Heavy metal （HM） is a major hazard to the soil-plant system. This study investigated the combined effects of cadium （Cd）, zinc （Zn） and lead （Pb） on activities of four enzymes in soil, including calatase, urea...Heavy metal （HM） is a major hazard to the soil-plant system. This study investigated the combined effects of cadium （Cd）, zinc （Zn） and lead （Pb） on activities of four enzymes in soil, including calatase, urease, invertase and alkalin phosphatase. HM content in tops of canola and four enzymes activities in soil were analyzed at two months after the metal additions to the soil. Pb was not significantly inhibitory than the other heavy metals for the four enzyme activities and was shown to have a protective role on calatase activity in the combined presence of Cd, Zn and Pb; whereas Cd significantly inhibited the four enzyme activities, and Zn only inhibited urease and calatase activities. The inhibiting effect of Cd and Zn on urease and calatase activities can be intensified significantly by the additions of Zn and Cd. There was a negative synergistic inhibitory effect of Cd and Zn on the two enzymes in the presence of Cd, Zn and Pb. The urease activity was inhibited more by the HM combinations than by the metals alone and reduced approximately 20%--40% of urease activity. The intertase and alkaline phosphatase activities significantly decreased only with the increase of Cd concentration in the soil. It was shown that urease was much more sensitive to HM than the other enzymes. There was a obvious negative correlation between the ionic impulsion of HM in soil, the ionic impulsion of HM in canola plants tops and urease activity. It is concluded that the soil urease activity may be a sensitive tool for assessing additive toxic combination effect on soil biochemical parameters.展开更多
Canola crop is rich in plant biomass. It is considered a major cash crop in North America and a potential source for biofuel. We evaluated six strains of white rot basidiomycetes under solid state fermentation (SSF) f...Canola crop is rich in plant biomass. It is considered a major cash crop in North America and a potential source for biofuel. We evaluated six strains of white rot basidiomycetes under solid state fermentation (SSF) for their potentials to secrete oxidative and hydrolytic enzymes to biodegrade canola plant biomass (CPB), and release sugars. Fuscoporia gilva and Pleurotus tuberregium produced high amount of laccase (440.86 U/L and 480.63 U/L at day 7), as well as carboxylmethylcellulase (CMCase) (4.78 U/mL at day 21 and 3.13 U/mL at day 14) and xylanase (4.48 U/mL and 7.8 U/mL at day 21), respectively. Bjerkandera adusta showed high amount of MnP (50.4 U/L) and peroxidase (64.5 U/L), relative to the other strains. Loss of organic matter peaked after 21 days of incubation in all the tested strains;however, the best result (34.0%) was shown in P. tuberregium. The highest lignin loss was observed in Coriolopsis caperata strains. Among the sugar polymers, hemicellulose was highly degraded by P. tuberregium and P. pulmonarius (4.1% - 4.6%), while cellulose (3.3% - 4.3%) was mainly degraded by F. gilva and B. adusta. Glucose was the dominant sugar released by all the fungi tested, with the highest concentration of 1.25 mg/mL produced by B. adusta at day 14 of incubation. Results indicate that selected white rot fungi can achieve significant delignification of CPB within 14 days of solid state fermentation. Their importance in low cost pretreatment of lignocellulosic biomass prior to conversion into biofuels and bio-products of economic importance is discussed.展开更多
基金The Provincial Natural Science Foundation of Hebei Province in China
文摘Heavy metal （HM） is a major hazard to the soil-plant system. This study investigated the combined effects of cadium （Cd）, zinc （Zn） and lead （Pb） on activities of four enzymes in soil, including calatase, urease, invertase and alkalin phosphatase. HM content in tops of canola and four enzymes activities in soil were analyzed at two months after the metal additions to the soil. Pb was not significantly inhibitory than the other heavy metals for the four enzyme activities and was shown to have a protective role on calatase activity in the combined presence of Cd, Zn and Pb; whereas Cd significantly inhibited the four enzyme activities, and Zn only inhibited urease and calatase activities. The inhibiting effect of Cd and Zn on urease and calatase activities can be intensified significantly by the additions of Zn and Cd. There was a negative synergistic inhibitory effect of Cd and Zn on the two enzymes in the presence of Cd, Zn and Pb. The urease activity was inhibited more by the HM combinations than by the metals alone and reduced approximately 20%--40% of urease activity. The intertase and alkaline phosphatase activities significantly decreased only with the increase of Cd concentration in the soil. It was shown that urease was much more sensitive to HM than the other enzymes. There was a obvious negative correlation between the ionic impulsion of HM in soil, the ionic impulsion of HM in canola plants tops and urease activity. It is concluded that the soil urease activity may be a sensitive tool for assessing additive toxic combination effect on soil biochemical parameters.
文摘Canola crop is rich in plant biomass. It is considered a major cash crop in North America and a potential source for biofuel. We evaluated six strains of white rot basidiomycetes under solid state fermentation (SSF) for their potentials to secrete oxidative and hydrolytic enzymes to biodegrade canola plant biomass (CPB), and release sugars. Fuscoporia gilva and Pleurotus tuberregium produced high amount of laccase (440.86 U/L and 480.63 U/L at day 7), as well as carboxylmethylcellulase (CMCase) (4.78 U/mL at day 21 and 3.13 U/mL at day 14) and xylanase (4.48 U/mL and 7.8 U/mL at day 21), respectively. Bjerkandera adusta showed high amount of MnP (50.4 U/L) and peroxidase (64.5 U/L), relative to the other strains. Loss of organic matter peaked after 21 days of incubation in all the tested strains;however, the best result (34.0%) was shown in P. tuberregium. The highest lignin loss was observed in Coriolopsis caperata strains. Among the sugar polymers, hemicellulose was highly degraded by P. tuberregium and P. pulmonarius (4.1% - 4.6%), while cellulose (3.3% - 4.3%) was mainly degraded by F. gilva and B. adusta. Glucose was the dominant sugar released by all the fungi tested, with the highest concentration of 1.25 mg/mL produced by B. adusta at day 14 of incubation. Results indicate that selected white rot fungi can achieve significant delignification of CPB within 14 days of solid state fermentation. Their importance in low cost pretreatment of lignocellulosic biomass prior to conversion into biofuels and bio-products of economic importance is discussed.
