The common bean is one of the most important legumes in the human diet, but little is known about the endophytic bacteria associated with the leaves of this plant. The objective of this study was to characterize the culturable endophytic bacteria of common bean (Phaseolus vulgaris) leaves from three different cultivars (Vermelhinho, Talismã, and Ouro Negro) grown under the same field conditions. The density of endophytic populations varied from 4.5 x 10 2 to 2.8 x 10 3 CFU g The isolates from the Talismã cultivar were less diverse than the isolates derived from the other two cultivars. The results of this work indicate that the cultivar of the plant may contribute to the structure of the endophytic community associated with the common bean. This is the first report of endophytic bacteria from the leaves of P. vulgaris cultivars. Future studies will determine the potential application of these isolates in biological control, growth promotion and enzyme production for biotechnology.

Endophytic bacteria play a key role in the biocontrol of phytopathogenic microorganisms. In this study, genotypic diversity was analyzed via repetitive element PCR (rep-PCR) of endophytic isolates of the phylum Actinobacteria that were previously collected from leaves of cultivars of common bean (Phaseolus vulgaris). Considerable variability was observed, which has not been reported previously for this phylum of endophytic bacteria of the common bean. Furthermore, the ethanol extracts from cultures of various isolates inhibited the growth of pathogenic bacteria in vitro, especially Gram-positive pathogens. Extracts from cultures of Microbacterium testaceum BAC1065 and BAC1093, which were both isolated from the 'Talismã' cultivar, strongly inhibited most of the pathogenic bacteria tested. Bean endophytic bacteria were also demonstrated to have the potential to inhibit the quorum sensing of Gram-negative bacteria. This mechanism may regulate the production of virulence factors in pathogens. The ability to inhibit quorum sensing has also not been reported previously for endophytic microorganisms of P. vulgaris. Furthermore, M. testaceum with capacity to inhibit quorum sensing appears to be widespread in common bean. The genomic profiles of M. testaceum were also analyzed via pulsed-field gel electrophoresis, and greater differentiation was observed using this method than rep-PCR; in general, no groups were formed based on the cultivar of origin. This study showed for the first time that endophytic bacteria from common bean plants exhibit high variability and may be useful for the development of strategies for the biological control of diseases in this important legume plant.

The psychrotrophic bacteria count and the profile of Gram-negative bacteria present in commercial Brazilian organic dairy products (27 samples, pasteurized whole milk, Minas Frescal cheese, and yoghurt, equally distributed) as well as the biofilmproducing capacity and the production of deteriorating enzymes were investigated. Most of the samples (59%) presented psychrotrophic bacteria counts higher than 4 log CFU/g, indicating problems in the microbiological quality of the products. The identification of Gram-negative bacteria revealed the presence of micro-organisms that can be potentially harmful (39.4% Acinetobacter baumanii/calcoaceticus, 23.2% Burkoderia pseudomallei, 10.1% Halfnia alvei) and/or deteriorating microorganisms (6.1% Pseudomonas aeruginosa) with the capacity of producing proteases (36.4%), lecithinases (41.4%), and lipases (4%). Roughly, 68.7% of micro-organisms were non-producers of biofilms, 28.3% were medium biofilm producers, and 3.0% were high biofilm producers. The findings suggest there are problems related to the good practices of obtaining organic milk and in the manufacture of dairy products.

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