Chemotaxis response of Erwinia carotovora on sugars and amino acids of root exudates of Panax ginseng / 中国中药杂志

The chemotaxis response of Erwinia carotovora to different sugars and amino acids in four kinds of chemotactic parameters (concentration, time, temperature and pH ) was determined by capillary method. The results showed that when pH was 8, concentration was 0.025 mg•L ⁻¹, culture temperature was 25 ℃ and the duration was 60 minutes, the optimal chemotaxis rate of lysine was 2.509,when pH was 6, concentration was 0.25 mg•L ⁻¹, culture temperature was 25 ℃ and the duration was 60 minutes, the optimal chemotaxis rate of arginine was 2.218 8,when pH was 7, concentration was 0.25 mg•L ⁻¹, culture temperature was 30 ℃ and the duration was 60 minutes, the optimal chemotaxis rate of L-rhamnose was 3.091 2, when pH was 6, concentration was 0.25 mg•L ⁻¹, culture temperature was 30 ℃ and the duration was 45 minutes, the optimal chemotaxis rate of D-arabinose was 3.026 3. Sugars and amino acids had obvious chemotaxis with E. carotovora,the high concentration of carbohydrate and amino acid exited an inhibitory effect on chemotaxis response of E. carotovora, and the chemotaxis response decreased with the increase of concentration of carbohydrates and amino acids.

Growth Inhibition of Some Phytopathogenic Bacteria by Cell-Free Extracts from Enterococcus sp.

Aims: To inhibit of bacterial growth of three important phyto-pathogenic bacteria: Erwinia carotovora, Clavibacter michiganensis sp. michiganensis and Xanthomonas axonopodis by cell-free extracts from submerged cultures of two strains of Enterococcus sp. was tested. Study Design: A complete randomized experimental design with factorial fix was used to evaluate the efficiency of growth inhibition against the phytopathogenic bacteria. Place and Duration of Study: Laboratory of Bioprocesses, Department of Food Science and Technology, School of Chemistry, Universidad Autonoma de Coahuila, Mexico, between December 2011 and July 2012. Methodology: Enterococci strains were isolated from goat milk, buttermilk and whey by typical microbiological procedures and primarily identified based on biochemical tests. Strains were subsequently activated in MRS broth and cells were separated by centrifugation and filtration. Cell-free extracts were tested against plant pathogenic bacteria to determine their growth inhibition potential. Results: Strains of Enterococcus MII-1 and MIV-2 were able to inhibit the growth of three pathogenic bacteria, demonstrating to be an attractive alternative for biological control assays. Conclusion: The cell-free extracts of Enterococcus spp. show inhibition potential to inhibit phytopathogenic bacteria that cause diseases in horticultural crops. Further studies are needed to completely evidence the high potential of use of cell-free extracts from Enterococcus MII-1 and MIV-2.

Bacillus thuringiensis: en el manejo del agente de la pudrición blanda de la papa Erwinia carotovora / Bacillus thuringiensis control of the potato soft rot Erwinia carotovora

En Colombia el cultivo de papa es el cuarto en importancia en la economía del país, y su producción alcanza las 300 millones de toneladas aproximadamente. Erwinia carotovora es una bacteria Gram negativa, anaeróbica facultativa causante de la pudrición blanda de la papa, puede llegar a generar hasta el 100% de daño en la cosecha, lo cual ocasiona grandes pérdidas económicas. Se ha establecido que la bacteria Bacillus thuringiensis es capaz de suprimir la virulencia de E. caratovora debido a que produce N-acil-homoserina-lactonasa, una potente enzima que degrada de N-acil-homoserinolactonas, que son indispensables en el mecanismo de quorum-sensing de E. caratovora. Esta circunstancia, puede ser una alternativa importante para el control de la enfermedad de la pudrición blanda de la papa. Considerando lo anterior, en este artículo se describe el proceso que emplea la bacteria Bacillus thuringiensis para inhibir la actividad de E. caratovora.

In Colombia the potato crop is the fourth in importance in the economy of the country, its production reached 300 million tons. Erwinia carotovora is a Gram-negative bacterium, facultative anaerobic which causes the soft rotting of the potato; it can potentially generate up to 100% damage in the crop, which causes large economic losses. It has been established that the bacterium Bacillus thuringiensis is able to suppress the virulence of E. caratovora because it produces N-acyl-homoserine-lactonasa, a powerful enzyme that degrades of N-acyl-homoserinolactonas, which are indispensable in the quorum-sensing mechanism of E. caratovora. This can be an important alternative for the control of the disease of the soft rotting of the potato. Considering the above, this article describes the process used by the bacterium B. thuringiensis to inhibit the activity of E. caratovora.

Podridão-mole em plantas de cebolinha causada por Pectobacterium carotovorumsubsp. carotovorum em Roraima / Soft rot of bunching onion plants caused by Pectobacterium carotovorumsubsp. carotovorum in Roraima, Brazil

A ocorrência de Pectobacterium carotovorum subsp. carotovorum (=Erwinia carotovora subsp. carotovora) em cebolinha (Allium fistulosum) é relatada pela primeira vez na região norte do Brasil. Até então sua ocorrência estava registrada apenas no Distrito Federal.

This is the first report of Pectobacterium carotovorum subsp. carotovorum (=Erwinia carotovora subsp. carotovora) causing soft rot of bunching onion (Allium fistulosum) plants in Roraima, Brazil. Its occurrence is reported only in Distrito Federal.

Study on the Identification and Potency Determination of L-asparaginases from 2 Kinds of Strain / 中国药房

OBJECTIVE: To discuss the identification method of L-asparaginases prepared from E.coliASI.357 and Erwinia carotovora and the optimal enzymatic reaction conditions of potency determination.METHODS: HPLC method and isoelectric focusing electrophoresis were applied for the identification of L-asparaginase from 2 kinds of strain.The effects of category of buffer solution and pH value on enzymatic reaction of potency determination of L-asparaginase were investigated.RESULTS: HPLC chromatogram of L-asparaginases from E.coli ASI.357 was different from that from Erwinia carotovora.The retention time of the peaks were 11.0 min and 11.8 min.The isoelectric point (PI) of L-asparaginase produced from E.coliASI.357 was within 4.65～5.1 and that produced from Erwinia carotovora was within 7.1～8.20.The optimal enzymatic reaction conditions of potency determination of L-asparaginase produced from E.coliASI.35 were Tris-HCl (pH=9.0) as buffer and that produced from Erwinia carotovora was 0.2 mol?L-1 phosphate (pH=8.0) as buffer.CONCLUSION: The isoelectric point (PI) of L-asparaginases produced from 2 kinds of strain is different from each other as well as their optimal enzymatic reaction conditions of potency determination.The L-asparaginases from 2 kinds of strains should be controlled as 2 different categories.