PubMed · 14801087
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A GATTONI. 1950. [Active carbons].. https://pubmed.ncbi.nlm.nih.gov/14801087/
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Pectobacterium brasiliense 1692 (Pbr1692) is a necrotrophic pathogen that infects many crops such as potatoes and ornamental plants and derives nutrients from degraded plant tissue. Previous studies have identified Pbr1692 genes required for ecological fitness and virulence, however there is a lack of information on nutrient utilization in Pbr1692. Carbon source utilization profiling in Pbr1692 could provide a platform to decipher its metabolic flexibility and adaptation. This study assessed the nutrient utilization of Pbr1692 in different carbon sources, using Biolog Phenotypic Microarray (PM). An array of carbon sources utilized by Pbr1692 were identified, 32 carbohydrates and 8 carboxylic acids were among the preferred carbon nutrients utilized by Pbr1692. The PM results also revealed that the citric acid cycle, amino acid metabolism, and pentose phosphate metabolic pathways might be used to produce energy for Pbr1692. In addition, growth of Pbr1692 cells in minimal medium supplemented with citric acid, glucose, and aspartic acid retained the typical rod shape, suggesting that nutrient variation did not influence Pbr1692 cell morphology adaptation. This study provides an understanding on the adaptation of Pbr1692 and lays a foundation for understanding carbon metabolism of Pbr1692.
A quantitative laboratory assessment of the different C and N forms in soil humus fractions was carried out by incubation of a mineral substrate after the addition of (15)N-labeled compost. The experimental design included (i) preparation of the (15)N-labeled organic matter (city refuse compost, 640 g kg(-1) wheat straw and K(15)NO(3) composted for 80 days), (ii) a further 80 day incubation of a mixture of the labeled compost with a mineral soil (32 g kg(-1)), (iii) measurement of stable isotope ratios, and (iv) isolation and structural comparison by (13)C and (15)N cross-polarization, magic-angle spinning nuclear magnetic resonance (NMR) of different organic fractions, i.e., soluble, colloidal (humic and fulvic type), and particulate (free organic matter and humin), from both the compost and the compost-treated soil. The results showed that the amide forms dominated in all of the newly formed N compounds, but an increased amount of alkali insoluble organic fractions was observed after incubation of the soil. The analysis of the insoluble, particulate fractions shows that nonextractable amides constitute the major pool of newly formed N compounds. The particulate soil fraction isolated by flotation in CHBr(3)-MeOH contained 16.8% of the total soil N and 26% of the (15)N. The (13)C NMR spectra showed that the fulvic acid-like fraction (7.6% of the soil N, 8.8% of (15)N) consisted almost completely of a C=O-containing carbohydrate material, whereas the humic acid-like fraction (20.3% of the total soil N, 8.6% of (15)N) resembled an oxidized lignoproteic fraction containing the most significant aromatic domain. The water soluble fraction was, in both soil and compost, the one with the highest isotopic abundance of (15)N (96%), but the (15)N NMR spectrum revealed minor amounts of soluble mineral N in this fraction and the remainder consisting of amide compounds.
Dissolved and particulate organic carbon concentrations were measured and annual loads estimated for the Trinity River, the main freshwater input source to Galveston Bay, which lies on the upper Gulf coast of Texas, USA, during 2000-2001. This river drains the forested lowlands south of a relatively large reservoir lake, Lake Livingston. A weak relationship between dissolved organic carbon (DOC) and Q(TR) indicated hydrologic control but separation of the data, based on individual discharge events, was necessary to improve interpretation. For instance, the first rain of the season resulted in only a modest increase in DOC concentrations and led to an inverse relationship with discharge, due to decreased lateral flow and increased infiltration of rainwater, with the lower flows being more efficient at DOC leaching from soils. In contrast, a long duration high discharge river crest event resulted in an opposite trend, i.e. a linear increase in DOC with increasing discharge rates. A short duration high discharge tropical storm showed reduced Trinity River DOC concentrations and the highest POC concentrations measured, likely resulting from the relatively short duration, and minimal contact time, of this event. In contrast to DOC, the concentrations of particulate organic carbon, POC (mg C l(-1)) were linearly correlated to suspended particulate matter (SPM) concentrations and accounted for between 10 and 12% of the total suspended load at low discharge but decreased to approximately 2% at high discharge. This suggests dilution by larger particles with a reduced organic carbon content, possibly silicate minerals, more readily resuspended at elevated levels of discharge. The annual total organic carbon (TOC) load to Galveston Bay, estimated from the slope of the daily load vs. discharge relationship, was 11.2 x 10(10) g C and calculated export coefficients (g C m(-2) year(-1)) were in good agreement with previous results. Using this relationship, accurate assessments of TOC flux inputs to Galveston Bay over the past quarter-century and in the future are possible by obtaining annual Trinity River discharge rates, which are readily available from the USGS. Comparing DOC riverine inputs to benthic sources in Trinity Bay, measured directly on the same day, indicates that the sediments contribute approximately 20% of total inputs of DOC to Trinity Bay. However, assuming a constant benthic source during low-flow conditions, which can occur for periods of up to 14 months in this region of Texas, benthic fluxes would account for > 80% of the total inputs into Trinity Bay. At high levels of discharge, the Trinity River discharges approximately 1.0 x 10(9) g C day(-1) and dominates DOC inputs to Trinity Bay.