Microbial transformations of acyclic monoterpenes

Microbial degradation of geraniol, citronellol, linalool and their corresponding acetates, structurally modified linalool and linalyl acetate, α-terpineol and β-myrcene are presented. Oxygenative and prototropic rearrangements are normally observed during the microbial metabolism of monoterpenes. Three types of oxygenation reactions are observed, namely, (a) allylic oxygenation (b) oxygenation on a double bond and (c) addition of water across the double bond. The studies indicate commonality in the reaction types or processes occurring during the metabolism of various related monoterpenes and also establish the convergence of degradative pathways at a central catabolic intermediate.

Microbial transformations in phosphonate biosynthesis and catabolism, and their importance in nutrient cycling

Phosphorus cycling in the biosphere has traditionally been thought to involve almost exclusively transformations of the element in its pentavalent oxidation state. Recent evidence, however, suggests that a significant fraction of environmental phosphorus may exist in a more reduced form. Most abundant of these reduced phosphorus compounds are the phosphonates, with their direct carbon–phosphorus bonds, and striking progress has recently been made in elucidating the biochemistry of microbial phosphonate transformations. These advances are now presented in the context of their contribution to our understanding of phosphorus biogeochemistry and of such diverse fields as the productivity of the oceans, marine methanogenesis and the discovery of novel microbial antimetabolites.

Microbial Transformations of Aryltetralone and Aryltetralin Lignans by Cunninghamella echinulata and Beauveria bassiana

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Microbial transformations of Aryltetralone and Aryltetralin Lignans by Cunninghamella echinulata and Beauveria bassiana

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Comparative phytotoxicity of nitrophenolic soil pollutants and their microbial metabolites to the growth of cucumber

2,4-Dinitrophenol and paranitrophenol are two major soil pollutants which are known to be metabolized by different soil microbes. Relative phytotoxicities of these parent compounds and their metabolic transformation products to the growth of cucumber seedlings were assessed. It was evident that such microbial transformations widely occurring in the soil are effective detoxification reactions and are beneficial for the plants.

Microbial transformation of a fungicide-derived amine, dimethyl-p-phenylene diamine by Alcaligenes DM4

Abstract Microbial transformation of N, N-dimethyl-p-phenylene diamine (DMPDA), a microbial product formed from the fungicide fenaminosulf (p-dimethylaminobenzenediazo sodium sulfonate) was studied by enriching microbes in soils treated with the amine. Microorganisms isolated from DMPDA-treated soil belonged to the genera of Micrococcus, Alcaligenes, and Corynebacterium. Of the various isolates, Alcaligenes DM4 showed maximal growth on DMPDA utilizing it as sources of carbon and nitrogen. When grown in mineral salts basal medium containing 0.05% DMPDA to serve as carbon and nitrogen sources, Alcaligenes DM4 grew exponentially up to 18 h. Even though the characterization of the complete pathway of microbial degradation of DMPDA could not be carried out due to the auto-oxidation of the compound, the initial transformation product of DMPDA by Alcaligenes DM4 has been identified as a dimer. The dimer is generated into the culture medium presumably by the extra-cellular oxidase of Alcaligenes DM4. It is suggested that the risk-benefit evaluation on the use of fenaminosulf is to be made taking into consideration the microbial transformations of the fungicide.

Photochemical and Microbial Alteration of Dissolved Organic Matter in Temperate Headwater Streams Associated with Different Land Use

[1] Photochemical and microbial transformations of DOM were evaluated in headwater streams draining forested and human-modified lands (pasture, cropland, and urban development) by laboratory incubations. Changes in DOC concentrations, DOC isotopic signatures, and DOM fluorescence properties were measured to assess the amounts, sources, ages, and properties of reactive and refractory DOM under the influence of photochemistry and/or bacteria. DOC in streams draining forest-dominated watersheds was more photoreactive than in streams draining mostly human-modified watersheds, possibly due to greater contributions of terrestrial plant-derived DOC and lower amounts of prior light exposure in forested streams. Overall, the percentage of photoreactive DOC in stream waters was best predicted by the relative content of terrestrial fluorophores. The bioreactivity of DOC was similar in forested and human-modified streams, but variations were correlated with temperature and may be further controlled by the diagenetic status of organic matter. Alterations to DOC isotopes and DOM fluorescence properties during photochemical and microbial incubations were similar between forested and human-modified streams and included (1) negligible effects of microbial alteration on DOC isotopes and DOM fluorescence properties, (2) selective removal of 13C-depleted and 14C-enriched DOC under the combined influence of photochemical and microbial processes, and (3) photochemical alteration of DOM resulting in a preferential loss of terrestrial humic fluorescence components relative to microbial fluorescence components. This study provides a unique comparison of DOC reactivity in a regional group of streams draining forested and human-modified watersheds and indicates the importance of land use on the photoreactivity of DOC exported from upstream watersheds.

