Aims: This study compared the antimicrobial activity of Melaleuca alternifolia (tea tree) oil wit... more Aims: This study compared the antimicrobial activity of Melaleuca alternifolia (tea tree) oil with that of some of its components, both individually and in two-component combinations. Methods and Results: Minimum inhibitory concentration and time-kill assays revealed that terpinen-4-ol, the principal active component of tea tree oil, was more active on its own than when present in tea tree oil. Combinations of terpinen-4-ol and either c-terpinene or p-cymene produced similar activities to tea tree oil. Concentration-dependent reductions in terpinen-4-ol activity and solubility also occurred in the presence of c-terpinene. Conclusions: Non-oxygenated terpenes in tea tree oil appear to reduce terpinen-4-ol ef®cacy by lowering its aqueous solubility. Signi®cance and Impact of the Study: These ®ndings explain why tea tree oil can be less active in vitro than terpinen-4-ol alone and further suggest that the presence of a non-aqueous phase in tea tree oil formulations may limit the microbial availability of its active components.
The minimum inhibitory concentrations (MIC) of 60 terpenoids against Pseudomonas aeruginosa, Esch... more The minimum inhibitory concentrations (MIC) of 60 terpenoids against Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus and Candida albicans have been determined. Hierarchical cluster analysis was used to group the compounds into five groups according to their activity patterns against the four micro-organisms. K-Means cluster analysis was then used to confirm these groupings and to show the differences in the activity
Methods for the measurement of the minimum inhibitory concentration (MIC) of antibacterial agents... more Methods for the measurement of the minimum inhibitory concentration (MIC) of antibacterial agents have been developed for water-soluble substances and require adaptation for use with water-insoluble essential oils. This paper reports a standardized agar dilution MIC method, using 0.5% v/v Tween 20 as a dispersant, which provides a reliable and reproducible technique. The method was tested using two Melaleuca alternifolia
An efficient conversion of glucose and xylose is a requisite for a profitable process of bioethan... more An efficient conversion of glucose and xylose is a requisite for a profitable process of bioethanol production from lignocellulose. Considering the approaches available for this conversion, co-culture is a simple process, employing two different organisms for the fermentation of the two sugars. An innovative fermentation scheme was designed, co-culturing immobilized Zymomonas mobilis and free cells of Pichia stipitis in a
Methods for the measurement of the minimum inhibitory concentration (MIC) of antibacterial agents... more Methods for the measurement of the minimum inhibitory concentration (MIC) of antibacterial agents have been developed for water-soluble substances and require adaptation for use with water-insoluble essential oils. This paper reports a standardized agar dilution MIC method, using 0.5% v/v Tween 20 as a dispersant, which provides a reliable and reproducible technique. The method was tested using two Melaleuca alternifolia
Essential oils, extracted from species of the genus Zieria using cold methanol extraction, were u... more Essential oils, extracted from species of the genus Zieria using cold methanol extraction, were used to divide the Zieria species into eight groups based on the chemical compositions of their oils using hierarchical cluster analysis. The major components of most Zieria oils were oxygenated terpenes or other related compounds including car-3-en-2-one, chrysanthenone, eucarvone, methyl eugenol, elemicin and safrole. In several
Free-solution capillary electrophoresis (CE), or capillary zone electrophoresis, with direct UV d... more Free-solution capillary electrophoresis (CE), or capillary zone electrophoresis, with direct UV detection was used for the first time for the determination of mono- and disaccharides, sugar alcohols, and ethanol in fermentation broths. Sample preparation proved to be minimal: no derivatization or specific sample purification was needed. The CE conditions can be adapted to the type of fermentation by simply altering the background electrolyte (BGE). KOH (130 mM) or NaOH (130 mM) as the BGE led to the fastest analysis time when monitoring simple fermentations. A mixture of 65 mM NaOH and 65 mM LiOH led to a 19% improvement in resolution for a complex mixture of carbohydrates. Quantification of a simple carbohydrate fermentation by CE showed values in close agreement with that of high-performance anion exchange chromatography and high-performance liquid chromatography (HPLC) on a cation exchange resin. For complex fermentations, quantification of carbohydrates by HPLC and CE led to similar results, whereas CE requires an injection volume of only 10-20 nL. Analysis of an ethanol fermentation of hydrolyzed plant fiber demonstrated the robustness of the separation and detection of carbohydrates, as well as ethanol. Ethanol determination is achieved by coupling the CE method to pressure mobilization, using the same instrument and the same sample.
