El uso de las bacterias promotoras del crecimiento vegetal (PGPB) es una posibilidad para sustituir parcialmente el empleo de fertilizantes químicos en cultivos comerciales, que no solo encarecen la producción sino que también tienen efectos negativos sobre el medioambiente.  El trabajo tuvo como objetivo evaluar el potencial de cepas de Bacillus para la promoción del crecimiento vegetal in vivo en tres diferentes cultivos hortícolas de importancia económica. Se utilizaron cuatro cepas de Bacillus, dos aisladas de los cultivos del maíz (Zea mays L.) cultivar híbrido P-7928 y dos de cafeto (Coffea arabica L.) cultivar Caturra rojo, para evaluar su efecto en diferentes variables fenológicas y de crecimiento en plantas de maíz, tomate (Solanum  lycopersicum Mill.) y zanahoria (Daucus carota subsp. sativus L.) en condiciones de invernadero.  Las cepas mostraron un efecto estimulador de la germinación de las semillas de maíz, las cuales presentaron mayor porcentaje e índice de germinación y vigor de plántula que los testigos sin inocular; no obstante no todas las cepas estimularon los mismos indicadores del crecimiento en este cultivo, aunque se destacan las cepas RM5, RC9 y RC15 en la materia seca de raíz. En los cultivos de tomate y zanahoria los resultados fueron variables, por tanto se sugiere profundizar los estudios en estos cultivos.

Genotypic and phenotypic characterization of Bacillus spp. from polluted freshwater has been poorly addressed. The objective of this research was to determine the diversity and enzymatic potentialities of Bacillus spp. strains isolated from the Almendares River. Bacilli strains from a polluted river were characterized by considering the production of extracellular enzymes using API ZYM. 14 strains were selected and identified using 16S rRNA, gyrB and aroE genes. Genotypic diversity of the Bacillus spp. strains was evaluated using pulsed field gel electrophoresis. Furthermore, the presence of genetic determinants of potential virulence toxins of the Bacillus cereus group and proteinaceous crystal inclusions of Bacillus thuringiensis was determined. 10 strains were identified as B. thuringiensis, two as Bacillus megaterium, one as Bacillus pumilus and one as Bacillus subtilis. Most strains produced proteases, amylases, phosphatases, esterases, aminopeptidases and glucanases, which reflect the abundance of biopolymeric matter in Almendares River. Comparison of the typing results revealed a spatio-temporal distribution among B. thuringiensis strains along the river. The results of the present study highlight the genotypic and phenotypic diversity of Bacillus spp. strains from a polluted river, which contributes to the knowledge of genetic diversity of Bacilli from tropical polluted freshwater ecosystems.

The objective of the present study was to analyze the influence of different physicochemical and microbiological indicators on bacterial assemblages in a freshwater ecosystem located in a Biosphere Res erve.The bacterioplankton communities composition was determined by denaturing gradient gel electrophoresis (DGGE) of 16S rDNA during three sampling campaigns in three sampling stations of San Juan Ri ver.Multivariate statistical analyses of gel patterns, in relat i on t o chemi cal , biological and physical parameters were performed. The analyses showed a seasonal variation of bacterial community at the l ess pol l ut ed stations. The correspondence canonical analysis showed that total dissolved solids (TDS), E. coli concentration and dissolved oxygen were significantly influencing the DGGE profiles at San Juan River, indicating that at least two of the three sampling stations analyzed possessed good water quality. With the combination of environmental variabl es and t he DGGE molecular data it could be appreciated the influence of chemical and microbial contamination on the bacterial community of San Juan River. At the less polluted stations low concentrations of TDS and bacterial indicators of fecal contamination were related with bacterial diversity. The present investigation constitutes the first cultureindependent analysis of freshwater bacterial communities in a Biosphere Reserve of the Caribbean islands.

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