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Antonia María Ruiz Jiménez - One of the best experts on this subject based on the ideXlab platform.

  • kinetic analysis of the anaerobic digestion of untreated vinasses and vinasses previously treated with Penicillium decumbens
    Journal of Environmental Management, 2006
    Co-Authors: Antonia María Ruiz Jiménez, Rafael Borja, Antonio Martín, F Raposo
    Abstract:

    A kinetic study was carried out on the anaerobic digestion of untreated vinasses and vinasses previously fermented with Penicillium decumbens. Two 1-l volume continuous-flow stirred tank reactors (CFSTR) operating at mesophilic temperature (35 degrees C) were used for the study. One reactor was fed with untreated vinasses (COD concentration of 80.5 g/l) and the other with vinasses previously fermented (COD concentration of 23.0 g/l). Both reactors were operated at organic loading rates in the range of 1.5-7.5 g chemical oxygen demand (COD)/l-d. The results obtained were evaluated using the Chen-Hashimoto methane production model to determine the values of the maximum specific growth rate (micromax) and the model kinetic constant (K) of the process for each case studied. The kinetic constants (micromax and K) were affected by the pre-treatment, and the respective values were 9.6 and 6.9 times higher for pretreated vinasses than those of untreated vinasses. This was significant at the 95% confidence level. This behaviour is believed to be due to the lower levels of phenolic compounds present in the pretreated vinasses, as compared to untreated vinasses, resulting in an improved process performance, kinetics and stability. Finally, the experimental values of methane production were reproduced with deviations equal to or less than 4% and 10% for pretreated and untreated vinasses, respectively.

  • Kinetic analysis of the anaerobic digestion of untreated vinasses and vinasses previously treated with Penicillium decumbens
    Journal of Environmental Management, 2006
    Co-Authors: Antonia María Ruiz Jiménez, Rafael Borja, Alex Martin, Francisco Raposo
    Abstract:

    A kinetic study was carried out on the anaerobic digestion of untreated vinasses and vinasses previously fermented with Penicillium decumbens. Two 1-l volume continuous-flow stirred tank reactors (CFSTR) operating at mesophilic temperature (35 °C) were used for the study. One reactor was fed with untreated vinasses (COD concentration of 80.5 g/l) and the other with vinasses previously fermented (COD concentration of 23.0 g/l). Both reactors were operated at organic loading rates in the range of 1.5–7.5 g chemical oxygen demand (COD)/l-d. The results obtained were evaluated using the Chen–Hashimoto methane production model to determine the values of the maximum specific growth rate (?max) and the model kinetic constant (K) of the process for each case studied. The kinetic constants (?max and K) were affected by the pre-treatment, and the respective values were 9.6 and 6.9 times higher for pretreated vinasses than those of untreated vinasses. This was significant at the 95% confidence level. This behaviour is believed to be due to the lower levels of phenolic compounds present in the pretreated vinasses, as compared to untreated vinasses, resulting in an improved process performance, kinetics and stability. Finally, the experimental values of methane production were reproduced with deviations equal to or less than 4% and 10% for pretreated and untreated vinasses, respectively.

  • Mathematical modelling of aerobic degradation of vinasses with Penicillium decumbens
    Process Biochemistry, 2005
    Co-Authors: Antonia María Ruiz Jiménez, Rafael Borja, Alex Martin, Francisco Raposo
    Abstract:

    Abstract Growth, substrate and phenolic compound biodegradation by Penicillium decumbens was studied on vinasses. This fungus was selected because of its tolerance to the phenolic compounds present in this waste. The biodegradation process of vinasses was researched in batch regime by conducting experiments where the initial concentration of substrate and phenolic compounds were 42.6 g COD/L and 0.21 g gallic acid/L, respectively. This fungus significantly degraded the total phenolic compounds in vinasses aerobically without the need for any nutrient supplements in the medium. A maximum value of phenols removal of 74% was achieved after 3 days’ treatment. P. decumbens produces a decolourization of the vinasses from the 1st day of incubation. Higher reductions in colour were achieved between the 4th and 5th days of treatment, the best result being 41% of the initial colour removed after 4 days’ treatment. A mathematical model based on three differential equations was formulated to describe this biodegradation process assuming that a fraction of the organic content of vinasses is non-biodegradable. The proposed equations were validated by comparing the theoretical curves obtained with the corresponding experimental data of substrate and biomass concentrations. The small deviations obtained in both cases (lower than 5%) demonstrated the suitability of the mathematical model proposed and suggested that this model very accurately described the variation of substrate and biomass concentrations with time in the aerobic degradation process of vinasses with P. decumbens and that the parameters obtained represent the activity of this microorganism effecting the aerobic degradation of this waste. Finally, the biomass yield coefficient was found to be 0.35 g VSS/g COD through the relationship between the amount of cells produced and substrate uptake. This value coincides with that obtained theoretically from the mathematical model formulated.

