Molecular methods for diversity assessment among xanthomonads of Bulgarian and Macedonian pepper

ABSTRACT Bacterial spot is an important disease of pepper in Bulgaria and Macedonia. For characterization of Xanthomonas species associated with bacterial spot, 161 strains were collected from various field pepper-growing regions. Among them, 131 strains were identified as Xanthomonas euvesicatoria and 30 as Xanthomonas vesicatoria using species-specific primers and polymerase chain reaction followed by restriction fragment length polymorphism analysis. To assess the genetic diversity of the strains, two methods (Random Amplified Polymorphic DNA and Repetitive Element Palindromic-Polymerase Chain Reaction) were applied. Discriminatory index was calculated and analysis of molecular variance was carried out.Combined random amplified polymorphic DNA analysis of the X. euvesicatoria strains with primers CUGEA-4 and CUGEA-6 had greater discriminative power (0.60) than repetitive element palindromic-polymerase chain reaction with ERIC and BOX A1R primers, which makes this method applicable for strain diversity evaluation. Discrimination among the X. vesicatoria strains was achieved by the use of ERIC primers and only for the Bulgarian strains. The results demonstrated that X. euvesicatoria was more diverse than X. vesicatoria and heterogeneity was observed mainly in the Bulgarian populations. According to the analysis of molecular variance, genetic variations in X. euvesicatoria were observed among and within populations from different regions, while the differences between the two countries were minor. Following the principal coordinates analysis, a relation between the climatic conditions of the regions and a genetic distance of the populations may be suggested.

AFLP analysis of Xanthomonas axonopodis and X arboricola strains used in xanthan production studies reveal high levels of polymorphism

Amplified fragment length polymorphism (AFLP) was used to analyze the genetic diversity of 14 strains of Xanthomonas arboricola pv. pruni and seven strains of X. axonopodis pv. phaseoli, which are used in xanthan production studies. Relationships identified by the AFLP profiles were assessed for xanthan production capacity, geographical location and host plant. Strains were isolated from 10 different geographic regions in South and Southeast States in Brazil. Data were analyzed for genetic similarity using the Dice coefficient and subjected to UPGMA cluster analysis. A total of 128 AFLP fragments were generated from four primer combinations: EcoRI+C/MseI+0, EcoRI+A/MseI+0, EcoRI+G/MseI+T and EcoRI+G/MseI+A. Of these, 96.1 percent were polymorphic. X. axonopodis pv. phaseoli (S D = 0.27) was shown to be more polymorphic than X. arboricola pv. pruni (S D = 0.58). All 14 pathovar pruni strains were included in a single main group (S D = 0.58), while the pathovar phaseoli strains were divided into three separate groups, with one group containing five strains (S D = 0.38) and two isolated groups (S D = 0.31 and 0.27) composed of only one strain each. Species were distinguished by three and eight specific AFLP markers present in the pathovar phaseoli and the pathovar pruni, respectively. For the unique strain without xanthan production capacity (X. axonopodis pv. phaseoli str. 48), nine specific AFLP bands were found. There was no evidence that geographic area or host plant influenced genetic heterogeneity. Correlations between AFLP patterns and xanthan production capacity were found in some strains, but were not consistent enough to establish a relationship.

Degradation of predigested distillery effluent by isolated bacterial strains.

Batch studies were conducted on degradation of anaerobically digested distillery wastewater by three bacterial strains, viz. Xanthomonas fragariae, Bacillus megaterium and Bacillus cereus in free and immobilized form, isolated from the activated sludge of a distillery wastewater treatment plant. The removal of COD and colour with all the three strains increased with time up to 48 hr and only marginal increase in COD and colour removal efficiency was observed beyond this period up to 72 hr. After this period removal efficiency remained fairly constant up to 120 hr. The maximum COD and colour removal efficiency varied from 66 to 81% and 65 to 75%, respectively for both free and immobilized cells of all the three strains. The strain Bacillus cereus showed the maximum efficiency of COD (81%) and colour (75%) removal out of the three strains. An interrelationship between the percent COD and colour removal was carried out by correlation and regression analysis and was justified by high values of coefficient of correlation (r = 0.99) for all the cases. The first order removal rate kinetics was also applied and rate constants were evaluated for COD and colour removal efficiencies.

Isolation, screening and identification of bacterial strains for degradation of predigested distillery wastewater.

Three bacterial isolates from the activated sludge of a distillery wastewater treatment plant identified as Xanthomonas fragariae, Bacillus megaterium and Bacillus cereus were found to remove COD and colour from anaerobically digested distillery wastewater in the range of 55 to 68% and 38 to 58% respectively.

Caracterización de Xanthomonas campestris pv. cucurbitae, agente causal de la mancha bacteriana del zapallo / Characterization of Xanthomonas campestris pv. cucurbitae, causal agent of the bacterial spot of squash

En este trabajo se realizó por primera vez en la Argentina, la caracterización del agente causal de la mancha bacteriana del zapallo. Al mismo tiempo, se probó su patogenicidad sobre distintas Cucubitaceae. El patógeno aislado de zapallito redondo de tronco (Cucubita maxima var. zapllito) fue Xanthomonas campestris pv. cucurbitae (Bryan) Dye. La identificación del mismo se basó en la sintomatología observada y en sus caracteres culturales, morfológicos y fisiológicos. En inoculaciones cruzadas, la bacteria resultó patógena para zapallo, zapallito, pepino y sandía y no lo fue para melón