RESUMEN
This study investigated effects of the simultaneous application of thymol and salicylic acid (SIMTSA) on the target sites of Rhizopus stolonifer, as well as the defenceenzymes of postharvest tomato, when applied as edible coating. SIMTSA induced the changes of ultrastructure and membrane integrity of R. stolonifer. When the concentrations of the fungistat increased, cells stained with propidium iodide and leakage of 260/280â¯nm-absorbing materials increased while ergosterol synthesis decreased, suggesting damage of cell membrane. Furthermore, SIMTSA treatment significantly reduced the citric acid content and the activities of enzymes related to the tricarboxylic acid cycle, and increased the mitochondrial membrane potential and the reactive oxygen species, indicating damage of mitochondrial-related functions. Moreover, SIMTSA edible coating increased the defence enzyme activities in tomato. Based on the results, SIMTSA can be used as a potential preservation method for tomato as it showed a targeted effect on the cell membrane and mitochondria of R. stolonifer.
Asunto(s)
Antifúngicos/farmacología , Rhizopus/efectos de los fármacos , Ácido Salicílico/farmacología , Solanum lycopersicum/microbiología , Timol/farmacología , Membrana Celular/efectos de los fármacos , Ácido Cítrico/metabolismo , Enzimas/metabolismo , Ergosterol/metabolismo , Microbiología de Alimentos , Conservación de Alimentos/métodos , Potencial de la Membrana Mitocondrial/efectos de los fármacos , Mitocondrias/efectos de los fármacos , Especies Reactivas de Oxígeno/metabolismo , Rhizopus/citología , Rhizopus/ultraestructuraRESUMEN
Herein, a facile one-pot synthetic method was explored for the fabrication of glutathione capped Mn2+ dopedzinc sulphide quantum dots (GSH-Mn2+-ZnS QDs) for both fluorescent detection of Cu2+ and Hg2+ ions and for fluorescence imaging of two cancer (RIN5F and MDAMB231) and fungal (Rhizopus oryzae) cells. Particularly, doping of Mn2+ into ZnS QDs nanocrystal structure resulted a great improvement in the fluorescence properties of ZnS QDs. The emission peak of undoped ZnS QDs was found at 447â¯nm, which is due to the large number of surface defects in the ZnS QDs nanostructures. Under identical conditions, there is a good linear relationship between the quenching of fluorescence intensity and analytes (Cu2+ and Hg2+ ions) concentration in the range of 0.005 to 0.2â¯mM and of 0.025 to 0.4â¯mM for Cu2+ and Hg2+ ions, respectively. The GSH-Mn2+-ZnS QDs exhibit least cytotoxicity against RIN5F and MDAMB231 cells, demonstrating the multifunctional applications in sensing of metal ions and biocompatibility towards cancer (RIN5F and MDAMB231) and fungal (Rhizopus oryzae) cells.
Asunto(s)
Cobre/análisis , Colorantes Fluorescentes/química , Mercurio/análisis , Puntos Cuánticos/química , Sulfuros/química , Compuestos de Zinc/química , Ciclo Celular/efectos de los fármacos , Línea Celular Tumoral , Agua Dulce/análisis , Agua Dulce/química , Glutatión/química , Humanos , Concentración de Iones de Hidrógeno , Manganeso/química , Ensayo de Materiales , Nanopartículas/química , Puntos Cuánticos/toxicidad , Rhizopus/citología , Espectrometría de Fluorescencia/métodos , Espectrofotometría Ultravioleta , Contaminantes Químicos del Agua/análisisRESUMEN
An extracellular polysaccharide (EPS1-1) extracted from the fermentation broth of Rhizopus nigricans has been proved to enhance the immunity of immunosuppressed mice. The purpose of this study was to investigate the beneficial effects of EPS1-1 on the intestinal immunity of mice with colorectal cancer induced by azoxymethane (AOM) and dextran sodium sulfate (DSS). The results showed that EPS1-1 could resist hydrolysis in an artificial stomach. Oral EPS1-1 modulated gut microbiota and increased the concentration of total short-chain fatty acids (SCFAs) in the feces of colorectal cancer mice compared with the AOM/DSS only-treated mice. Furthermore, EPS1-1 increased the villus length, ratio of villus length and crypt depth in colonic tissues, and improved the number of acid mucus-secreting goblet cells in mice with colorectal cancer. These findings suggest that EPS1-1 might play an important role in the improvement of intestinal function in mice with colorectal cancer, which indicate its strong potential as efficient bio-secure immunotherapy for clinical applications or adjuvant drug.
