Kinetic study of growth of Pseudomonas putida mt-2 was investigated in batch culture under aerobi... more Kinetic study of growth of Pseudomonas putida mt-2 was investigated in batch culture under aerobic conditions, on glucose as initial carbon and energy source. Cell growth was continuous and three phases were found regarding accumulation of intermediates: (1) glucose was largely converted to gluconate and 2-ketogluconate, (2) then gluconate was converted to 2-ketogluconate and (3) the latter was consumed after gluconate depletion. Examination of growth kinetics and yields showed that glucose flux was mainly oriented to oxidation reduction in the periplasm and less towards biosynthesis. Values of respiratory quotient and of CO2/biomass and O2/biomass yields were characteristic of each phase. Main enzymatic activities involved in the use of these substrates were always detected meaning that concomitant assimilation is possible. However the levels of these activities varied during growth. Membrane conversions seem to have a significant energetic contribution explaining the higher specific growth rate obtained in glucose phase compared to gluconate and 2-ketogluconate ones. This is also noticeable through the evolution of the yields Y(O2)/X and Y(CO2)/X. Although the three convergent pathways are operational and can be genetically controlled, the progression of the culture in successive phases highlights an overall level of regulation in response to the energetic needs.
ABSTRACT Textile effluents (TEs) without correct treatment cause high environmental impact becaus... more ABSTRACT Textile effluents (TEs) without correct treatment cause high environmental impact because they display several problems mainly due to toxicity and recalcitrance of dyestuffs. The aim of this work was to examine the performance of Pseudomonas putida mt-2 in treating TE. P. putida was able to completely decolorize the studied effluent after 8 h of incubation under agitation in an aerobic bioreactor. Genotoxicity of effluent, before and after biodegradation with P. putida mt-2, was evaluated in vitro using the SOS chromotest and in vivo in mouse bone marrow, by assessing the percentage of cells bearing different chromosome aberrations compared with untreated mice. Results indicated that TE showed a significant ability to induce DNA damage, which was evaluated in both SOS (IF = 3.52) and chromosome aberration assay systems (23.5%). In addition, TE reduced strongly the acetylcholinesterse (60%) and butyrylcholinesterase (51%) activities and induces a remarkable lipid peroxidation effect (increased markedly by approximately fivefold). This toxicity was imputed to the presence of dye compounds of TE. However, toxicity in TE was significantly reduced after 8 h of aerobic incubation with P. putida mt-2 strain. The present study demonstrates that P. putida mt-2, incubated under aerobic conditions, has a metabolism that enables it to degrade TE and, especially, to detoxify the effluent mixtures.
Environmental Toxicology and Pharmacology, Mar 1, 2009
The SOS-chromotest in Escherichia coli is a widely used bacterial genotoxicity assay to test pote... more The SOS-chromotest in Escherichia coli is a widely used bacterial genotoxicity assay to test potential carcinogens. The aim of this work is to evaluate the genotoxic and antigenotoxic activities of essential oils obtained from aerial parts of Pituranthos chloranthus. The tested essential oils were not genotoxic towards both E. coli PQ37 and PQ35 strains. These essential oils reduced significantly Nifuroxazide and H(2)O(2)-induced genotoxicity. Essential oils showed a protective effect against damages induced by radicals, obtained from the photolysis of H(2)O(2), on DNA plasmid through free radical scavenging mechanisms. The scavenging capacity of these essential oils was also estimated by evaluating the inhibition of ABTS(+.) radical.
... Knowledge-based control of fermentation processes. Biotechnol. Bioeng., 39, 479-86. Mahjoub, ... more ... Knowledge-based control of fermentation processes. Biotechnol. Bioeng., 39, 479-86. Mahjoub, M., Rachid, A. & Lamotte, M. (1991). On fuzzy controller robustness. Paper presented at IMACS-MCTS Symposium, Villeneuve, France. Mamdani, EH & Assilian, S. (1975). ...
