Current Issue : January - March Volume : 2012 Issue Number : 1 Articles : 6 Articles
Biosurfactant production was screened in four lactobacilli strains. The highest biosurfactant production (excreted and cell-bound biosurfactants) was achieved with Lactobacillus paracasei ssp. paracasei A20, a strain isolated from a Portuguese dairy plant, with a decrease in the surface tension of 6.4?mN?m-1 and 22.0?mN?m-1, respectively. Biosurfactant production by this strain was evaluated under different culture broth compositions. The use of different nitrogen sources revealed that yeast extract is essential for bacterial growth, while peptone is crucial for biosurfactant synthesis. For biosurfactant production, the use of peptone and meat extract yielded a higher production when compared to the standard medium, with a surface tension reduction of 24.5?mN?m-1. Furthermore, experiments were also conducted in a reactor with pH and temperature control. Biomass and biosurfactant production in bioreactor was higher comparing with the experiments conducted in shake flaks. The optimization procedure adopted in the current work was found to improve the biosurfactant production and opened new perspectives for the use of L. paracasei ssp. paracasei A20 as a promising biosurfactant-producer....
Discriminant analysis classification (DAC) and decision tree classifiers (DTC) were used for digital mapping of soil drainage in the\r\nBras-d�Henri watershed (QC, Canada) using earth observation data (RADARSAT-1 and ASTER) and soil survey dataset. Firstly,\r\na forward stepwise selection was applied to each land use type identified by ASTER image in order to derive an optimal subset of\r\nsoil drainage class predictors. The classification models were then applied to these subsets for each land use and merged to obtain\r\na digital soil drainage map for the whole watershed. The DTC method provided better classification accuracies (29 to 92%) than\r\nthe DAC method (33 to 79%) according to the land use type. A similarity measure (S) was used to compare the best digital soil\r\ndrainage map (DTC) to the conventional soil drainage map. Medium to high similarities (0.6 = S < 0.9) were observed for 83%\r\n(187 km2) of the study area while 3% of the study area showed very good agreement (S = 0.9). Few soil polygons showed very\r\nweak similarities (S < 0.3). This study demonstrates the efficiency of combining radar and optical remote sensing data with a\r\nrepresentative soil dataset for producing digital maps of soil drainage....
There is a critical need to investigate how land application of dedicated biofuel oilseed meals affects soil ecosystems. In this study, mustard (Brassica juncea) and flax (Linum usitatissimum) seed meals and sorghum-sudangrass (Sorghum bicolor) were added to soil at levels of 0, 1, 2.5, and 5% (w/w). Both the type of amendment and application rate affected soil organic C, total C & N, and C & N mineralization. Mustard meal amendment initially inhibited C mineralization as compared to flax, but >50% of mustard and flax organic C was mineralized within 51?d. Nitrogen mineralization was similar for flax and mustard, except for the 2.5% rate for which a lower proportion of mustard N was converted to nitrate. The mustard meal greatly impacted microbial community composition, appearing to select for specific fungal populations. The potential varying impacts of different oilseed meals on soil ecosystems should be considered when developing recommendations for land application....
A model was established to simulate an ecosystem service of avoiding reservoir sedimentation and its economic value based on the process of sediment delivery in a watershed. The model included fabricating the watershed of the study reservoir. The sediment retention coefficient of different land cover types were used to simulate the spatial patterns of the annual quantity of the sediment that were prevented from entering the reservoir by the vegetation in each cell followed the flow path in watershed. The economic value of the ecosystem service in this model was determined by the marginal cost of reservoir desilting. This study took the Ertan reservoir as an example. The results showed that most eroded soil was intercepted by different types of ecosystems in the process of sediment delivery in a watershed. The region with a higher quantity of sediment retention was around the reservoir. The absolute quantity of average sediment retention in forestland was lower, so the sediment retention ability of forestland failed to be brought into fullest play in watershed....
The study evaluated the efficacy of organic- and hard-rock mine waste type materials on aided phytostabilization of Cu mine tailings under semiarid Mediterranean conditions in order to promote integrated waste management practices at local levels and to rehabilitate large-scale (from 300 to 3,000?ha) postoperative tailings storage facilities (TSFs). A field trial with 13 treatments was established on a TSF to test the efficacy of six waste-type locally available amendments (grape and olive residues, biosolids, goat manure, sediments from irrigation canals, and rubble from Cu-oxide lixiviation piles) during early phases of site rehabilitation. Results showed that, even though an interesting range of waste-type materials were tested, biosolids (100?t?ha-1 dry weight, d.w.) and grape residues (200?t?ha-1 d.w.), either alone or mixed, were the most suitable organic amendments when incorporated into tailings to a depth of 20?cm. Incorporation of both rubble from Cu-oxide lixiviation piles and goat manure into upper tailings also had effective results. All these treatments improved chemical and microbiological properties of tailings and lead to a significant increase in plant yield after three years from trial establishment. Longer-term evaluations are, however required to evaluate self sustainability of created systems without further incorporation of amendments....
Physico-chemical studies were conducted in river Cauvery situated in Kumbakonam, Tamil Nadu, India. The study was conducted from January 2010 to January 2011. The present paper deals with nutrient status in Cauvery river, for this three stations were selected for the sampling methods i.e., S1, S2 and S3 the main aim of the study was to determine the nutrient status of Cauvery River and the suitability of the water for domestic and other purposes, in the light of water quality criteria prescribed by WHO standards. The parameters analyzed were water Temperature, pH, dissolved oxygen, Free CO2, Calcium, Magnesium Sodium, potassium, Ammonia, Nitrate, Nitrite, Phosphate, Sulphate and Silicate. The results indicated that most of the physico-chemical quality parameters of River Cauvery were within the WHO limits for drinking water and, therefore, may be suitable for domestic purposes. However, nutrients levels were low during the study period and did not give any clear seasonal variation. The results revealed that the values of Nitrate and Phosphate do not compile with WHO standards. Water quality assessment of delta regions of Cauvery River revealed slightly contamination from anthropogenic activities....
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