Asunto(s)
Neoplasias Colorrectales/inmunología , Espacio Extracelular/química , Polisacáridos Fúngicos/farmacología , Intestinos/inmunología , Rhizopus/química , Animales , Digestión , Ácidos Grasos Volátiles/metabolismo , Heces/química , Polisacáridos Fúngicos/metabolismo , Microbioma Gastrointestinal/efectos de los fármacos , Humanos , Mucosa Intestinal/metabolismo , Intestinos/microbiología , Lactatos/metabolismo , Ratones , Ratones Endogámicos BALB C , Rhizopus/citologíaRESUMEN
A novel fermentation system was employed whereby the mycelial mat of Rhizopus oryzae was attached to a polypropylene tube. Batch operation was used for growth, while continuous operation was employed during the fumaric acid production phase. A clear decrease in respiration, fumaric acid (FA) and ethanol production was observed when zero nitrogen was fed in the production phase, with FA productivity decreasing from an initial 0.7â¯gâ¯L-1â¯h-1 to 0.3â¯gâ¯L-1â¯h-1 after 150â¯h. With the addition of 0.625â¯mgâ¯L-1â¯h-1 of urea FA productivity dropped to only 0.4â¯gâ¯L-1â¯h-1 after 150â¯h and 0.3â¯gâ¯L-1â¯h-1 after 400â¯h. Under these conditions it was observed that the ethanol production rate decreased 20 times faster compared with the FA production rate, therefore resulting in high FA yields towards the end of the fermentation (instantaneous 0.96â¯gâ¯g-1 and average 0.81â¯gâ¯g-1 after 400â¯h). Increasing the urea feed rate to 1.875â¯mgâ¯L-1â¯h-1 resulted in a clear increase in FA production and respiration rates. This condition also resulted in a 25% increase in biomass after 150â¯h, while the decline in the ethanol production rate was seven times lower than in the 0.625â¯mgâ¯L-1â¯h-1 urea fermentation, resulting in lower FA yields.
Asunto(s)
Células Inmovilizadas/metabolismo , Fumaratos/metabolismo , Nitrógeno/metabolismo , Rhizopus/metabolismo , Células Inmovilizadas/citología , Etanol/metabolismo , Rhizopus/citologíaRESUMEN
We have found a remarkable capacity for the ubiquitous Gram-negative rod bacterium Serratia marcescens to migrate along and kill the mycelia of zygomycete molds. This migration was restricted to zygomycete molds and several basidiomycete species. No migration was seen on any molds of the phylum Ascomycota. S. marcescens migration did not require fungal viability or surrounding growth medium, as bacteria migrated along aerial hyphae as well.S. marcescens did not exhibit growth tropism toward zygomycete mycelium. Bacterial migration along hyphae proceeded only when the hyphae grew into the bacterial colony. S. marcescens cells initially migrated along the hyphae, forming attached microcolonies that grew and coalesced to generate a biofilm that covered and killed the mycelium. Flagellum-defective strains of S. marcescens were able to migrate along zygomycete hyphae, although they were significantly slower than the wild-type strain and were delayed in fungal killing. Bacterial attachment to the mycelium does not necessitate type 1 fimbrial adhesion, since mutants defective in this adhesin migrated equally well as or faster than the wild-type strain. Killing does not depend on the secretion of S. marcescens chitinases, as mutants in which all three chitinase genes were deleted retained wild-type killing abilities. A better understanding of the mechanisms by which S. marcescens binds to, spreads on, and kills fungal hyphae might serve as an excellent model system for such interactions in general; fungal killing could be employed in agricultural fungal biocontrol.
