Evaluation of Isolation Method of Exopolysaccharide Produced by Lactobacillus Acidophilus

Exopolysaccharides (EPS) are produced by various microorganisms, including lactic acid bacteria (LAB), which are recognized as food-grade organisms.Furthermore, these compounds have been strongly suggested to possess health-promoting properties.This study examines the potential of two strains of Lactobacillus acidophilus, namely L. acidophilus LAC-1 and L. acidophilus ATCC 4356 which was used as a positive control strain for EPS production, to produce EPS when cultivated on MRS medium supplemented with 2% (w/v) lactose.The study also evaluates the performance of the EPS isolation method, particularly with regard to potential interference from proteinaceous materials in EPS quantification.Both strains exhibited comparable growth and EPS production patterns.Analysis of various EPS and supernatant fractions revealed the presence of interferents, including proteinaceous materials from the fermentation medium.These types of interferents likely interact with the carbohydrates in the medium, leading to an overestimation of the levels of crude EPS produced.Nonetheless, employing more efficient EPS isolation methods can mitigate this issue.In the current study, it was observed that by incorporating at least two purification/precipitation steps in the isolation process, the presence of sugars and proteins in the medium is significantly reduced, reaching in the case of protein a maximum reduction of 89% for L. acidophilus LAC-1 and 91% for L. acidophilus ATCC 4356 strains.