Technological Interest and Antimicrobial Activity of Lactic Acid Bacteria Isolated from Date Paste of the Ghers Variety (Bechar, South-West of Algeria)

Background: Dates are high nutritional value fruits. They are the basis of many traditional products and compose several oases by-products. Among these products, date paste represents a form of conservation widely practiced in Algeria to valorize common date’s surplus production for commercial purposes. Methods: First, microbiological analysis was carried out to isolate lactic acid bacteria (LAB) from date’s paste and microbial contaminants from both date fruit by-products according to standard microbiological methods before investigating the technological characteristics attributed to the isolated LAB. Second, the antimicrobial effect was evaluated through three different techniques. Result: Nine microbial contaminants were isolated from date paste and date extract, while eight LAB strains were isolated from date paste, which belong to the Streptococci and Leuconostoc strains. The SLM1 strain revealed a good acidifying power going up to 5.13 g/L of lactic acid within 6 hours of incubation compared to the other LAB strains. A moderate to strong antibacterial effect ranging up to a 20 mm zone of inhibition was revealed against bacterial contaminants. In decreasing order, the antifungal effect was significant against Penicillium sp, Aspergillus niger and A. flavus. The isolated lactic strains of streptococci could be good candidates for food preservation by extending the shelf life of foods and improving their nutraceutical and hygienic quality.