A total of 27 methanol extracts obtained from different plant parts of 10 species of rain forest ... more A total of 27 methanol extracts obtained from different plant parts of 10 species of rain forest trees belonging to four genera of the Flacourtiaceae and originating from Australia were investigated. In vitro cytotoxicity was measured by an ATP Lite-M assay method against the mouse P388 lymphocytic leukemia cell line. The total antioxidant activity has been assessed based on scavenging activity of stable ABTS free radicals. The minimum inhibition concentration (MIC) was determined by the dilution method performed in 96 well plates against four different microbes. The leaf extract of Casearia sp. (RB 3051), mature stem extract of Casearia grayi and stem extract of Scolopia braunii were found to have most antioxidant activity (IC50 = 2.9 microg/ml), cytotoxic activity (LC50 = 0.89 microg/ml) and antimicrobial activity against all four different microbes, respectively. The results obtained suggested that among the four genera studied Casearia is the most promising in respect of finding significant antioxidant, cytotoxic and also antimicrobial activity.
Research into the mode of action of the essential oil of Melaleuca alternifolia (Tea tree oil) is... more Research into the mode of action of the essential oil of Melaleuca alternifolia (Tea tree oil) is briefly reviewed. Its mode of action is interpreted in terms of the membrane-toxicity of its monoterpenoid components and different approaches for determining cell membrane damage are discussed.
A hot water extract of the Australian native sarsaparilla Smilax glyciphylla Sm. (Smilaceae) inhi... more A hot water extract of the Australian native sarsaparilla Smilax glyciphylla Sm. (Smilaceae) inhibited peroxidation of phosphatidylcholine liposomes initiated by Fe 2+ /ascorbate (IC 50 , 10 g/mL) and AAPH (IC 50 , 33 g/mL) in vitro. It also inhibited deoxyribose degradation and quenched chemically generated superoxide anion (IC 50 , 50 g/mL). Reactivity towards ABTS (2,2 -azinobis(3-ethylbenzothiazoline 6sulphonate) radical cation was equivalent to 48.4 mM TROLOX, the water soluble ␣-tocopherol analogue. Smilax glyciphylla is a rich source of the dihydrochalcone glycyphyllin. Given the reported level of activity it is unlikely that glycyphyllin would provide direct antioxidant protection in tissues affected by oxidative stress. However, consuming Smilax glyciphylla as a tea may be sufficient to reduce oxidative damage in the gastrointestinal tract. It is also possible that glycyphyllin is metabolised and adsorbed as phloretin, a compound with known anticancer properties. These findings indicate that further studies of the chemopreventative properties of Smilax glyciphylla is warranted.
