%0 Journal Article
%T Molecular Phylogeny and Phenotypic Characterization of Yeasts with a Broad Range of pH Tolerance Isolated from Natural Aquatic Environments
%A Naoto Urano
%A Ayaka Shirao
%A Yuka Naito
%A Masahiko Okai
%A Masami Ishida
%A Masachika Takashio
%J Advances in Microbiology
%P 56-73
%@ 2165-3410
%D 2019
%I Scientific Research Publishing
%R 10.4236/aim.2019.91005
%X In this study, yeasts with broad range of pH tolerance were isolated and characterized from natural aquatic environments in Japan. Only a few basic and application studies of alkali-tolerant yeasts have been reported, despite the unmet industrial needs. First, we surveyed alkali-tolerant yeasts from natural aquatic environments at pH 7.6 - 9.4. We isolated 35 yeast strains that grew in pH 9.0 medium, from seven genera and nine species: 25 strains (N1, N2, through N6, N9, K1, K3 through K19) were <i>Rhodotorula mucilaginosa</i>; one (N7) was <i>Rhodosporidium fluvial</i>; one (N8) was <i>Scheffersomyces spartinae</i>; two (N10 and N13) were <i>Wicherhamonyces anomalus</i>; one (N11) was <i>Cyberlindnera saturnus</i>; one (S1) was <i>Candida</i> sp.; two (S2 and S4) were <i>Candida intermedia</i>; one (S3) was <i>Candida quercuum</i>; and one (K2) was <i>Cryptococcus liquefacience</i>. We examined the effects of pH on the growth of representative yeast strains. Strains K12 and S4 showed high growth at pH 3 - 10. Strains N7, N8, N10, N11, and S3 showed high growth at pH 3 - 9. Strains K2 and S1 showed high growth at pH 4 - 8. All nine of these strains had neutralizing activities from acidic media at pH 3 - 5 to pH 6 - 8. We previously isolated acid-tolerant yeasts (<i>Cryptococcus</i> sp. T1 [1] and <i>Candida intermedia</i> CeA16 [2]) from extremely acidified environments; they showed high growth at pH 3 - 9 and neutralizing activities of acidic media by releasing ammonium ions. Thus, alkali-tolerant yeasts and acid-tolerant yeasts were found to be similar species and have both high growth at a broad range of pH and neutralizing activities of acid media. Previously, we also isolated acid-tolerant, acid-neutralizing yeasts from neutral natural environments (26 strains, 12 species) [3]. Next, we constructed the phylogenetic trees of both acid-tolerant yeasts and alkali-tolerant yeasts. All were situated in the same classification position. Similar yeast species with a broad range of pH tolerance were living in natural aquatic environments at pH values from alkali to acid.
%K pH Tolerance
%K Yeast Species
%K Aquatic Environment
%K Phylogenetic Tree
%K Fermentation
%U http://www.scirp.org/journal/PaperInformation.aspx?PaperID=89932