Métodos de obtenção de lignanas de Holostylis reniformis provenientes de duas regiões brasileiras

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Microbiota do solo em sistemas de produção de grãos no plantio direto

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Chiral HPLC analysis of donepezil, 5-O-desmethyl donepezil and 6-O-desmethyl donepezil in culture medium: application to fungal biotransformation studies

An high performance liquid chromatography (HPLC) method for the enantioselective determination of donepezil (DPZ), 5-O-desmethyl donepezil (5-ODD), and 6-O-desmethyl donepezil (6-ODD) in Czapek culture medium to be applied to biotransformation studies with fungi is described for the first time. The HPLC analysis was carried out using a Chiralpak AD-H column with hexane/ethanol/methanol (75:20:5, v/v/v) plus 0.3 % triethylamine as mobile phase and UV detection at 270 nm. Sample preparation was carried out by liquid-liquid extraction using ethyl acetate as extractor solvent. The method was linear over the concentration range of 100-10,000 ng mL(-1) for each enantiomer of DPZ (r a parts per thousand yenaEuro parts per thousand 0.9985) and of 100-5,000 ng mL(-1) for each enantiomer of 5-ODD (r a parts per thousand yenaEuro parts per thousand 0.9977) and 6-ODD (r a parts per thousand yenaEuro parts per thousand 0.9951). Within-day and between-day precision and accuracy evaluated by relative standard deviations and relative errors, respectively, were lower than 15 % for all analytes. The validated method was used to assess DPZ biotransformation by the fungi Beauveria bassiana American Type Culture Collection (ATCC) 7159 and Cunninghamella elegans ATCC 10028B. Using the fungus B. bassiana ATCC 7159, a predominant formation of (R)-5-ODD was observed while for the fungus C. elegans ATCC 10028B, DPZ was biotransformed to (R)-6-ODD with an enantiomeric excess of 100 %.

Nitrogen fertilizer (15N) leaching in a central pivot fertigated coffee crop

Nitrogen has a complex dynamics in the soil-plant-atmosphere system. N fertilizers are subject to chemical and microbial transformations in soils that can result in significant losses. Considering the cost of fertilizers, the adoption of good management practices like fertigation could improve the N use efficiency by crops. Water balances (WB) were applied to evaluate fertilizer N leaching using 15N labeled urea in west Bahia, Brazil. Three scenarios (2008/2009) were established: i) rainfall + irrigation the full year, ii) rainfall only; and iii) rainfall + irrigation only in the dry season. The water excess was considered equal to the deep drainage for the very flat area (runoff = 0) with a water table located several meters below soil surface (capillary rise = 0). The control volume for water balance calculations was the 0 - 1 m soil layer, considering that it involves the active root system. The water drained below 1 m was used to estimate fertilizer N leaching losses. WB calculations used the mathematic model of Penman-Monteith for evapotranspiration, considering the crop coefficient equal to unity. The high N application rate associated to the high rainfall plus irrigation was found to be the main cause for leaching, which values were 14.7 and 104.5 kg ha-1 for the rates 400 and 800 kg ha-1 of N, corresponding to 3.7 and 13.1 % of the applied fertilizer, respectively.

Plant secondary compounds and soil microbial processes in carbon and nitrogen cycling in relation to tree species

The aim of this study was to explore soil microbial activities related to C and N cycling and the occurrence and concentrations of two important groups of plant secondary compounds, terpenes and phenolic compounds, under silver birch (Betula pendula Roth), Norway spruce (Picea abies (L.) Karst) and Scots pine (Pinus sylvestris L.) as well as to study the effects of volatile monoterpenes and tannins on soil microbial activities. The study site, located in Kivalo, northern Finland, included ca. 70-year-old adjacent stands dominated by silver birch, Norway spruce and Scots pine. Originally the soil was very probably similar in all three stands. All forest floor layers (litter (L), fermentation layer (F) and humified layer (H)) under birch and spruce showed higher rates of CO2 production, greater net mineralisation of nitrogen and higher amounts of carbon and nitrogen in microbial biomass than did the forest floor layers under pine. Concentrations of mono-, sesqui-, di- and triterpenes were higher under both conifers than under birch, while the concentration of total water-soluble phenolic compounds as well as the concentration of condensed tannins tended to be higher or at least as high under spruce as under birch or pine. In general, differences between tree species in soil microbial activities and in concentrations of secondary compounds were smaller in the H layer than in the upper layers. The rate of CO2 production and the amount of carbon in the microbial biomass correlated highly positively with the concentration of total water-soluble phenolic compounds and positively with the concentration of condensed tannins. Exposure of soil to volatile monoterpenes and tannins extracted and fractionated from spruce and pine needles affected carbon and nitrogen transformations in soil, but the effects were dependent on the compound and its molecular structure. Monoterpenes decreased net mineralisation of nitrogen and probably had a toxic effect on part of the microbial population in soil, while another part of the microbes seemed to be able to use monoterpenes as a carbon source. With tannins, low-molecular-weight compounds (also compounds other than tannins) increased soil CO2 production and nitrogen immobilisation by soil microbes while the higher-molecular-weight condensed tannins had inhibitory effects. In conclusion, plant secondary compounds may have a great potential in regulation of C and N transformations in forest soils, but the real magnitude of their significance in soil processes is impossible to estimate.