Ibrahim Ibrahim Mohamed Ibrahim RussiaFayoum University, Egypt, Fayoum, POBox: 63514 (Egypt)imb00@fayoum.edu.eghttps://orcid.org/0000-0002-5374-3508 Author's articles Evaluation of the secondary structure of poly-γ-glutamic acid produced by Bacillus subtilis EGP5QL12 by circular dichroism spectroscopy method