title: Colicin type 7 produced by majority of Shigella sonnei isolated from Thai patients with diarrhoea.
abstract: Thirty one out of 153 strains of Shigella sonnei isolated from Thai patients with diarrhoea showed antibacterial activity against S. sonnei by agar well diffusion method. All of them harbor plasmids with the genetic determination of colicin type 7 (Js) gene but without colicin E and colicin U gene. The PCR product obtained from strain 35/44 was shown to be the gene for colicin type 7 lytic protein (cja). The partially purified bacteriocin (PPB) containing colicin type 7 of strain 35/44 was prepared and used for characterization. The antibacterial activity of PPB against a total of 17 selected Gram-positive and Gram-negative bacteria was tested. It was found that PPB of strain 35/44 was active against E. coli O157, S. sonnei and S. boydii. The sensitivity of PPB from this strain to proteinase K, trypsin and α-chymotrypsin suggests the proteinaceous nature of these antimicrobial substances. Therefore, this isolated bacterium can be regarded as bacteriocin producing bacteria. The bacteriocin produced by this isolated S. sonnei was heat stable as evidenced by its ability to maintain the activity at 80 °C for 60 min. In addition, it was stable within a wide range of pH (3-9). The molecular weight of colicin type 7 from isolated S. sonnei strain 35/44 analyzed by SDS-PAGE was 54.4 kDa composing of at least five subunits. It is to our knowledge; the first report of Thai patients with diarrhoea that S. sonnei isolated from them contained colicin type 7.
authors: Graduate Program in Biomedical Sciences, Faculty of Allied Health Sciences, Thammasat University, Rangsit Campus, Klonglaung, Pathumthai, Thailand.
authors: Siriporn
authors: S
authors: Kaewklom
authors: Department of Medical Technology, Faculty of Allied Health Sciences, Thammasat University, Rangsit Campus, Klonglaung, Pathumthai, Thailand.
authors: Seksun
authors: S
authors: Samosornsuk
authors: Department of Medical Technology, Faculty of Allied Health Sciences, Thammasat University, Rangsit Campus, Klonglaung, Pathumthai, Thailand.
authors: Duangnate
authors: D
authors: Pipatsatitpong
authors: Graduate Program in Biomedical Sciences, Faculty of Allied Health Sciences, Thammasat University, Rangsit Campus, Klonglaung, Pathumthai, Thailand.
authors: Ratchaneewan
authors: R
authors: Aunpad
mesh_terms: D003087:Colicins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D004405:Dysentery, Bacillary / Q000382:microbiology*; D004591:Electrophoresis, Polyacrylamide Gel; D006090:Gram-Negative Bacteria / Q000187:drug effects; D006094:Gram-Positive Bacteria / Q000187:drug effects; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008970:Molecular Weight; D010957:Plasmids / Q000032:analysis; D055550:Protein Stability; D059748:Proteolysis; D012764:Shigella sonnei / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism*; D013696:Temperature; D013785:Thailand
chemical_list: D003087:Colicins
keywords: Shigella sonnei; colicin type 7; diarrhoea