Asunto(s)
Biopelículas/crecimiento & desarrollo , Hongos/fisiología , Serratia marcescens/fisiología , Antibiosis/fisiología , Adhesión Bacteriana/fisiología , Quitinasas/genética , Quitinasas/metabolismo , Fimbrias Bacterianas , Flagelos/genética , Flagelos/fisiología , Hongos/citología , Interacciones Huésped-Patógeno , Hifa/citología , Hifa/fisiología , Viabilidad Microbiana , Mutación , Micelio/citología , Micelio/fisiología , Control Biológico de Vectores , Rhizopus/citología , Rhizopus/fisiología , Serratia marcescens/citologíaRESUMEN
The contribution of different fungal cell wall components in adsorption of polycyclic aromatic hydrocarbons (PAHs) is still unclear. We isolated Rhizopus oryzae cell walls components with sequential extraction, characterized functional groups with NEXAFS spectra, and determined partition coefficients of PAHs on cell walls and cell wall components with cosolvent model. Spectra of NEXAFS indicated that isolated cell walls components were featured with peaks at ~532.7 and ~534.5eV energy. The lipid cosolvent partition coefficients were approximately one order of magnitude higher than the corresponding carbohydrate cosolvent partition coefficients. The partition coefficients for four tested carbohydrates varied at approximate 0.5 logarithmic units. Partition coefficients between biosorbents and water calculated based cosolvent models ranged from 0.8 to 4.2. The present study proved the importance of fungal cell wall components in adsorption of PAHs, and consequently the role of fungi in PAHs bioremediation.
Asunto(s)
Pared Celular/metabolismo , Metanol/química , Modelos Biológicos , Hidrocarburos Policíclicos Aromáticos/metabolismo , Rhizopus , Solventes/química , Contaminantes Químicos del Agua/análisis , Agua/química , Adsorción , Biodegradación Ambiental , Polisacáridos/química , Polisacáridos/metabolismo , Rhizopus/citología , Rhizopus/metabolismoRESUMEN
Respiratory-deficient mutants of Rhizopus oryzae (R. oryzae) AS 3.3461 were acquired by ultraviolet (UV) irradiation to investigate changes in intracellular NADH metabolic pathway and its influence on the fermentation characteristics of the strain. Compared with R. oryzae AS 3.3461, the intracellular ATP level of the respiratory-deficient strain UV-1 decreased by 52.7 % and the glucose utilization rate rose by 8.9 %; When incubated for 36 h, the activities of phosphofructokinase (PFK), hexokinase (HK), and pyruvate kinase (PK) in the mutant rose by 74.2, 7.2, and 12.0 %, respectively; when incubated for 48 h, the intracellular NADH/NAD(+) ratio of the mutant rose by 14.6 %; when a mixed carbon source with a glucose/gluconic acid ratio of 1:1 was substituted to culture the mutant, the NADH/NAD(+) ratio decreased by 4.6 %; the ATP content dropped by 27.6 %; the lactate dehydrogenase (LDH) activity rose by 22.7 %; and the lactate yield rose by 11.6 %. These results indicated that changes to the NADH metabolic pathway under a low-energy charge level can effectively increase the glycolytic rate and further improve the yield of L-lactate of R. oryzae.
