6038T, and A.marinum IP7T, respectively. The neighbour-joining phylogenetic tree indicated that strain CAU 1569T clustered with members of the genus Snuella (Fig. 1). The draft genome of strain CAU 1569T was composed 57 contigs (average length 76,651 bp) and a total genome size of 4.4 Mb. DNA G+C content of CAU 1569T was 35.7 mol%, this value is lower than that of closely related members of the genus Snuella (Table 1). The K-mer coverage was 272.8, and the N50 value was 147,344 bp. The genome of strain CAU 1569T was composed contained 3,437 protein-coding genes with 3,462 coding sequences, 3 rRNAs (5, 16, and 23S), and 43 tRNAs. The overall genome related index (OGRI) was not calculated according to minimal standards for using genome data (Chun et al., 2018), which is the threshold value of 16S sequence similarity (< 98.5%) of a novel species. The subsystem genome features of strain CAU 1569T with RAST server are summarized in Fig. S1. Genome annotations (> 7%) of strain CAU 1569T were included “Amino Acids and Derivatives” (214 genes), “Carbohydrates” (122 genes), “Respiration” (26 genes), and “Cofactors, Vitamins, Prosthetic Groups, Pigments” (148 genes).
Table 1
Differential properties of strain CAU 1569T and the type strains of the most closely related taxa
|
Characteristic
|
1
|
2
|
3
|
4
|
5
|
6
|
Temperature (°C):
|
|
|
|
|
|
|
Range
|
4-37
|
10-40 a
|
4-37 b
|
4-37 c
|
5-40 d
|
23-39 e
|
Optimum
|
25-30
|
30 a
|
23-25 b
|
30 c
|
25-30 d
|
33-36 e
|
pH:
|
|
|
|
|
|
|
Range
|
4.5-12.0
|
6.0-9.0a
|
5.5-10.0b
|
6.0-11.0c
|
6.0-8.5d
|
5.0-8.0e
|
Optimum
|
7.0-7.5
|
7.0a
|
7.5/8.3b
|
7.0-9.0 c
|
7.0d
|
7.0e
|
NaCl (%, w/v)
|
|
|
|
|
|
|
Range
|
0.0-15.0
|
1.0-7.0a
|
0.5–9.0a
|
0.5–9.0b
|
1.0-8.0c
|
0.5-3.0e
|
Optimum
|
0.0-4.0
|
3.0-4.0a
|
0.0-6.0 a
|
2.0-4.0b
|
1.0-2.0c
|
1.0e
|
Nitrate reduction
|
–
|
–
|
–
|
+
|
–
|
–
|
Enzyme activities:
|
|
|
|
|
|
|
Cystine arylamidase
|
+
|
–
|
+
|
+
|
+
|
+
|
Trypsin
|
–
|
–
|
+
|
+
|
+
|
–
|
α-chymotrypsin
|
–
|
–
|
+
|
–
|
–
|
–
|
α-galactosidase
|
–
|
–
|
–
|
+
|
+
|
–
|
β-galactosidase
|
–
|
–
|
–
|
+
|
–
|
+
|
α-glucosidase
|
+
|
–
|
–
|
+
|
+
|
–
|
α-fucosidase
|
+
|
+
|
–
|
+
|
–
|
–
|
Assimilation:
|
|
|
|
|
|
|
Glucose
|
–
|
–
|
+
|
–
|
–
|
–
|
d-Mannose
|
–
|
–
|
+
|
–
|
–
|
–
|
Acid production:
|
|
|
|
|
|
|
Arbutin
|
–
|
–
|
–
|
–
|
+
|
–
|
Cellobiose
|
–
|
–
|
–
|
–
|
+
|
–
|
DNA G+C content (mol %)
|
35.7
|
35.0a
|
35.7b
|
37.4c
|
46.4d
|
51.4e
|
Strains: 1, CAU 1569T; 2, S. lapsa KACC 14152T (this study and Yi et al. (2011)a); 3, M. gromovii KCTC 12570T (this study and Nedashkovskaya et al. (2006)b); 4, A. marinum KCTC 52521T (this study and Choi et al. (2018)c); 5, A. suncheonense KACC 16186T (this study and Jeong et al. (2013)d); 6 Y. aromativorans KCCM 42019T (this study and Kwon et al. (2006)e). All data were obtained in the present study unless otherwise indicated. All strains were positive for the esculin hydrolysis, alkaline phosphate, esterase (C4), leucine arylamidase, valine arylamidase, acid phosphatase, napthol-AS-BI-phosphohydrolase, N-acetyl-β-glucosaminidase and 5-keto-gluconate.
+ Positive, – Negative.
|
Physiological characterization
Strain CAU 1569T were gram-stain-negative, aerobic, motile by gliding and rod-shaped (0.6 – 0.8 µm in width and 1.8 - 2.5 µm in length). Colonies were observed to be yellow, circular, smooth, opaque and convex with entire margins with 1.0 – 3.0 mm in diameter. Cells have no flagella (Fig. S2). Gliding motility, which does not require flagella or pili, is common characterization among the family Flavobacteriaceae (Gavriilidou et al., 2020). Strain CAU 1569T grew at temperature range of 20–37°C, NaCl concentration of 2–6% (w/v) and pH 6.0–9.0. The characteristics between strain CAU 1569T and closely related reference strains of the genus Snuella were summarized in Table 1. Strain CAU 1569T was positive for catalase, esculin hydrolysis, citrate utilization, acetoin production, cystine arylamidase, α-glucosidase, β-glucosidase, α-fucosidase and potassium 5-keto-gluconate, but negative for oxidase production, hydrolysis of casein and starch, urease, gelatinase, nitrate reduction, indole production, arginine dihydrolase, lysine decarboxylase, and tryptophane deaminase. Strain CAU 1569T differed from closely related species, namely, S. lapsa JC2132T, based on negative reactions for oxidase production. In addition, strain CAU 1569T differed from M. gromovii KMM 6038T, A. marinum IP7T, A. suncheonense SC17T and Y. aromativorans GW1-1T based on positive reactions for α-fucosidase. Based on the comparison of phenotypic characteristics, strain CAU 1569T could be distinguished from recognized species of the genus Snuella.
