Antimicrobial activity of apitoxin, melittin and phospholipase A2 of honey bee (Apis mellifera) venom against oral pathogens.

In this work, we used the Minimum Inhibitory Concentration (MIC) technique to evaluate the antibacterial potential of the apitoxin produced by Apis mellifera bees against the causative agents of tooth decay. Apitoxin was assayed in natura and in the commercially available form. The antibacterial actions of the main components of this apitoxin, phospholipase A2, and melittin were also assessed, alone and in combination. The following bacteria were tested: Streptococcus salivarius, S. sobrinus, S. mutans, S. mitis, S. sanguinis, Lactobacillus casei, and Enterococcus faecalis. The MIC results obtained for the commercially available apitoxin and for the apitoxin in natura were close and lay between 20 and 40 µg / mL, which indicated good antibacterial activity. Melittin was the most active component in apitoxin; it displayed very promising MIC values, from 4 to 40 µg / mL. Phospholipase A2 presented MIC values higher than 400 µg / mL. Association of mellitin with phospholipase A2 yielded MIC values ranging between 6 and 80 µg / mL. Considering that tooth decay affects people's health, apitoxin and its component melittin have potential application against oral pathogens.

Bacteriophages and insertion sequences of Chromobacterium violaceum ATCC 12472.

A fluid genome is a great advantage to prokaryotes, enabling quick adaptation to various types of ecological niches and to diverse environmental selective pressures. A substantial portion of these sudden changes is mediated by lateral gene transfer (LGT), through genetic recombination mechanisms, such as transformation, conjugation and transduction. The recent sequencing of several organisms has offered a new approach to the study of LGT, using comparison and analysis of nucleotide sequences dispersed throughout the genome of these species. This analysis in Choromobacterium violaceum has revealed four prophage and 12 insertion sequences, suggesting genetic exchange with several other bacterial species, including Salmonella enterica, Ralstonia and Xanthomonas. An Rhs (recombination hot spot) element (containing a vgr-like gene) was also observed, the function of which remains unknown, but it has a sequence related to species of Acinetobacter and Sphingomonas. These results support the role of LGT in the acquisition of new traits by C. violaceum.