Asunto(s)
Ácido Láctico/biosíntesis , Mutación , NAD/metabolismo , Rhizopus/citología , Rhizopus/metabolismo , Adenosina Trifosfato/metabolismo , Relación Dosis-Respuesta a Droga , Metabolismo Energético/efectos de los fármacos , Metabolismo Energético/efectos de la radiación , Fermentación/efectos de los fármacos , Fermentación/efectos de la radiación , Gluconatos/farmacología , Glucólisis/efectos de los fármacos , Glucólisis/efectos de la radiación , Espacio Intracelular/efectos de los fármacos , Espacio Intracelular/metabolismo , Espacio Intracelular/efectos de la radiación , Mutagénesis/efectos de la radiación , Mutación/efectos de la radiación , Oxidación-Reducción/efectos de los fármacos , Oxidación-Reducción/efectos de la radiación , Rhizopus/genética , Rayos Ultravioleta/efectos adversosRESUMEN
Rhizopus is the most common genus of invasive mucormycosis, whose prognosis and outcome was not improved over the past decades. We studied the apoptotic-like phenotype in Rhizopus arrhizus exposed to hydrogen peroxide (H2 O2 ) and amphotericin B (AMB). The strain provided by Fungal Genetic Stock centre was studied about the apoptotic-like phenotype treated with different concentrations of H2 O2 and AMB, and then analyzed by fluorescent microscopy (observed by Annexin-V/FITC and TUNEL staining), flow cytometry (stained with DHR123/PI), and DNA agarose gel electrophores. When R. arrhizus was treated with H2 O2 and AMB, there was a loss of viability associated with different phenotype of apoptosis makers. Membrane externalization of phosphatidylserine (PS) on the cell surface, DNA fragmentation, chromatin condensation can be induced and observed obviously by Annexin-V/FITC, DAPI and TUNEL staining. DNA smear not DNA ladder was also visible in R. arrhizus. Flowcytometry of R. arrhizus cells revealed not only the increase of apoptosis cell stained with DHR123 under the nonfungicida doses but dead cells stained with PI under the fungicida concentrations.This study indicated that both H2 O2 and AMB could induce the apoptotic-like phenotype in R. arrhizus.
Asunto(s)
Anfotericina B/farmacología , Antifúngicos/farmacología , Apoptosis/efectos de los fármacos , Peróxido de Hidrógeno/farmacología , Rhizopus/efectos de los fármacos , ADN de Hongos/aislamiento & purificación , Citometría de Flujo , Viabilidad Microbiana/efectos de los fármacos , Fenotipo , Fosfatidilserinas/metabolismo , Especies Reactivas de Oxígeno/metabolismo , Rhizopus/citologíaRESUMEN
The antifungal activities of chitosan and oligochitosan have been used to control postharvest decay of the fruits. The effect of chitosan and oligochitosan on mycelium growth, spore germination, and mitochondrial function of Rhizopus stolonifer was evaluated in order to establish a connection between fungus development and the main organelle in charge to provide energy to the cell. The mycelium growth of R. stolonifer was significantly reduced on minimum media amended with chitosan or oligochitosan. The highest antifungal indexes were obtained on media containing chitosan or oligochitosan at 2.0 mg ml(-1). Microscopic observation showed that chitosan and oligochitosan affected the spore germination and hyphae morphology. Both polymers increased oxygen consumption of R. stolonifer. Respiratory activity was restored with NADH in permeabilized treated and untreated cells, and was inhibited with rotenone and flavones. Complex III and IV were inhibited by antimycin A and cyanide, respectively, in treated and untreated cells. Chitosan and oligochitosan increased NADH dehydrogenase activity in isolated mitochondria. However, there were not changes in the cytochrome c oxidase and ATPase activities by effect of these polymers. These results suggest that both chitosan and oligochitosan affect the development of R. stolonifer and might be implicated in the mitochondrial dysfunction.
