Antagonistic activity expressed by Shigella sonnei: identification of a putative new bacteriocin

Abstract

Bacteriocins are antibacterial, proteinaceous substances that mediate microbial dynamics. Bacteriocin production is a highly disseminated property among all major lineages of bacteria, including Shigella. In this paper, we addressed the purification and characterisation of a bacteriocin produced by a Shigella sonnei strain (SS9) isolated from a child with acute diarrhoea. The substance was purified through ammonium-sulphate precipitation and sequential steps of chromatography. The intracellular fraction obtained at 75% ammonium sulphate maintained activity following exposure to pH values from 1-11 and storage at -80ºC for more than two years and was inactivated by high temperatures and proteases. The molecular mass of the purified bacteriocin was determined by mass spectrometry to be 18.56 kDa. The N-terminal sequence of the bacteriocin did not match any other antibacterial proteins described. A putative new bacteriocin produced by S. sonnei has been detected. This bacteriocin may represent a newly described protein or a previously described protein with a newly detected function. Considering that SS9 expresses antagonism against other diarrhoeagenic bacteria, the bacteriocin may contribute to S. sonnei virulence and is potentially applicable to either preventing or controlling diarrhoeal disease.

Partial Characterization of Novel Bacteriocin SF1 Produced by Shigella flexneri and Their Lethal Activity on Members of Gut Microbiota

“…According to the results, bacteriocin SF1 maintains antibacterial capacity at 80°C, but not at 100°C. The thermolability at 100 and 121°C of this antagonistic substance is also consistent with its chemical composition and corroborates data reported by other authors who have demonstrated that colicins produced by Shigella are generally heat labile [7, 20]. By SDS-PAGE, a single band was obtained for bacteriocin SF1.…”

RESEARCH, EXTRACTION AND PARTIAL CHARACTERIZATION OF BACTERIOCIN-TYPE ANTAGONIST SUBSTANCE PRODUCED BY Fusobacterium necrophorum

“…Enzyme solutions were filter-sterilized (Millex-GP, 0.22 µm, PES), aliquots of C-50 and C-80 were two-fold diluted in each enzyme solution, and mixtures were incubated at 37ºC for 2 h. Remaining antagonistic activity after enzyme treatment was determined as described previously. Diluted C-50 and C-80 (0.01 M Tris-HCl, pH 7.2) and enzyme solutions were used as controls [28].…”

PLASMÍDIOS CONJUGATIVOS ISOLADOS DO ENTEROPATÓGENO Shigella sonnei CODIFICAM SUBSTÂNCIA(S) ANTAGONISTA(S) E RESISTÊNCIA ANTIMICROBIANA

“…After centrifugation at 29,830 g, for 30 min, at 4° C sediments were dissolved in the same buffer, generating the intracellular extracts named as C-30 and C-75. C-75 was dialyzed against the same buffer at 4°C overnight, aliquoted, and kept at -80 °C (Moreira, 2011, Sousa et al 2013.…”

“…After incubation at the same conditions described before, the presence of inhibition zones was considered indicative of antagonistic activity. Tris-HCl buffer and ultrapure water were employed as controls (Booth et al 1977;Sousa et al 2013). The assay was used to determine the antagonistic activity of the samples obtained from the purification steps.…”