Investigation of Staphylococcus aureus positive for Staphylococcal enterotoxin S and T genes

Staphylococcus aureus produces staphylococcal enterotoxins (SEs) and causes food poisoning. It is known that almost all SE-encoding genes are present on various types of mobile genetic elements and can mobilize among S. aureus populations. Further, plasmids comprise one of SE gene carriers. Previously, we reported novel SEs, SES and SET, harbored by the plasmid pF5 from Fukuoka5. In the present study, we analyzed the distribution of these SEs in various S. aureus isolates in Japan. We used 526 S. aureus strains and found 311 strains positive for at least one SE/SE-like toxin gene, but only two strains (Fukuoka5 and Hiroshima3) were positive for ses and set among the specimens. We analyzed two plasmids (pF5 and pH3) from these strains and found that they were different. Whereas these plasmids partially shared similar sequences involved in the ser/selj/set/ses gene cluster, other sequences were different. A comparison of these plasmids with those deposited in the NCBI database revealed that only one plasmid had the ser/selj/set/ses cluster with a stop mutation in set similar to that in pH3. In addition, the chromosomes of Fukuoka5 and Hiroshima3, positive for ses and set, were classified into different genotypes. Despite the low rate of gene positivity for these SEs, it is suggested that there is diversity in plasmids and strains carrying these two SEs. Consequently, regarding the entire feature of SE prevalence, we improved the multiplex PCR detection method for the SE superfamily to obtain further insight.     

Decreasing radioactive cesium in lodged buckwheat grain after harvest

This study assessed soil contamination with high radioactive cesium (R–Cs) concentration in buckwheat grains by lodging, and assessed the possibility of R–Cs reduction in grain through post-harvest preparation. Analysis of buckwheat grain produced in farmers’ fields and reports from farmers indicated that grain from fields that had lodging showed higher R–Cs than grain from fields with no lodging. A field experiment demonstrated that R–Cs in grain after threshing and winnowing (TW) was about six times higher in lodged plants than in nonlodged plants. In lodged plants, R–Cs in grain was decreased to about one-fourth by polishing, and was decreased to about one-seventh by ultrasonic cleaning, compared with R–Cs in grain after TW. These results demonstrate that R–Cs of buckwheat grain of lodged plants can be decreased by removing soil from the grain surface by polishing and winnowing.     

A feline hemoplasma, 'Candidatus Mycoplasma haemominutum', detected in dog in Japan

We examined for 'Candidatus Mycoplasma haemominutum' infection in 167 blood samples collected from domestic dogs between 2008 and 2009 in the Tohoku area, Japan, and found 5 (3.0%) were positive by PCR assay. This is the first demonstration of 'Candidatus Mycoplasma haemominutum', a feline haemotropic mycoplasma, in the dogs raised in Japan.     

Decomposition activity of peat soils in geogenous mires in Sasakami, central Japan

Decomposition rates of peat and cellulose, and oxygen consumption rates were studied in three minerotrophic peat mires in Sasakami, central Japan. These mires had differences in topography, pedology and hydrology. Two dominant vegetation types in each mire, a Sphagnum palustre–S. cuspidatum community and a Rhynchospora fauriei community, were selected as the decomposition study sites. The objective of this study was to examine how the environmental and vegetational differences in mires correlate with the activity of decomposition. Decomposition rates of peat and the rates of cellulolysis were studied in the field for 6 months. Oxygen consumption rates were measured in the field using a closed chamber equipped with an oxygen electrode. In situ peat decomposition rates showed significant differences among the three mires, whereas in situ cellulolysis rates showed significant differences between communities. Peat mass loss rates positively correlated with the nitrogen and carbon concentration of the peat. Cellulolysis rates positively correlated with the range of water table fluctuation. Oxygen consumption rates showed significant negative correlation with the averaged and minimum water table depth, and positive correlation with the range of water table fluctuation. There was a significant positive correlation between cellulolysis rates and oxygen consumption rates. These are useful parameters for evaluating how the decomposition activity in soil depends on the vegetation types and water conditions.     

Growth of Tyzzer's organisms in preneoplastic hepatocytes of rats.

Tyzzer's disease in rats carrying preneoplastic or neoplastic lesions in the liver was studied histopathologically and immunohistochemically. The formation of necrotic foci and the growth of organisms were detected within both glutathione S-transferase placental type (GST-P) positive preneoplastic or neoplastic hepatocyte areas and GST-P negative areas. However, plasma glutamic oxaloacetic transaminase (GOT) and glutamic pyruvic transaminase (GPT) values and number of necrotic foci of infected animals having preneoplastic lesions in the liver were smaller than those of infected animals receiving no carcinogenic procedure. These results suggest that the environment consisted of preneoplastic hepatocytes was unsuitable for the growth of organisms as compared with that of intact hepatocytes though the organism could grow within the preneoplastic hepatocytes.     

Effects of a combination of hinokitiol (β‐thujaplicin) and an organic acid mixture on ruminal fermentation in heifers fed a high‐grain diet

This study evaluated the effects of hinokitiol (a natural antibacterial compound extracted from Thujopsis dolabrata var. hondai) and an organic acid mixture (citrate content 50%) on ruminal fermentation. Antibacterial properties were examined by measuring minimal inhibitory concentration. Hinokitiol at 1.56 µg/mL or an organic acid mixture at 1600 µg/mL inhibited Streptococcus bovis growth. The combination of 0.78 µg/mL hinokitiol and 200 µg/mL of an organic acid mixture also inhibited S. bovis growth. Both hinokitiol and the hinokitiol and an organic acid mixture combination showed strong antibacterial properties on Gram‐positive bacteria such as S. bovis, but relatively weak antibacterial activities on Gram‐negative bacteria such as Megasphaera elsdenii. Three ruminally cannulated heifers were fed a bloat‐producing diet containing barley, pelleted alfalfa meal, soybean meal and salt without long‐cut roughage to investigate the ruminal characteristics in vivo. Feeding to heifers a bloat‐producing diet containing 7.8 mg/kg hinokitiol and 0.2% of an organic acid mixture significantly decreased the increase in stable ingesta volume. Hinokitiol or an organic acid mixture did not affect ruminal volatile fatty acids, protozoa and bacteria. These results suggest that a combination of hinokitiol and an organic acid mixture might reduce frothy bloat in cattle fed high‐grain diets.