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Antimicrobial protein candidates from the thermophilic Geobacillus sp. Strain ZGt-1 : Production, proteomics, and bioinformatics analysis

  • Rawana N. Alkhalili
  • Katja Bernfur
  • Tarek Dishisha
  • Gashaw Mamo
  • Jenny Schelin
  • Björn Canbäck
  • Cecilia Emanuelsson
  • Rajni Hatti-Kaul
Publishing year: 2016-08-19
Language: English
Publication/Series: International Journal of Molecular Sciences
Volume: 17
Issue: 8
Document type: Journal article

Abstract english

A thermophilic bacterial strain, Geobacillus sp. ZGt-1, isolated from Zara hot spring in Jordan, was capable of inhibiting the growth of the thermophilic G. stearothermophilus and the mesophilic Bacillus subtilis and Salmonella typhimurium on a solid cultivation medium. Antibacterial activity was not observed when ZGt-1 was cultivated in a liquid medium; however, immobilization of the cells in agar beads that were subjected to sequential batch cultivation in the liquid medium at 60 °C showed increasing antibacterial activity up to 14 cycles. The antibacterial activity was lost on protease treatment of the culture supernatant. Concentration of the protein fraction by ammonium sulphate precipitation followed by denaturing polyacrylamide gel electrophoresis separation and analysis of the gel for antibacterial activity against G. stearothermophilus showed a distinct inhibition zone in 15-20 kDa range, suggesting that the active molecule(s) are resistant to denaturation by SDS. Mass spectrometric analysis of the protein bands around the active region resulted in identification of 22 proteins with molecular weight in the range of interest, three of which were new and are here proposed as potential antimicrobial protein candidates by in silico analysis of their amino acid sequences. Mass spectrometric analysis also indicated the presence of partial sequences of antimicrobial enzymes, amidase, and DD-carboxypeptidase.


  • Microbiology
  • Biochemistry and Molecular Biology
  • Antimicrobial proteins
  • Cell-recycling
  • Food spoilage bacteria
  • Geobacillus
  • Immobilization
  • SDS-resistant proteins
  • Thermophile


  • Microbial Ecology
  • ISSN: 1661-6596
Björn Canbäck
E-mail: bjorn [dot] canback [at] biol [dot] lu [dot] se

Senior lecturer

Molecular Cell Biology

+46 46 222 94 19

+46 73 022 62 50


Sölvegatan 35, Lund