Senecavirus A (SVA) is an emerging non-enveloped virus with a single-stranded, positive-sense RNA genome that belongs to the Senecavirus genus in the Picornaviridae family. Senecavirus A-associated swine idiopathic vesicular disease and epidemic transient neonatal losses have caused substantial economic losses for the swine industry. Here, we describe a case of re-emerging vesicular disease among sows and finishing pigs on a swine farm in Fujian Province of southeast China. Other causative pathogens, including FMDV, SVDV and VSV, were excluded, and a novel SVA strain, CH-FJZZ-2017, was isolated. Sequencing and phylogenetic analysis of the complete genome and individual viral proteins revealed that CH-FJZZ-2017 is closely related to the US strains in 2015. The results further showed that Chinese SVAs have formed two distinct subclades with 2016 as the turning point. Viruses causing outbreaks after late 2016 shared higher nucleotide identities with the US strains in 2015. There is still some evolutionary distance between CH-FJZZ-2017 and other strains isolated in late 2016, suggesting that Chinese SVA isolates have been evolving in different directions. This study provides a basis for the development of effective prevention and control strategies.

Alginate-degrading bacteria or alginate lyases can be used to oligomerize alginate. In this study, an alginate-degrading bacterium with high alginolytic activity was successfully screened by using Sargassum fusiforme sludge. When the strain was grown on a plate containing sodium alginate, the transparent ring diameter (D) was 2.2 cm and the ratio (D/d) of transparent ring diameter to colony diameter (d) was 8.8. After 36 h in culture at a temperature of 28 °C shaken at 150 r/min, the enzymatic activity of the fermentation supernatant reached 160 U/mL, and the enzymatic activity of the bacterial precipitate harvested was 2,645 U/mL. The strain was named Cobetia sp. cqz5-12. Its genome is circular in shape, 4,209,007 bp in size, with a 62.36% GC content. It contains 3,498 predicted coding genes, 72 tRNA genes, and 21 rRNA genes. The functional annotations for the coding genes demonstrated that there were 181 coding genes in the genome related to carbohydrate transport and metabolism and 699 coding genes with unknown functions. Three putative coding genes, alg2107, alg2108 and alg2112, related to alginate degradation were identified by analyzing the carbohydrate active enzyme (CAZy) database. Moreover, proteins Alg2107 and Alg2112 were successfully expressed and exhibited alginate lyase activity. Alginate is a kind of water-soluble acidic polysaccharide found on the cell walls of algae, such as Gigantophtha, Charcot algae, Laminaria japonica, and Sargassum fusiformis. It is formed by the random combination of beta-d-1,4-mannosuronic acid and alpha-l-1,4-gulosuronic acid 1, 2. Because of its high degree of polymerization, high molecular weight, and high viscosity, it not easily absorbed and utilized by the human body, which limits its potential applications 3. The oligomerization of alginate can widen the scope of its potential applications and results in more biological activities. The oligomeric alginate is called alginate oligosaccharide (AOS). AOS, a kind of functional oligosaccharide, exhibits a variety of properties such as increasing fruit quality 4 , and antioxidative 5 , anticoagulant 6 , and antineoplastic 7 potential. Moreover, AOS has broad application prospects in the fields of pharmaceuticals, functional food, and green agriculture. Nowadays, there are many ways to achieve alginate oligomerization. At present, it is recognized that the environmentally friendly and mildly efficient method of alginate oligomerization is to use alginate-degrading microorganisms or alginate lyase 8 extracted from microorganisms. Until now, scientists have isolated several strains of alginate-degrading microorganisms, including Cobetia sp. NAP1 9 , Microbulbifer mangrovi DD-13 T10 , Vibrio weizhoudaoensis M010 11 , Isoptericola halotolerans NJ-05 12 , V. splendidus 12B01 13 , Sphingomonas sp. A1 14 , Pseudoalteromonas sp. CY24 15 , etc. Some alginate lyase enzymes have also been isolated and purified from these strains 11-13, 15. With the improvement of sequencing technology and the dramatic reduction in sequencing costs, th...