RESUMO

The aim of this study was to evaluate the biosynthesis of flavor compounds from rice bran by fermentation facilitated by Kluyveromyces marxianus and Debaryomyces hansenii. The growth of both yeasts was assessed by specific growth rates and doubling time. The biosynthesis of flavor compounds was evaluated by gas chromatography-olfactometry (GC-O), gas chromatography-mass spectrometry (GC-MS), and Spectrum™ sensory analysis. The specific growth rate (µ) and doubling time (td) of K. marxianus was calculated as 0.16/h and 4.21h, respectively, whereas that of D. hansenii was determined as 0.13/h and 5.33h, respectively. K. marxianus and D. hansenii produced significant levels of higher alcohols and acetate esters from rice bran. Results showed that K. marxianus can produce 827.27 µg/kg of isoamyl alcohol, 169.77 µg/kg of phenyl ethyl alcohol, and 216.08 µg/kg of phenyl ethyl acetate after 24-h batch fermentation. A significant amount of isovaleric acid was also synthesized by K. marxianus (4013 µg/kg) after the batch fermentation of 96 h. 415.64 µg/kg of isoamyl alcohol and 135.77 µg/kg of phenyl ethyl acetate was determined in rice bran fermented by D. hansenii after 24-h fermentation. Fermented cereals and rose were the characteristic flavor descriptors of the fermented rice bran samples. Rose flavor in fermented rice bran samples was found to be associated with phenyl ethyl alcohol, phenyl ethyl acetate, isoamyl acetate, and guaiacol. Thus, the findings of this study demonstrate that the valorization of rice bran can be achieved with the production of natural flavor compounds by yeast metabolism.

Assuntos

Debaryomyces , Kluyveromyces , Oryza , Etanol/metabolismo , Fermentação , Cromatografia Gasosa-Espectrometria de Massas , Kluyveromyces/metabolismo , Oryza/metabolismo , Leveduras/metabolismo

RESUMO

In this study we report the potential of alcohols as morphogenetic regulators in Candida albicans. All the alcohols tested influenced various modes of growth like planktonic as well as biofilm forms. Viability was affected at high concentrations. Among the alcohols, the response of C. albicans to amyl alcohol (pentanol) was noteworthy. Amyl alcohol at a concentration 0.5% which was not inhibitory to growth and viability specifically inhibited morphogenetic switching from yeast to hyphal forms. It also inhibited normal biofilm development favoring yeast dominated biofilms. Based on this study we hypothesize that alcohols produced under anaerobic conditions may not favor biofilm development and support dissemination of yeast cells. Since anaerobic conditions are not found to favor production of quorum sensing molecules like farnesol, the alcohols may play a role in morphogenetic regulation.

Assuntos

Álcoois/metabolismo , Biofilmes/crescimento & desenvolvimento , Candida albicans/efeitos dos fármacos , Candida albicans/fisiologia , Candida albicans/citologia , Candida albicans/crescimento & desenvolvimento , Viabilidade Microbiana/efeitos dos fármacos

RESUMO

In the Saccharomyces cerevisiae glycolytic pathway, 11 enzymes catalyze the stepwise conversion of glucose to two molecules of ethanol plus two CO2 molecules. In the highly crowded cytoplasm, this pathway would be very inefficient if it were dependent on substrate/enzyme diffusion. Therefore, the existence of a multi-enzymatic glycolytic complex has been suggested. This complex probably uses the cytoskeleton to stabilize the interaction of the various enzymes. Here, the role of filamentous actin (F-actin) in stabilization of a putative glycolytic metabolon is reported. Experiments were performed in isolated enzyme/actin mixtures, cytoplasmic extracts and permeabilized yeast cells. Polymerization of actin was promoted using phalloidin or inhibited using cytochalasin D or latrunculin. The polymeric filamentous F-actin, but not the monomeric globular G-actin, stabilized both the interaction of isolated glycolytic pathway enzyme mixtures and the whole fermentation pathway, leading to higher fermentation activity. The associated complexes were resistant against inhibition as a result of viscosity (promoted by the disaccharide trehalose) or inactivation (using specific enzyme antibodies). In S. cerevisiae, a glycolytic metabolon appear to assemble in association with F-actin. In this complex, fermentation activity is enhanced and enzymes are partially protected against inhibition by trehalose or by antibodies.

