Hanseniaspora menglaensis f.a., sp. nov., a novel apiculate yeast species isolated from rotting wood.

Two apiculate strains (NYNU 181072 and NYNU 181083) of a bipolar budding yeast species were isolated from rotting wood samples collected in Xishuangbanna Tropical Rainforest in Yunnan Province, southwest PR China. On the basis of phenotypic characteristics and the results of phylogenetic analysis of the D1/D2 domain of the large subunit (LSU) rRNA, internal transcribed spacer (ITS) region and the actin (ACT1) gene, the two strains were found to represent a single novel species of the genus Hanseniaspora, for which the name Hanseniaspora menglaensis f.a., sp. nov. (holotype CICC 33364T; MycoBank MB 847437) is proposed. In the phylogenetic tree, H. menglaensis sp. nov. showed a close relationship with Hanseniaspora lindneri, Hanseniaspora mollemarum, Hanseniaspora smithiae and Hanseniaspora valbyensis. H. menglaensis sp. nov. differed from H. lindneri, the most closely related known species, by 1.2 % substitutions in the D1/D2 domain, 2.5 % substitutions in the ITS region and 5.4 % substitutions in the ACT1 gene, respectively. Physiologically, H. menglaensis sp. nov. can also be distinguished from H. lindneri by its ability to assimilate d-gluconate.

Effect of XlogP and hansen solubility parameters on the prediction of small molecule modified docetaxel, doxorubicin and irinotecan conjugates forming stable nanoparticles.

Small molecule-chemotherapeutic drug conjugate nanoparticles (SMCDC NPs) has a great advantage in improving drug loading. However, the factors which influence these conjugates forming stable nanoparticles (NPs) are currently unclear. In our previous studies, we synthesized a series of fatty acid-paclitaxel conjugates and suggested that the changes in the hydrophobic parameters (XlogP), solubility parameters and crystallinity of these fatty acid-paclitaxel conjugates were the key factors for affecting these small molecule-chemotherapeutic drug conjugates (SMCDCs) forming stable NPs in water. Here, we selected clinically widely used chemotherapeutic drug (docetaxel (DTX), doxorubicin (DOX) and irinotecan (Ir)) as model drug, and chose three straight-chain fatty acids (acetic acid (Ac), hexanoic acid (HA) and stearic acid (SA)) and one branched small molecule (N-(tert-butoxycarbonyl) glycine (B-G)) to synthesize 12 SMCDCs. Our results indicated that our prediction criterions obtained from paclitaxel conjugates were also appropriated for these synthesized SMCDCs. We suggested that the present studies expanded the scope of application of the above-mentioned influencing factors, provided research ideas for the rational design of SMCDC forming NPs and a basis for screening NPs with good anticancer activity.

Does Consumption of Baker's Yeast (Saccharomyces cerevisiae) by Black Soldier Fly (Diptera: Stratiomyidae) Larvae Affect Their Fatty Acid Composition?

Fatty acids are important compounds for insects, but the requirements for essential fatty acids may differ between insect species. Most of the fatty acids are acquired through the insect's diet; therefore, supplementing the diet with baker's yeast (Saccharomyces cerevisiae Meyen ex E.C. Hansen), which produces unsaturated fatty acids, was predicted to affect the fatty acid composition of the insect. The tested insect was the black soldier fly (BSF) (Hermetia illucens L.), that is used as a source of protein and fat in feed. Therefore, there is importance for BSF larvae (BSFL) nutritional composition, especially the unsaturated fatty acids content, which is one of the nutritional limitations for mammalian diets. The dominant fatty acids of the tested BSFL were the saturated fatty acids: lauric, myristic, and palmitic acids, as found in other BSF studies. Oleic acid (c18:1) and linoleic acid (C18:2) were the abundant unsaturated fatty acids in the BSFL. The proportion of linoleic acid was higher in the substrate with the supplemental yeast; however, this did not affect its proportion in the larvae. The higher proportion of linoleic acid may have been exploited as a source for production of saturated lauric acid. Therefore, providing unsaturated fatty acids to the substrate through supplemental baker's yeast is not the most efficient way to increase the proportion of unsaturated fatty acids in the larvae.

Blautia argi sp. nov., a new anaerobic bacterium isolated from dog faeces.

Two isolates of a Gram-positive, non-motile, coccoid or oval-shaped anaerobic bacterium, designated strains N6H1-15T and YH1_16, were isolated from faecal samples obtained from a mature dog. Analysis of 16S rRNA gene sequences indicated that the isolates belonged to the Blautia coccoidesrRNA gene group (cluster XIVa) and were closely related to Blautia hansenii KCTC 5951T, Blautia stercoris KCTC 5981T, Blautia producta producta KCTC 3695T and B. coccoides DSM 15327T, with 96.7, 94.4, 94.2 and 93.9 % sequence similarity, respectively. The two isolates contained m-diaminopimelic acid within their peptidoglycans. The major polar lipids were diphosphatidylglycerol and phosphatidylglycerol, and the major fatty acids were C16 : 0 (18.5 %), C16 : 0 (18.0 %) and C18 : 1cis 9 (16.2 %). The predominant metabolic end products of glucose fermentation were acetic and lactic acids, and the G+C content was 44.2 mol%. Thus, the polyphasic data suggest that the two new isolates represent a new species, proposed as Blautia argi sp. nov. The type strain is N6H1-15T (=KCTC 15426=JCM 31394).

