ABSTRACT
In this study, waste peach (WP) liquid culture conditions for the maintenance of high triacylglycerol (TG)-accumulation ability in Lipomyces wild-type strain, obtained from WP plate medium were investigated. As the concentration of WP juice was high, the medium viscosity became high, and TG accumulation ability was suppressed. In a 5-L jar fermenter, the negative influence of viscosity on TG-accumulation ability was significantly improved by an agitation speed of 150 rpm (0.4 vvm). Where a bench scale pilot plant (90-L jar fermenter) was operated at 40 rpm, TG-accumulation ability reached 6.8 mg/108cells. This ability was 85% of that obtained with WP plate medium.
Subject(s)
Culture Media/metabolism , Fruit and Vegetable Juices/microbiology , Lipomyces/metabolism , Prunus persica/microbiology , Triglycerides/biosynthesis , Bioreactors , Culture Media/chemistry , Fermentation , Refuse Disposal/methods , ViscosityABSTRACT
The yeast Lipomyces accumulates triacylglycerols (TAGs) as intracellular fat globules, and these TAGs can be used as source materials for biodiesel production. In this study, we aimed to use this yeast to produce lipids from renewable resources. Using plate culture and micrograph methods, strains with a high lipid-accumulation ability were screened from 15,408 types of systems combining renewable resources, strains, and culture temperatures. The lipid-accumulation ability of the strains was estimated from the fat globule volume, which was calculated using a micrograph. The reliability of this method was examined, and strains with a high lipid-accumulation ability were identified for each renewable resource. Seventy-seven Lipomyces strains (7 deposit, 68 wild-type, 2 mutants) with a high lipid-accumulation ability were selected. A few strains possessed the ability to accumulate large amounts of TAGs from more than four different renewable resources. We found that strains with a high lipid-accumulation ability could efficiently convert consumed carbon sources into TAGs, which could be easily recovered from the fat globules of these strains through physical disruption.
Subject(s)
Biofuels/microbiology , Conservation of Energy Resources/methods , Lipid Metabolism/genetics , Lipomyces/genetics , Biofuels/analysis , Carbon/metabolism , Culture Media , Industrial Microbiology , Lipid Droplets/metabolism , Lipomyces/metabolism , Reproducibility of Results , Triglycerides/metabolismABSTRACT
Four novel Lipomyces strains were isolated from soil collected in the Okinawa and Yamanashi prefectures, Japan. Based on their morphological and biochemical characteristics, along with sequence typing using the D1/D2 domain of the LSU rRNA, internal transcribed spacer (ITS) region including 5.8S rRNA, and translation elongation factor 1 alpha gene (EF-1α), the four strains were shown to represent two novel species of the genus Lipomyces, described as Lipomyces okinawensis sp. nov. (type strain No.3-a(35)T=NBRC 110620T=CBS 14747T) and Lipomyces yamanashiensis f.a., sp. nov. (type strain No.313T=NBRC 110621T=CBS 14748T).
