Richness and biotechnological potential of the yeast community associated with the bromeliad phylloplane in the Brazilian Neotropical Forest

Different plant compartments, different yeasts: the example of the bromeliad phyllosphere

The plant phyllosphere is one of the largest sources of microorganisms, including yeasts. In bromeliads, the knowledge of yeasts is dispersed and still incipient. To understand the extent of our knowledge on the subject, this review proposes to compile and synthesize existing knowledge, elucidating possible patterns, biotechnological and taxonomic potentials, bringing to light new knowledge, and identifying information gaps. For such, we systematically review scientific production on yeasts in bromeliads using various databases. The results indicated that the plant compartments flowers, fruits, leaves, and water tank (phytotelma) have been studied when focusing on the yeast community in the bromeliad phyllosphere. More than 180 species of yeasts and yeast-like fungi were recorded from the phyllosphere, 70% were exclusively found in one of these four compartments and only 2% were shared among all. In addition, most of the community had a low frequency of occurrence, and approximately half of the species had a single record. Variables such as bromeliad subfamilies and functional types, as well as plant compartments, were statistically significant, though inconclusive and with low explanatory power. At least 50 yeast species with some biotechnological potentials have been isolated from bromeliads. More than 90% of these species were able to produce extracellular enzymes. In addition, other biotechnological applications have also been recorded. Moreover, new species have been described, though yeasts were only exploited in approximately 1% of the existing bromeliads species, which highlights that there is still much to be explored. Nevertheless, it appears that we are still far from recovering the completeness of the diversity of yeasts in this host. Furthermore, bromeliads proved to be a good ecological model for prospecting new yeasts and for studies on the interaction between plants and yeasts. In addition, the yeast community diverged among plant compartments, establishing bromeliads as a microbiologically complex and heterogeneous mosaic. This article is protected by copyright. All rights reserved.

Tremella ananatis sp. nov. and Tremella lamprococci sp. nov., two yeast species associated with bromeliads

Eight yeast isolates with an affinity to the genus Tremella were obtained from bromeliads from different locations in Brazil. Although the formation of basidia and basidiocarp were not observed, on the basis of the results of sequence analysis of the D1/D2 domain of the large subunit (LSU) rRNA gene and internal transcribed spacer (ITS) region, we suggest that these isolates represent two novel species of the genus Tremella. These yeasts are phylogenetically related to Tremella saccharicola and Tremella globispora. Therefore, we propose Tremella ananatis sp. nov. and Tremella lamprococci sp. nov. as novel yeast species of the order Tremellales (Agaricomycotina, Basidiomycota). Sequence analysis revealed that Tremella ananatis sp. nov. differs by 11 and 28 nucleotide substitutions from Tremella saccharicola in the D1/D2 sequence and ITS region, respectively. Moreover, Tremella lamprococci sp. nov. differs by 15 and 29 nucleotide substitutions from Tremella globispora in the D1/D2 sequence and ITS region, respectively. The holotypes of Tremella ananatis sp. nov. and Tremella lamprococci sp. nov. are CBS 14568T and CBS 14567T, and the MycoBank numbers are MB840480 and MB840481, respectively.

Plant growth-promoting traits of yeasts isolated from the tank bromeliad Vriesea minarum L.B. Smith and the effectiveness of Carlosrosaea vrieseae for promoting bromeliad growth

Yeasts can play important roles in promoting plant growth; however, little information is available in this regard for yeasts in water of bromeliad tanks. Here, we characterize the ability of 79 yeast isolates from tank bromeliad Vriesea minarum, an endangered species, to solubilize phosphate, secrete siderophores, and synthesize indole-3-acetic acid (IAA). The results showed that 67.8% of all assayed yeast isolates mobilized inorganic phosphate; 40.0% secreted siderophores; and 89.9% synthetized IAA and IAA-like compounds. Among the species studied, Carlosrosaea vrieseae UFMG-CM-Y6724 is highlighted for producing IAA (76.1 μg mL^-1) and siderophores, and solubilizing phosphate. In addition, evaluation of the effects of filtrate containing IAA-like compounds produced by the C. vrieseae on the development and photosynthetic performance of V. minarum seedlings found it to improve seedling growth equal to that of commercial IAA. These results demonstrate that C. vrieseae can produce compounds with great potential for future use as biofertilizer agents.