Isolement et caractérisation de souches probiotiques d’origine algérienne à potentiel psychobiotique et application dans un produit laitier fonctionnel

Abstract

Fermented dairy products represent an important source of indigenous lactic acid bacteria (LAB) with potential technological and probiotic properties. The present study aimed to isolate and characterize autochthonous lactic acid bacteria from Algerian Raïb and to evaluate their safety, probiotic characteristics, technological robustness and functional properties related to a potential psychobiotic activity. Three types of Raïb, including traditional and commercial products, were investigated. The experimental approach included isolation and purification of presumptive LAB, phenotypic and biochemical characterization, molecular identification, assessment of technological and safety-related traits, and evaluation of selected probiotic properties. Nine bacterial isolates were obtained from Raïb samples. Six isolates exhibited a bacillary morphology, while three were coccoid; all isolates were Gram-positive and catalase-negative, consistent with the general characteristics of lactic acid bacteria. Biochemical characterization revealed a homogeneous fermentative profile among the isolates. Based on their overall characteristics, three isolates (RS1, RH1 and RT1) were selected for further probiotic evaluation. These isolates showed the ability to maintain viability under bile salt stress at 0.3%, with mean survival rates of 36.34 ± 0.52%, 43.28 ± 4.49% and 71.21 ± 26.42%, respectively. The isolates also displayed tolerance to several technological stresses, supporting their potential for further investigation as functional starter cultures. The study highlights the Algerian Raïb as a valuable reservoir of indigenous LAB with promising physiological and technological characteristics. However, the available data do not allow a definitive classification of the selected isolates as probiotics or psychobiotics. In particular, quantitative data on GABA production and short-chain fatty acids were not available for interpretation. Further molecular, functional and technological investigations are therefore required to confirm the identity, safety, probiotic potential and possible psychobiotic functionality of the selected strains and to assess their suitability for incorporation into a functional fermented dairy product.