The known antimicrobially active oxygenated terpenes, carvone, terpinen-4-ol, α-terpineol, carveo... more The known antimicrobially active oxygenated terpenes, carvone, terpinen-4-ol, α-terpineol, carveol and myrtenol were found to cause significant K+ leakage from E. coli cells. In contrast, the relatively inactive oxygenated terpenes, 1,8-cineole and p-menth-6-ene-2,8-diol, did not cause significant K+ leakage. Slight structural differences between active terpenes were found to affect the rate of K+ leakage from E. coli cells. The membrane
Four pairs of oxygenated terpenes, with closely related chemical structures but considerably diff... more Four pairs of oxygenated terpenes, with closely related chemical structures but considerably different minimum inhibitory concentration values (1) against P. aeruginosa or E. coli, showed differences in rate of cells killed over 2 h. Addition of polymyxin B nonapeptide (PMBN) as an outer membrane permeabilising agent was found to significantly increase the initial rates and overall numbers of cells killed
Cytotoxicity of Australian tea tree oil (oil of Melaleuca al#ernifoliu) and its major oxygenated ... more Cytotoxicity of Australian tea tree oil (oil of Melaleuca al#ernifoliu) and its major oxygenated monoterpenes: terpinen-4-01, 1,8-cineole and a-terpineol were investigated using the MTS [(3-(4,5-dimethylthiazol-2-yl)-5-(3-carbo~metho~phenyl)-2-(4-sulfophenyl)-2H-tetrazolium)] assay at two exposure times: 4 and 24 h on five different human cell lines. These cell lines included: Hep G2, a heptaocellular carcinomic human cell line; HeLa, an epithelioid carcinomic cell line; MOLT-4, a human lymphoblastic leukaemic T-cell line; K-562, a human chronic myelogenous leukaemia cell line; and CTVR-1, an early B-cell line from the bone marrow cells of a patient with acute myeloid leukaemia. The overall rating for cytotoxicity of tea tree oil and its components was a-terpineobtea tree oil>terpinen-4-ol>l,8-cineole and with comparison with the controls used mercuric chloride>tea tree oibaspirin. Antimicrobial activity (MICs) displayed a similar pattern where a-terpineobterpinen-4-obtea tree oil>l,8-cineole. The IC,, (a concentration that causes a reduction by half of the activity of mitochondria1 dehydrogenase) value of tea tree oil ranged from 0.02 g/L for the Hep G2 cell line to 2.8 g/L for the HeLa cell line.
The minimum inhibitory concentrations (MIC) of 60 terpenoids against Pseudomonas aeruginosa, Esch... more The minimum inhibitory concentrations (MIC) of 60 terpenoids against Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus and Candida albicans have been determined. Hierarchical cluster analysis was used to group the compounds into five groups according to their activity patterns against the four micro-organisms. K-Means cluster analysis was then used to confirm these groupings and to show the differences in the activity
An efficient conversion of glucose and xylose is a requisite for a profitable process of bioethan... more An efficient conversion of glucose and xylose is a requisite for a profitable process of bioethanol production from lignocellulose. Considering the approaches available for this conversion, co-culture is a simple process, employing two different organisms for the fermentation of the two sugars. An innovative fermentation scheme was designed, co-culturing immobilized Zymomonas mobilis and free cells of Pichia stipitis in a modified fermentor for the glucose and xylose fermentation, respectively. A sugar mixture of 30g/l glucose and 20g/l of xylose was completely converted to ethanol within 19h. This gave a volumetric ethanol productivity of 1.277g/l/h and an ethanol yield of 0.49–0.50g/g, which is more than 96% of the theoretical value. Extension of this fermentation scheme to sugarcane bagasse hydrolysate resulted in a complete sugar utilisation within 26h; ethanol production peaked at 40h with a yield of 0.49g/g. These values are comparable to the best results reported. Cell interaction was observed between Z. mobilis and P. stipitis. Viable cells of Z. mobilis inhibited the cell activity of P. stipitis and the xylose fermentation. Z. mobilis showed evidence of utilising a source other than glucose for growth when co-cultured with P. stipitis.
Brazilian Archives of Biology and Technology, 2010
The present study describes the chemical composition and antimicrobial activity of essential oils... more The present study describes the chemical composition and antimicrobial activity of essential oils obtained by hydrodistillation from the leaves of Pimenta pseudocaryophyllus (1.0% w/w) and Tynanthus micranthus (1.1% w/w). GC and GC/MS analysis demonstrated that ...
