Correlation of Fourier transform infrared spectroscopy data for optimizing Gramicidin production in corn kernel aqueous stream

In this work, an aqueous corn kernel stream (CKS) fermented in the presence of Aneurinibacillus aneurinilyticus was subjected to an extraction process with phosphate buffer saline (PBS) to evaluate the conditions that promote the production of Gramicidin (GR) in this aqueous stream. To do so, a fast and simple technique was used based on Fourier Transform Infrared Spectroscopy (FTIR) analysis combined with a statistical correlation treatment of the spectra in comparison with a standard spectrum of Gramicidin A (GR-A) and Gramicidin S (GR-S). The correlation analysis employed made it possible to obtain a similarity index using Pearson (PP) and Spearman (PS) coefficients for pairs of FTIR transmittance spectra, associated to different fermentation conditions. More favorable PPand PS similarity indices were obtained for pairs with GR-S rather than GR-A when compared with the samples under evaluation, observing that production of GR-S was promoted under high concentration of CKS (400 g/L) with similarity index of 0.752 and 0.813 for PPand PS, respectively, considering the FTIR spectra between 400 and 4000 cm−1, whereas low concentration of CKS (100 g/L) provided non favorable correlation factors (PP similarity indices lower than 0.4). The same behavior was observed when the study was considered between 1450 and 1750 cm−1 corresponding with the interval absorbance of amide I, amide II, and ammonium dominate bands in GR-S. Finally, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) corroborated this correlation study, proving that FTIR could be an interesting tool for establishing the optimal conditions of biotechnological processes. [Display omitted] •FTIR is an interesting tool for optimizing biotechnological production of Gramicidin S.•Good correlation regarding FTIR pair of data of Gramicidin S and Aneurinibacillus corn extracts.•Gramicidin S purity increased when using high corn kernel extract concentrations.•Gramicidin S purity increased with a longer fermentation time.