Representative cider microorganisms (47 yeast strains and 16 bacterial strains) were studied for their ability to produce volatile phenols in a synthetic medium simulating cider conditions and ...supplemented with the necessary precursors. The various strains were tested for cinnamoyl esterase activity and only Lactobacillus collinoides were able to hydrolyse chlorogenic acid. Phenolic acid decarboxylase (PAD) activities were observed for 6 yeasts and 4 bacterial species allowing them to produce vinylphenols from hydroxycinnamic acids. On the other hand, 4 bacterial species exhibited phenolic acid reductase (PAR) activities leading to the formation of hydroxyphenylpropionic acids. Brettanomyces/Dekkera anomala and L. collinoides were able to produce 4-ethylcatechol (4-EC) and 4-ethylphenol (4-EP) from caffeic and p-coumaric acid, respectively, indicating that both species exhibit PAD and vinylphenol reductase (VPR) activities. In the experimental conditions used, the production of ethylphenols by L. collinoides was faster than the one observed for D. anomala.
► Representative cider yeasts and bacteria (63 strains) were studied. ► Only Lactobacillus collinoides presented a cinnamoyl esterase activity. ► Among 19 tested species, 4 bacterial species exhibited PAR activities. ► PAD activities were observed for 6 yeasts and 4 bacterial species. ► L. collinoides and D. anomala were able to produce ethylphenols.
Gas chromatography coupled with mass spectrometry (GC/MS), using both electron impact (EI) and chemical ionization (CI) detection modes on apolar and polar stationary phases, led to the determination ...of the volatile composition of the essential oil obtained from tubers of Cyperus rotundus (Cyperaceae). In this study, more than 33 compounds were identified and then compared with the results obtained in our previous work. Cyperene, α‐cyperone, isolongifolen‐5‐one, rotundene, and cyperorotundene were the principal compounds comprising 62% of the oil. An in vitro cytotoxicity assay with MTT indicated that this oil was very effective against L1210 leukaemia cells line. This result correlates with significantly increased apoptotic DNA fragmentation. The oxidative effects of the essential oil were evaluated using the 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH), xanthine/xanthine oxidase assays, and the scavenging of superoxide radical assay generated by photo‐reduction of riboflavin. The antimutagenic activity of essential oil has been examined by following the inhibition of H2O2 UV photolysis which induced strand‐break formation in pBS plasmid DNA scission assay. Based on all these results, it is concluded that C. rotundus essential‐oil composition established by GC/MS analysis, in EI‐ and CI‐MS modes, presents a variety of a chemical composition we were not able to detect with only GC/MS analysis in our previous work. This essential oil exhibited antioxidant, cytotoxic, and apoptotic properties.
Mutagenicity of acid orange 52 (AO52) and its degradation products by Pseudomonas putida mt-2 was evaluated with the use of Salmonella Typhimurium TA102 and TA104 with and without the metabolic ...activation system (S9). No mutagenicity was observed in the absence of S9 and in the presence of S9 for biodegradation under shaking conditions, but it increased significantly in the presence of S9 after biodegradation under static conditions. In addition, the ability of tested compounds to induce DNA damage in vitro was evaluated with the DNA strand scission assay. The toxicity generated by the pure azo dye and the corresponding azoreduction products (4-aminobenzenesulfonic acid and N,N'-dimethyl-p-phenylenediamine) were compared. We suggest that the mutagenicity mechanism of these molecules occurs through free radical generation processes. In this study, we demonstrate that P. putida mt-2 incubated under aerobic conditions undergoes catabolism that enables it to degrade AO52 completely and, especially, to detoxify the dye mixtures.
Introduction Acid violet 7 (AV7), mostly used in food, paper, cosmetic, and especially in textile industries, was degraded by Pseudomonas putida mt-2 at concentrations up to 200 mg/l. Materials and ...methods In this study, toxicity of AV7, before and after biodegradation, was evaluated in vivo, in mouse bone marrow, by assessing the percentage of cells bearing different chromosome aberrations, membrane lipid peroxidation, and acetylcholinesterasic activity inhibition. The studies included same conditions for animal treatment, corresponding to increasing doses by intraperitoneal (ip) injection. Results Results indicated that AV7 showed a significant ability to induce chromosome aberrations, lipid peroxidation, and acetylcholinesterase inhibitory effect. The toxicity of AV7 increased significantly after static biodegradation with P. putida mt-2 and totally disappeared after shaken incubation. In addition, the toxicity generated by the pure azo dye and the corresponding azoreduction metabolites (4'-aminoacetanilide (4'-AA) and 5-acetamido-2-amino-1-hydroxy-3,6-naphtalene disulfonic acid (5-ANDS)) were compared. 4'-AA and 5-ANDS would be responsible of static biodegradation medium toxicity. The present study demonstrates that P. putida mt-2, incubated under aerobic condition, has a catabolism which enables it to degrade AV7, and especially to completely detoxify the dye mixture.
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 CO
2
/biomass and O
2
/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
and
. 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.