Rhodovulum algae sp. nov., isolated from an algal mat.

A reddish-brown-pigmented, phototrophic bacterium, designated strain JA877T, was isolated from a brown algae mat sample collected from Jalandhar beach, Gujarat, India. On the basis of the 16S rRNA gene sequence, strain JA877T belongs to the class Alphaproteobacteria and is closely related to the type strains Rhodovulum viride JA756T (99.0 %), Rhodovulum sulfidophilum Hansen W4T (98.9 %), Rhodovulumvisakhapatnamense JA181T (98.8 %),Rhodovulum kholense JA297T (97.5 %) and Rhodovulum salis JA746T (97.0). However, strain JA877T showed only 20-45 % relatedness with its phylogenetic neighbours and had a ∆Tm between 5.8 and 7.0 °C. The major respiratory quinone was ubiquinone-10 (Q10), and the polar lipid profile was composed of the major components phosphatidylglycerol, phosphatidylethanolamine, an unidentified phospholipid, two unidentified sulfolipids and five unidentified lipids. The major fatty acids were C18 : 1ω5c, C18 : 1ω7c/C18 : 1ω6c, C16 : 0 and C18 : 0. The DNA G+C content was 64.5 mol%. On the basis of 16S rRNA gene sequence analysis, physiological data, and chemotaxonomic and molecular differences, strain JA877T is significantly different from other species of the genus Rhodovulum and represents a novel species, for which the name Rhodovulum algae sp. nov. is proposed. The type strain is JA877T (=LMG 29228T= KCTC 42963T).

Bio-Based Solvents for Green Extraction of Lipids from Oleaginous Yeast Biomass for Sustainable Aviation Biofuel.

Lipid-based oleaginous microorganisms are potential candidates and resources for the sustainable production of biofuels. This study was designed to evaluate the performance of several alternative bio-based solvents for extracting lipids from yeasts. We used experimental design and simulation with Hansen solubility simulations and the conductor-like screening model for realistic solvation (COSMO-RS) to simulate the solubilization of lipids in each of these solvents. Lipid extracts were analyzed by high performance thin-layer chromatography (HPTLC) to obtain the distribution of lipids classes and gas chromatography coupled with a flame ionization detector (GC/FID) to obtain fatty acid profiles. Our aim was to correlate simulation with experimentation for extraction and solvation of lipids with bio-based solvents in order to make a preliminary evaluation for the replacement of hexane to extract lipids from microorganisms. Differences between theory and practice were noted for several solvents, such as CPME, MeTHF and ethyl acetate, which appeared to be good candidates to replace hexane.

Rhodovulum salis sp. nov. and Rhodovulum viride sp. nov., phototrophic Alphaproteobacteria isolated from marine habitats.

Two strains (JA746(T) and JA756(T)) having yellowish brown-to-green pigment were isolated from a solar saltern and a pink pond, respectively. While both strains were non-motile and shared the presence of bacteriochlorophyll-a, major cellular fatty acids (C18 : 1ω7c, C16 : 0, C18 : 0), quinone (Q-10), polar lipids and hopanoids, they differed from each other in their carotenoid composition. The G+C content of genomic DNA of strains JA746(T) and 756(T) was 62.4 and 63.3 mol%, respectively. The 16S rRNA gene-based EzTaxon-e blast search analysis of strains JA746(T) and 756(T) indicated highest sequence similarity with members of the genus Rhodovulum in the family Rhodobacteraceae of the class Alphaproteobacteria. Strain JA746(T) has high sequence similarities with Rhodovulum visakhapatnamense JA181(T) (97.3 %), Rhodovulum steppense A-20s(T) (97.3 %), Rhodovulum phaeolacus JA580(T) (97 %), Rhodovulum strictum MB-G2(T) (97 %) and other members of the genus Rhodovulum (<97 %). Strain JA756(T) has high sequence similarities with Rhodovulum visakhapatnamense JA181(T) (99.8 %), Rhodovulum sulfidophilum Hansen W4(T) (99.1 %), Rhodovulum kholense JA297(T) (97.9 %) and other members of the genus Rhodovulum (<97 %). The sequence similarity between strains JA746(T) and JA756(T) was 97.5 %. However, these strains are not closely related to each other or to their phylogenetic neighbours since the DNA-DNA reassociation values were less than 56 %. The genomic information was also supported by phenotypic and chemotaxonomic results, leading us to classify strains JA746(T) ( = NBRC 108898(T) = KCTC 15180(T)) and JA756(T) ( = NBRC 109122(T) = KCTC 15223(T)) as the type strains of two novel species of the genus Rhodovulum, for which the names Rhodovulum salis sp. nov. and Rhodovulum viride sp. nov. are proposed, respectively.