A bacterium was isolated from the river of Oued Hamdoun (Tunisia), and its phenotypic features, p... more A bacterium was isolated from the river of Oued Hamdoun (Tunisia), and its phenotypic features, physiological and chemotaxonomic characteristics and phylogenetic analysis of 16S ribosomal RNA sequence revealed it as Pseudomonas peli ( P. peli). Chlorpyrifos ethyl (CP) was used as the sole source of carbon and energy by P. peli, and it was cometabolised in the presence of glucose. CP was completely degraded by P. peli after 96 h of shake incubation. High-performance liquid chromatography analysis indicated that the biodegradation kinetics was not affected by the addition of glucose into the culture medium. In the present study, only transient accumulation of one major no-identified product was observed after 48 h of incubation, with no other persistent metabolites detected. Cytotoxicity of CP, before and after biodegradation with P. peli, was evaluated in vitro using the MTT-colorimetric assay against three human cancer cell lines (A549, lung cell carcinoma, HT29, colon adenocarcinoma and MCF7, breast adenocarcinoma). CP reduced viability of all human cell lines in a dose-dependent manner. Its activity was very remarkable against A549 cell line. However, cytotoxicity strongly decreased in CP obtained after incubation with P. peli. Hence, we conclude that when incubated under appropriate conditions, P. peli has a metabolism that completely detoxifies CP.
FT-IR spectroscopy is a non-destructive testing technique that requires minimal sample preparatio... more FT-IR spectroscopy is a non-destructive testing technique that requires minimal sample preparation time and allows the rapid characterization of structural features of complex, polymeric material. This technique has been frequently used in the past for the detection of PHA (Polyhydroxyalkanoates) but rarely for their quantification. In this work, by using cluster and discriminant statistical analysis of FT-IR data, different models are proposed for rapid identification of PHA monomers produced under different growth conditions by bacterial strains, and for their semi quantification. The results on the ability to produce large amounts of PHA (of 21 strains) in different environmental conditions of medium, substrates and deficiency of nutrients are presented. The spectral data analysis gives qualitative and semi quantitative information about the PHA produced in the samples. Models are proposed to test a large number of cultural conditions of strains and substrates in the field of screening and for identifying best conditions of PHA production in lab scale bioreactor and on industrial scale.
Annales De Chimie-science Des Materiaux, Apr 17, 2008
La diffraction des rayons X, la spectroscopie Raman et l'analyse par spectroscopie d'emis... more La diffraction des rayons X, la spectroscopie Raman et l'analyse par spectroscopie d'emission optique ont ete utilisees pour etudier l'effet des ions magnesium, calcium et sulfate sur la cinetique de precipitation et la microstructure du carbonate de calcium forme, par la methode de degazage controle, a partir des solutions synthetiques equivalentes a l'eau de mer standard. Pour toutes les experiences, la phase aragonite a ete obtenue. La presence des ions Mg 2+ et SO 4 2- dans la solution augmente le temps de germination et diminue la vitesse de croissance de l'aragonite. Les ions magnesium ont ete inseres dans la structure cristalline de l'aragonite en substituant les ions calcium. Cette substitution depend de la concentration des ions Mg2 + , Ca 2+ et SO 4 2- . L'augmentation de la concentration du calcium mene a un faible taux d'incorporation de Mg 2+ . Les ions sulfates peuvent etre adsorbes sur les surfaces de l'aragonite ou inhibent la substitution du calcium par le magnesium, suivant les concentrations ajoutees.
FT-IR spectroscopy is a non-destructive testing technique that requires minimal sample preparatio... more FT-IR spectroscopy is a non-destructive testing technique that requires minimal sample preparation time and allows the rapid characterization of structural features of complex, polymeric material. This technique has been frequently used in the past for the detection of PHA (Polyhydroxyalkanoates) but rarely for their quantification. In this work, by using cluster and discriminant statistical analysis of FT-IR data, different models are proposed for rapid identification of PHA monomers produced under different growth conditions by bacterial strains, and for their semi quantification. The results on the ability to produce large amounts of PHA (of 21 strains) in different environmental conditions of medium, substrates and deficiency of nutrients are presented. The spectral data analysis gives qualitative and semi quantitative information about the PHA produced in the samples. Models are proposed to test a large number of cultural conditions of strains and substrates in the field of screening and for identifying best conditions of PHA production in lab scale bioreactor and on industrial scale.
