1-Ethyl-3-methylimidazolium tolerance and intracellular lipid accumulation of 38 oleaginous yeast species.

Pretreatment with ionic liquids (IL) such as 1-ethyl-3-methylimidazolium chloride or acetate is an effective method for aiding deconstruction of lignocellulosic biomass; however, the residual IL remaining in hydrolysates can be inhibitory to growth of ethanologenic or oleaginous yeasts that have been examined in the literature. The aim of this study was to identify oleaginous yeasts that are tolerant of the IL [C2C1Im][OAc] and [C2C1Im]Cl using 45 strains belonging to 38 taxonomically diverse species within phyla Ascomycota and Basidiomycota. Yeasts were cultivated in laboratory medium supplemented with 0, 2, or 4% IL in 96-well plates. The eight most tolerant strains were then cultivated in 10-mL media with no IL, 242mM [C2C1Im][OAc], or 242mM [C2C1Im]Cl. The effects of [C2C1Im]+ exposure on cell mass production and lipid accumulation varied at the species and strain level. The acetate salt decreased cell biomass and lipid production more severely than did the chloride ion for six strains. Lipid output was not markedly different (2.1 vs. 2.3 g/L) in Yarrowia lipolytica UCDFST 51-30, but decreased from 5 to 65% in other yeasts. An equimolar concentration of the chloride salt resulted in much milder effects, from 25% decrease to 66% increase in lipid output. The highest lipid outputs in this media were 8.3 and 7.9 g/L produced by Vanrija humicola UCDFST 10-1004 and UCDFST 12-717, respectively. These results demonstrated substantial lipid production in the presence of [C2C1Im]Cl at concentrations found in lignocellulosic hydrolysates, and thus, these two strains are ideal candidates for further investigation.

Three novel species of d-xylose-assimilating yeasts, Barnettozyma xylosiphila sp. nov., Barnettozyma xylosica sp. nov. and Wickerhamomyces xylosivorus f.a., sp. nov.

This study describes three novel xylose-assimilating yeasts, which were isolated from decayed wood collected from Bung Hatta Botanical Garden in West Sumatra and Cibodas Botanic Garden in West Java, or from litter from Eka Karya Bali Botanic Garden in Bali, Indonesia. Phylogenetic analysis was performed based on the sequences of the D1/D2 domains of the large ribosomal subunit (LSU), the small ribosomal subunit (SSU), the internal transcribed spacer (ITS) and elongation factor-1α (EF-1α), and the three strains were found to represent three novel species belonging to genera Barnettozyma or Wickerhamomyces. The morphological, biochemical and physiological characteristics indicated that the strains were distinct from other closely related species. Strains 13Y206T and 14Y196T belonging to the Barnettozyma clade are described as the type strains of Barnettozyma xylosiphila sp. nov. (type strain 13Y206T=NBRC 110202T=InaCC Y726T; MycoBank MB808598) and Barnettozyma xylosica sp. nov. (type strain 14Y196T=NBRC 111558T=InaCC Y1030T; MycoBank MB819485). Strain 14Y125T belonging to the Wickerhamomyces clade is described as the type strain of Wickerhamomyces xylosivorus f.a., sp. nov. (type strain 14Y125T=NBRC 111553T=InaCC Y1026T; MycoBank MB819484).

Discovery of synthesis and secretion of polyol esters of fatty acids by four basidiomycetous yeast species in the order Sporidiobolales.

Polyol esters of fatty acids (PEFA) are amphiphilic glycolipids produced by yeast that could play a role as natural, environmentally friendly biosurfactants. We recently reported discovery of a new PEFA-secreting yeast species, Rhodotorula babjevae, a basidiomycetous yeast to display this behavior, in addition to a few other Rhodotorula yeasts reported on the 1960s. Additional yeast species within the taxonomic order Sporidiobolales were screened for secreted glycolipid production. PEFA production equal or above 1 g L-1 were detected in 19 out of 65 strains of yeast screened, belonging to 6 out of 30 yeast species tested. Four of these species were not previously known to secrete glycolipids. These results significantly increase the number of yeast species known to secrete PEFA, holding promise for expanding knowledge of PEFA synthesis and secretion mechanisms, as well as setting the groundwork towards commercialization.

