The addition of municipal solid wastes （MSW） is considered as a possible strategy for soil rehabilitation in southeast Spain. The objective of this study was to evaluate the long-term （17 years） effect of five dos...The addition of municipal solid wastes （MSW） is considered as a possible strategy for soil rehabilitation in southeast Spain. The objective of this study was to evaluate the long-term （17 years） effect of five doses of MSW addition on the microbiological, biochemical, and physical properties of semiarid soil. Increased values of several parameters that serve as indicators of general microbiological activity, such as, basal respiration, adenosine triphosphate （ATP） or dehydrogenase activity; microbial population size （microbial biomass C）, and extracellular hydrolase activity related to macronutrient cycles, such as, urease, 3-glucosidase, and N-a-benzoyl-L-argininamide protease, were observed in the amended soils. The highest MSW doses showed the highest values in these hydrolase activities. The incorporation of municipal waste resulted in a more dense development of the plant cover, 50% greater in higher doses than in the control treatment, which generated a substantial increase in several C fractions. Total organic carbon reached 12 g kg^-1 soil with the highest MSW doses, compared to 4.30 g kg^-1 soil in the control treatment. The physical properties of the soil were also improved, showing greater percentage of stable aggregates and water holding capacity. Positive correlation coefficients between C fractions and parameters related to microbial activity and aggregate stability were observed. Although these improvements were greater in the soils receiving the highest doses of organic amendment, the increases were not proportional to the amount added, demonstrating the existence of a threshold, above which an increase in the amount of organic matter added is not reflected in an increase in the soil＇s physical, biochemical, and microbiological properties. However, the addition of municipal solid wastes proved its suitability for improving soil quality, thereby indicating the potential of such an amendment, to prevent desertification in Mediterranean areas such as those studied.展开更多
Hydrocarbon contamination may affect the soil microbial community, in terms of both diversity and function. A laboratory experiment was set-up, with a semi-arid control soil and the same soil but artificially contamin...Hydrocarbon contamination may affect the soil microbial community, in terms of both diversity and function. A laboratory experiment was set-up, with a semi-arid control soil and the same soil but artificially contaminated with diesel oil, to follow changes in the dominant species of the microbial community in the hydrocarbon-polluted soil via proteomics. Analysis of the proteins extracted from enriched cultures growing in Luria-Bertani （LB） media showed a change in the microbial community. The majority of the proteins were related to gIycolysis pathways, structural or protein synthesis. The results showed a relative increase in the complexity of the soil microbial community with hydrocarbon contamination, especially after 15 days of incubation. Species such as Ralstonia solanacearum, Synechococcus elongatus and different Clostridium sp. were adapted to contamination, not appearing in the control soil, although Bacillus sp. dominated the growing in LB in any of the treatments. We conclude that the identification of microbial species in soil extracts by culture-dependent proteomics is able to partially explain the changes in the diversity of the soil microbial community in hydrocarbon polluted semi-arid soils, but this information is much more limited than that provided by molecular methods.展开更多
An incubation experiment was designed in order to determine the further microbiological response to an addition （500 m3 ha-1） of fresh olive mill wastewater （FOMWW） in a soil that has been frequently amended with ...An incubation experiment was designed in order to determine the further microbiological response to an addition （500 m3 ha-1） of fresh olive mill wastewater （FOMWW） in a soil that has been frequently amended with uncontrolled doses of OMWW since the 1990s in an active disposal site （ADS soil）. To achieve this aim, the phospholipid fatty acid （PLFA） profiles, microbial biomass C （Cmic）, and dehydrogenase （DHA） and urease activities （URA） were monitored at the beginning （To）, 3 h （T1） and 97 d （Tf, i.e., the end） of incubation after FOMWW addition. After the FOMWW addition, an increase in the ratio of fungal to bacterial PLFAs was observed in ADS soil. Moreover, a relative increase of monounsaturated fatty acids （MUFAs） with respect to saturated fatty acids （SATFA） was found in the ADS soil. An increase of the Gram-positive to Gram-negative ratio was observed in this soil at the end of the incubation. While DHA and Cmic increased in the ADS soil after FOMWW addition, URA showed a decrease. Fungi and Gram-positive bacterial biomass experienced an increase after addition of a high dose of FOMWW in laboratory conditions.展开更多
基金Project supported by the EU and the Spanish Ministry of Science and Technology.