Asunto(s)
Antifúngicos/metabolismo , Quitosano/metabolismo , Mitocondrias/efectos de los fármacos , Mitocondrias/fisiología , Rhizopus/efectos de los fármacos , Rhizopus/crecimiento & desarrollo , Adenosina Trifosfatasas/metabolismo , Medios de Cultivo/química , Complejo IV de Transporte de Electrones/metabolismo , Microscopía , Micelio/citología , Micelio/efectos de los fármacos , Micelio/crecimiento & desarrollo , NAD/metabolismo , Oxígeno/metabolismo , Rhizopus/citología , Esporas Fúngicas/citología , Esporas Fúngicas/efectos de los fármacos , Esporas Fúngicas/crecimiento & desarrolloRESUMEN
Sweetpotato is a nutritional source worldwide. Soft rot caused by Rhizopus spp. is a major limiting factor in the storage of produce, rendering it potentially unsafe for human consumption. In this study, Rhizopus oryzae was used to develop a concept of postharvest disease control by weakening the pathogen through induction of spore germination under starvation conditions. We isolated the sweetpotato active fractions (SPAFs) that induce spore germination and used them at a low dose to enhance spore weakening caused by starvation. Germination in SPAF at 1 mg/ml weakened the pathogen spores by delaying their ability to form colonies on rich media and by increasing their sensitivity to heat stress. The weakening effect was also supported by reduced metabolic activity, as detected by Alarmar Blue fluorescent dye assays. Spores incubated with SPAF at 1 mg/ml showed DNA fragmentation in some of their nuclei, as observed by TUNEL assay. In addition, these spores exhibited changes in ultrastructural morphology (i.e., shrinkage of germ tubes, nucleus deformation, and vacuole formation) which are hallmarks of programmed cell death. We suggest that induction of spore germination under starvation conditions increases their susceptibility to stress and, therefore, might be considered a new strategy for pathogen control.
Asunto(s)
Ipomoea batatas/química , Enfermedades de las Plantas/microbiología , Extractos Vegetales/farmacología , Rhizopus/efectos de los fármacos , Esporas Fúngicas/efectos de los fármacos , Apoptosis , Fragmentación del ADN , Relación Dosis-Respuesta a Droga , Calor , Ipomoea batatas/microbiología , Extractos Vegetales/aislamiento & purificación , Rhizopus/citología , Rhizopus/genética , Rhizopus/fisiología , Esporas Fúngicas/fisiologíaRESUMEN
BACKGROUND: Given its availability and low price, glycerol derived from biodiesel industry has become an ideal feedstock for the production of fuels and chemicals. A solution to reduce the negative environmental problems and the cost of biodiesel is to use crude glycerol as carbon source for microbial growth media in order to produce valuable organic chemicals. In the present paper, crude glycerol was used as carbon substrate for production of L (+)-lactic acid using pelletized fungus R. oryzae NRRL 395 on batch fermentation. More, the experiments were conducted on media supplemented with inorganic nutrients and lucerne green juice. RESULTS: Crude and pure glycerols were first used to produce the highest biomass yield of R. oryzae NRRL 395. An enhanced lactic acid production then followed up using fed-batch fermentation with crude glycerol, inorganic nutrients and lucerne green juice. The optimal crude glycerol concentration for cultivating R. oryzae NRRL 395 was 75 g l(-1), which resulted in a fungal biomass yield of 0.72 g g(-1) in trial without lucerne green juice addition and 0.83 g g(-1) in trial with lucerne green juice. The glycerol consumption rate was 1.04 g l(-1) h(-1) after 48 h in trial with crude glycerol 75 g l(-1) while in trial with crude glycerol 10 g l(-1) the lowest rate of 0.12 g l(-1) h(-1) was registered. The highest L (+)-lactic acid yield (3.72 g g(-1)) was obtained at the crude glycerol concentration of 75 g l(-1) and LGJ 25 g l(-1), and the concentration of lactic acid was approximately 48 g l(-1). CONCLUSIONS: This work introduced sustainable opportunities for L (+)-lactic acid production via R. oryzae NRRL 395 fermentation on biodiesel crude glycerol media. The results showed good fungal growth on crude glycerol at 75 g l(-1) concentration with lucerne green juice supplementation of 25 g l(-1). Lucerne green juice provided a good source of nutrients for crude glycerol fermentation, without needs for supplementation with inorganic nutrients. Crude glycerol and lucerne green juice ratio influence the L (+)-lactic acid production, increasing the lactate productivity with the concentration of crude glycerol.
