## 3 Results and Discussion  
### Morphological, Physiological, and Biochemical Characteristics  
Transmission electron microscope (TEM) observation of OS4T indicated that OS4T was non-flagella, which was similar to the relatively closed strains _J. helgolandensis_ 14858T and _J. aquimarina_ GSW-M26T (Figure 2) [7; 18]. The Gram-staining result indicates that OS4T is Gram-negative, which is consistent with species in the genus _Januschia_. The TEM showed that OS4T was oval with a length of 0.8-2.0 \(\upmu\)m and a width of 0.5-0.8 \(\upmu\)m. The growth was poor at 20 \({}^{\circ}\)C, ranging to 37 \({}^{\circ}\)C, with an optimum temperature of 25 \({}^{\circ}\)C. Poor growth was observed in the absence of sea salts. The pH range tolerated for growth was 7.0-8.5 (with 8.0 as optimum pH) (Table 1). Strain OS4T showed the ability to hydrolyze alginate and casein but not starch and tween (20, 40, 60, and 80) (Table 1). According to the API ZYM results, strain OS4T and its relative species showed positive reactions for alkaline phosphatase, esterase (C4), and esterase lipase (C8), and only OS4T has lipase (C14), leucine arylamidase, valine arylamidase, cystine arylamidase, and acid phosphatase activities. _The antibiotic susceptibility results showed that strain OS4T was susceptible to clarithromycin, ceftaxone, penicillin, erythromycinromycin, cefotaxime, rifampicin, norfloxacin, polymorphxin B, vancomycin, and limomycin but resistant to kanamycin, carbenicillin, neomycin, chloramphenicol, gentamycin, ofloxacin, oxytetracycline, streptomycin, ampicillin, tobramycin, tetracycline, and clindamycin (Table S1)._ Broad-spectrum profiles of ARG abundance were conducted with the assembled genome by CARD GRI. Including _ompA_, _adeL_,\(S\), _tetA_,\(B\), _AAC_(_6_')-_lak_, _lptD_, _bcr-1_, and _optrA_, 86 hits belonging to 10 ARG types were detected in OS4T, which is consistent with the phenotypic antibiotic resistance measurements (Table S2). The detailed phenotypical features and species description are shown in Table 1.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Characteristics** & **OS4T** & **1485S1T** & **GSW-M26T** \\ \hline
**Cell size (\(\upmu\)m)** & 0.5–0.8 \(\times\) 0.8–2.0 & 0.7–1.1 \(\times\) 1.9–3.2 & 0.5–0.7 \(\times\) 0.5–4.0 \\
**pH range for growth** & 7.0–8.5 (8.0) & 7.0–8.0 (7.5) & 5.5–8.0 (7.0–8.0) \\
**NaCl range (\%)** & 0–5.0 (2.0) & 1–7.0 (2.0) & 0–7.0 (2) \\
**Growth temperature (\({}^{\circ}\)C)** & 20–37 (25) & 15–30 (25) & 15–37 (30) \\
**Catalase** & + & + & + \\
**Oxidase** & + & + & + \\
**Hydrolysis of** & - & + & + \\ Starch & + & - & - \\ Alginate & + & - & - \\ Tween (20, 40, 60, 80) & - & - & + \\ Casein & + & - & - \\
**Utilization of:** & + & - & + \\ Sucrose & - & + & + \\ yesD-xylose & - & + & + \\ D-glucose & - & - & + \\ D-ructose & + & + & + \\ Asesculin & w & - & - \\ D-mannose & - & - & + \\
5-ketoglucate & - & + & + \\
**Enzyme activity** & & & \\ alkaline phosphatase & + & + & + \\ esterase(C4) & + & + & + \\ esterase lipase (C8) & + & W & + \\ lipase (C14) & + & - & + \\ leucine arylamidase & + & - & + \\ valine arylamidase & + & - & + \\ cystine arylamidase & W & - & W \\ Trypsin & - & - & - \\ \(\alpha\)-chymotrypsin & - & - & - \\ acid phosphatase & + & - & + \\ naphtol-AS-BI-phosphhydrolase & - & - & W \\ \(\alpha\)-galactosidasease & - & - & + \\ \(\beta\)-galactosidasease & - & - & - \\ \(\beta\)-glucuronidase & - & - & - \\ \(\alpha\)-glucose & + & - & + \\ \(\beta\)-glucosidase & - & - & + \\ \hline \hline \end{tabular} Values in bracket represent the optimal temperature, pH, and NaCl for growth. All the data were obtained from this study unless otherwise indicated +, Positive; -, negative; w, weakly positive.  
\end{table}
Table 1: Differential phenotypic characteristics of strain OS4T and its related species.  
Figure 2: Transmission electron microscope (bar, 500 nm) images of cells of strain OS4T.