Kinetic study of growth of Pseudomonas putida mt-2 was investigated in batch culture under aerobi... more Kinetic study of growth of Pseudomonas putida mt-2 was investigated in batch culture under aerobic conditions, on glucose as initial carbon and energy source. Cell growth was continuous and three phases were found regarding accumulation of intermediates: (1) glucose was largely converted to gluconate and 2-ketogluconate, (2) then gluconate was converted to 2-ketogluconate and (3) the latter was consumed after gluconate depletion. Examination of growth kinetics and yields showed that glucose flux was mainly oriented to oxidation reduction in the periplasm and less towards biosynthesis. Values of respiratory quotient and of CO2/biomass and O2/biomass yields were characteristic of each phase. Main enzymatic activities involved in the use of these substrates were always detected meaning that concomitant assimilation is possible. However the levels of these activities varied during growth. Membrane conversions seem to have a significant energetic contribution explaining the higher specific growth rate obtained in glucose phase compared to gluconate and 2-ketogluconate ones. This is also noticeable through the evolution of the yields Y(O2)/X and Y(CO2)/X. Although the three convergent pathways are operational and can be genetically controlled, the progression of the culture in successive phases highlights an overall level of regulation in response to the energetic needs.
ABSTRACT Textile effluents (TEs) without correct treatment cause high environmental impact becaus... more ABSTRACT Textile effluents (TEs) without correct treatment cause high environmental impact because they display several problems mainly due to toxicity and recalcitrance of dyestuffs. The aim of this work was to examine the performance of Pseudomonas putida mt-2 in treating TE. P. putida was able to completely decolorize the studied effluent after 8 h of incubation under agitation in an aerobic bioreactor. Genotoxicity of effluent, before and after biodegradation with P. putida mt-2, was evaluated in vitro using the SOS chromotest and in vivo in mouse bone marrow, by assessing the percentage of cells bearing different chromosome aberrations compared with untreated mice. Results indicated that TE showed a significant ability to induce DNA damage, which was evaluated in both SOS (IF = 3.52) and chromosome aberration assay systems (23.5%). In addition, TE reduced strongly the acetylcholinesterse (60%) and butyrylcholinesterase (51%) activities and induces a remarkable lipid peroxidation effect (increased markedly by approximately fivefold). This toxicity was imputed to the presence of dye compounds of TE. However, toxicity in TE was significantly reduced after 8 h of aerobic incubation with P. putida mt-2 strain. The present study demonstrates that P. putida mt-2, incubated under aerobic conditions, has a metabolism that enables it to degrade TE and, especially, to detoxify the effluent mixtures.
Environmental Toxicology and Pharmacology, Mar 1, 2009
The SOS-chromotest in Escherichia coli is a widely used bacterial genotoxicity assay to test pote... more The SOS-chromotest in Escherichia coli is a widely used bacterial genotoxicity assay to test potential carcinogens. The aim of this work is to evaluate the genotoxic and antigenotoxic activities of essential oils obtained from aerial parts of Pituranthos chloranthus. The tested essential oils were not genotoxic towards both E. coli PQ37 and PQ35 strains. These essential oils reduced significantly Nifuroxazide and H(2)O(2)-induced genotoxicity. Essential oils showed a protective effect against damages induced by radicals, obtained from the photolysis of H(2)O(2), on DNA plasmid through free radical scavenging mechanisms. The scavenging capacity of these essential oils was also estimated by evaluating the inhibition of ABTS(+.) radical.
... Knowledge-based control of fermentation processes. Biotechnol. Bioeng., 39, 479-86. Mahjoub, ... more ... Knowledge-based control of fermentation processes. Biotechnol. Bioeng., 39, 479-86. Mahjoub, M., Rachid, A. & Lamotte, M. (1991). On fuzzy controller robustness. Paper presented at IMACS-MCTS Symposium, Villeneuve, France. Mamdani, EH & Assilian, S. (1975). ...
