Rhizosphere

Isolation and characterization of genetic variability in bacteria with β-hemolytic and antifungal activity isolated from the rhizosphere of Medicago truncatula plants

J. E. Hernandez-Salmeron, Prieto-Barajas, C. M., Valencia-Cantero, E., Moreno-Hagelsieb, G., and Santoyo, G., Isolation and characterization of genetic variability in bacteria with β-hemolytic and antifungal activity isolated from the rhizosphere of Medicago truncatula plants, vol. 13, pp. 4967-4975, 2014.

In the present study, we analyzed the frequency of hemolytic and antifungal activities in bacterial isolates from the rhizosphere of Medicago truncatula plants. Of the 2000 bacterial colonies, 96 showed β-hemolytic activities (frequency, 4.8 x 10-2). Hemolytic isolates were analyzed for their genetic diversity by using random amplification of polymorphic DNA, yielding 88 haplotypes. The similarity coefficient of Nei and Li showed a polymorphic diversity ranging from 0.3 to 1.

Isolation and molecular characterization of a novel strain of Bacillus with antifungal activity from the sorghum rhizosphere

S. C. Martinez-Absalon, Orozco-Mosqueda, Mdel C., Martinez-Pacheco, M. M., Farias-Rodriguez, R., Govindappa, M., and Santoyo, G., Isolation and molecular characterization of a novel strain of Bacillus with antifungal activity from the sorghum rhizosphere, vol. 11, pp. 2665-2673, 2012.

We looked for bacterial strains with antifungal activity in the sorghum rhizosphere. A prescreening procedure to search for hemolytic activity among the isolated strains allowed us to detect good fungitoxic activity in a bacterial isolate that we named UM96. This bacterial isolate showed strong growth inhibition in bioassays against the pathogens Diaporthe phaseolorum, Colletotrichum acutatum, Rhizoctonia solani, and Fusarium oxysporum.

Diversity of bacterial endophytes in roots of Mexican husk tomato plants (Physalis ixocarpa) and their detection in the rhizosphere

H. A. Marquez-Santacruz, Hernandez-Leon, R., Orozco-Mosqueda, M. C., Velazquez-Sepulveda, I., and Santoyo, G., Diversity of bacterial endophytes in roots of Mexican husk tomato plants (Physalis ixocarpa) and their detection in the rhizosphere, vol. 9, pp. 2372-2380, 2010.

Endophytic bacterial diversity was estimated in Mexican husk tomato plant roots by amplified rDNA restriction analysis and se­quence homology comparison of the 16S rDNA genes. Sixteen opera­tional taxonomic units from the 16S rDNA root library were identified based on sequence analysis, including the classes Gammaproteobacte­ria, Betaproteobacteria, Actinobacteria, and Bacilli. The predominant genera were Stenotrophomonas (21.9%), Microbacterium (17.1%), Bur­kholderia (14.3%), Bacillus (14.3%), and Pseudomonas (10.5%).

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