Screening and identification of lactic acid bacteria and yeast strains from raw materials with potential for application in sourdough technology<b></b>

This study focuses on the screening and identification of lactic acid bacteria (LAB) and yeast strains isolated from Kazakh raw materials, specifically wheat flour and kumis, to evaluate their potential for sourdough technology. The research was designed as a controlled experiment assessing the biotechnological properties of eight specific microbial isolates. These experimental units were allocated to standardized treatments for genetic identification via 16S rRNA and ITS sequencing, morphological characterization, and functional screening for acid production and antagonistic activity. The results identified the most active isolates as Lacticaseibacillus paracasei (strain B-319), Lacticaseibacillus rhamnosus (B-449), and Lacticaseibacillus paracasei (B-27). Morphological analysis confirmed the presence of stable, genus-specific traits, including cell morphology and the absence of sporulation. In the acidity determination assays, strain B-319 exhibited the highest acidifying capacity, reducing the medium pH to 4.55. The antagonistic screening against key bread spoilage agents—Bacillus subtilis, Bacillus mesentericus, and Penicillium notatum—revealed that strains B-449 and B-27 possess superior inhibitory potential. The findings demonstrate that these indigenous strains provide a robust biological barrier against microbial spoilage. These isolates represent high-value candidates for the development of specialized starter cultures to improve the safety, shelf life, and quality of bakery products.