Subject(s)
Lipomyces/classification , Phylogeny , Soil Microbiology , DNA, Fungal/genetics , DNA, Ribosomal Spacer/genetics , Genes, Fungal , Japan , Lipomyces/genetics , Lipomyces/isolation & purification , Mycological Typing Techniques , Peptide Elongation Factor 1/genetics , RNA, Ribosomal/genetics , Sequence Analysis, DNAABSTRACT
Lipomyces starkeyi is an oleaginous yeast, and has been classified in four distinct groups, i.e., sensu stricto and custers α, ß, and γ. Recently, L. starkeyi clusters α, ß, and γ were recognized independent species, Lipomyces mesembrius, Lipomyces doorenjongii, and Lipomyces kockii, respectively. In this study, we investigated phylogenetic relationships within L. starkeyi, including 18 Japanese wild strains, and its related species, based on internal transcribed spacer sequences and evaluated biochemical characters which reflected the phylogenetic tree. Phylogenetic analysis showed that most of Japanese wild strains formed one clade and this clade is more closely related to L. starkeyi s.s. clade including one Japanese wild strain than other clades. Only three Japanese wild strains were genetically distinct from L. starkeyi. Lipomyces mesembrius and L. doorenjongii shared one clade, while L. kockii was genetically distinct from the other three species. Strains in L. starkeyi s.s. clade converted six sugars, D-glucose, D-xylose, L-arabinose, D-galactose, D-mannose, and D-cellobiose to produce high total lipid yields. The Japanese wild strains in subclades B, C, and D converted D-glucose, D-galactose, and D-mannose to produce high total lipid yields. Lipomyces mesembrius was divided into two subclades. Lipomyces mesembrius CBS 7737 converted D-xylose, L-arabinose, D-galactose, and D-cellobiose, while the other L. mesembrius strains did not. Lipomyces doorenjongii converted all the sugars except D-cellobiose. In comparison to L. starkeyi, L. mesembrius, and L. doorenjongii, L. kockii produced higher total lipid yields from D-glucose, D-galactose, and D-mannose. The type of sugar converted depended on the subclade classification elucidated in this study.
Subject(s)
Lipomyces/classification , Lipomyces/metabolism , Oils/metabolism , Phylogeny , Japan , Lipomyces/genetics , Lipomyces/isolation & purification , Molecular Sequence Data , Monosaccharides/metabolism , Mycological Typing TechniquesABSTRACT
We have identified the enzyme responsible for erythritol utilization and its reaction product in the yeast Lipomyces starkeyi CBS 1807. The enzyme, a polyol dehydrogenase requiring NAD+ as a coenzyme, was induced by erythritol in this yeast. We confirmed that the enzyme product was L-erythrulose by MS, NMR, and polarimeter analyses, meaning that we clarified the first step of erythritol utilization in yeasts for the first time. In the case of the oxidative reaction, D-threitol, (2R,3R)-2,3-butanediol, and erythritol were much better substrates than 21 other polyols tested. These three substrates are tetroses and have an R configuration at C-3, and whose third carbon results in easiest oxidation in this enzyme. The research of the substrate specificity in the reductive reaction demonstrated that L-erythrulose and dihydroxyacetone were better substrates, that D-acetoin was inactive and L-erythrose (aldose) was slightly active.
Subject(s)
Ascomycota/enzymology , Ascomycota/metabolism , Erythritol/metabolism , L-Iditol 2-Dehydrogenase/chemistry , Biotechnology/methods , Carbohydrates/chemistry , Cell-Free System , Dihydroxyacetone/chemistry , Magnetic Resonance Spectroscopy , Mass Spectrometry , Sequence Analysis, Protein , Substrate SpecificityABSTRACT
A preparation method of total DNA from Lipomyces yeasts was improved in order to exclude extracellular acidic polysaccharide thoroughly. The method combined an ultracentrifuge and polyethylene glycol precipitation with the usual method. The total DNAs obtained were analyzed for G + C content and by DNA-DNA hybridization. The results all agreed almost completely with literature data. All the DNA samples prepared using this method were pure enough for these taxonomic analyses and could also be used as templates of PCR for amplification of small subunit ribosomal DNA and the internal transcribed spacer region.
Subject(s)
DNA, Fungal/isolation & purification , Polysaccharides/chemistry , Yeasts/chemistry , Yeasts/classification , Classification , Nucleic Acid Hybridization , Polyethylene Glycols/chemistry , RNA, Fungal/biosynthesis , RNA, Fungal/isolation & purification , Reverse Transcriptase Polymerase Chain Reaction , UltracentrifugationABSTRACT
A chemically defined sporulation medium (AF medium) for the yeasts belonging to the genus Lipomyces was developed. The chemical composition was derived from chemical analyses of soybean extract. Some chemical modification of the AF medium indicated that the nitrogen sources (aspartic and glutamic acids) and zinc ion were essential for sporulation. The significance of medium pH was discussed.
