Role of tannin-binding salivary proteins and tannase-producing bacteria in the acclimation of the Japanese wood mouse to acorn tannins.

We studied the defense mechanisms against the negative effects of tannins in acorns by using the Japanese wood mouse (Apodemus speciosus) and acorns of a Japanese deciduous oak Quercus crispula, which contain 9.9% tannins on a dry weight basis. For the experiment, we allocated 26 wood mice into two groups: acclimated (N = 12) and nonacclimated (N = 14). Mice in the nonacclimated group were fed only acorns for 10 d after 4 wk of receiving a tannin-free diet. In contrast, mice in the acclimated group received ca. 3 g acorns daily in addition to the tannin-free diet for the first 4 wk, then they were fed only acorns for 10 d. Body weight, food intake, and digestibility were monitored. In addition, the amount of salivary proline-rich proteins (PRPs) and abundance of tannase-producing bacteria (TPB) in the feces of mice were measured. Of the 14 mice in the nonacclimated group, 8 died, whereas only 1 of the 12 in the acclimated group died. During the first 5 d of feeding acorns only, mice in the nonacclimated group lost, on average, 17.5% of their body mass, while those in the acclimated group lost only 2.5%. Food intake, dry matter digestibility, and nitrogen digestibility were higher in the acclimated group than in the nonacclimated group. The results indicate that wood mice can mitigate the negative effects of tannins by acclimation. Path analysis revealed that increased secretion of PRPs and abundance of Lactobacillus type of TPB might explain the acclimation to tannins.

Isolation of tannin-degrading bacteria isolated from feces of the Japanese large wood mouse, Apodemus speciosus, feeding on tannin-rich acorns.

Bacteria with tannase activity were isolated from the feces of the Japanese large wood mouse, Apodemus speciosus. They were largely classified into two groups: Gram-positive cocci and Gram-positive bacilli. Genotypic analysis using a species-specific PCR assay as well as biochemical tests identified all cocci as Streptococcus gallolyticus. A PCR assay targeting a genus-specific sequence in the 16S/23S rDNA spacer region and additional 16S rDNA sequencing indicated that the bacilli belong to the genus Lactobacillus, with L. animalis and L. murinus being closely related taxa. Subsequent estimation of guanine-plus-cytosine content, amplified ribosomal DNA restriction analysis, and DNA/ DNA hybridization assay confirmed that the bacilli are homologous to each other but different from L. animalis or L. murinus. Consequently, a novel species of the genus Lactobacillus may be proposed. To date, this study is the first to report on the isolation of tannase-positive bacteria from the feces of a rodent species. These bacteria may play an essential role for the host organism in digesting tannin-rich acorns available in their natural habitats, thereby endowing them with a greater ecological advantage.

ARDRA and RAPD analyses of human and animal isolates of Streptococcus gallolyticus.

A total of 23 Streptococcus gallolyticus strains, consisting of 12 strains from feces of healthy animals and 11 from clinical cases of human or cow mastitis milk, were examined genealogically. Four strains of S. bovis "biotype II/1" and 3 strains of S. equinus, the closely related organisms to S. gallolyticus, were also analyzed for outgroup comparison. Neither the amplified ribosomal DNA restriction analysis (ARDRA) nor the randomly amplified polymorphic DNA (RAPD) analysis that had been designed to recognize S. gallolyticus strains virulent in pigeons could differentiate clinical strains from the others of S. gallolyticus. No correspondence between the DNA profile in either analysis and the host animal species was detected.

Genotypic analyses of lactobacilli with a range of tannase activities isolated from human feces and fermented foods.

A total of 77 tannase producing lactobacilli strains isolated from human feces or fermented foods were examined for their genotypic profiles and intensities of tannase production. With a PCR-based assay targeting recA gene, all strains except one isolate were assigned to either Lactobacillus plantarum, L. paraplantarum, or L. pentosus whereas a 16/23S rDNA targeted PCR-based assay identified all except 6 isolates (inclusive of the above one isolate) as one of the closely related species. Subsequent DNA/DNA hybridization assays revealed that these 6 exceptional isolates showed low homology (between 1.2% and 55.8% relative DNA binding) against type strains of the three species. Supplemental carbohydrate fermentation profiles on the 6 isolates indicated that two of them were identified as L. acidophilus, one as Pediococcus acidilactici, one as P. pentosaceus, and two remained unidentifiable. The evidence suggests that the 16/23S rDNA targeted PCR assay can be used as a reliable identification tool for the closely related lactobacilli, and that the tannase gene is widely distributed within members of the Lactobacillaceae family. Meanwhile, a randomly amplified polymorphism DNA (RAPD) analysis revealed that all except 8 isolates were well allocated in 4 major RAPD clusters, though not species specific, consisting of two L. plantarum predominant clusters, one L. paraplantarum predominant, and one L. pentosus predominant. The RAPD patterns of the 8 non-clustered isolates, which consisted of the 6 unidentifiable isolates and 2 isolates identified as L. pentosus, were <40% similarity to those belonging to the 4 clusters. A quantitative assay of the tannase activities showed that there was a marked variation in the activities among the strains, which did not correlate with either species identification or clustering by RAPD.

Development of a diagnostic PCR assay targeting the Mn-dependent superoxide dismutase gene (sodA) for identification of Streptococcus gallolyticus.

A PCR-based assay to identify Streptococcus gallolyticus has been developed. The assay uses an oligonucleotide primer pair targeting a partial sequence of the manganese-dependent superoxide dismutase gene (sodA). The assay distinguished members of the S. gallolyticus group from other, closely related taxa successfully by yielding a 408-bp specific amplicon.