The continent of Antarctica breeds numerous special extremophiles that have adapted to the extreme variation of environment with a wide range of novel biodiversity. A cold-adapted bacterium Shewanella frigidimarina W32-2, isolated from Antarctic sediments, was identified to be a promising candidate of exopolysaccharides (EPS) production. In the present study, the physiochemistry and bioactivities of the EPS were investigated to promote its application in aquaculture. Physiological characterisation of this strain was firstly performed by means of combined API 20NE and API ZYM tests. A biochemical analysis revealed that the EPS contained a majority of carbohydrates (56.34 +/- 1.29%), uronic acids (8.23 +/- 0.55%) and high content of sulphate groups (35.43 +/- 1.84%), which were also confirmed by the FTIR spectrum showing various functional groups with potential antioxidant activities. The bioactive properties of the EPS in vitro and in vivo were both evaluated. The effect of the EPS on the non-specific immunity of red tilapia via serum injection exhibited 100% of survival rate. Improvement of activities in different serum enzymes, including AKP, ACP, SOD, CAT and LZM, was observed generally at the early stage of EPS treatment (except LZM at later stage). This study explores novel EPS from an extremophile exhibiting powerful bioactivity with immense potential in aquaculture sustainability.

Ethnopharmacological relevance: Baihe Wuyao decoction (BWD), a prescription of Traditional Chinese Medicines, composed of alum brownii var. viridulum Baker.(Lilii Bulbus) and Lindera aggregata (Sims) Kosterm. (Linderae Radix), has been used to treat epigastric pain and superficial gastritis for hundreds of years in China. Recently, some compounds obtained from Lilii Bulbus and Linderae Radix had active effects of hepatic protection or liver fibrosis alleviation. Thus, we aim to evaluate the effects of BWD on treatment of chronic liver injury and liver fibrosis induced by carbon tetrachloride (CCl4) and to elucidate the possible molecular mechanism. Materials and methods: Mice were treated with BWD (low, medium and high dose), diammonium glycyrrhizinate or vehicle by oral gavage once daily, simultaneously intraperitoneal injected with a single dose of CCl4 (1 mu l/g body weight) twice a week for consecutive 6 weeks. Next, all mice were sacrificed after fasted 12 h, and serums and liver tissues were harvested for analysis. The hepatic injury was detected by serum biomarker assay, including aspartate aminotransferase (AST) and alanine aminotransferase (ALT). The hepatic histology and collagen were illustrated by hematoxylin-eosin staining and Sirius red staining respectively. The antioxidant capacity of liver tissues was evaluated by the contents of superoxide dismutase (SOD) and malondialdehyde (MDA) in liver homogenization. The mRNA gene or protein expressions related to fibrosis, oxidative stress and inflammation molecules were performed by real-time quantitative PCR (RT-PCR) or Western-blot. Results: BWD exhibited a good hepatic protection with ameliorating liver histological changes, decreasing serum AST and ALT contents, and reducing hepatic fibrosis with stimulation ECMs (such as Collagen1 and Collagen3) degradation. BWD inhibited hepatic stellate cells (HSCs) activation, promoted matrix metalloproteinase-2 (MMP2), MMP9, and MMP12 while suppressing tissue inhibitors of matrix metalloproteinase-1 (TIMP1) expression, and blocked traditional fibrosis TGF-beta 1/Smad2/3 signal pathway. Moreover, BWD exhibited antiinflammation effect proved by the reduction of liver Interleukin-1 beta (IL-1 beta), TNF-alpha, IL-11 mRNA levels and promoted anti-oxidation effects determined by inhibition of liver MDA and iNOS levels while promoting liver SOD and Mn-SOD. Conclusion: BWD ameliorates CCl4-induced CLI and liver fibrosis which is correlated to its blocking TGF-beta 1/Smad2/3 signaling, anti-inflammation, and anti-oxidation effects. BWD, as a small traditional prescription, is a promising treatment for CLI and liver fibrosis through multiple pharmacological targets.