Pseudomonas stutzeri OX1 meta pathway genes for toluene and o-xylene catabolism were analyzed, and loci encoding phenol hydroxylase, catechol 2,3-dioxygenase, 2-hydroxymuconate semialdehyde dehydrogenase, and 2-hydroxymuconate semialdehyde hydrolase were mapped. Phenol hydroxylase converted a broad range of substrates, as it was also able to transform the nongrowth substrates 2,4-dimethylphenol and 2,5-dimethylphenol into 3,5-dimethylcatechol and 3,6-dimethylcatechol, respectively, which, however, were not cleaved by catechol 2,3-dioxygenase. The identified gene cluster displayed a gene order similar to that of the Pseudomonas sp. strain CF600 dmp operon for phenol catabolism and was found to be coregulated by the tou operon activator TouR. A hypothesis about the evolution of the toluene and o-xylene catabolic pathway in P. stutzeri OX1 is discussed.In bacteria, aerobic catabolic pathways for aromatic hydrocarbon degradation can schematically be divided into two major biochemical steps. First, early reactions, the so-called upper pathways or peripheral routes, channel the hydrocarbons towards the formation of partially oxidized aromatic intermediates. Then, dihydroxylated aromatic molecules that can undergo the cleavage of the ring are produced and further processed to give compounds that can enter the tricarboxylic acid cycle. Whereas a wide variety of very different peripheral routes for the oxidation of many different aromatic hydrocarbons exists, only a limited number of dihydroxylated compounds that can be cleaved and productively processed to enter the tricarboxylic acid cycle are known.A good example of this is represented by the diversity of the known toluene catabolic pathways. Toluene is oxidized through different routes: via progressive oxidation of the methyl group (TOL pathway) (6), via dioxygenation (25), or via monooxygenations of the aromatic ring in different positions (18,22,31). Most of these pathways give rise to (methyl)catechols further processed through meta cleavage pathways. At least in one strain, Pseudomonas mendocina KR1, protocatechuate is produced and then cleaved in intradiol position (27). The genes coding for upper and lower pathways may be clustered in one (32), two (6), or more (18, 29) operons, independently but coordinately regulated.The combination of different upper operons with one or more lower operons can thus increase not only the number of pathways through which a certain molecule can be degraded but also the range of substrates utilized for growth (10), and it is recognized as a mode for the evolution of new catabolic pathways (23, 28).Pseudomonas stutzeri OX1 is able to utilize toluene and o-xylene as the sole carbon and energy sources. For both compounds the degradation proceeds through two successive monooxygenations of the aromatic nucleus catalyzed by toluene-o-xylene monooxygenase (ToMO) followed by extradiol ring cleavage (3). Here we investigate the organization of genes involved in the further degradation of toluene and oxylene derivatives produced by the act...
Natural colchicinoids and their semisynthetic derivatives are important active ingredients for pharmaceutical applications. Thiocolchicoside (3-demethoxy-3-glucosyloxythiocolchicine) is used in several countries as standard therapy for the treatment of diseases of the muscle-skeletal system, due to its potent antiinflammatory and myorelaxant properties. Manufacturing of thiocolchicoside requires a key step, the regioselective demethylation and glucosylation of chemically derivative thiocolchicine. High selectivity and efficiency of this transformation cannot be achieved in a satisfactory way with a chemical approach. In particular, the chemical demethylation, a part from requiring toxic and aggressive reagents, generates a complex mixture of products with no industrial usefulness. We report herein an efficient, direct and green biotransformation of thiocolchicine into thiocolchicoside, performed by a specific strain of Bacillus megaterium. The same process, with minor modifications, can be used to convert the by-product 3-O-demethyl-thiocolchicine into thiocolchicoside. In addition, we describe the B. megaterium strain selection process and the best conditions for this effective double biotransformation. The final product has a pharmaceutical quality, and the process has been industrialised.
Background: The present study aimed to evaluate the effects of a new food-grade bioavailable delivery system of bergamot on human gut microbiota, in order to demonstrate the potential correlation of microbiota modulation in cardiovascular health.The identification of human gut microbiota modification was performed after ex-vivo incubation with bergamot phytosome (Vazguard™) of individual faecal slurries from healthy women (45–53 years) as follows: after incubation at 37°C in anaerobic condition, DNA was extracted and a 16S Metagenomic Sequencing Analysis performed. Results: Twenty-five different phyla were identified, among which 4 were modulated: Firmicutes, Proteobacteria, Bacteroidetes, Actinobacteria. The decreased Firmicutes/Bacteroidetes ratio and the increase of Proteobacteria were observed indicating a positive modulation of microbiota possibly linked to cardiovascular health. 418 different genera were also identified, among which several of them were mildly modulated.Conclusions: For the first time, a gut microbiome modulation was associated to the new delivery system of bergamot phytosome, supporting its clinical efficacy for cardiovascular health. New potential applications in weight control and gastrointestinal benefits were suggested.
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