CONTRIBUTION OF S-LAYER PROTEINS TO THE MOSQUITOCIDAL ACTIVITY OF Lysinibacillus sphaericus

MARIANA C ALLIEVI; MARÍA MERCEDES PALOMINO; MARIANO PRADO ACOSTA; FINA MARTIN, JOAQUINA; PABLO WAEHNER; RUZAL SANDRA M.; SANCHEZ RIVAS CARMEN

Mar del Plata

Congreso; X Congreso Argentino de Microbiología General; 2014

Sociedad Argentina de Microbiología General

Lysinibacillus sphaericus strains belonging the antigenic group H5a5b, produce spores with larvicidal activity against Culex mosquito?s larvae. C7, a new isolated strain, that presents similar biochemical characteristics and Bin toxins in their spores as the reference strain 2362, was however up to 20-fold more active against Culex mosquitos? larvae. The contribution of the surface layer protein (S-layer) to this behaviour was envisaged since this envelope protein has been implicated in the pathogenicity of several bacilli and we have previously reported its association to spores. Microscopic observation by immunofluorescence detection with anti S-layer antibody in the spores confirms their attachment. S-layers and BinA BinB toxins formed high molecular weight multimers in spores as shown by SDS-PAGE and western blot detection. Purified S-layer from both L. sphaericus C7 and 2362 strains were by itself toxic against Culex sp larvae, however that from C7 strain was also toxic against Aedes aegypti. Synergistic effect between purified S-layer and spore-crystal preparations was observed against Culex sp. and Aedes aegypti larvae in particular with the C7 strain. In silico analysis of the S-layer sequence suggest the presence of hemolytic and chitin-binding domains. Both biochemical characteristics were observed for both S-layers´ strains that must justify their contribution to pathogenicity.