ABSTRACT
The glucoamylase from Aspergillus niger, immobilized into poly(vinylalcohol) hydrogel lens-shaped capsules LentiKats, was used for simultaneous saccharification and fermentation (SSF) with Zymomonas mobilis in free form. This system was stable in both the repeated batch and continuous mode of SSF. The microorganism was found to adsorb on the capsules with immobilized enzyme. This increased the ethanol productivity of the repeated batch system with 5% w/v of immobilized glucoamylase almost 2.1 times (7.2 g l(-1) h(-1)) compared to free enzyme-free microorganism system (3.5 g l(-1) h(-1)). The continuous SSF with the immobilized glucoamylase (11.5% w/v) tested for 15 days had productivity 10 g l(-1) h(-1), which is comparable to continuous experiments on semi-defined glucose medium (10 g l(-1) h(-1)). These two systems were stable in both glucoamylase activity and microorganism productivity.
Subject(s)
Enzymes, Immobilized/metabolism , Ethanol/metabolism , Glucan 1,4-alpha-Glucosidase/metabolism , Hydrogel, Polyethylene Glycol Dimethacrylate/chemistry , Polyvinyl Alcohol/chemistry , Starch/metabolism , Aspergillus niger/enzymology , Enzymes, Immobilized/chemistry , Fermentation , Glucan 1,4-alpha-Glucosidase/chemistry , Time Factors , Zymomonas/metabolismABSTRACT
AIMS: To examine the potential of Zymomonas mobilis entrapped into polyvinylalcohol (PVA) lens-shaped immobilizates in batch and continuous ethanol production. METHODS AND RESULTS: Cells, free or immobilized in PVA hydrogel-based lens-shaped immobilizates - LentiKats, were cultivated on glucose medium in a 1 l bioreactor. In comparison with free cell cultivation, volumetric productivity of immobilized batch culture was nine times higher (43.6 g l(-1) h(-1)). The continuously operated system did not improve the efficiency (volumetric productivity of the immobilized cells 30.7 g l(-1) h(-1)). CONCLUSIONS: We demonstrated Z. mobilis capability, entrapped into LentiKats, in the cost-efficient batch system of ethanol production. SIGNIFICANCE AND IMPACT OF THE STUDY: The results reported here emphasize the potential of bacteria in combination with suitable fermentation technology in industrial scale. The innovation compared with traditional systems is characterized by excellent long-term stability, high volumetric productivity and other technological advantages.
Subject(s)
Cells, Immobilized/metabolism , Ethanol , Industrial Microbiology , Zymomonas/metabolism , Biotechnology/instrumentation , Biotechnology/methods , Fermentation , Polyvinyl Alcohol/metabolism , Zymomonas/geneticsABSTRACT
The yeast strains of the genus Dipodascus were used for the bioconversion of fumaric acid to L-malic acid. Under nongrowth conditions, the fumarase activity in the intact cells or in the cell-free extract of Dipodascus was 10 times higher than that of Saccharomyces cerevisiae cells. Pretreatment of the Dipodascus with malonate was not necessary because succinate was not detected as a by-product. The fumarase activity in Dipodascus magnusii CCM 8235 was increased approximately 100% when Triton X-305 (0.1%) was added to the reaction mixture.
Subject(s)
Malates/metabolism , Saccharomycetales/enzymology , Biomass , Culture Media , Detergents/pharmacology , Fumarate Hydratase/metabolism , Saccharomyces cerevisiae/drug effects , Saccharomyces cerevisiae/enzymology , Saccharomyces cerevisiae/growth & development , Saccharomycetales/drug effects , Saccharomycetales/growth & developmentABSTRACT
Growth and L-lactic acid production on 24 different carbohydrates and polyols (glycerol, mannitol and sorbitol) by Rhizopus arrhizus CCM 8109 were determined. The D- but not the L-forms of xylose, fructose, galactose, mannose, glucose, cellobiose, maltose and sucrose and partially hydrolysed starch were converted to L-lactic acid. Changes in lipid formation and fatty acid composition were detected in biomass grown on the different sugars. In the presence of polyols, growth and considerable production of lipids were observed with little or no lactate production. Invertase was mainly associated with the mycelium during growth on sucrose, whereas glucoamylase and α-amylase were produced extracellularly during growth on starch.
ABSTRACT
The production of L(+)-lactic acid and formation of gamma-linolenic acid by 50 Rhizopus strains growing on saccharidic substrates were investigated. Formation of acids was observed on solid cultivation media but mainly during submerged fermentation. Strains with the highest selectivity of both L(+)-lactic acid production and gamma-linolenic acid formation were tested in a laboratory fermenter. The best producer was treated by UV irradiation to increase the fatty acid content in the biomass, especially that of gamma-linolenic acid. The conversion of 10% saccharidic substrate by this newly prepared strain Rhizopus arrhizus CCM 8109 results in more than 95% of theoretical yield of L(+)-lactic acid and permits a volume productivity of 0.4 g gamma-linolenic acid per liter.
