The phylogenetic classification of the species Burkholderia andropogonis within the Burkholderia genus was reassessed using 16S rRNA gene phylogenetic analysis and multilocus sequence analysis (MLSA). Both phylogenetic trees revealed two main groups, named A and B, strongly supported by high bootstrap values (100%). Group A encompassed all of the Burkholderia species complex, whi.le Group B only comprised B. andropogonis species, with low percentage similarities with other species of the genus, from 92 to 95% for 16S rRNA gene sequences and 83% for conserved gene sequences. Average nucleotide identity (ANI), tetranucleotide signature frequency, and percentage of conserved proteins POCP analyses were also carried out, and in the three analyses B. andropogonis showed lower values when compared to the other Burkholderia species complex, near 71% for ANI, from 0.484 to 0.724 for tetranucleotide signature frequency, and around 50% for POCP, reinforcing the distance observed in the phylogenetic analyses. Our findings provide an important insight into the taxonomy of B. andropogonis. It is clear from the results that this bacterial species exhibits genotypic differences and represents a new genus described herein as Robbsia andropogonis gen. nov., comb. nov.

The rpoB gene was evaluated as an alternative molecular marker for the differentiation of Xanthomonas species and in order to understand better the phylogenetic relationships within the genus. PCR-RFLP experiments using HaeIII allowed differentiation of Xanthomonas species, particularly those that affect the same plant host such as Xanthomonas albilineans and X. sacchari, pathogenic to sugar cane, Xanthomonas cucurbitae and X. melonis, which cause disease in melon, and Xanthomonas gardneri, X. vesicatoria and X. euvesicatoria/X. perforans, pathogenic to tomato. Phylogenetic relationships within the genus Xanthomonas were also examined by comparing partial rpoB gene sequences (612 nt) and the Xanthomonas species were separated into two main groups. Group I, well supported by bootstrap values of 99 %, comprised X. euvesicatoria, X. perforans, X. alfalfae, X. citri, X. dyei, X. axonopodis, X. oryzae, X. hortorum, X. bromi, X. vasicola, X. cynarae, X. gardneri, X. campestris, X. fragariae, X. arboricola, X. cassavae, X. cucurbitae, X. pisi, X. vesicatoria, X. codiaei and X. melonis. Group II, again well supported by bootstrap values of 99 %, comprised X. albilineans, X. sacchari, X. theicola, X. translucens and X. hyacinthi. The rpoB gene sequence similarity observed among the species in this study ranged from 87.8 to 99.7 %. The results of PCR-RFLP of the rpoB gene indicated that this technique can be used for diagnosis and identification of most Xanthomonas strains, including closely related species within the genus. However, species that showed identical profiles could be differentiated clearly only by sequence analysis. The results obtained in our phylogenetic analysis suggested that the rpoB gene can be used as an alternative molecular marker for genetic relatedness in the genus Xanthomonas. The results of PCR-RFLP of the rpoB gene indicate that this technique can be used for diagnosis and identification of closely related species within the genus, representing a rapid and inexpensive tool that can be easily standardized between laboratories.

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Two new actinobacteria, designated strains IBSBF 2807T and IBSBF 2953T, isolated from scab lesions on potato tubers grown in the southern Brazilian states of Rio Grande do Sul and Santa Catarina, respectively, were characterized and identified through a polyphasic approach. Phylogenetic analyses of 16S rRNA sequences revealed that these two strains belong to the genus Streptomyces . Multilocus sequence analysis using five concatenated genes, atpD, gyrB, recA, rpoB and trpB, allocated strains IBSBF 2807T and IBSBF 2953T in distinct branches of Streptomyces phytopathogenic strains. PCR-RFLP analysis of the atpD gene also confirmed that these strains differ from the type strains of Streptomyces associated with potato scab. The morphological, physiological and biochemical characterization, along with the overall genome-related index properties, indicated that these two strains could be distinguished from their closest phylogenetic relatives and each other. According to the data, IBSBF 2807T and IBSBF 2953T represent two new Streptomyces species related to potato scab. The proposed names for these strains are Streptomyces hilarionis sp. nov. (IBSBF 2807T=CBMAI 2674T=ICMP 24297T=MUM 22.66T) and Streptomyces hayashii sp. nov (IBSBF 2953T=CBMAI 2675T=ICMP 24301T=MUM 22.68T).