International Biodeterioration & Biodegradation, 2015
Olive mill wastewater (OMWW) is the toxic, malodorous, recalcitrant waste from the three-phase de... more Olive mill wastewater (OMWW) is the toxic, malodorous, recalcitrant waste from the three-phase decanter system used in the processing of olives for oil. The waste has a high organic load, and is high in polyphenols which largely account for its phytotoxicity, preventing its use in irrigation or its discharge into waterways. A white-rot basidiomycete, previously found to reduce phenols and phytotoxicity of OMWW, produced substantial laccase activity during cultivation. Putatively identified as Cerrena consors, laccase production was maximal during idiophase. Copper (0.75 mM) increased laccase activity by more than 500% and addition of spent OMWW-based culture fluid to the medium was also inductive. The laccase isoform pattern changed depending on whether fresh or aged OMWW was used as the growth medium. Moreover, OMWW was found to be a source of natural laccase mediators which appear to have increased the effectiveness of phenol removal from the wastewater. Laccases can degrade and detoxify many organic pollutants, but their use is hindered by the inability to produce them cheaply. This work also suggests that OMWW may be a useful substrate for the production of laccases from white-rot fungi that are capable of utilising toxic wastes such as OMWW containing polyphenols.
World Journal of Microbiology and Biotechnology, 2010
Olive mill wastewater (OMWW) is a significant pollutant and its phytotoxicity is attributed mostl... more Olive mill wastewater (OMWW) is a significant pollutant and its phytotoxicity is attributed mostly to the phenols present. 220 fungi were screened for their ability to produce detoxifying enzymes and/or grow in OMWW. Four isolates, species of Cerrena, Byssochlamys, Lasiodiplodia and Bionectria were selected and compared against Phanerochaete chrysosporium for their ability to bioremediate OMWW in the presence of a competing indigenous microflora. For the first time we report that a Cerrena sp. achieved a 75% reduction of phenolics in OMWW and that, unusually, the reduction occurred within 2 h of the addition to the OMWW.
Aims: This study compared the antimicrobial activity of Melaleuca alternifolia (tea tree) oil wit... more Aims: This study compared the antimicrobial activity of Melaleuca alternifolia (tea tree) oil with that of some of its components, both individually and in two-component combinations. Methods and Results: Minimum inhibitory concentration and time-kill assays revealed that terpinen-4-ol, the principal active component of tea tree oil, was more active on its own than when present in tea tree oil. Combinations of terpinen-4-ol and either c-terpinene or p-cymene produced similar activities to tea tree oil. Concentration-dependent reductions in terpinen-4-ol activity and solubility also occurred in the presence of c-terpinene. Conclusions: Non-oxygenated terpenes in tea tree oil appear to reduce terpinen-4-ol ef®cacy by lowering its aqueous solubility. Signi®cance and Impact of the Study: These ®ndings explain why tea tree oil can be less active in vitro than terpinen-4-ol alone and further suggest that the presence of a non-aqueous phase in tea tree oil formulations may limit the microbial availability of its active components.