文摘The addition of municipal solid wastes （MSW） is considered as a possible strategy for soil rehabilitation in southeast Spain. The objective of this study was to evaluate the long-term （17 years） effect of five doses of MSW addition on the microbiological, biochemical, and physical properties of semiarid soil. Increased values of several parameters that serve as indicators of general microbiological activity, such as, basal respiration, adenosine triphosphate （ATP） or dehydrogenase activity; microbial population size （microbial biomass C）, and extracellular hydrolase activity related to macronutrient cycles, such as, urease, 3-glucosidase, and N-a-benzoyl-L-argininamide protease, were observed in the amended soils. The highest MSW doses showed the highest values in these hydrolase activities. The incorporation of municipal waste resulted in a more dense development of the plant cover, 50% greater in higher doses than in the control treatment, which generated a substantial increase in several C fractions. Total organic carbon reached 12 g kg^-1 soil with the highest MSW doses, compared to 4.30 g kg^-1 soil in the control treatment. The physical properties of the soil were also improved, showing greater percentage of stable aggregates and water holding capacity. Positive correlation coefficients between C fractions and parameters related to microbial activity and aggregate stability were observed. Although these improvements were greater in the soils receiving the highest doses of organic amendment, the increases were not proportional to the amount added, demonstrating the existence of a threshold, above which an increase in the amount of organic matter added is not reflected in an increase in the soil＇s physical, biochemical, and microbiological properties. However, the addition of municipal solid wastes proved its suitability for improving soil quality, thereby indicating the potential of such an amendment, to prevent desertification in Mediterranean areas such as those studied.
基金Supported by the JAE-Program for Ph.D. Students of Spanish Research Council
文摘Hydrocarbon contamination may affect the soil microbial community, in terms of both diversity and function. A laboratory experiment was set-up, with a semi-arid control soil and the same soil but artificially contaminated with diesel oil, to follow changes in the dominant species of the microbial community in the hydrocarbon-polluted soil via proteomics. Analysis of the proteins extracted from enriched cultures growing in Luria-Bertani （LB） media showed a change in the microbial community. The majority of the proteins were related to gIycolysis pathways, structural or protein synthesis. The results showed a relative increase in the complexity of the soil microbial community with hydrocarbon contamination, especially after 15 days of incubation. Species such as Ralstonia solanacearum, Synechococcus elongatus and different Clostridium sp. were adapted to contamination, not appearing in the control soil, although Bacillus sp. dominated the growing in LB in any of the treatments. We conclude that the identification of microbial species in soil extracts by culture-dependent proteomics is able to partially explain the changes in the diversity of the soil microbial community in hydrocarbon polluted semi-arid soils, but this information is much more limited than that provided by molecular methods.
基金Supported by the European Union's LIFE Programme PROSODOL (No. LIFE07 ENV/GR/000280)
文摘An incubation experiment was designed in order to determine the further microbiological response to an addition （500 m3 ha-1） of fresh olive mill wastewater （FOMWW） in a soil that has been frequently amended with uncontrolled doses of OMWW since the 1990s in an active disposal site （ADS soil）. To achieve this aim, the phospholipid fatty acid （PLFA） profiles, microbial biomass C （Cmic）, and dehydrogenase （DHA） and urease activities （URA） were monitored at the beginning （To）, 3 h （T1） and 97 d （Tf, i.e., the end） of incubation after FOMWW addition. After the FOMWW addition, an increase in the ratio of fungal to bacterial PLFAs was observed in ADS soil. Moreover, a relative increase of monounsaturated fatty acids （MUFAs） with respect to saturated fatty acids （SATFA） was found in the ADS soil. An increase of the Gram-positive to Gram-negative ratio was observed in this soil at the end of the incubation. While DHA and Cmic increased in the ADS soil after FOMWW addition, URA showed a decrease. Fungi and Gram-positive bacterial biomass experienced an increase after addition of a high dose of FOMWW in laboratory conditions.