  • A comparative kinetic evaluation of the anaerobic digestion of untreated molasses and molasses previously fermented with Penicillium decumbens in batch reactors
    Biochemical Engineering Journal, 2004
    Co-Authors: Antonia María Ruiz Jiménez, Rafael Borja, Antonio Martín
    Abstract:

    Abstract A comparative kinetic study was carried out on the anaerobic digestion of untreated beet molasses alcoholic fermentation wastewater and beet molasses previously fermented with Penicillium decumbens. Three 1 l volume stirred tank reactors were used for the study, one with freely suspended biomass (Control), and the other two with biomass supported on Saponite (magnesium silicate) and Esmectite (aluminium silicate), respectively. The reactors were batch fed at mesophilic temperature (35 °C) using COD loadings of between 12 and 140 ml of untreated molasses with a COD of 80.5 g/l and of between 43 and 304 ml of molasses previously fermented with a COD of 23.0 g/l. The anaerobic digestion process of both substrates was found to follow a first-order kinetics and the experimental accumulated methane volume (G)–time (t) data to conform to an equation of the form: G=Gm[1−exp(−K0t)], from which the specific rate constants, K0, were calculated. In the case of untreated molasses, the K0 values decreased considerably from 2.87 to 0.10 (Saponite), from 2.78 to 0.10 (Esmectite) and from 2.16 to 0.07 per days (Control) when the loading of molasses applied and initial COD added were increased from 12 to 140 ml and 1 to 10 g/l, respectively; this showed an inhibition phenomenon in the three reactors studied. In contrast to this, the kinetic constants of the anaerobic digestion of pre-treated molasses were virtually constant over the COD range used (1–7 g/l) in the three reactors considered. Finally, the average methane yield coefficient for pre-treated molasses was 305 ml CH4 STP/g CODremoved, viz. 35% higher than that provided by untreated molasses.

  • influence of aerobic pretreatment with Penicillium decumbens on the anaerobic digestion of beet molasses alcoholic fermentation wastewater in suspended and immobilized cell bioreactors
    Journal of Chemical Technology & Biotechnology, 1997
    Co-Authors: Antonia María Ruiz Jiménez, Rafael Borja, Valle Alonso, Antonio Martín
    Abstract:

    A comparative study was carried out on the anaerobic digestion of untreated and previously-fermented (with Penicillium decumbens) beet molasses. Four continuous stirred tank reactors were used for the study, two with freely suspended biomass, and the other with biomass supported on saponite. The reactors operated satisfactorily between hydraulic retention times (HRT) of 53.3-10.6 days and 15.4-3.1 days for untreated and previously-fermented molasses respectively. The anaerobic digestion processes of untreated and pretreated molasses were found to follow first-order kinetics for biomass loading rates in the range of 0-0.55 and 0-0.75 g chemical oxygen demand (COD) g -1 volatile suspended solids (VSS) day -1 respectively. The experimental data [namely unitary conversion or efficiency (X), HRT, biomass concentration (M) and incoming substrate concentration (S o )] conformed to an equation of the form: X/HRT = KM(I - X)-(KMS R /S 0 ), from which the kinetic constant, K, was calculated. The kinetic constants were influenced by the pretreatment carried out and were 1.7 and 2.5 times higher for pretreated molasses than for untreated molasses in the reactors with suspended and immobilized biomass respectively. This was significant at a 95% confidence level. The specific rate of substrate uptake for cell maintenance (m) decreased by a factor of approximately 2 for the previously fermented molasses in relation to the observed values for the untreated molasses. This may be attributable to the fact that higher phenolic compound concentrations inhibit and interfere with the activity of anaerobic bacteria.

Yuqi Qin - One of the best experts on this subject based on the ideXlab platform.

