Recovery of Lactobacillus casei strain Shirota (LcS) from the intestine of healthy Vietnamese adults after intake of fermented milk.

To demonstrate the gastrointestinal survival of Lactobacillus casei strain Shirota (LcS) in healthy Vietnamese adults, a fermented milk drink containing LcS was administered daily for 14 days. Twenty-six healthy Vietnamese adults took part in the study. Each participant consumed 65 mL of a fermented milk drink containing LcS daily for 14 days. The drink contained a dose of 10 8 CFU/mL LcS. Fecal samples were collected before, during and after consuming the fermented milk drink. LcS was confirmed by culture and ELISA. After 7 and 14 days of ingesting fermented milk drink, LcS was recovered from fecal samples at average of 5.0×10 7 CFU/g feces (n=26) and 5.4×10 7 CFU/g feces (n=26), respectively. LcS persisted in 8 voluteers until day 42 (after 14 days stopping fermented milk drink) at 0.0033×10 7 CFU/g feces (n=8). We confirmed survival of LcS after passage through the gastrointestinal tract of Vietnamese adults.

Taxonomic and ecological studies of actinomycetes from Vietnam: isolation and genus-level diversity.

Actinomycetes were isolated from 109 soil and 93 leaf-litter samples collected at five sites in Vietnam between 2005 and 2008 using the rehydration-centrifugation (RC) method, sodium dodecyl sulfate-yeast extract dilution method, dry-heating method and oil-separation method in conjunction with humic acid-vitamin agar as an isolation medium. A total of 1882 strains were identified as Vietnamese (VN)-actinomycetes including 1080 (57%) streptomycetes (the genus Streptomyces isolates) and 802 (43%) non-streptomycetes. The 16S ribosomal RNA gene sequences of the VN-actinomycetes were analyzed using BLAST searches. The results showed that these isolates belonged to 53 genera distributed among 21 families. Approximately 90% of these strains were members of three families: Streptomycetaceae (1087 strains, 58%); Micromonosporaceae (516 strains, 27%); and Streptosporangiaceae (89 strains, 5%). Motile actinomycetes of the genera Actinoplanes, Kineosporia and Cryptosporangium, which have quite common morphological characteristics, were frequently isolated from leaf-litter samples using the RC method. It is possible that these three genera acquired common properties during a process of convergent evolution. By contrast, strains belonging to the suborder Streptosporangineae were exclusively isolated from soils. A comparison of the sampling sites revealed no significant difference in taxonomic diversity between these sites. Among the non-streptomycetes, 156 strains (19%) were considered as new taxa distributed into 21 genera belonging to 12 families. Interestingly, the isolation of actinomycetes from leaf-litter samples using the RC method proved to be the most efficient way to isolate new actinomycetes in Vietnam, especially the Micromonosporaceae species.