Management of black pod rot in cacao (Theobroma cacao L.): a review.

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This study provides a theoretical basis for the potential use of Ps. chlororaphis CP07 as a biocontrol agent for the protection of cacao plants from P. palmivora infection.

The saprophytic bacterium Burkholderia cepacia has been shown to play an active role as plant growth promoting bacteria (PGPB). In this study, the ability of cell-free culture medium (CFCM) of B. cepacia to improve early developmental stages of plants has been assessed on two agronomically important crops, maize (Zea mays) and rice (Oryza sativa). Treating maize and rice seeds for 45 min before germination significantly improved seed germination and consequent seedling growth. The effect of CFCM was confirmed by the increased biomass of the shoot and, mainly, the root systems of treated seedlings. Chromatographic characterization of the CFCM revealed that the spent culture medium of B. cepacia is a complex mix of different classes of metabolites including, among others, salicylic acid, indole-3-acetic acid (IAA) and several unidentified phenolic compounds. Fractionation of the CFCM components revealed that the impressive development of the root system of CFCM-treated seedlings is due to the synergistic action of several groups of components rather than IAA alone. The data presented here suggest that a CFCM of B. cepacia can be used to improve crop germination.

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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.

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.