Asunto(s)
Biopelículas/crecimiento & desarrollo , Reactores Biológicos/microbiología , Ácido Láctico/metabolismo , Rhizopus/citología , Agregación Celular , Técnicas de Cultivo de Célula/métodos , Glicerol , Ácido Láctico/biosíntesis , Ácido Láctico/aislamiento & purificación , Proteínas/metabolismo , Rhizopus/metabolismo , Rhizopus/fisiologíaRESUMEN
Pelleted growth provides many advantages for filamentous fungi, including decreased broth viscosity, improved aeration, stirring, and heat transfer. Thus, the factors influencing the probability of pellet formation of Rhizopus sp. in a defined medium was investigated using a multifactorial experimental design. Temperature, agitation intensity, Ca(2+)-concentration, pH, and solid cellulose particles, each had a significant effect on pelletization. Tween 80, spore concentration, and liquid volume were not found to have a significant effect. All of the effects were additive; no interactions were significant. The results were used to create a simple defined medium inducing pelletization, which was used for immobilization of a flocculating strain of Saccharomyces cerevisiae in the zygomycetes pellets. A flor-forming S. cerevisiae strain was also immobilized, while a non-flocculating strain colonized the pellets but was not immobilized. No adverse effects were detected as a result of the close proximity between the filamentous fungus and the yeast, which potentially allows for co-fermentation with S. cerevisiae immobilized in pellets of zygomycetes.
Asunto(s)
Calcio/química , Polisorbatos/química , Rhizomucor/química , Rhizopus/química , Saccharomyces cerevisiae/química , Células Inmovilizadas/química , Células Inmovilizadas/citología , Floculación , Rhizomucor/citología , Rhizopus/citología , Saccharomyces cerevisiae/citologíaRESUMEN
Zygomycosis encompasses infections due to two distinct orders of fungi, Mucorales and Entomophthorales. With rare exception, Entomophthorales are restricted to tropical areas. By contrast, mucorales are ubiquitous opportunistic fungi, which play a crucial part in the natural decay process. In human pathology, they may be opportunistic agents and be responsible for rare infection called (Mucormycosis) zygomycosis. We report two cases of zygomycosis from Madhya Pradesh, Central India, one caused by Rhizopus oryzae in a diabetic patient and another caused by Rhizopus microsporus in an apparently healthy patient. The cases were diagnosed by direct microscopy, histopathological examination and culture. Both the patients were successfully treated with liposomal amphotericin B. Rhizopus microsporus is, for the first time reported from Madhya Pradesh, India, causing rhino-maxillary orbital zygomycosis.
Asunto(s)
Rhizopus/aislamiento & purificación , Cigomicosis/diagnóstico , Cigomicosis/patología , Adulto , ADN de Hongos/química , ADN de Hongos/genética , Femenino , Histocitoquímica , Humanos , India , Masculino , Microscopía , Persona de Mediana Edad , Datos de Secuencia Molecular , Rhizopus/clasificación , Rhizopus/citología , Rhizopus/genética , Análisis de Secuencia de ADNRESUMEN
The cell wall-cosolvent partition coefficients (Km) of polycyclic aromatic hydrocarbons (PAHs) were determined for Rhizopus oryzae cell walls by controlling the volume fraction of methanol (f) ranging from 0.1 to 0.5. Five cosolvent models were employed for extrapolating the cell wall-water partition coefficients (Kw) in pure water. The extrapolated Kw values of four PAHs on R. oryzae cell walls were ranged from 2.9 to 5.1. Comparison of various Kw values of pyrene generated from extrapolation and the QSPR model, together with predicted different (PD), mean percentage deviations (MPD), and root mean square errors (RSE), revealed that the performance of the LL and Bayesian models were the best among all five tested cosolvent models. This study suggests that R. oryzae cell walls play an important role in the partitioning of PAHs during bioremediation because of the high Kw of fungal cell walls.
