Irritable bowel syndrome (IBS) is a prevalent gut disorder linked to changes in the gut microbiota, including lactic acid bacteria (LAB). However, research on LAB biodiversity in IBS patients is limited. This study aimed to compare LAB microbiota in healthy individuals and those with IBS through biochemical and molecular techniques. Fecal samples from 15 IBS patients and 13 healthy individuals were collected, and LAB were isolated using biochemical methods. Fifty isolates were chosen based on Gram staining and catalase tests and identified through 16S rRNA gene sequencing. A phylogenetic tree was used to analyze strain diversity, and correlation diagrams and swarm plots were employed to explore variable relationships. The study revealed a significant difference in LAB numbers between IBS and healthy subjects, with average of 5.91 and 6.63, respectively. Most bacteria were Gram-positive cocci or bacilli, with homofermentative characteristics, except for one heterofermentative sample from the healthy group. Both IBS and healthy groups exhibited strains from Lactobacillus and Enterococcus genera, with Enterococcus faecium being predominant in both. Demographic analysis showed higher IBS prevalence among individuals aged 20–40, with IBS-C more common in women and IBS-D in men. The study concluded that individuals with IBS had significantly lower LAB microbiota counts, potentially impacting intestinal defense function. Further exploration of LAB behavioral and immunomodulatory traits may enhance understanding of intestinal microbiota\\\\\\\'s role in IBS and aid in developing treatment strategies.

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