Assuntos

Citoesqueleto de Actina/metabolismo , Actinas/metabolismo , Glicólise , Metaboloma , Complexos Multienzimáticos/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/metabolismo , Citoesqueleto de Actina/efeitos dos fármacos , Actinas/agonistas , Actinas/antagonistas & inibidores , Actinas/química , Anticorpos Antifúngicos/farmacologia , Compostos Bicíclicos Heterocíclicos com Pontes/farmacologia , Citocalasina D/farmacologia , Citoplasma/efeitos dos fármacos , Citoplasma/enzimologia , Citoplasma/metabolismo , Estabilidade Enzimática/efeitos dos fármacos , Fermentação/efeitos dos fármacos , Glicólise/efeitos dos fármacos , Cinética , Metaboloma/efeitos dos fármacos , Complexos Multienzimáticos/antagonistas & inibidores , Complexos Multienzimáticos/química , Faloidina/farmacologia , Polimerização/efeitos dos fármacos , Saccharomyces cerevisiae/efeitos dos fármacos , Saccharomyces cerevisiae/enzimologia , Proteínas de Saccharomyces cerevisiae/agonistas , Proteínas de Saccharomyces cerevisiae/antagonistas & inibidores , Proteínas de Saccharomyces cerevisiae/química , Tiazolidinas/farmacologia , Trealose/farmacologia , Moduladores de Tubulina/farmacologia , Viscosidade

RESUMO

In this study we report the potential of alcohols as morphogenetic regulators in Candida albicans. All the alcohols tested influenced various modes of growth like planktonic as well as biofilm forms. Viability was affected at high concentrations. Among the alcohols, the response of C. albicans to amyl alcohol (pentanol) was noteworthy. Amyl alcohol at a concentration 0.5% which was not inhibitory to growth and viability specifically inhibited morphogenetic switching from yeast to hyphal forms. It also inhibited normal biofilm development favoring yeast dominated biofilms. Based on this study we hypothesize that alcohols produced under anaerobic conditions may not favor biofilm development and support dissemination of yeast cells. Since anaerobic conditions are not found to favor production of quorum sensing molecules like farnesol, the alcohols may play a role in morphogenetic regulation.

Assuntos

Álcoois/metabolismo , Biofilmes/crescimento & desenvolvimento , Candida albicans/efeitos dos fármacos , Candida albicans/fisiologia , Candida albicans/citologia , Candida albicans/crescimento & desenvolvimento , Viabilidade Microbiana/efeitos dos fármacos

RESUMO

In this study we report the potential of alcohols as morphogenetic regulators in Candida albicans. All the alcohols tested influenced various modes of growth like planktonic as well as biofilm forms. Viability was affected at high concentrations. Among the alcohols, the response of C. albicans to amyl alcohol (pentanol) was noteworthy. Amyl alcohol at a concentration 0.5% which was not inhibitory to growth and viability specifically inhibited morphogenetic switching from yeast to hyphal forms. It also inhibited normal biofilm development favoring yeast dominated biofilms. Based on this study we hypothesize that alcohols produced under anaerobic conditions may not favor biofilm development and support dissemination of yeast cells. Since anaerobic conditions are not found to favor production of quorum sensing molecules like farnesol, the alcohols may play a role in morphogenetic regulation.

RESUMO

In this study we report the potential of alcohols as morphogenetic regulators in Candida albicans. All the alcohols tested influenced various modes of growth like planktonic as well as biofilm forms. Viability was affected at high concentrations. Among the alcohols, the response of C. albicans to amyl alcohol (pentanol) was noteworthy. Amyl alcohol at a concentration 0.5% which was not inhibitory to growth and viability specifically inhibited morphogenetic switching from yeast to hyphal forms. It also inhibited normal biofilm development favoring yeast dominated biofilms. Based on this study we hypothesize that alcohols produced under anaerobic conditions may not favor biofilm development and support dissemination of yeast cells. Since anaerobic conditions are not found to favor production of quorum sensing molecules like farnesol, the alcohols may play a role in morphogenetic regulation.