Screening, optimization and characterization of exopolysaccharides produced by novel strains isolated from Moroccan raw donkey milk

Reda Derdak; Souraya Sakoui; Oana Lelia Pop; Dan Cristian Vodnar; Boutaina Addoum; Abdelhakim Elmakssoudi; Faouzi Errachidi; Ramona Suharoschi; Abdelaziz Soukri; Bouchra El Khalfi

doi:10.1016/j.fochx.2022.100305

Screening, optimization and characterization of exopolysaccharides produced by novel strains isolated from Moroccan raw donkey milk

Food Chem X. 2022 Apr 9:14:100305. doi: 10.1016/j.fochx.2022.100305. eCollection 2022 Jun 30.

Authors

Affiliations

¹ Laboratory of Physiopathology, Molecular Genetics & Biotechnology, Faculty of Sciences Ain Chock, Health and Biotechnology Research Centre, Hassan II University of Casablanca, Maarif B.P 5366, Casablanca, Morocco.
² Department of Food Science, University of Agricultural Science and Veterinary Medicine, 3-5 Calea Mănăștur, Cluj-Napoca 400372, Romania.
³ Molecular Nutrition and Proteomics Lab, CDS3, Life Science Institute, University of Agricultural Science and Veterinary Medicine, Calea Mănăștur 3-5, Cluj-Napoca 400372, Romania.
⁴ Food Biotechnology and Molecular Gastronomy, CDS7, Life Science Institute, University of Agricultural Science and Veterinary Medicine, Calea Mănăștur 3-5, Cluj-Napoca 400372, Romania.
⁵ Department of Chemistry, Laboratory of Organic Synthesis, Extraction, and Valorization, Faculty of Sciences Aïn Chock, Hassan II University of Casablanca, Maarif B.P 5366, Casablanca, Morocco.
⁶ Laboratory of Functional Ecology and Engineering Environment, Faculty of Sciences and Technologies, Sidi Mohamed Ben Abdellah University, Imouzzer Street, B.P. 2202, Fez, Morocco.

Abstract

Two exopolysaccharides (EPS) producing strains, isolated from raw donkey milk were identified as Leuconostoc mesenteroides SL and Enterococcus viikkiensis N5 using 16S rDNA sequencing. The Box Benheken design exhibited the highest yield of EPS-SL (672.342 mg/L) produced by SL and of EPS-N5 (901 mg/L) produced by N5. The molecular weight was 1.68×10⁴ for EPS-SL and 1.55×10⁴ Da for EPS-N5. FTIR, NMR and GC-MS analysis showed that the EPS are heteropolysaccharides. The SEM image showed that the EPS-SL was smooth and represented a lotus leaf shape and EPS-N5 revealed a stiff-like, porous appearance and was more compact than EPS-SL. The TGA analyses showed high thermal stability and degradation temperature. Additionally, the two EPSs possessed antibacterial and antioxidant activity, and the EPS-SL had the stronger antioxidant activity. Consequently, these results suggest that the functional and biological properties of EPS-SL and EPS-N5 imply the potential application in the food and pharmaceutical industries.

Keywords: Biological activity; Characterization; Donkey milk; Exopolysaccharide; Optimization.