**Abstract**

Lactic acid bacteria are gram-positive microorganisms that are characterized by the production of lactic acid as a key fermentation product. LAB, specifically *Lactobacillus delbrueckii* subsp. *bulgaricus*, are essential dairy starter cultures for the manufacture of several fermented dairy products such as yogurt. Some LAB are useful microorganisms and are well known to have probiotic effects to provide foods with unique sensory qualities such as aroma and taste. Probiotic strains help to strengthen the human immune system, increasing the body's resistance to diseases. Additionally, probiotics and postbiotics improve gut microbiome balance and prevent health issues. Postbiotics are substances that are produced by microbes' metabolic activities and have a positive impact on diseases, either directly or indirectly. Extensive research has shown that postbiotics possess immunomodulatory and significant clinical effects. Their use has been found to enhance general health and alleviate symptoms of various disorders in healthy individuals. Furthermore, postbiotics exhibit anti-inflammatory, antioxidant, and anticancer properties. Therefore, this chapter presents an overview and the importance of LAB as a probiotic and its importance to human health, metabolic fermentation, and antioxidant potential. The review also discusses different biotechnological methods that improve the survival rate of probiotics during processing and GIT transit like microbial encapsulation.

**Keywords:** lactic acid bacteria (LAB), probiotics, lactobacillus, postbiotics, bifidobacteria, delivery system, microorganisms
