Nurmi-type Culture Prepared using Culture Media without l-Cysteine Enhances Salmonella Exclusion in Hatched Layer Chicks.

To determine the influence of media composition on Salmonella exclusion of Nurmi-type cultures, two and four types of cultures in the first and second trial, respectively, were prepared from the cecal contents of conventional laying hens, and Salmonella exclusion was assessed in newly hatched chicks. In the first trial, modified Viande Levure (VL) broth or nutrient broth (NB) were used to prepare Nurmi-type cultures (N-VL and N-NB), which were administered to the newly hatched chicks. Twenty-four hours later, the chicks were challenged with Salmonella enterica Typhimurium EF85-9 (ST). ST recoveries (log10 colony forming units/g of cecal contents) from the N-VL-, N-NB-, and control-treated groups 5 days after the challenge were 7.6±0.6, 0.9±1.9, and 7.7±0.4, respectively. The results suggested the influence of l-cysteine (Cys) present in the VL broth. Thus, we determined the effect of Cys in the second trial. We prepared two other cultures using VL broth without Cys (N-VL-Cys) and NB with Cys (NNB-Cys). ST recoveries from the cecal contents of the N-VL-, N-VL-Cys-, and control-treated groups were 6.3±0.9, 2.1±2.5, and 9.2±0.8, respectively. ST was not recovered from the N-NB- and N-NB-Cys-treated groups. To identify bacteria with Salmonella exclusion activity, we isolated 41 bacterial strains from the ceca of N-NB-treated chicks without Salmonella challenge. Most isolates were identified as Enterococcus faecalis or E. mundtii based on 16S rRNA gene sequencing, and only four cultures excluded Salmonella. Therefore, VL broth containing Cys was not always required for preparing Nurmi-type cultures. The use of media prepared with Cys at the lowest possible concentration or without Cys would promote to enhance Salmonella exclusion from Nurmi-type cultures.

Seawater inundation from the 2011 Tohoku tsunami continues to strongly affect soil bacterial communities 1 year later.

The effects of inundation caused by the 2011 Tohoku tsunami on soil bacterial communities in agricultural fields were evaluated. Bacterial communities were compared across three different types of soil, unflooded field (UF) soil, soil flooded for 2 weeks (short term (ST)), and soil flooded for 2 months (long term (LT)), using polymerase chain reaction-pyrosequencing of 16S rRNA genes. Acidobacteria were dominant in UF, with a relative abundance of approximately 35 %, and Proteobacteria dominated flooded soils (30-67 %). Hierarchical cluster analysis indicated that the community structure of soil bacteria in flooded soils (ST and LT) clearly differed from that in UF. Differences between LT and ST fields were rarely observed in terms of chemical properties and microbial community structure at the phylum level. However, sulfur-oxidizing bacteria (SOB) and nitrite-oxidizing bacteria (NOB) in LT tended to occur at high and low abundances, respectively. Halothiobacillus, a halotolerant SOB, was detected in all LT fields. Unexpectedly, a zeta-Proteobacteria, which had previously only been detected in marine environments, was detected in LT fields only. Our results demonstrate that the effects of the 2011 Tohoku tsunami on soil bacterial communities in agricultural fields may have lasted at least 1 year. Furthermore, SOB, NOB, and zeta-Proteobacteria may serve as indicators of the effects of seawater inundation on microorganisms.

Enzymatic synthesis of novel branched sugar alcohols mediated by the transglycosylation reaction of pullulan-hydrolyzing amylase II (TVA II) cloned from Thermoactinomyces vulgaris R-47.

Transglycosylation reactions are useful for preserving a specific sugar structure during the synthesis of branched oligosaccharides. We have previously reported a panosyl unit transglycosylation reaction by pullulan-hydrolyzing amylase II (TVA II) cloned from Thermoactinomyces vulgaris R-47 (Tonozuka et al., Carbohydr. Res., 1994, 261, 157-162). The acceptor specificity of the TVA II transglycosylation reaction was investigated using pullulan as the donor and sugar alcohols as the acceptor. TVA II transferred the α-panosyl unit to the C-1 hydroxyl group of meso-erythritol, C-1 and C-2 of xylitol, and C-1 and C-6 of d-sorbitol. TVA II differentiated between the sugar alcohols' hydroxyl groups to produce five novel non-reducing branched oligosaccharides, 1-O-α-panosylerythritol, 1-O-α-panosylxylitol, 2-O-α-panosylxylitol, 1-O-α-panosylsorbitol, and 6-O-α-panosylsorbitol. The Trp(356)→Ala mutant showed similar transglycosylation reactions; however, panose production by the mutant was 4.0-4.5-fold higher than that of the wild type. This suggests that Trp(356) is important for recognizing both water and the acceptor molecules in the transglycosylation and the hydrolysis reaction.