Pichia chibodasensis sp. nov., isolated in Indonesia.

Three strains (14Y260T, 14Y268 and 14Y276) of xylose-assimilating yeasts were isolated from decayed wood and soil collected in West Java in Indonesia. A phylogenetic analysis was performed based on the sequences of the D1/D2 domains of LSU, SSU and EF-1α, and the three strains were found to belong to the genus Pichia. The morphological, biochemical, physiological and chemotaxonomic characteristics indicated that these strains were distinct from other closely related species. Strains 14Y260T, 14Y268 and 14Y276 belonged to the Pichia clade and represent a novel species, named Pichia chibodasensis sp. nov. ; The type strain is 14Y260T (=NBRC 111569T=InaCC Y1042T).

New species of the genus Metschnikowia isolated from flowers in Indonesia, Metschnikowia cibodasensis sp. nov.

A novel species, Metschnikowia cibodasensis, is proposed to accommodate eight strains (ID03- 0093(T), ID03-0094, ID03-0095, ID03-0096, ID03-0097, ID03-0098, ID03-0099, and ID03-0109) isolated from flowers of Saurauia pendula, Berberis nepalensis, and Brunfelsia americana in Cibodas Botanical Garden, West Java, Indonesia. The type strain of M. cibodasensis is ID03- 0093(T) (= NBRC 101693(T) =UICC Y-335(T) = BTCC-Y25(T)). The common features of M. cibodasensis are a spherical to ellipsoidopedunculate shaped ascus, which contains one or two needleshaped ascospores, and lyse at maturity. Asci generally develop directly from vegetative cells but sometimes from chlamydospores. The neighbor-joining tree based on the D1/D2 domain of nuclear large subunit (nLSU) ribosomal DNA sequences strongly supports that M. cibodasensis (eight strains) and its closest teleomorphic species, M. reukaufii, are different species by a 100% bootstrap value. The type strain of M. cibodasensis, ID03-0093(T), differed from M. reukaufii NBRC 1679(T) by six nt (five substitutions and one deletion) in their D1/D2 region of nLSU rDNA, and by 18 nt (five deletions, four insertions, and nine substitutions) in their internal transcribed spacer regions of rDNA, respectively. Four strains representative of M. cibodasensis (ID03-0093(T), ID03-0095, ID03-0096, and ID03-0099) showed a mol% G+C content of 44.05 ± 0.25%, whereas that of M. reukaufii NBRC 1679(T) was 41.3%. The low value of DNADNA homology (5-16%) in four strains of M. cibodasensis and M. reukaufii NBRC 1679(T) strongly supported that these strains represent a distinct species.

Natural product libraries to accelerate the high-throughput discovery of therapeutic leads.

A high-throughput (HT) paradigm generating LC-MS-UV-ELSD-based natural product libraries to discover compounds with new bioactivities and or molecular structures is presented. To validate this methodology, an extract of the Indo-Pacific marine sponge Cacospongia mycofijiensis was evaluated using assays involving cytoskeletal profiling, tumor cell lines, and parasites. Twelve known compounds were identified including latrunculins (1-4, 10), fijianolides (5, 8, 9), mycothiazole (11), aignopsanes (6, 7), and sacrotride A (13). Compounds 1-5 and 8-11 exhibited bioactivity not previously reported against the parasite T. brucei, while 11 showed selectivity for lymphoma (U937) tumor cell lines. Four new compounds were also discovered including aignopsanoic acid B (13), apo-latrunculin T (14), 20-methoxy-fijianolide A (15), and aignopsane ketal (16). Compounds 13 and 16 represent important derivatives of the aignopsane class, 14 exhibited inhibition of T. brucei without disrupting microfilament assembly, and 15 demonstrated modest microtubule-stabilizing effects. The use of removable well plate libraries to avoid false positives from extracts enriched with only one or two major metabolites is also discussed. Overall, these results highlight the advantages of applying modern methods in natural products-based research to accelerate the HT discovery of therapeutic leads and/or new molecular structures using LC-MS-UV-ELSD-based libraries.