  • g protein camp signaling pathway mediated by pga3 plays different roles in regulating the expressions of amylases and cellulases in Penicillium decumbens
    Fungal Genetics and Biology, 2013
    Co-Authors: Guodong Liu, Yuqi Qin, Xin Song
    Abstract:

    Heterotrimeric G proteins (G proteins) have been extensively investigated for their regulatory functions in morphogenesis and development in filamentous fungi. In addition, G proteins were also shown to be involved in the regulation of cellulase expression in some fungi. Here, we report the different regulatory effects of PGA3, a group III G protein α subunit, on the expressions of amylases and cellulases in Penicillium decumbens. Deletion of pga3 resulted in impaired amylase production and significantly decreased transcription of the major amylase gene amy15A. Supplementation of exogenous cAMP or its analog dibutyryl-cAMP restored amylase production in Δpga3 strain, suggesting an essential role of PGA3 in amylase synthesis via controlling cAMP level. On the other hand, the transcription of major cellulase gene cel7A-2 increased, nevertheless cellulase activity in the medium was not affected, in Δpga3. The above regulatory effects of PGA3 are carbon source-independent, and are achieved, at least, by cAMP-mediated regulation of the expression level of transcription factor AmyR. The functions of PGA3 revealed by gene deletion were partially supported by the analysis of the mutant carrying dominantly-activated PGA3. The results provided new insights into the understanding of the physiological functions of G protein-cAMP pathway in filamentous fungi.

  • promotion of extracellular lignocellulolytic enzymes production by restraining the intracellular β glucosidase in Penicillium decumbens
    Bioresource Technology, 2013
    Co-Authors: Mei Chen, Yuqi Qin, Guodong Liu, Qing Cao, Jian Zhao
    Abstract:

    In this study, the functions of β-glucosidases in regulation of the lignocellulolytic enzymes production in Penicillium decumbens 114-2 were investigated. The major extracellular β-glucosidase gene bgl1 and the major intracellular β-glucosidase gene bgl2 were deleted in P. decumbens 114-2 respectively. In Δbgl2, the production of extracellular lignocellulolytic enzymes (including endoglucanases, cellobiohydrolases and xylanases) on insoluble cellulose was significantly promoted, while in Δbgl1 there was no any difference compared with that of 114-2. The enhancement of the production of lignocellulolytic enzymes in Δbgl2 was likely attributed to the accumulation of intracellular cellobiose. Induction experiment in Δbgl1Δbgl2 showed that cellobiose was an inducer of lignocellulolytic enzymes expression in P. decumbens 114-2, and the induction was unrelated to the formation, if any, of gentiobiose or sophorose from cellobiose.

  • an endo 1 4 β glucanase pdcel5c from cellulolytic fungus Penicillium decumbens with distinctive domain composition and hydrolysis product profile
    Enzyme and Microbial Technology, 2013
    Co-Authors: Guodong Liu, Yuqi Qin, Meirong Gao, Shengjuan Peng
    Abstract:

    Cellulases from fungi typically contain one catalytic domain with or without a cellulose-binding domain. We characterized an endo-acting cellulase PdCel5C from industrial cellulase-producing fungus Penicillium decumbens with distinctive domain composition. In addition to a cellulose-binding domain and a catalytic domain, PdCel5C contains two immunoglobulin (Ig)-like domains near the C-terminal end. Truncated mutation experiment reveals that the two Ig-like domains are important for the hydrolytic activity of PdCel5C. Moreover, PdCel5C releases cello-oligosaccharides from cellulosic substrates, which is different from that of most characterized cellulases in the same glycoside hydrolase family 5. To the best of our knowledge, this is the first report on the characterization of an Ig-like domain-containing cellulase in fungi. The results expand our understanding on the diversity of cellulases in fungi, and suggest possible shared catalytic mechanisms between bacterial and fungal cellulases.

  • Genomic and secretomic analyses reveal unique features of the lignocellulolytic enzyme system of Penicillium decumbens.
    PloS one, 2013
    Co-Authors: Guodong Liu, Yuqi Qin, Xiaomin Wei, Lei Zhang, Zou, Huajun Zheng, Shengyue Wang, Chengshu Wang
    Abstract:

    Many Penicillium species could produce extracellular enzyme systems with good lignocellulose hydrolysis performance. However, these species and their enzyme systems are still poorly understood and explored due to the lacking of genetic information. Here, we present the genomic and secretomic analyses of Penicillium decumbens that has been used in industrial production of lignocellulolytic enzymes in China for more than fifteen years. Comparative genomics analysis with the phylogenetically most similar species Penicillium chrysogenum revealed that P. decumbens has evolved with more genes involved in plant cell wall degradation, but fewer genes in cellular metabolism and regulation. Compared with the widely used cellulase producer Trichoderma reesei, P. decumbens has a lignocellulolytic enzyme system with more diverse components, particularly for cellulose binding domain-containing proteins and hemicellulases. Further, proteomic analysis of secretomes revealed that P. decumbens produced significantly more lignocellulolytic enzymes in the medium with cellulose-wheat bran as the carbon source than with glucose. The results expand our knowledge on the genetic information of lignocellulolytic enzyme systems in Penicillium species, and will facilitate rational strain improvement for the production of highly efficient enzyme systems used in lignocellulose utilization from Penicillium species.

  • Penicillium decumbens BrlA extensively regulates secondary metabolism and functionally associates with the expression of cellulase genes
    Applied Microbiology and Biotechnology, 2013
    Co-Authors: Yuqi Qin, Longfei Bao, Meirong Gao, Yunfeng Lei, Mei Chen, Guodong Liu, Yinbo Qu
    Abstract:

    Penicillium decumbens has been used in the industrial production of lignocellulolytic enzymes in China for more than 15 years. Conidiation is essential for most industrial fungi because conidia are used as starters in the first step of fermentation. To investigate the mechanism of conidiation in P. decumbens, we generated mutants defective in two central regulators of conidiation, FluG and BrlA. Deletion of fluG resulted in neither "fluffy" phenotype nor alteration in conidiation, indicating possible different upstream mechanisms activating brlA between P. decumbens and Aspergillus nidulans. Deletion of brlA completely blocked conidiation. Further investigation of brlA expression in different media (nutrient-rich or nutrient-poor) and different culture states (liquid or solid) showed that brlA expression is required but not sufficient for conidiation. The brlA deletion strain exhibited altered hyphal morphology with more branches. Genome-wide expression profiling identified BrlA-dependent genes in P. decumbens, including genes previously reported to be involved in conidiation as well as previously reported chitin synthase genes and acid protease gene (pepB). The expression levels of seven secondary metabolism gene clusters (from a total of 28 clusters) were drastically regulated in the brlA deletion strain, including a downregulated cluster putatively involved in the biosynthesis of the mycotoxins roquefortine C and meleagrin. In addition, the expression levels of most cellulase genes were upregulated in the brlA deletion strain detected by real-time quantitative PCR. The brlA deletion strain also exhibited an 89.1 % increase in cellulase activity compared with the wild-type strain. The results showed that BrlA in P. decumbens not only has a key role in regulating conidiation, but it also regulates secondary metabolism extensively as well as the expression of cellulase genes.

Guodong Liu - One of the best experts on this subject based on the ideXlab platform.

  • g protein camp signaling pathway mediated by pga3 plays different roles in regulating the expressions of amylases and cellulases in Penicillium decumbens
    Fungal Genetics and Biology, 2013
    Co-Authors: Guodong Liu, Yuqi Qin, Xin Song
    Abstract:

    Heterotrimeric G proteins (G proteins) have been extensively investigated for their regulatory functions in morphogenesis and development in filamentous fungi. In addition, G proteins were also shown to be involved in the regulation of cellulase expression in some fungi. Here, we report the different regulatory effects of PGA3, a group III G protein α subunit, on the expressions of amylases and cellulases in Penicillium decumbens. Deletion of pga3 resulted in impaired amylase production and significantly decreased transcription of the major amylase gene amy15A. Supplementation of exogenous cAMP or its analog dibutyryl-cAMP restored amylase production in Δpga3 strain, suggesting an essential role of PGA3 in amylase synthesis via controlling cAMP level. On the other hand, the transcription of major cellulase gene cel7A-2 increased, nevertheless cellulase activity in the medium was not affected, in Δpga3. The above regulatory effects of PGA3 are carbon source-independent, and are achieved, at least, by cAMP-mediated regulation of the expression level of transcription factor AmyR. The functions of PGA3 revealed by gene deletion were partially supported by the analysis of the mutant carrying dominantly-activated PGA3. The results provided new insights into the understanding of the physiological functions of G protein-cAMP pathway in filamentous fungi.