Chemotaxonomic characterization
The isoprenoid quinone detected from strain CAU 1569T was only MK-6, which is typical feature of the genus Snuella (Yi and Chun, 2011) as well as the family Flavobacteriaceae (Bernardet et al., 1992). The major fatty acids (> 10% of the total fatty acids) of strain CAU 1569T were iso-C15:0 (22.3%), C17:0 iso 3-OH (15.7%) and C15:1-iso G (12.0%). The fatty acids profile of strain CAU 1569T was similar with those of S. lapsa JC2132T, A. marinum IP7T, A. suncheonense SC17T and Y. aromativorans GW1-1T, especially iso-C15:0, C15:1-iso G, and C17:0 iso 3-OH were major fatty acids (Table 2). The major polar lipids of strain CAU 1569T were diphosphatidylglycerol and aminoglycolipid, and minor components were unidentified aminolipid, and three unidentified lipids (Fig. S3). The major polar lipids of strain CAU 1569T were similar with those of S. lapsa JC2132T in that diphosphatidylglycerol and aminoglycolipid are major components.
Table 2
Cellular fatty acid compositions (%) of strain CAU 1569T and the type strains of the most closely related taxa
|
Fatty acid
|
1
|
2
|
3
|
4
|
5
|
6
|
Saturated
|
|
|
|
|
|
|
C13:0-iso
|
0.7
|
1.0
|
0.9
|
TR
|
0.7
|
0.7
|
C14:0
|
TR
|
TR
|
0.5
|
TR
|
1.7
|
0.7
|
C14:0-iso
|
0.8
|
1.1
|
1.2
|
0.9
|
0.8
|
2.2
|
C15:0-iso
|
22.3
|
20.0
|
-
|
26.7
|
28.3
|
20.3
|
C15:0 anteiso
|
5.4
|
4.3
|
6.8
|
4.9
|
5.7
|
7.4
|
C15:1 anteiso A
|
1.0
|
0.9
|
1.1
|
0.8
|
TR
|
TR
|
C15:1-iso
|
-
|
-
|
18.3
|
-
|
-
|
-
|
C15:1-iso G
|
12.0
|
12.5
|
18.3
|
11.7
|
5.8
|
6.8
|
C16:0
|
1.9
|
1.6
|
1.8
|
1.7
|
8.2
|
2.2
|
C16:0-iso
|
0.5
|
1.0
|
1.3
|
2.1
|
1.4
|
3.6
|
C16:1-iso H
|
0.8
|
0.8
|
0.5
|
0.9
|
1.9
|
1.5
|
C17:0-iso
|
TR
|
TR
|
-
|
TR
|
TR
|
0.6
|
C17:0 anteiso
|
-
|
-
|
-
|
-
|
-
|
0.2
|
C17:1 anteiso ω9c
|
-
|
-
|
-
|
-
|
2.0
|
-
|
Unsaturated
|
|
|
|
|
|
|
C15:1 ω6c
|
1.6
|
2.3
|
4.9
|
1.1
|
TR
|
1.0
|
C17:1 ω6c
|
1.1
|
1.2
|
1.1
|
1.0
|
TR
|
1.0
|
C17:1 ω8c
|
0.6
|
0.7
|
0.9
|
TR
|
TR
|
0.8
|
C18:1 ω5c
|
0.6
|
TR
|
-
|
TR
|
0.9
|
TR
|
Hydroxy
|
|
|
|
|
|
|
C15:0 2-OH
|
1.3
|
1.6
|
2.2
|
1.1
|
0.9
|
1.7
|
C15:0 3-OH
|
2.8
|
3.0
|
2.9
|
1.5
|
-
|
1.7
|
C16:0 3-OH
|
2.0
|
1.5
|
1.2
|
1.5
|
3.4
|
1.4
|
C17:0 2-OH
|
2.2
|
1.9
|
1.8
|
1.6
|
1.7
|
2.6
|
C17:0 3-OH
|
0.9
|
0.9
|
1.0
|
-
|
-
|
-
|
C15:0 iso 3-OH
|
8.9
|
8.8
|
6.7
|
5.8
|
5.2
|
4.4
|
C16:0 iso 3-OH
|
5.2
|
7.1
|
6.1
|
5.4
|
3.9
|
10.6
|
C17:0 iso 3-OH
|
15.7
|
16.1
|
12.2
|
18.1
|
14.6
|
12.6
|
Summed feature*
|
|
|
|
|
|
|
3; C16:1 ω6c/C16:1 ω7c
|
7.1
|
7.5
|
7.0
|
9.7
|
6.1
|
10.0
|
9; (iso-C17:1 ω9c/C16 :0 10-methyl
|
3.0
|
2.0
|
0.6
|
1.4
|
5.1
|
4.5
|
Strains: 1, CAU 1569T; 2, S. lapsa KACC 14152T; 3, M. gromovii KCTC 12570T; 4, A. marinum KCTC 52521T; 5, A. suncheonense KACC 16186T; 6 Y. aromativorans KCCM 42019T. All data were obtained from this study. –, not detected, TR, Trace amount (<0.5%).
|