Asunto(s)
Pared Celular/metabolismo , Modelos Biológicos , Hidrocarburos Policíclicos Aromáticos/metabolismo , Rhizopus/citología , Rhizopus/metabolismo , Solventes/metabolismo , Agua/metabolismo , Adsorción , Pirenos/metabolismoRESUMEN
Semicontinuous fermentation using pellets of Rhizopus oryzae has been recognized as a promising technology for L-lactic acid production. In this work, semicontinuous fermentation of R. oryzae AS 3.819 for L-lactic acid production has been developed with high L-lactic acid yield and volumetric productivity. The effects of factors such as inoculations, CaCO3 addition time, and temperature on L-lactic acid yield and R. oryzae morphology were researched in detail. The results showed that optimal fermentation conditions for the first cycle were: inoculation with 4% spore suspension, CaCO3 added to the culture medium at the beginning of culture, and culture temperature of 32-34 °C. In orthogonal experiments, high L-lactic acid yield was achieved when the feeding medium was (g/l): glucose, 100; (NH4)2SO4, 2; KH2PO4, 0.1; ZnSO4·7H2O, 0.33; MgSO4·7H2O, 0.15; CaCO3, 50. Twenty cycles of semicontinuous fermentation were carried out in flask culture. L: -lactic acid yield was 78.75% for the first cycle and 80-90% for the repeated cycles; the activities of lactate dehydrogenases (LDH) were 7.2-9.2 U/mg; fermentation was completed in 24 h for each repeated cycle. In a 7-l magnetically stirred fermentor, semicontinuous fermentation lasted for 25 cycles using pellets of R. oryzae AS 3.819 under the optimal conditions determined from flask cultures. The final L-lactic acid concentration (LLAC) reached 103.7 g/l, and the volumetric productivity was 2.16 g/(l·h) for the first cycle; in the following 19 repeated cycles, the final LLAC reached 81-95 g/l, and the volumetric productivities were 3.40-3.85 g/(l·h).
Asunto(s)
Reactores Biológicos/microbiología , Ácido Láctico/biosíntesis , Rhizopus/metabolismo , Carbonato de Calcio/farmacología , Medios de Cultivo , Fermentación , L-Lactato Deshidrogenasa , Rhizopus/citología , TemperaturaRESUMEN
Rhizopus oryzae was immobilized on a cotton matrix in a static bed bioreactor. Compared with free cells in a stirred tank bioreactor, immobilized R. oryzae in this bioreactor gave higher lactic acid production but lower ethanol production. The highest lactic acid production rate (2.09 g/L h) with the final concentration of 37.83 g/L from 70 g/L glucose was achieved when operating the bioreactor at 700 rpm and 0.5 vvm air. To better understand the relationship between shear effects (agitation and aeration) and R. oryzae morphology and metabolism, oxygen transfer rate, fermentation kinetics, and lactate dehydrogenase activity were determined. In immobilized cell culture, higher oxygen transfer rate and lactic acid production were achieved but lower lactate dehydrogenase activity was found as compared with those in free cell culture operated at the same conditions. These results clearly imply that mass transport was the rate controlling step in lactic acid fermentation by R. oryzae.
Asunto(s)
Reactores Biológicos/microbiología , Ácido Láctico/biosíntesis , Consumo de Oxígeno/fisiología , Oxígeno/metabolismo , Rhizopus/metabolismo , Células Inmovilizadas/metabolismo , Rhizopus/citologíaRESUMEN
Microbes and their cell filtrates are known to synthesize metal nanoparticles. But maintenance of aseptic conditions and irregularly shaped and sized nanoparticles are major drawbacks of the system. In this study cell filtrate from inactive biomass of Rhizopus stolonifer was used for the first time to produce near uniformly sized and shaped Ag and Au nanoparticles at room temperature. The size of Ag and Au nanoparticles were found in the range of 25-30 nm and 1-5 nm, respectively. UV-vis spectrum, TEM and XRD measurements confirmed the formation of Ag and Au nanoparticles.