The minimum inhibitory concentrations (MIC) of 60 terpenoids against Pseudomonas aeruginosa, Esch... more The minimum inhibitory concentrations (MIC) of 60 terpenoids against Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus and Candida albicans have been determined. Hierarchical cluster analysis was used to group the compounds into five groups according to their activity patterns against the four micro-organisms. K-Means cluster analysis was then used to confirm these groupings and to show the differences in the activity
Methods for the measurement of the minimum inhibitory concentration (MIC) of antibacterial agents... more Methods for the measurement of the minimum inhibitory concentration (MIC) of antibacterial agents have been developed for water-soluble substances and require adaptation for use with water-insoluble essential oils. This paper reports a standardized agar dilution MIC method, using 0.5% v/v Tween 20 as a dispersant, which provides a reliable and reproducible technique. The method was tested using two Melaleuca alternifolia
An efficient conversion of glucose and xylose is a requisite for a profitable process of bioethan... more An efficient conversion of glucose and xylose is a requisite for a profitable process of bioethanol production from lignocellulose. Considering the approaches available for this conversion, co-culture is a simple process, employing two different organisms for the fermentation of the two sugars. An innovative fermentation scheme was designed, co-culturing immobilized Zymomonas mobilis and free cells of Pichia stipitis in a
Methods for the measurement of the minimum inhibitory concentration (MIC) of antibacterial agents... more Methods for the measurement of the minimum inhibitory concentration (MIC) of antibacterial agents have been developed for water-soluble substances and require adaptation for use with water-insoluble essential oils. This paper reports a standardized agar dilution MIC method, using 0.5% v/v Tween 20 as a dispersant, which provides a reliable and reproducible technique. The method was tested using two Melaleuca alternifolia
Essential oils, extracted from species of the genus Zieria using cold methanol extraction, were u... more Essential oils, extracted from species of the genus Zieria using cold methanol extraction, were used to divide the Zieria species into eight groups based on the chemical compositions of their oils using hierarchical cluster analysis. The major components of most Zieria oils were oxygenated terpenes or other related compounds including car-3-en-2-one, chrysanthenone, eucarvone, methyl eugenol, elemicin and safrole. In several
Free-solution capillary electrophoresis (CE), or capillary zone electrophoresis, with direct UV d... more Free-solution capillary electrophoresis (CE), or capillary zone electrophoresis, with direct UV detection was used for the first time for the determination of mono- and disaccharides, sugar alcohols, and ethanol in fermentation broths. Sample preparation proved to be minimal: no derivatization or specific sample purification was needed. The CE conditions can be adapted to the type of fermentation by simply altering the background electrolyte (BGE). KOH (130 mM) or NaOH (130 mM) as the BGE led to the fastest analysis time when monitoring simple fermentations. A mixture of 65 mM NaOH and 65 mM LiOH led to a 19% improvement in resolution for a complex mixture of carbohydrates. Quantification of a simple carbohydrate fermentation by CE showed values in close agreement with that of high-performance anion exchange chromatography and high-performance liquid chromatography (HPLC) on a cation exchange resin. For complex fermentations, quantification of carbohydrates by HPLC and CE led to similar results, whereas CE requires an injection volume of only 10-20 nL. Analysis of an ethanol fermentation of hydrolyzed plant fiber demonstrated the robustness of the separation and detection of carbohydrates, as well as ethanol. Ethanol determination is achieved by coupling the CE method to pressure mobilization, using the same instrument and the same sample.
A total of 27 methanol extracts obtained from different plant parts of 10 species of rain forest ... more A total of 27 methanol extracts obtained from different plant parts of 10 species of rain forest trees belonging to four genera of the Flacourtiaceae and originating from Australia were investigated. In vitro cytotoxicity was measured by an ATP Lite-M assay method against the mouse P388 lymphocytic leukemia cell line. The total antioxidant activity has been assessed based on scavenging activity of stable ABTS free radicals. The minimum inhibition concentration (MIC) was determined by the dilution method performed in 96 well plates against four different microbes. The leaf extract of Casearia sp. (RB 3051), mature stem extract of Casearia grayi and stem extract of Scolopia braunii were found to have most antioxidant activity (IC50 = 2.9 microg/ml), cytotoxic activity (LC50 = 0.89 microg/ml) and antimicrobial activity against all four different microbes, respectively. The results obtained suggested that among the four genera studied Casearia is the most promising in respect of finding significant antioxidant, cytotoxic and also antimicrobial activity.
Research into the mode of action of the essential oil of Melaleuca alternifolia (Tea tree oil) is... more Research into the mode of action of the essential oil of Melaleuca alternifolia (Tea tree oil) is briefly reviewed. Its mode of action is interpreted in terms of the membrane-toxicity of its monoterpenoid components and different approaches for determining cell membrane damage are discussed.
