Contribution of S-Layer Proteins to the Mosquitocidal Activity of Lysinibacillus sphaericus

Abstract

Lysinibacillus sphaericus strains belonging the antigenic group H5a5b produce spores with larvicidal activity against larvae of Culex mosquitoes. C7, a new isolated strain, which presents similar biochemical characteristics and Bin toxins in their spores as the reference strain 2362, was, however, more active against larvae of Culex mosquitoes. 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 had 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 and 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 strain cultures was 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. This effect was more evident with the C7 strain. In silico analyses of the S-layer sequence suggest the presence of chitin-binding and hemolytic domains. Both biochemical characteristics were detected for both S-layers strains that must justify their contribution to pathogenicity.

A genome-scale metabolic reconstruction of Lysinibacillus sphaericus unveils unexploited biotechnological potentials

“…sphaericus TL [25]. There are several hypotheses about how this protein works and how it is regulated.…”

Biological Control Activities of Rice-Associated Bacillus sp. Strains against Sheath Blight and Bacterial Panicle Blight of Rice

“…xylanilyticus were shown to have antimicrobial activities against foodborne bacterial and fungal pathogens possibly through bacteriocins [ 61 ] and some strains of L . sphaericus have toxic activities against the larvae of Culex mosquitoes, which are conferred at least in part by S-layer proteins [ 62 ] and Mtx toxins [ 63 ]. L .…”

Complete Genome Sequence of Lysinibacillus sphaericus WHO Reference Strain 2362

“…After its grade of mosquitocidal activity was confirmed, this strain was introduced into the WHO Collaborating Centre (Columbus, OH, USA) ( 2 ). Since then, this strain has been extensively used, not only as a reference in research about larvicidal activity of L. sphaericus ( 1 , 3 ), but also as a point of comparison for studying metal tolerance ( 4 , 5 ), the structure of surface proteins such as the S-layer ( 6 , 7 ), and biosurfactant production ( 8 ).…”