  • promotion of extracellular lignocellulolytic enzymes production by restraining the intracellular β glucosidase in Penicillium decumbens
    Bioresource Technology, 2013
    Co-Authors: Mei Chen, Yuqi Qin, Guodong Liu, Qing Cao, Jian Zhao
    Abstract:

    In this study, the functions of β-glucosidases in regulation of the lignocellulolytic enzymes production in Penicillium decumbens 114-2 were investigated. The major extracellular β-glucosidase gene bgl1 and the major intracellular β-glucosidase gene bgl2 were deleted in P. decumbens 114-2 respectively. In Δbgl2, the production of extracellular lignocellulolytic enzymes (including endoglucanases, cellobiohydrolases and xylanases) on insoluble cellulose was significantly promoted, while in Δbgl1 there was no any difference compared with that of 114-2. The enhancement of the production of lignocellulolytic enzymes in Δbgl2 was likely attributed to the accumulation of intracellular cellobiose. Induction experiment in Δbgl1Δbgl2 showed that cellobiose was an inducer of lignocellulolytic enzymes expression in P. decumbens 114-2, and the induction was unrelated to the formation, if any, of gentiobiose or sophorose from cellobiose.

  • an endo 1 4 β glucanase pdcel5c from cellulolytic fungus Penicillium decumbens with distinctive domain composition and hydrolysis product profile
    Enzyme and Microbial Technology, 2013
    Co-Authors: Guodong Liu, Yuqi Qin, Meirong Gao, Shengjuan Peng
    Abstract:

    Cellulases from fungi typically contain one catalytic domain with or without a cellulose-binding domain. We characterized an endo-acting cellulase PdCel5C from industrial cellulase-producing fungus Penicillium decumbens with distinctive domain composition. In addition to a cellulose-binding domain and a catalytic domain, PdCel5C contains two immunoglobulin (Ig)-like domains near the C-terminal end. Truncated mutation experiment reveals that the two Ig-like domains are important for the hydrolytic activity of PdCel5C. Moreover, PdCel5C releases cello-oligosaccharides from cellulosic substrates, which is different from that of most characterized cellulases in the same glycoside hydrolase family 5. To the best of our knowledge, this is the first report on the characterization of an Ig-like domain-containing cellulase in fungi. The results expand our understanding on the diversity of cellulases in fungi, and suggest possible shared catalytic mechanisms between bacterial and fungal cellulases.

  • Genomic and secretomic analyses reveal unique features of the lignocellulolytic enzyme system of Penicillium decumbens.
    PloS one, 2013
    Co-Authors: Guodong Liu, Yuqi Qin, Xiaomin Wei, Lei Zhang, Zou, Huajun Zheng, Shengyue Wang, Chengshu Wang
    Abstract:

    Many Penicillium species could produce extracellular enzyme systems with good lignocellulose hydrolysis performance. However, these species and their enzyme systems are still poorly understood and explored due to the lacking of genetic information. Here, we present the genomic and secretomic analyses of Penicillium decumbens that has been used in industrial production of lignocellulolytic enzymes in China for more than fifteen years. Comparative genomics analysis with the phylogenetically most similar species Penicillium chrysogenum revealed that P. decumbens has evolved with more genes involved in plant cell wall degradation, but fewer genes in cellular metabolism and regulation. Compared with the widely used cellulase producer Trichoderma reesei, P. decumbens has a lignocellulolytic enzyme system with more diverse components, particularly for cellulose binding domain-containing proteins and hemicellulases. Further, proteomic analysis of secretomes revealed that P. decumbens produced significantly more lignocellulolytic enzymes in the medium with cellulose-wheat bran as the carbon source than with glucose. The results expand our knowledge on the genetic information of lignocellulolytic enzyme systems in Penicillium species, and will facilitate rational strain improvement for the production of highly efficient enzyme systems used in lignocellulose utilization from Penicillium species.

  • Penicillium decumbens BrlA extensively regulates secondary metabolism and functionally associates with the expression of cellulase genes
    Applied Microbiology and Biotechnology, 2013
    Co-Authors: Yuqi Qin, Longfei Bao, Meirong Gao, Yunfeng Lei, Mei Chen, Guodong Liu, Yinbo Qu
    Abstract:

    Penicillium decumbens has been used in the industrial production of lignocellulolytic enzymes in China for more than 15 years. Conidiation is essential for most industrial fungi because conidia are used as starters in the first step of fermentation. To investigate the mechanism of conidiation in P. decumbens, we generated mutants defective in two central regulators of conidiation, FluG and BrlA. Deletion of fluG resulted in neither "fluffy" phenotype nor alteration in conidiation, indicating possible different upstream mechanisms activating brlA between P. decumbens and Aspergillus nidulans. Deletion of brlA completely blocked conidiation. Further investigation of brlA expression in different media (nutrient-rich or nutrient-poor) and different culture states (liquid or solid) showed that brlA expression is required but not sufficient for conidiation. The brlA deletion strain exhibited altered hyphal morphology with more branches. Genome-wide expression profiling identified BrlA-dependent genes in P. decumbens, including genes previously reported to be involved in conidiation as well as previously reported chitin synthase genes and acid protease gene (pepB). The expression levels of seven secondary metabolism gene clusters (from a total of 28 clusters) were drastically regulated in the brlA deletion strain, including a downregulated cluster putatively involved in the biosynthesis of the mycotoxins roquefortine C and meleagrin. In addition, the expression levels of most cellulase genes were upregulated in the brlA deletion strain detected by real-time quantitative PCR. The brlA deletion strain also exhibited an 89.1 % increase in cellulase activity compared with the wild-type strain. The results showed that BrlA in P. decumbens not only has a key role in regulating conidiation, but it also regulates secondary metabolism extensively as well as the expression of cellulase genes.

Rafael Borja - One of the best experts on this subject based on the ideXlab platform.

  • kinetic analysis of the anaerobic digestion of untreated vinasses and vinasses previously treated with Penicillium decumbens
    Journal of Environmental Management, 2006
    Co-Authors: Antonia María Ruiz Jiménez, Rafael Borja, Antonio Martín, F Raposo
    Abstract:

    A kinetic study was carried out on the anaerobic digestion of untreated vinasses and vinasses previously fermented with Penicillium decumbens. Two 1-l volume continuous-flow stirred tank reactors (CFSTR) operating at mesophilic temperature (35 degrees C) were used for the study. One reactor was fed with untreated vinasses (COD concentration of 80.5 g/l) and the other with vinasses previously fermented (COD concentration of 23.0 g/l). Both reactors were operated at organic loading rates in the range of 1.5-7.5 g chemical oxygen demand (COD)/l-d. The results obtained were evaluated using the Chen-Hashimoto methane production model to determine the values of the maximum specific growth rate (micromax) and the model kinetic constant (K) of the process for each case studied. The kinetic constants (micromax and K) were affected by the pre-treatment, and the respective values were 9.6 and 6.9 times higher for pretreated vinasses than those of untreated vinasses. This was significant at the 95% confidence level. This behaviour is believed to be due to the lower levels of phenolic compounds present in the pretreated vinasses, as compared to untreated vinasses, resulting in an improved process performance, kinetics and stability. Finally, the experimental values of methane production were reproduced with deviations equal to or less than 4% and 10% for pretreated and untreated vinasses, respectively.

  • Kinetic analysis of the anaerobic digestion of untreated vinasses and vinasses previously treated with Penicillium decumbens
    Journal of Environmental Management, 2006
    Co-Authors: Antonia María Ruiz Jiménez, Rafael Borja, Alex Martin, Francisco Raposo
    Abstract:

    A kinetic study was carried out on the anaerobic digestion of untreated vinasses and vinasses previously fermented with Penicillium decumbens. Two 1-l volume continuous-flow stirred tank reactors (CFSTR) operating at mesophilic temperature (35 °C) were used for the study. One reactor was fed with untreated vinasses (COD concentration of 80.5 g/l) and the other with vinasses previously fermented (COD concentration of 23.0 g/l). Both reactors were operated at organic loading rates in the range of 1.5–7.5 g chemical oxygen demand (COD)/l-d. The results obtained were evaluated using the Chen–Hashimoto methane production model to determine the values of the maximum specific growth rate (?max) and the model kinetic constant (K) of the process for each case studied. The kinetic constants (?max and K) were affected by the pre-treatment, and the respective values were 9.6 and 6.9 times higher for pretreated vinasses than those of untreated vinasses. This was significant at the 95% confidence level. This behaviour is believed to be due to the lower levels of phenolic compounds present in the pretreated vinasses, as compared to untreated vinasses, resulting in an improved process performance, kinetics and stability. Finally, the experimental values of methane production were reproduced with deviations equal to or less than 4% and 10% for pretreated and untreated vinasses, respectively.