A hot water extract of the Australian native sarsaparilla Smilax glyciphylla Sm. (Smilaceae) inhi... more A hot water extract of the Australian native sarsaparilla Smilax glyciphylla Sm. (Smilaceae) inhibited peroxidation of phosphatidylcholine liposomes initiated by Fe 2+ /ascorbate (IC 50 , 10 g/mL) and AAPH (IC 50 , 33 g/mL) in vitro. It also inhibited deoxyribose degradation and quenched chemically generated superoxide anion (IC 50 , 50 g/mL). Reactivity towards ABTS (2,2 -azinobis(3-ethylbenzothiazoline 6sulphonate) radical cation was equivalent to 48.4 mM TROLOX, the water soluble ␣-tocopherol analogue. Smilax glyciphylla is a rich source of the dihydrochalcone glycyphyllin. Given the reported level of activity it is unlikely that glycyphyllin would provide direct antioxidant protection in tissues affected by oxidative stress. However, consuming Smilax glyciphylla as a tea may be sufficient to reduce oxidative damage in the gastrointestinal tract. It is also possible that glycyphyllin is metabolised and adsorbed as phloretin, a compound with known anticancer properties. These findings indicate that further studies of the chemopreventative properties of Smilax glyciphylla is warranted.
The known antimicrobially active oxygenated terpenes, carvone, terpinen-4-ol, α-terpineol, carveo... more The known antimicrobially active oxygenated terpenes, carvone, terpinen-4-ol, α-terpineol, carveol and myrtenol were found to cause significant K+ leakage from E. coli cells. In contrast, the relatively inactive oxygenated terpenes, 1,8-cineole and p-menth-6-ene-2,8-diol, did not cause significant K+ leakage. Slight structural differences between active terpenes were found to affect the rate of K+ leakage from E. coli cells. The membrane
Four pairs of oxygenated terpenes, with closely related chemical structures but considerably diff... more Four pairs of oxygenated terpenes, with closely related chemical structures but considerably different minimum inhibitory concentration values (1) against P. aeruginosa or E. coli, showed differences in rate of cells killed over 2 h. Addition of polymyxin B nonapeptide (PMBN) as an outer membrane permeabilising agent was found to significantly increase the initial rates and overall numbers of cells killed
Cytotoxicity of Australian tea tree oil (oil of Melaleuca al#ernifoliu) and its major oxygenated ... more Cytotoxicity of Australian tea tree oil (oil of Melaleuca al#ernifoliu) and its major oxygenated monoterpenes: terpinen-4-01, 1,8-cineole and a-terpineol were investigated using the MTS [(3-(4,5-dimethylthiazol-2-yl)-5-(3-carbo~metho~phenyl)-2-(4-sulfophenyl)-2H-tetrazolium)] assay at two exposure times: 4 and 24 h on five different human cell lines. These cell lines included: Hep G2, a heptaocellular carcinomic human cell line; HeLa, an epithelioid carcinomic cell line; MOLT-4, a human lymphoblastic leukaemic T-cell line; K-562, a human chronic myelogenous leukaemia cell line; and CTVR-1, an early B-cell line from the bone marrow cells of a patient with acute myeloid leukaemia. The overall rating for cytotoxicity of tea tree oil and its components was a-terpineobtea tree oil>terpinen-4-ol>l,8-cineole and with comparison with the controls used mercuric chloride>tea tree oibaspirin. Antimicrobial activity (MICs) displayed a similar pattern where a-terpineobterpinen-4-obtea tree oil>l,8-cineole. The IC,, (a concentration that causes a reduction by half of the activity of mitochondria1 dehydrogenase) value of tea tree oil ranged from 0.02 g/L for the Hep G2 cell line to 2.8 g/L for the HeLa cell line.
