Identification of an Extracellular Endoglucanase That Is Required for Full Virulence in Xanthomonas citri subsp. citri.

Xanthomonas citri subsp. citri causes citrus canker disease, which is characterized by the formation of water-soaked lesions, white or yellow spongy pustules and brown corky canker. In this work, we report the contribution of extracellular endoglucanase to canker development during infection. The ectopic expression of nine putative cellulases in Escherichia coli indicated that two endoglucanases, BglC3 and EngXCA, show carboxymethyl cellulase activity. Both bglC3 and engXCA genes were transcribed in X. citri subsp. citri, however, only BglC3 protein was detected outside the cell in western blot analysis. The deletion of bglC3 gene resulted in complete loss of extracellular carboxymethyl cellulase activity and delayed the onset of canker symptoms in both infiltration- and wound-inoculation assays. When growing in plant tissue, the cell density of bglC3 mutant was lower than that of the wild type. Our data demonstrated that BglC3 is an extracellular endoglucanase required for the full virulence of X. citri subsp. citri.

Production and characterization of cellulase-free xylanase from Trichoderma inhamatum.

The production of extracellular cellulase-free xylanase from Trichoderma inhamatum was evaluated in liquid Vogel medium with different carbon sources as natural substrates and agricultural or agro-industrial wastes. Optimal production of 244.02 U/mL was obtained with xylan as carbon source, pH 6.0 at 25 degrees C, 120 rpm, and 60-h time culture. Optimal conditions for enzyme activity were 50 degrees C and pH 5.5. Thermal stability of T. inhamatum xylanolytic complex expressed as T1/2 was 2.2 h at 40 degrees C and 2 min at 50 degrees C. The pH stability was high from 4.0 to 11.0. These results indicate possible employment of such enzymatic complex in some industrial processes which require activity in acid pH, wide-ranging pH stability, and cellulase activity absence.

[Genetic regulation of pathogenicity and virulence factors in bacteria Erwinia carotovora subsp. atroseptica: phenotypic characteristic of bacteria with the mutant kduD gene]. / Geneticheskaia reguliatsiia faktorov patogennosti i virulentnosti u bakterii Erwinia carotovora subsp. atroseptica. Fenotipicheskaia charakteristika mutantnykh po genu kduD bakterii.

In contrast to the closely related bacteria Erwinia chrysanthemi, bacteria Erwinia carotovora subsp. atroseptica produce lower levels of main pathogenicity and virulence factors (pectate lyases, cellulases, and proteases) in the presence of pectins. This effect was shown to be connected with the accumulation of the intermediate product of intracellular degradation of these substances, 2,5-diketo-3-deoxygluconate (DK2). The presence of DK2 in the culture broth of mutant bacteria, connected to its export in the environment, was established. The production of pectate lyases, cellulases, and proteases is repressed by DK2 only at its high concentrations in the cultivation medium, whereas low concentrations of DK2 induce the production of virulence factors. Genes involved in the intracellular catabolism of pectin substances and induced by both low and high DK2 concentrations in the cultivation medium are not repressed by this metabolite.

Protocolos antienvejecimiento / Antiaging protocols

El autor presenta la necesidad de protocolizar los métodos de diagnóstico y tratamiento con el fin de sistematizar la terapia antienvejecimiento. En relación a los protocolos establecidos, remarca la importancia de valorar, de forma práctica, las distintas pruebas tanto químicas como biológicas: estudio de los componentes sanguíneos, de la composición corporal, el índice de masa corporal o BMl, el índice metabólico basal o BMR, los análisis del colesterol, lipoproteínas, triglicéridos y glucosa y el llamado estado biológico. A continuación expone como Se pueden valorar todos estos datos obtenidos para poder aplicar el correspondiente tratamiento mediante un aporte enzimático (enzimas digestivas, metabólicas y alimentarias), analizando la influencia corporal de los déficits de determinadas enzimas alimentarias (proteasa, amilasa, lipasa, celulasa, etc) así como sus mecanismos y niveles de actuación para finalmente exponer una serie de puntos clave y las diferentes soluciones recomendables para modificar el proceso del envejecimiento con especial énfasis en el ejercicio y sus diversas modalidades (AU)

Altered pectin composition in primary cell walls of korrigan, a dwarf mutant of Arabidopsis deficient in a membrane-bound endo-1,4-beta-glucanase.

Korrigan (kor) is a dwarf mutant of Arabidopsis thaliana (L.) Heynh. that is deficient in a membrane-bound endo-1,4-beta-glucanase. The effect of the mutation on the pectin network has been studied in kor by microscopical techniques associated with various probes specific for different classes of pectic polysaccharides. The localisation of native crystalline cellulose was also examined using the cellobiohydrolase I-gold probe. The investigations were focused on the external cell walls of the epidermis, a cell layer that, in a number of plant species, has been shown to be growth limiting. Anionic sites associated with pectic polymers were quantified using the cationic gold probe. Homogalacturonans were quantified using polyclonal anti-polygalacturonic acid/rhamnogalacturonan I antibodies recognising polygalacturonic acid, and monoclonal JIM7 and JIM5 antibodies recognising homogalacturonans with a high or low degree of methyl-esterification, respectively. Rhamnogalacturonans were quantified with two monoclonal antibodies, LM5, recognising beta-1,4 galactan side chains of rhamnogalacturonan I, and CCRCM2. Our results show a marked increase in homogalacturonan epitopes and a decrease in rhamnogalacturonan epitopes in kor compared to the wild type. A substantial decrease in cellobiohydrolase I-gold labelling was also observed in the mutant cell walls. These findings demonstrate that a deficiency in an endo-1,4-beta-glucanase, which is in principle not directly implicated in pectin metabolism, can induce important changes in pectin composition in the primary cell wall. The changes indicate the existence of feedback mechanisms controlling the synthesis and/or deposition of pectic polysaccharides in primary cell walls.

Genes encoding xylan and beta-glucan hydrolysing enzymes in Bacillus subtilis: characterization, mapping and construction of strains deficient in lichenase, cellulase and xylanase.

The gene encoding extracellular xylanase (xynA) was amplified as a 770 bp DNA fragment from Bacillus subtilis 168 chromosomal DNA by PCR. The genes encoding endo-beta-1,4-glucanase (eglS) and endo-beta-1,3-1,4-glucanase (bglS) were isolated from a genomic library of B. subtilis 168. The sequences of xynA and eglS were identical to those of the xylanase and cellulase genes from B. subtilis PAP115. Integrative plasmids containing DNA fragments with deletions in the coding region of the genes were constructed and used to replace the chromosomal eglS, bglS and xynA genes of B. subtilis 168. Strains without any detectable activity against xylan (Xyn-), carboxymethylcellulose (Egl-) or mixed linked beta-1,3-1,4-glucan (Egl- Bgl-) were obtained. The genes were mapped at 170 degrees (eglS), 175 degrees (xynA) and 340 degrees (bglS) on the B. subtilis chromosome.