RESUMO
Yeast extract (YE) is the most common nitrogen source in a variety of bioprocesses in spite of the high cost. Therefore, the use of YE in culture media is one of the major technical hurdles to be overcome for the development of low-cost fermentation routes, making the search for alternative-cheaper nitrogen sources particularly desired. The aim of the current study is to develop cost-effective media based on corn steep liquor (CSL) and locally available vinasses in order to increase the economic potential for larger-scale bioproduction. Three microorganisms were evaluated: Lactobacillus rhamnosus , Debaryomyces hansenii , and Aspergillus niger . The amino acid profile and protein concentration was relevant for the xylitol and citric acid production by D. hansenii and A. niger , respectively. Metals also played an important role for citric acid production, meanwhile, D. hansenii showed a strong dependence with the initial amount of Mg(2+). Under the best conditions, 28.8 g lactic acid/L (Q(LA) = 0.800 g/L.h, Y(LA/S) = 0.95 g/g), 35.3 g xylitol/L (Q(xylitol) = 0.380 g/L.h, Y(xylitol/S) = 0.69 g/g), and 13.9 g citric acid/L (Q(CA) = 0.146 g/L.h, Y(CA/S) = 0.63 g/g) were obtained. The economic efficiency (E(p/euro)) parameter identify vinasses as a lower cost and more effective nutrient source in comparison to CSL.
Assuntos
Aspergillus niger/metabolismo , Meios de Cultura/economia , Debaryomyces/metabolismo , Aditivos Alimentares/metabolismo , Microbiologia Industrial/economia , Microbiologia Industrial/métodos , Lacticaseibacillus rhamnosus/metabolismo , Aspergillus niger/química , Ácido Cítrico/análise , Ácido Cítrico/metabolismo , Análise Custo-Benefício , Meios de Cultura/análise , Meios de Cultura/metabolismo , Debaryomyces/química , Fermentação , Aditivos Alimentares/análise , Ácido Láctico/análise , Ácido Láctico/metabolismo , Lacticaseibacillus rhamnosus/química , Xilitol/análise , Xilitol/metabolismoRESUMO
Microbial transformation of 13R,14R,15-trihydroxylabd-7-ene (5) and 13R,14R,15-trihydroxylabd-8(17)-ene (6) by the fungus Debaryomyces hansenii gave 1 (13R,14R,15-trihydroxy-6-oxolabd-8-ene) and 3 (7alpha,13R,14R,15-tetrahydroxy-labd-8(17)-ene), respectively. While, microbial transformation of 5 by Aspergillus niger afforded 2 (3beta,13R,14R,15-tetrahydroxy-labd-7-ene), and 13R,14R,15-trihydroxylabd-8,17-ene (6) gave 3 and 4 (3R,14R,15-3-oxotetrahydroxy-labd-7-ene). The structures of the new compounds, 1 and 2, were assigned by 1D and 2D high-field NMR spectroscopic methods. Antimicrobial activity of these compounds were tested and their MIC were determined.