RESUMO
To obtain an industrial strain with high lipid yield, the wild strain G0 of Geotrichum robustum was mutated by means of nitrogen ions implantation. Mutagenic effects of strain G0 by low energy N+ ion implantation were studied. The experimental results indicated that the survival rate curve took a "saddle" shape, and the positive mutation rate was increased to 22.00 percent at the dose of nitrogen ions 2.0 x 10(15) ions/cm² when the survival rate was 28.60 percent. By repeated screening, a high lipid producing strain G9 was obtained. The biomass, lipid content and lipid yield of the mutant can reach 40.25 g/L, 71.14 percent and 28.63 g/L after cultured in a 5L fermenter for 8 days, increasing by 52.81 percent, 68.82 percent and 157.93 percent to those of wild strain, respectively. Analysis results on fatty acids composition and relative content by gas chromatography and mass spectrometry showed that the lipid in strain G9 was mainly composed of 16-carbon and 18-carbon fatty acids, including 37.360 percent oleic acid, 23.631 percent palmitic acid, 4.458 percent linoleic acid and 26.465 percent stearic acid. Such compositional features were quite similar to plant oil. Geotrichum robustum strain G9 may be an ideal high lipid producing strain for biodiesel production.
Assuntos
Geotrichum/efeitos da radiação , Geotrichum/genética , Íons , Lipídeos/análise , Mutação , Ácidos Graxos/análise , Fermentação , Cromatografia Gasosa-Espectrometria de Massas , Geotrichum/química , Radioisótopos de NitrogênioRESUMO
New bioemulsifier-producing yeasts were isolated from the biological wastewater treatment plant of a dairy industry. Of the 31 bioemulsifier-producing strains, 12 showed emulsifying activity after 2months of incubation, with E(24) values ranging from 7% to 78%. However, only Trichosporon loubieri CLV20, Geotrichum sp. CLOA40, and T. montevideense CLOA70 exhibited high emulsion-stabilizing capacity, with E(24) values of 78%, 67%, and 66%, respectively. These isolates were shown to induce a strong emulsion stabilizing activity rather than the reduction of the interfacial tension. These strains exhibited similar growth rates in the exponential growth phase, with a clear acceleration after 24h and stabilization of the activity after 144h. Emulsification and stability properties of the bioemulsifiers were compared to those of commercial surfactants after the addition of NaCl and exposure to temperature of 100 degrees C. The compounds produced by the isolates appeared to be lipid-polysaccharide complexes. Gas chromatograph analysis of the lipidic fraction of the bioemulsifiers from CLV20, CLOA40, and CLOA70 shows the prevalence of (9Z,12Z)-octadeca-9,12-dienoic acid, in concentrations of 42.8%, 25.9%, and 49.8%, respectively. The carbohydrate composition, as determined by GC-MS of their alditol acetate derivatives, showed a predominance of mannose, galactose, xylose and arabinose.
Assuntos
Indústria de Laticínios/métodos , Emulsões/química , Purificação da Água/métodos , Cromatografia Gasosa/métodos , DNA Intergênico , Genes Fúngicos , Geotrichum/genética , Resíduos Industriais , Indústrias , Cinética , Espectrometria de Massas/métodos , Reação em Cadeia da Polimerase , Temperatura , Trichosporon/genética , Eliminação de Resíduos Líquidos/métodosRESUMO
Four strains of an asexual arthroconidial yeast species were isolated from Drosophila flies in two Atlantic rain forest sites in Brazil and two strains from oak tasar silkworm larvae (Antheraea proylei) in India. Analysis of the sequences of the D1/D2 large subunit rRNA gene showed that this yeast represented a novel species of the genus Geotrichum, described as Geotrichum silvicola sp. nov. The novel species was related to the ascogenous genus Galactomyces. The closest relatives of Geotrichum silvicola were Galactomyces sp. strain NRRL Y-6418 and Galactomyces geotrichum. The type culture of Geotrichum silvicola is UFMG-354-2T (=CBS 9194T=NRRL Y-27641T).