[Metchnikoff and a century of probiotics. From intuition to science]

Microbiology, a scientific field dedicated to the study of microorganisms, has undergone profound development since its inception in the 17th century. Its history is marked by key discoveries and technological advancements that have shaped our understanding of life at the microscopic level and transformed medicine, agriculture, and industry.Early Foundations of MicrobiologyThe early foundations of microbiology were built on groundbreaking observations and the development of pioneering...

Probiotics are live, non-pathogenic microorganisms that confer health benefits by modulating the gut microbiota. The human gastrointestinal tract harbors a complex microbial ecosystem, and the balance of this microbiota is crucial for digestive and systemic health. Among the most extensively studied and utilized probiotics are species formerly classified within the genera Lactobacillus and Bifidobacterium. These organisms not only naturally colonize the human gut but are also consumed through...

Microorganisms play a fundamental role in vaccine development, gene therapy, and therapeutic production. Their biological properties are harnessed to advance medicine and public health. Beyond immunization, microorganisms contribute to gut health, antibiotic synthesis, and genetic disease treatment.Live Attenuated and Inactivated VaccinesLive attenuated vaccines, such as the measles, mumps, and rubella (MMR) vaccine, utilize weakened forms of pathogens to closely resemble natural infections.

Microorganisms colonize various regions of the human body, including the mouth, nasal passages, throat, stomach, intestines, urogenital tract, and skin. The total number of microbial cells is estimated to range from 10¹³ to 10¹⁴—comparable to, or exceeding, the number of human somatic cells. This host–microbiome relationship has led to the conceptualization of humans as supraorganisms, wherein microbial communities perform vital roles in development, immunity, and disease...

Antibiotics have revolutionized modern medicine by saving countless lives from bacterial infections. However, their widespread use has inadvertently harmed the delicate balance of the human gut microbiota. The gut microbiota, a complex community of bacteria, archaea, viruses, and fungi, plays a vital role in regulating metabolism, immune responses, and maintaining intestinal health. Antibiotics, especially broad-spectrum types, disrupt this ecosystem by eradicating both harmful and beneficial...

Lactic acid bacteria (LAB) and molds are instrumental in fermenting plant-based foods to enhance preservation and ensure year-round availability. These microbial processes convert plant carbohydrates into organic acids and other metabolites that inhibit spoilage organisms and contribute to the sensory qualities of the final product.In sauerkraut production, cabbage goes through a microbial succession that starts with cocci such as Leuconostoc mesenteroides. These microbes begin fermentation by...