Streptococcus ruminicola sp. nov., new species of the Streptococcus bovis/Streptococcus equinus complex (SBSEC) isolated from the rumen of Korean domestic ruminants.

A total of three Gram-positive, and oxidase and catalase-negative facultative anaerobic non-motile bacteria were isolated from the rumen fluid of cows and goats and these strains were designated CNU_G2T, CNU_77-61, and CNU_G3. They grew at 20-45 °C, pH 6.5-7, and 0-6.5% NaCl (w/v). The G + C contents (%) of the three isolates were 37.9, 37.8 and 37.8, respectively. Phylogenomic analysis indicated that these strains were distinct from other Streptococcus species. The average nucleotide identity between the isolates and the closest strain S. infantarius subsp. infantarius ATCC BAA-102T was 94.0-94.5%, while the digital DNA-DNA hybridization (dDDH) values between the isolates and the aforementioned related strain were 58.2-61.4%, respectively. Fatty acid analysis revealed higher proportions of C16:0 (> 28%) in all three isolates, while the proportion of C18:0 was higher in CNU_G2T (25.8%); however, it was less than 12% in all the representing strains used in the study. The C14:0 composition of strains CNU_77-61 (22.1%) and CNU_G3 (24.1%) was higher than that of type strains of CNU_G2T (8.1%). Based on the morphological, biochemical, and molecular phylogenetic features of the three novel isolates, they represent a novel species of the genus Streptococcus, for which we propose as Streptococcus ruminicola sp. nov. The type strain is CNU_G2T (= KCTC 43308T = GDMCC 1.2785T).

Determination of plutonium isotopes (238,239,240Pu) and strontium (90Sr) in seafood using alpha spectrometry and liquid scintillation spectrometry.

The present study was carried out to survey the levels of plutonium isotopes (238,239,240Pu) and strontium (90Sr) in domestic seafood in Korea. In current, regulatory authorities have analyzed radionuclides, such as 134Cs, 137Cs and 131I, in domestic and imported food. However, people are concerned about contamination of other radionuclides, such as plutonium and strontium, in food. Furthermore, people who live in Korea have much concern about safety of seafood. Accordingly, in this study, we have investigated the activity concentrations of plutonium and strontium in seafood. For the analysis of plutonium isotopes and strontium, a rapid and reliable method developed from previous study was used. Applicability of the test method was verified by examining recovery, minimum detectable activity (MDA), analytical time, etc. Total 40 seafood samples were analyzed in 2014-2015. As a result, plutonium isotopes (238,239,240Pu) and strontium (90Sr) were not detected or below detection limits in seafood. The detection limits of plutonium isotopes and strontium-90 were 0.01 and 1 Bq/kg, respectively.