Isolation, characterization and complete genome sequence of PhaxI: a phage of Escherichia coli O157 :H7

Bacteriophages are considered as promising biological agents for the control of infectious diseases. Sequencing of their genomes can ascertain the absence of antibiotic resistance, toxin or virulence genes. The anti-O157 :H7 coliphage, PhaxI, was isolated from a sewage sample in Iran. Morphological studies by transmission electron microscopy showed that it has an icosahedral capsid of 85–86 nm and a contractile tail of 115�15 nm. PhaxI contains dsDNA composed of 156 628 nt with a G+C content of 44.5 mol% that encodes 209 putative proteins. In MS analysis of phage particles, 92 structural proteins were identified. PhaxI lyses Escherichia coli O157 :H7 in Luria-Bertani medium and milk, has an eclipse period of 20 min and a latent period of 40 min, and has a burst size of about 420 particles per cell. PhaxI is a member of the genus ‘Viunalikevirus’ of the family Myoviridae and is specific for E. coli O157 : H7

Recombinant Nep1 From Fusarium oxysporum as a biological agent for control of Convolvulus arvensis

Introduction: Nep1 is a natural bio-herbicide protein which has an effective necrosis stimulant in dicotyledonous weeds. This protein was first purified in 1995 form fermentation broth of Fusarium oxysporum. Materials and methods: In this study, the nep1gene was isolated form F. oxysporum, after removal of signal peptide from the beginning of the gene; final pET16b-nep1 construct was cloned and transformed into E. coli BL21 (DE3). The recombinant Nep1 was produced in E. coli. Recombinant protein was purified, diluted and prepared for biological assay on weed. Results: Two ml of recombinant Nep1 with 60 µg/ ml final concentrations was sprayed on Convolvulus arvensis. Our results showed necrosis and chlorosis symptoms were started on the plant leaves after 2 days, also significant necrosis on the leaves of C. arvensis was seen after 5 days. No necrosis lesion was seen in the negative control plants that sprayed only with buffer and denatured recombinant Nep1 in 100 ºC for 15 min. Discussion and conclusion: Our results introduced recombinant Nep1 as a biological potent agent for biocontrol of C. arvensis