Preliminary Study on Some Actinomycetes and Evaluation of Their Potential Antagonism against Fungal Pathogens.

Aims: Control of microbial pathogens by using antagonistic microorganisms is a promising alternative to chemical fungicides. The objective of the present study was to isolate and characterize soil actinomycetes and to their inhibitory activity against some fungal plant pathogens. Place and Duration of Study: National Park “El Chico”, Hidalgo State, and Laboratory of the Southeast Unit of CIATEJ, Yucatán, México, between June 2010 and May 2011. Methodology: Actinomycete species were isolated from six composite soil samples using microbiological standard procedures. All isolates were phenotypically characterized. Antagonistic isolates were selected according to the inhibitory growing of Fusarium sp. and Candida albicans. Afterwards, a new evaluation for the isolates selected was done against Helminthosporium sp., Curvularia sp., and Aspergillus niger. Actinomycetes were identified performing an analysis of the 16S rDNA gene sequence. Results: 164 actinomycete strains were characterized by morphological and biochemical features. Six of them, inhibited the growth of Fusarium sp. and C. albicans from 5 to 10 mm distance in between the actinomycete´s colony growth border of fungal or yeast. A growing reduction from 50 to 83 % in the in vitro antagonism assays was observed for Helminthosporium sp., Curvularia sp., and Aspergillus niger. Results in disc diffusion assays suggested an inhibitory growing capacity of CACIA-1.46HGO for P. capsici, this behavior could be due to the production of diffusible compounds related to secondary metabolism, hydrolytic enzymes, or both of them. Four antagonistic isolates were identified into Streptomyces genus and one as Microbacterium sp. through 16S rDNA gene sequence. Conclusion: Actinomycetes could be potentially a control tool to prevent several fungal commercial plants diseases. However, in situ isolate evaluations are suggested to be investigated.

In vitro cell activating properties of the composite ribosomal vaccine D53

D53 (RibomuntyR) is a composite vaccine made of immunogenic ribosomes from 4 bacterial species (Klebsiella pneumoniae, Haemophilus influenzae, Streptococcus pyogenes and Streptococcus pneumoniae) associated with a membrane proteoglycan from a non encapsulated strain of Klebsiella pneumoniae. D53 is a potent inducer of interleukin-1 production by mouse BALB/c spleen cells as shown by the C3H/HeJ thymocyte co-stimulation assay. Furthermore D53 triggers DNA synthesis by mouse spleen cells and induces the maturation of B lymphocytes into immunoglobulin secreting cells. Polyclonal B cell activation by D53 was readily achieved in the C3H/HeJ strain which is deficient in its response to E. coli lipopolysaccharide. The proliferative response to D53 was abrogated by removal of B cells from the spleen cell suspension, but it was not altered after depletion of T cells or adherent cells. D53 induced polyclonal B cell activation of spleen cells from athymic nude mice and from CBA/N mice. Each component of D53 induced polyclona B cell activation except ribosomes from Streptococcus pneumoniae. Each triggered Interleukin-1 synthesis except ribosomes from Klebsiella penumoniae. These in vitro properties may account for some of the in vivo immunostimulating properties of this composite vaccine.