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.

Strain VN07A0015 T was isolated from soil collected on Cat Ba Island, Vietnam. The taxonomic position of strain VN07A0015 T was near Streptomyces aomiensis M24DS4 T (98.5 % 16S rRNA gene sequence similarity) and Streptomyces scabrisporus NBRC 100760 T (95.6 %), and it clustered within them; however, this cluster was distant from the type strains of other species of the genus Streptomyces. The aerial mycelia of strain VN07A0015 T were greyish and formed imperfect spiral spore chains (retinaculiaperti type) with smooth-surfaced spores. The morphological features of strain VN07A0015 T were different from those of the type strains of S. aomiensis and S. scabrisporus. The chemotaxonomic characteristics of strain VN07A0015 T were typical for all members of the genus Streptomyces, which possessed LL-type diaminopimelic acid, menaquinone MK-9(H 6 , H 8 ) and the major fatty acids iso-C 16 : 0 and iso-C 15 : 0 . DNA-DNA relatedness between strain VN07A0015 T and S. aomiensis NBRC 106164 T was less than 30 %. In addition, some physiological and biochemical traits differed from those of S. aomiensis. Therefore, we propose that strain VN07A0015 T be classified in the genus Streptomyces as a representative of Streptomyces catbensis sp. nov. (type strain VN07A0015 T 5VTCC-A-1889 T 5NBRC 107860 T ).

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Probiotic properties in vitroof the Saccharomyces boulardii SB2 yeast, was isolated from fruit at Cuc Phuong National Park were evaluated based on biological characteristics and tolerance in simulated intestinal conditions. In the present work, studies were carried out to improve cell growth kinetics to produce cell mass of this biotherapeutic yeast in shake flaskand 30-L bioreactor levels. In case of shake flask, the highest biomass was obtained under the culture conditions as YM medium, at 37oC, pH 6, inoculum concentration of 5 %, with shaking for 32 h; the best sources of carbon and nitrogen were found to be glucose and mixture of peptone, yeast extract, malt extract; cell dry weight and cell density reached 2.43 g L-1 and 109 CFU/ml repetitively. During 30-L bioreactor cultivation, the maximal cell mass in agitation speed of 200 rpm, aeration rate of 1.2 v v-1 min-1; at 32 h of incubation, was 3.58 g L-1 in pH controlled culture and 3.08 g L-1 in uncontrolled pH. This is considered as the first step for cell mass production of this probiotic yeast in industrial scale Keywords: Saccharomyces boulardii SB2, probiotic, biomass, shake flask, 30-L bioreactor. References [1] FAO/WHO, Guidelines for the Evaluation of Probiotics in Food, Joint FAO/WHO Working Group Report on Drafting Guidelines for the Evaluation of Probiotics in Food London, Ontario, Canada, April 30 and May 1, 2002.[2] J. Park, M.H. Floch, Prebiotics, probiotics, and dietary fiber in gastrointestinal disease, Gastroenterology Clinics of North America, 36 (2007) 47-63. https://doi.org/10.1016/j.gtc.2007. 03.001. [3] F. Mansour-Ghanaei, N. Dehbashi, K. Yazdanparast, A Shafaghi, Efficacy of Saccharomyces boulardii with antibiotics in acute amoebiasis, World Journal of Gastroenterology, 9(2003)1832-1833. https:// dx.doi.org/10.3748/ wjg.v9.i8.1832.[4] I. Castagliuolo, M.F. Riegler, L. Valenick, J.T. LaMont, C. Pothoulakis, Saccharomyces boulardii protease inhibits the effects of Clostridium difficile toxins A and B in human colonic mucosa, Infection and Immunity, 67, 1(1999)302-307. [5] A. Qamar, S. Aboudola, M. Warny, P. Michetti, C. Pothoulakis, J.T. LaMont, C.P. Kelly, Saccharomyces boulardii stimulates intestinal immunoglobulin A immune response to Clostridium difficile toxin A in mice, Infection and Immunity, 69 (2001) 2762-2765. https:// doi.org/10.1128/IAI.69.4.2762-2765.2001.[6] T.S. Chin, N.Z. Othman, R. A. Malek, N. Elmarzugi, O. M. Leng, S. Ramli, N. F. Musa, R. Aziz and H. El Enshasy, Bioprocess optimization for biomass production of probiotics yeast Saccharomyces boulardii in semi-industrial scale, Journal of Chemical and Pharmaceutical Research, 7, 3(2015)122-132. [7] D.T.N. Diep, P. George, E. Gorczyca, S. Kasapis, Studies on the viability of Saccharomyces boulardii within microcapsules in relation to the thermomechanical properties of wheyprotein. Food Hydrocolloids, 42 (2014) 232-238. https:// doi.org/10.1016/j.foodhyd.2013.07.024.[8] G.L. Miller, Use of dinitrosalicylic acid reagent for determination of reducing sugar. Analytical Chemistry, 31 (1959) 426-428 https://doi.org/ 10.1021/ac60147a030.[9] H. A. El-Enshasy and A. A. El-Shereef, Optimization of high cell density cultivation of (Probiotic/Biotherapeutic) yeast Saccharomyces boulardii adapted to dryness stress, Deutsche Lebensmittel-Rundschau 104,93(2008)89-394.[10] K. Rajkowska, A. K.-S. Bska and A. Rygala, Probiotic activity of Saccharomyces cerevisiae var.boulardii against human pathogens, Food Technology and Biotechnology, 50, 2 (2012) 230–236. [11] R. Zbinden, E.E. Gonczi, M. Altwegg, Inhibition of Saccharomyces boulardii (nom. inval.) on cell invasion of Salmonella typhimurium and Yersinia enterocolitica, Microbial Ecology in Health and Disease, 11(1999)158–162. https://doi.org/10. 1080/089106099435736.[12] D. Czerucka, T. Piche, P. Rampal, Review article: Yeasts as probiotics – Saccharomyces boulardii, Alimentary Pharmacology Therapeutics, 26(2007)767–778. https://doi.org/10.1111/j.1365 -2036.2007.03442.x.[13] L.V. Mc Farland, P. Bernacoscani, Saccharomyces boulardii. A Review of an Innovative Biotherapeutic Agent, Microbial Ecology in Health and Disease, 6(1993)157-171. https://doi. org/10.3109/08910609309141323.[14] K. Rajkowska and A. Kunicka-Styczynska, Probiotic properties of yeasts isolated from chicken feces and kefirs, Polish Journal of Microbiology, 59,4(2010) 257-263.[15] J.L.R. Fietto R.S. Araujo and F.N. Valadao, Molecular and physiological comparisons between Saccharomy cescerevisiae and Saccharomyces boulardii, Canadian Journal of Microbiology, 50 (2004) 615–621. https://doi. org/10.1139/w04-050.[16] J.L. Muller, K.L. Protti, M.S. Machado, L.L.V. Lacerda, T.M.B. Bresolin, P.S. Podlech, Comparison of Saccharomyces boulardii growth in an air-lift fermentor and in a shaker, Ciência e Tecnologia de Alimentos, 27,4(2007)688-693. http://dx.doi.org/10.1590/S0101-206120070004 00003.