A total of 207 volatile compounds were identified in extracts of four French labeled brandies: Armagnac, Cognac, Calvados, and Mirabelle. Relative levels of all components were determined using GC-MS ...after integration of a selected peak of the mass spectrum of each. Each type of brandy could be clearly discriminated using PLS-DA statistical analyses based on these levels. French Mirabelle spirit, which was studied for the first time, was characterized by higher levels of many aldehydes and acetals and by the presence of compounds having an odd number of carbons together with benzaldehyde and some of its derivatives. Many possible derivatives of acrolein and high amounts of butan-2-ol were rather specific for the volatile composition of Calvados. The most important difference between the two wine-based samples seemed to be directly linked to the distillation system used. Many furanic compounds are specific to Cognac, whereas two or three compounds such as 1-(ethoxyethoxy)-2-methylbutane and γ-eudesmol were specific to Armagnac. These two brandies presented rather high distributions of isobutanol and isopentanols, whereas Mirabelle and Calvados compositions offer more concentrated aliphatic linear alcohols.
Polysulfone (PSf)/polyacrylic acid ultrafiltration (PSf/PAA) membranes were prepared from a polymer blend in dimethylformamide by coagulation in water according to the wet phase inversion method. ...Immobilization of water-soluble PAA within the non-soluble PSf matrix was proven by the increase of ion exchange capacity and the intensity of the carboxyl groups’ peak with the increase of PAA content as shown by Fourier transform infrared spectra. These results lead to consider that PSf and PAA form a semi-interpenetrating polymer networks. The obtained membranes showed a decrease of mean surface-pore sizes, the overall porosity and the hydraulic permeability with the increase in PAA content. Such results were imputed to the morphologic modifications of PSf film with the immobilization of increasing PAA amount.
PSf/PAA membranes showed high lead, cadmium and chromium rejection which reaches 100% at pH superior to 5.7 and a low rejection at low pH. Moreover, the heavy metal rejection decreases with feed solution concentration and applied pressure increases. These behaviors were attributed to the role of carboxylic groups in ion exchange or complexation. As a matter of fact, the strong lead ion–PAA interactions were revealed by the scanning electron microscopy with energy dispersive X-rays (SEM-EDX).
Introduction
Textile industry is one of the most common and essential sectors in Tunisia. However, the treatment of textile effluents becomes a university because of their toxic impacts on waters, ...soils, flora, and fauna.
Materials and methods
The aim of this work was to evaluate the ability of
Pseudomonas putida
mt-2 to decolorize a textile wastewater and to compare the biologic decolorization process to the chemical one currently used by the textile industry.
Results
P. putida
exhibited a high decolorizing capacity of the studied effluent, compared to the coagulation–flocculation method with decolorization percentage of 86% and 34.5%, respectively. Genotoxicity of the studied effluent, before and after decolorization by
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 to not treated mice. In addition, textile effluent statistically significant influenced acetylcholinesterase and butyrylcholinesterase activities and lipid peroxidation (
p
< 0.01) when compared to not-treated mice. Coagulation–flocculation treatment process used by industry was revealed to be ineffective. Indeed toxicities persisted after treatment and the effluent did not show any statistically significant decrease in toxicities compared to non-treated effluent. Our results indicate that
P. putida
is a promising and improved alternative to treating industrial scale effluent compared to current chemical decolorization procedures used by the Tunisian textile industry.
Acids yellow 17, violet 7 and orange 52, very important commercial azo dyes used in the textile, food, paper and cosmetic industries, were degraded by
Pseudomonas putida mt-2 at concentrations up to ...100
mg/l. The culture media was completely decolorized under static incubation for 60
h, this faster than under continuous shaking incubation. SOS chromotest using
Escherichia coli PQ37, with and without metabolic activation (S-9 preparations), was used to assess genotoxicity potential of these dyes before and after biodegradation. None of these dyes or their metabolites was found to be genotoxic in the absence of “Araclor-Induced rat liver microsome” preparations (S-9). However, in presence of the preparation S-9, the genotoxicity of the biodegradation products was highlighted. Metabolites resulting from static cultures were more genotoxic than those obtained in shaken conditions. In addition to genotoxic effects, metabolites have shown a significant ability to induce the formation of superoxide free radical anion (
O
2
-
). The toxicities generated by the pure azo dyes and the pure azo-reduction products (sulfanilic acid,
N,
N′-dimethyl-
p-phenylenediamine and 4′-aminoacetanilid) were compared.
These results suggest that
P. putida mt-2 degrades the studied azo dyes in two steps: an azo-reduction followed by an oxygen-dependent metabolization. Some of the derived metabolites would be responsible of genotoxicity and metabolic toxicity.
A new HPLC method using a diode array detector was developed and validated to quantify 4-ethylphenol, 4-vinylphenol, 4-ethylguaiacol, 4-vinylguaiacol and 4-ethylcatechol in cider. The procedure was ...linear up to 150
mg/l for each of the five volatile phenols, precise (RSD
<
2.9%) and sensitive, with limits of detection between 0.03 and 0.10
mg/l; moreover, it did not require any sample preparation. This method was applied to 11 phenolic off-flavour defective ciders. In these ciders, the main volatile phenol corresponded to 4-ethylcatechol. Moreover, the observed concentrations (maximum of 164
mg/l) indicated, for the first time, that this compound is an important phenolic off -flavour marker in cider. Then, volatile phenols concentrations were determined for 47 French commercial ciders and showed mean quantities of 3.2 (4-EC), 0.8 (4-EP), 0.1 (4-EG), 0.2 (4-VP) and 0.3
mg/l (4-VG). The majority of the tested commercial ciders presented low volatile phenol levels.
