The broad-spectrum lytic capability of Salmonella bacteriophages against various Salmonella species was evaluated to determine their potential as an alternative for antibiotics, and the safety and preventive effects of the bacteriophages were assessed on mice and pigs. Four bacteriophage cocktails were prepared using 13 bacteriophages, and the lytic capability of the four bacteriophage cocktails was tested using Salmonella reference strains and field isolates. Bacteriophage cocktail C (SEP-1, SGP-1, STP-1, SS3eP-1, STP-2, SChP-1, SAP-1, SAP-2; ≥109 pfu/ml) showed the best lytic activity against the Salmonella reference strains (100% of 34) and field isolates (92.5% of 107). Fifty mice were then orally inoculated with bacteriophage cocktail C to determine the distribution of bacteriophages in various organs, blood and feces. The effects of bacteriophages on Salmonella infection in weaned pigs (n=15) were also evaluated through an experimental challenge with Salmonella Typhimurium after treatment with bacteriophage cocktail C. All mice exhibited distribution of the bacteriophages in all organs, blood and feces until 15 days post infection (dpi). After 35 dpi, bacteriophages were not detected in any of these specimens. As demonstrated in a pig challenge study, treatment with bacteriophage cocktail C reduced the level of Salmonella shedding in feces. The metagenomic analyses of these pig feces also revealed that bacteriophage treatment decreased the number of species of the Enterobacteriaceae family without significant disturbance to the normal fecal flora. This study showed that bacteriophages effectively controlled Salmonella in a pig challenge model and could be a good alternative for antibiotics to control Salmonella infection.

Background Porcine reproductive and respiratory syndrome virus (PRRSV) is a macrophage-tropic arterivirus with extremely high genetic and pathogenic heterogeneity that causes significant economic losses in the swine industry worldwide. PRRSV can be divided into two species [PRRSV1 (European) and PRRSV2 (North American)] and is usually diagnosed and genetically differentiated into several lineages based on the ORF5 gene, which constitutes only 5% of the whole genome. This study was conducted to achieve nonselective amplification and whole-genome sequencing (WGS) based on a simplified sequence-independent, single-primer amplification (SISPA) technique with next-generation sequencing (NGS), and to genetically characterize Korean PRRSV field isolates at the whole genome level. Methods The SISPA-NGS method coupled with a bioinformatics pipeline was utilized to retrieve full length PRRSV genomes of 19 representative Korean PRRSV strains by de novo assembly. Phylogenetic analysis, analysis of the insertion and deletion (INDEL) pattern of nonstructural protein 2 (NSP2), and recombination analysis were conducted. Results Nineteen complete PRRSV genomes were obtained with a high depth of coverage by the SISPA-NGS method. Korean PRRSV1 belonged to the Korean-specific subtype 1A and vaccine-related subtype 1C lineages, showing no evidence of recombination and divergent genetic heterogeneity with conserved NSP2 deletion patterns. Among Korean PRRSV2 isolates, modified live vaccine (MLV)-related lineage 5 viruses, lineage 1 viruses, and nation-specific Korean lineages (KOR A, B and C) could be identified. The NSP2 deletion pattern of the Korean lineages was consistent with that of the MN-184 strain (lineage 1), which indicates the common ancestor and independent evolution of Korean lineages. Multiple recombination signals were detected from Korean-lineage strains isolated in the 2010s, suggesting natural interlineage recombination between circulating KOR C and MLV strains. Interestingly, the Korean strain GGYC45 was identified as a recombinant KOR C and MLV strain harboring the KOR B ORF5 gene and might be the ancestor of currently circulating KOR B strains. Additionally, two novel lineage 1 recombinants of NADC30-like and NADC34-like viruses were detected. Conclusion Genome-wide analysis of Korean PRRSV isolates retrieved by the SISPA-NGS method and de novo assembly, revealed complex evolution and recombination in the field. Therefore, continuous surveillance of PRRSV at the whole genome level should be conducted, and new vaccine strategies for more efficient control of the virus are needed.

An immunosuppressant tacrolimus-producing strain of Streptomyces sp. TST8 was isolated and developed by the TS corporation in Korea using the sequential adaptation of media containing tacrolimus (600-1600 mg/l). The aim of the tacrolimus sequential adaptation protocol was to select those cells with tacrolimus resistance and to reduce product inhibition of the tacrolimus-producing strain. The developed strains produced more tacrolimus than the original strain. In particular, the TST10 strain adapted in the medium containing 900 mg/l of tacrolimus produced 972 mg/l of tacrolimus in the final titer after 7 days of cultivation in a 5-l jar fermenter. This is the largest final titer of tacrolimus produced by a specific strain to date. Because the sequential adaptation protocol is limited by the solubility of tacrolimus in water, the final tacrolimus titer of TST11 adapted in the medium containing 1600 mg/l of tacrolimus was lower than that of TST10. The developed strains and the development method using sequential adaptation can facilitate the efficient and economical production of tacrolimus.

The objective of this study was to investigate the proper concentration of D-xylose which is expected to reduce the GI (Glycemic index) value of sucrose in the human body. When subjects took a sucrose mixture containing 5% and 10% D-xylose, the blood glucose levels were lowered by approximately 27.5% and 25.9%, respectively, compared to those of sucrose. The GI values of sucrose mixtures containing 5% and 10% D-xylose were 49.3 and 50.4, respectively. The reduction in GI value was not dependent on the D-xylose concentration, as the GI value of sucrose mixture containing 5% D-xylose (XyloSugar) was similar to that of sucrose mixture containing 10% D-xylose (XyloSugar10). D-xylose is not only more expensive but also less sweet than sucrose. So, low concentration of D-xylose has the advantage in the price and taste. It was determined that the proper concentration of D-xylose expected to reduce GI value of sucrose was 5% (w/w).

An adult male Eurasian river otter ( Lutra lutra) was diagnosed with systemic infection. Microbiologic findings identified Streptococcus suis serotype 2, clonal complex 28, and sequence type 629. Genetic analysis strongly suggested the transmission of S. suis isolate from pigs to wild animals through environmental contamination.