Mutagenesis and Immobilization Effect on Exopolysaccharide Production by Weissella confusa and Lactobacillus delbrueckii

Abstract

Aims: This work aimed at investigating the effect of mutation and immobilization on EPS production and to characterize the EPS produced by L. delbrueckii and Weissella confusa. Study Design: To determine the effect of mutation using UV irradiation and immobilization using different matrixes on EPS production by the strains and to characterize the EPS produced. Methodology: Weissella confusa and Lactobacillus delbrueckii was exposed to UV irradiation and the wild and mutants strains was immobilized. The immobilized wild and mutants was used for EPS production. The produced EPS was characterized. Results: The LAB count that survived the UV irradiation reduced as the exposure time increases. The Wild L. delbrueckii produced more EPS (583.72 mg/L) than its mutant strain (581.42 mg/L). However, wild Weissella confusa and wild Lactobacillus delbrueckii produced more EPS than the mutant strain. Production of EPS by wild and mutant Weissella confusa immobilized in Sodium alginate (WWCNA and WWCNA), agar matrix (WWCAA and MWCAA) and polyurethane foam (WWCPF and MWCPF) ranged from 240.25 – 544.28 mg/L with WWCPF producing the highest EPS. Production of EPS by wild and mutant L. delbrueckii immobilized in Sodium alginate (IWLDNA and IMLDNA), agar matrix (IWWCAA and IMLDAA) and polyurethane foam (WLDPF and MLDPF) ranged from 220.06 – 502.81 mg/L with IWLDPF producing the highest EPS. However, immobilization in agar matrix supported the least EPS production. Characterization of the EPS using FT-IR spectroscopy confirmed the presence of the different degrees of functional groups which indicates that they are polysaccharides, thus confirming the EPS. Un-immobilized Weissella confusa had the highest EPS production (558.72 mg/L and 583.61 mg/L) compared to the immobilized strains. Conclusion: Immobilization of mutant L. delbrueckii and Weissella confusa using polyurethane foam supported EPS production.