Plasma membrane composition of Debaryomyces hansenii adapts to changes in pH and external salinity.

Debaryomyces hansenii is a marine yeast that has to cope with different stress situations. Since changes in membrane properties can play an important function in adaptation, we have examined the fluidity and lipid composition of purified plasma membranes of D. hansenii grown at different external pH values and salt concentrations. Growth at low pH caused an increase in the sterol-to-phospholipid ratio and a decrease in fatty acid unsaturation which was reflected in decreased fluidity of the plasma membrane. High levels of NaCl increased the sterol-to-phospholipid ratio and fatty acid unsaturation, but did not significantly affect fluidity. The sterol-to-phospholipid ratios obtained in D. hansenii grown under any of these conditions were similar to the ratios that have been reported for halophilic/halotolerant black yeasts, but much smaller than those observed in the model yeast Saccharomyces cerevisiae.

The acyl-AMP ligase FadD32 and AccD4-containing acyl-CoA carboxylase are required for the synthesis of mycolic acids and essential for mycobacterial growth: identification of the carboxylation product and determination of the acyl-CoA carboxylase components.

Mycolic acids are major and specific long-chain fatty acids of the cell envelope of several important human pathogens such as Mycobacterium tuberculosis, M. leprae, and Corynebacterium diphtheriae. Their biosynthesis is essential for mycobacterial growth and represents an attractive target for developing new antituberculous drugs. We have previously shown that the pks13 gene encodes condensase, the enzyme that performs the final condensation step of mycolic acid biosynthesis and is flanked by two genes, fadD32 and accD4. To determine the functions of the gene products we generated two mutants of C. glutamicum with an insertion/deletion within either fadD32 or accD4. The two mutant strains were deficient in mycolic acid production and exhibited the colony morphology that typifies the mycolate-less mutants of corynebacteria. Application of multiple analytical approaches to the analysis of the mutants demonstrated the accumulation of a tetradecylmalonic acid in the DeltafadD32::km mutant and its absence from the DeltaaccD4::km strain. The parental corynebacterial phenotype was restored upon the transfer of the wild-type fadD32 and accD4 genes in the mutants. These data demonstrated that both FadD32 and AccD4-containing acyl-CoA carboxylase are required for the production of mycolic acids. They also prove that the proteins catalyze, respectively, the activation of one fatty acid substrate and the carboxylation of the other substrate, solving the long-debated question of the mechanism involved in the condensation reaction. We used comparative genomics and applied a combination of molecular biology and proteomic technologies to the analysis of proteins that co-immunoprecipitated with AccD4. This resulted in the identification of AccA3 and AccD5 as subunits of the acyl-CoA carboxylase. Finally, we used conditionally replicative plasmids to show that both the fadD32 and accD4 genes are essential for the survival of M. smegmatis. Thus, in addition to Pks13, FadD32 and AccD4 are promising targets for the development of new antimicrobial drugs against pathogenic species of mycobacteria and related microorganisms.

Acyl-CoA carboxylases (accD2 and accD3), together with a unique polyketide synthase (Cg-pks), are key to mycolic acid biosynthesis in Corynebacterianeae such as Corynebacterium glutamicum and Mycobacterium tuberculosis.

The Corynebacterianeae such as Corynebacterium glutamicum and Mycobacterium tuberculosis possess several unique and structurally diverse lipids, including the genus-specific mycolic acids. Although the function of a number of genes involved in fatty acid and mycolic acid biosynthesis is known, information relevant to the initial steps within these biosynthetic pathways is relatively sparse. Interestingly, the genomes of Corynebacterianeae possess a high number of accD genes, whose gene products resemble the beta-subunit of the acetyl-CoA carboxylase of Escherichia coli, providing the activated intermediate for fatty acid synthesis. We present here our studies on four putative accD genes found in C. glutamicum. Although growth of the accD4 mutant remained unchanged, growth of the accD1 mutant was strongly impaired and partially recovered by the addition of exogenous oleic acid. Overexpression of accD1 and accBC, encoding the carboxylase alpha-subunit, resulted in an 8-fold increase in malonyl-CoA formation from acetyl-CoA in cell lysates, providing evidence that accD1 encodes a carboxyltransferase involved in the biosynthesis of malonyl-CoA. Interestingly, fatty acid profiles remained unchanged in both our accD2 and accD3 mutants, but a complete loss of mycolic acids, either as organic extractable trehalose and glucose mycolates or as cell wall-bound mycolates, was observed. These two carboxyltransferases are also retained in all Corynebacterianeae, including Mycobacterium leprae, constituting two distinct groups of orthologs. Furthermore, carboxyl fixation assays, as well as a study of a Cg-pks deletion mutant, led us to conclude that accD2 and accD3 are key to mycolic acid biosynthesis, thus providing a carboxylated intermediate during condensation of the mero-chain and alpha-branch directed by the pks-encoded polyketide synthase. This study illustrates that the high number of accD paralogs have evolved to represent specific variations on the well known basic theme of providing carboxylated intermediates in lipid biosynthesis.