The minimum inhibitory concentrations (MIC) of 60 terpenoids against Pseudomonas aeruginosa, Esch... more The minimum inhibitory concentrations (MIC) of 60 terpenoids against Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus and Candida albicans have been determined. Hierarchical cluster analysis was used to group the compounds into five groups according to their activity patterns against the four micro-organisms. K-Means cluster analysis was then used to confirm these groupings and to show the differences in the activity
An efficient conversion of glucose and xylose is a requisite for a profitable process of bioethan... more An efficient conversion of glucose and xylose is a requisite for a profitable process of bioethanol production from lignocellulose. Considering the approaches available for this conversion, co-culture is a simple process, employing two different organisms for the fermentation of the two sugars. An innovative fermentation scheme was designed, co-culturing immobilized Zymomonas mobilis and free cells of Pichia stipitis in a modified fermentor for the glucose and xylose fermentation, respectively. A sugar mixture of 30g/l glucose and 20g/l of xylose was completely converted to ethanol within 19h. This gave a volumetric ethanol productivity of 1.277g/l/h and an ethanol yield of 0.49–0.50g/g, which is more than 96% of the theoretical value. Extension of this fermentation scheme to sugarcane bagasse hydrolysate resulted in a complete sugar utilisation within 26h; ethanol production peaked at 40h with a yield of 0.49g/g. These values are comparable to the best results reported. Cell interaction was observed between Z. mobilis and P. stipitis. Viable cells of Z. mobilis inhibited the cell activity of P. stipitis and the xylose fermentation. Z. mobilis showed evidence of utilising a source other than glucose for growth when co-cultured with P. stipitis.
Brazilian Archives of Biology and Technology, 2010
The present study describes the chemical composition and antimicrobial activity of essential oils... more The present study describes the chemical composition and antimicrobial activity of essential oils obtained by hydrodistillation from the leaves of Pimenta pseudocaryophyllus (1.0% w/w) and Tynanthus micranthus (1.1% w/w). GC and GC/MS analysis demonstrated that ...
International Biodeterioration & Biodegradation, 2015
Olive mill wastewater (OMWW) is the toxic, malodorous, recalcitrant waste from the three-phase de... more Olive mill wastewater (OMWW) is the toxic, malodorous, recalcitrant waste from the three-phase decanter system used in the processing of olives for oil. The waste has a high organic load, and is high in polyphenols which largely account for its phytotoxicity, preventing its use in irrigation or its discharge into waterways. A white-rot basidiomycete, previously found to reduce phenols and phytotoxicity of OMWW, produced substantial laccase activity during cultivation. Putatively identified as Cerrena consors, laccase production was maximal during idiophase. Copper (0.75 mM) increased laccase activity by more than 500% and addition of spent OMWW-based culture fluid to the medium was also inductive. The laccase isoform pattern changed depending on whether fresh or aged OMWW was used as the growth medium. Moreover, OMWW was found to be a source of natural laccase mediators which appear to have increased the effectiveness of phenol removal from the wastewater. Laccases can degrade and detoxify many organic pollutants, but their use is hindered by the inability to produce them cheaply. This work also suggests that OMWW may be a useful substrate for the production of laccases from white-rot fungi that are capable of utilising toxic wastes such as OMWW containing polyphenols.
World Journal of Microbiology and Biotechnology, 2010
Olive mill wastewater (OMWW) is a significant pollutant and its phytotoxicity is attributed mostl... more Olive mill wastewater (OMWW) is a significant pollutant and its phytotoxicity is attributed mostly to the phenols present. 220 fungi were screened for their ability to produce detoxifying enzymes and/or grow in OMWW. Four isolates, species of Cerrena, Byssochlamys, Lasiodiplodia and Bionectria were selected and compared against Phanerochaete chrysosporium for their ability to bioremediate OMWW in the presence of a competing indigenous microflora. For the first time we report that a Cerrena sp. achieved a 75% reduction of phenolics in OMWW and that, unusually, the reduction occurred within 2 h of the addition to the OMWW.
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Papers by Julie Markham