  • Mathematical modelling of aerobic degradation of vinasses with Penicillium decumbens
    Process Biochemistry, 2005
    Co-Authors: Antonia María Ruiz Jiménez, Rafael Borja, Alex Martin, Francisco Raposo
    Abstract:

    Abstract Growth, substrate and phenolic compound biodegradation by Penicillium decumbens was studied on vinasses. This fungus was selected because of its tolerance to the phenolic compounds present in this waste. The biodegradation process of vinasses was researched in batch regime by conducting experiments where the initial concentration of substrate and phenolic compounds were 42.6 g COD/L and 0.21 g gallic acid/L, respectively. This fungus significantly degraded the total phenolic compounds in vinasses aerobically without the need for any nutrient supplements in the medium. A maximum value of phenols removal of 74% was achieved after 3 days’ treatment. P. decumbens produces a decolourization of the vinasses from the 1st day of incubation. Higher reductions in colour were achieved between the 4th and 5th days of treatment, the best result being 41% of the initial colour removed after 4 days’ treatment. A mathematical model based on three differential equations was formulated to describe this biodegradation process assuming that a fraction of the organic content of vinasses is non-biodegradable. The proposed equations were validated by comparing the theoretical curves obtained with the corresponding experimental data of substrate and biomass concentrations. The small deviations obtained in both cases (lower than 5%) demonstrated the suitability of the mathematical model proposed and suggested that this model very accurately described the variation of substrate and biomass concentrations with time in the aerobic degradation process of vinasses with P. decumbens and that the parameters obtained represent the activity of this microorganism effecting the aerobic degradation of this waste. Finally, the biomass yield coefficient was found to be 0.35 g VSS/g COD through the relationship between the amount of cells produced and substrate uptake. This value coincides with that obtained theoretically from the mathematical model formulated.

  • A comparative kinetic evaluation of the anaerobic digestion of untreated molasses and molasses previously fermented with Penicillium decumbens in batch reactors
    Biochemical Engineering Journal, 2004
    Co-Authors: Antonia María Ruiz Jiménez, Rafael Borja, Antonio Martín
    Abstract:

    Abstract A comparative kinetic study was carried out on the anaerobic digestion of untreated beet molasses alcoholic fermentation wastewater and beet molasses previously fermented with Penicillium decumbens. Three 1 l volume stirred tank reactors were used for the study, one with freely suspended biomass (Control), and the other two with biomass supported on Saponite (magnesium silicate) and Esmectite (aluminium silicate), respectively. The reactors were batch fed at mesophilic temperature (35 °C) using COD loadings of between 12 and 140 ml of untreated molasses with a COD of 80.5 g/l and of between 43 and 304 ml of molasses previously fermented with a COD of 23.0 g/l. The anaerobic digestion process of both substrates was found to follow a first-order kinetics and the experimental accumulated methane volume (G)–time (t) data to conform to an equation of the form: G=Gm[1−exp(−K0t)], from which the specific rate constants, K0, were calculated. In the case of untreated molasses, the K0 values decreased considerably from 2.87 to 0.10 (Saponite), from 2.78 to 0.10 (Esmectite) and from 2.16 to 0.07 per days (Control) when the loading of molasses applied and initial COD added were increased from 12 to 140 ml and 1 to 10 g/l, respectively; this showed an inhibition phenomenon in the three reactors studied. In contrast to this, the kinetic constants of the anaerobic digestion of pre-treated molasses were virtually constant over the COD range used (1–7 g/l) in the three reactors considered. Finally, the average methane yield coefficient for pre-treated molasses was 305 ml CH4 STP/g CODremoved, viz. 35% higher than that provided by untreated molasses.

  • influence of aerobic pretreatment with Penicillium decumbens on the anaerobic digestion of beet molasses alcoholic fermentation wastewater in suspended and immobilized cell bioreactors
    Journal of Chemical Technology & Biotechnology, 1997
    Co-Authors: Antonia María Ruiz Jiménez, Rafael Borja, Valle Alonso, Antonio Martín
    Abstract:

    A comparative study was carried out on the anaerobic digestion of untreated and previously-fermented (with Penicillium decumbens) beet molasses. Four continuous stirred tank reactors were used for the study, two with freely suspended biomass, and the other with biomass supported on saponite. The reactors operated satisfactorily between hydraulic retention times (HRT) of 53.3-10.6 days and 15.4-3.1 days for untreated and previously-fermented molasses respectively. The anaerobic digestion processes of untreated and pretreated molasses were found to follow first-order kinetics for biomass loading rates in the range of 0-0.55 and 0-0.75 g chemical oxygen demand (COD) g -1 volatile suspended solids (VSS) day -1 respectively. The experimental data [namely unitary conversion or efficiency (X), HRT, biomass concentration (M) and incoming substrate concentration (S o )] conformed to an equation of the form: X/HRT = KM(I - X)-(KMS R /S 0 ), from which the kinetic constant, K, was calculated. The kinetic constants were influenced by the pretreatment carried out and were 1.7 and 2.5 times higher for pretreated molasses than for untreated molasses in the reactors with suspended and immobilized biomass respectively. This was significant at a 95% confidence level. The specific rate of substrate uptake for cell maintenance (m) decreased by a factor of approximately 2 for the previously fermented molasses in relation to the observed values for the untreated molasses. This may be attributable to the fact that higher phenolic compound concentrations inhibit and interfere with the activity of anaerobic bacteria.

Francisco Raposo - One of the best experts on this subject based on the ideXlab platform.

  • Kinetic analysis of the anaerobic digestion of untreated vinasses and vinasses previously treated with Penicillium decumbens
    Journal of Environmental Management, 2006
    Co-Authors: Antonia María Ruiz Jiménez, Rafael Borja, Alex Martin, Francisco Raposo
    Abstract:

    A kinetic study was carried out on the anaerobic digestion of untreated vinasses and vinasses previously fermented with Penicillium decumbens. Two 1-l volume continuous-flow stirred tank reactors (CFSTR) operating at mesophilic temperature (35 °C) were used for the study. One reactor was fed with untreated vinasses (COD concentration of 80.5 g/l) and the other with vinasses previously fermented (COD concentration of 23.0 g/l). Both reactors were operated at organic loading rates in the range of 1.5–7.5 g chemical oxygen demand (COD)/l-d. The results obtained were evaluated using the Chen–Hashimoto methane production model to determine the values of the maximum specific growth rate (?max) and the model kinetic constant (K) of the process for each case studied. The kinetic constants (?max and K) were affected by the pre-treatment, and the respective values were 9.6 and 6.9 times higher for pretreated vinasses than those of untreated vinasses. This was significant at the 95% confidence level. This behaviour is believed to be due to the lower levels of phenolic compounds present in the pretreated vinasses, as compared to untreated vinasses, resulting in an improved process performance, kinetics and stability. Finally, the experimental values of methane production were reproduced with deviations equal to or less than 4% and 10% for pretreated and untreated vinasses, respectively.

  • Mathematical modelling of aerobic degradation of vinasses with Penicillium decumbens
    Process Biochemistry, 2005
    Co-Authors: Antonia María Ruiz Jiménez, Rafael Borja, Alex Martin, Francisco Raposo
    Abstract:

    Abstract Growth, substrate and phenolic compound biodegradation by Penicillium decumbens was studied on vinasses. This fungus was selected because of its tolerance to the phenolic compounds present in this waste. The biodegradation process of vinasses was researched in batch regime by conducting experiments where the initial concentration of substrate and phenolic compounds were 42.6 g COD/L and 0.21 g gallic acid/L, respectively. This fungus significantly degraded the total phenolic compounds in vinasses aerobically without the need for any nutrient supplements in the medium. A maximum value of phenols removal of 74% was achieved after 3 days’ treatment. P. decumbens produces a decolourization of the vinasses from the 1st day of incubation. Higher reductions in colour were achieved between the 4th and 5th days of treatment, the best result being 41% of the initial colour removed after 4 days’ treatment. A mathematical model based on three differential equations was formulated to describe this biodegradation process assuming that a fraction of the organic content of vinasses is non-biodegradable. The proposed equations were validated by comparing the theoretical curves obtained with the corresponding experimental data of substrate and biomass concentrations. The small deviations obtained in both cases (lower than 5%) demonstrated the suitability of the mathematical model proposed and suggested that this model very accurately described the variation of substrate and biomass concentrations with time in the aerobic degradation process of vinasses with P. decumbens and that the parameters obtained represent the activity of this microorganism effecting the aerobic degradation of this waste. Finally, the biomass yield coefficient was found to be 0.35 g VSS/g COD through the relationship between the amount of cells produced and substrate uptake. This value coincides with that obtained theoretically from the mathematical model formulated.