A bacterium was isolated from the river of Oued Hamdoun (Tunisia), and its phenotypic features, p... more A bacterium was isolated from the river of Oued Hamdoun (Tunisia), and its phenotypic features, physiological and chemotaxonomic characteristics and phylogenetic analysis of 16S ribosomal RNA sequence revealed it as Pseudomonas peli ( P. peli). Chlorpyrifos ethyl (CP) was used as the sole source of carbon and energy by P. peli, and it was cometabolised in the presence of glucose. CP was completely degraded by P. peli after 96 h of shake incubation. High-performance liquid chromatography analysis indicated that the biodegradation kinetics was not affected by the addition of glucose into the culture medium. In the present study, only transient accumulation of one major no-identified product was observed after 48 h of incubation, with no other persistent metabolites detected. Cytotoxicity of CP, before and after biodegradation with P. peli, was evaluated in vitro using the MTT-colorimetric assay against three human cancer cell lines (A549, lung cell carcinoma, HT29, colon adenocarcinoma and MCF7, breast adenocarcinoma). CP reduced viability of all human cell lines in a dose-dependent manner. Its activity was very remarkable against A549 cell line. However, cytotoxicity strongly decreased in CP obtained after incubation with P. peli. Hence, we conclude that when incubated under appropriate conditions, P. peli has a metabolism that completely detoxifies CP.
FT-IR spectroscopy is a non-destructive testing technique that requires minimal sample preparatio... more FT-IR spectroscopy is a non-destructive testing technique that requires minimal sample preparation time and allows the rapid characterization of structural features of complex, polymeric material. This technique has been frequently used in the past for the detection of PHA (Polyhydroxyalkanoates) but rarely for their quantification. In this work, by using cluster and discriminant statistical analysis of FT-IR data, different models are proposed for rapid identification of PHA monomers produced under different growth conditions by bacterial strains, and for their semi quantification. The results on the ability to produce large amounts of PHA (of 21 strains) in different environmental conditions of medium, substrates and deficiency of nutrients are presented. The spectral data analysis gives qualitative and semi quantitative information about the PHA produced in the samples. Models are proposed to test a large number of cultural conditions of strains and substrates in the field of screening and for identifying best conditions of PHA production in lab scale bioreactor and on industrial scale.
Annales De Chimie-science Des Materiaux, Apr 17, 2008
La diffraction des rayons X, la spectroscopie Raman et l'analyse par spectroscopie d'emis... more La diffraction des rayons X, la spectroscopie Raman et l'analyse par spectroscopie d'emission optique ont ete utilisees pour etudier l'effet des ions magnesium, calcium et sulfate sur la cinetique de precipitation et la microstructure du carbonate de calcium forme, par la methode de degazage controle, a partir des solutions synthetiques equivalentes a l'eau de mer standard. Pour toutes les experiences, la phase aragonite a ete obtenue. La presence des ions Mg 2+ et SO 4 2- dans la solution augmente le temps de germination et diminue la vitesse de croissance de l'aragonite. Les ions magnesium ont ete inseres dans la structure cristalline de l'aragonite en substituant les ions calcium. Cette substitution depend de la concentration des ions Mg2 + , Ca 2+ et SO 4 2- . L'augmentation de la concentration du calcium mene a un faible taux d'incorporation de Mg 2+ . Les ions sulfates peuvent etre adsorbes sur les surfaces de l'aragonite ou inhibent la substitution du calcium par le magnesium, suivant les concentrations ajoutees.
FT-IR spectroscopy is a non-destructive testing technique that requires minimal sample preparatio... more FT-IR spectroscopy is a non-destructive testing technique that requires minimal sample preparation time and allows the rapid characterization of structural features of complex, polymeric material. This technique has been frequently used in the past for the detection of PHA (Polyhydroxyalkanoates) but rarely for their quantification. In this work, by using cluster and discriminant statistical analysis of FT-IR data, different models are proposed for rapid identification of PHA monomers produced under different growth conditions by bacterial strains, and for their semi quantification. The results on the ability to produce large amounts of PHA (of 21 strains) in different environmental conditions of medium, substrates and deficiency of nutrients are presented. The spectral data analysis gives qualitative and semi quantitative information about the PHA produced in the samples. Models are proposed to test a large number of cultural conditions of strains and substrates in the field of screening and for identifying best conditions of PHA production in lab scale bioreactor and on industrial scale.
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