Asunto(s)
Cristalización/métodos , Filtración , Oro/química , Nanopartículas del Metal/química , Rhizopus/citología , Plata/química , Nanopartículas del Metal/ultraestructura , Difracción de Rayos XRESUMEN
88 g/L lactic acid was produced from waste potato starch (equivalent to 100 g/L glucose) in a bubble column reactor using appropriate acid-adapted precultures of Rhizopus arrhizus. Further experiment showed that repeated dilution of cultures caused the decrease of lactic acid concentration and productivity due to formation of large fungal pellets.
Asunto(s)
Reactores Biológicos , Ácido Láctico/biosíntesis , Rhizopus/metabolismo , Etanol/metabolismo , Fumaratos/metabolismo , Glucosa/metabolismo , Concentración de Iones de Hidrógeno , Micelio/citología , Micelio/metabolismo , Rhizopus/citología , ResiduosRESUMEN
In order to control suitable mycelium morphology to obtain high lipase productivity by Rhizopus chinensis in submerged fermentation, the effects of fungal morphology on the lipase production by this strain both in shake flask and fermentor were investigated. Different inoculum level and shear stress were used to develop distinctive morphologies. Analyses and investigations both on micromorphology and macromorphology were performed. Study of micromorphology reveals that micromorphologies for dispersed mycelia and aggregated mycelia are different in cell shape, biosynthetic activity. Macromorphology and broth rheology study in fermentor indicate that pellet formation results in low broth viscosity. Under this condition, the oil can disperse sufficiently in broth which is very important for lipase production. These results indicate that morphology changes affected the lipase production significantly for R. chinensis and the aggregated mycelia were suggested to achieve high lipase production.
Asunto(s)
Reactores Biológicos/microbiología , Lipasa/biosíntesis , Mecanotransducción Celular/fisiología , Micelio/citología , Micelio/metabolismo , Rhizopus/citología , Rhizopus/metabolismo , Técnicas de Cultivo de Célula/métodos , Tamaño de la Célula , Estrés MecánicoRESUMEN
The fungus Rhizopus oligosporus (R. microsporus var. oligosporus) is traditionally used to make tempe, a fermented food based on soybeans. Interest in the fungus has steadily increased, as it can also ferment other substrates, produce enzymes, and treat waste material. R. oligosporus belongs to the R. microsporus group consisting of morphologically similar taxa, which are associated with food fermentation, pathogenesis, or unwanted metabolite production (rhizonins and rhizoxins). The ornamentation pattern, shape, and size of sporangiospores of 26 R. microsporus group strains and two R. oryzae strains were studied using low-temperature SEM (LT-SEM) and LM. This study has shown that: (1) LT-SEM generates images from well-conserved sporangiophores, sporangia, and spores. (2) Robust spore ornamentation patterns can be linked to all different taxa of the R. microsporus group, some previously incorrectly characterized as smooth. Ornamentation included valleys and ridges running in parallel, granular plateaus, or smooth polar areas. Distribution of ornamentation patterns was related to spore shape, which either was regular, ranging from globose to ellipsoidal, or irregular. Specific differences in spore shape, size, and ornamentation were observed between Rhizopus taxa, and sometimes between strains. (3) R. oligosporus has a defect in the spore formation process, which may be related to the domesticated nature of this taxon. It had a high proportion, 10-31%, of large and irregular spores, and was significantly differentiated from other, natural Rhizopus taxa as evaluated with partial least squares discriminant analysis. It is remarkable that the vehicle of distribution, the sporangiospore, is affected in the strains that are distributed by human activity. This provides information about the specificity and speed of changes that occur in fungal strains because of their use in (food) industry.