HMOs are a family of highly diverse glycans found exclusively in human milk, where they are the third most abundant component after lactose and lipids. They are considered a key component and many beneficial health traits have been attributed to these molecules, most notably regulating immune system response and shaping a healthy gut microbiota. These are especially important during the early development of infants. Since the latest research has shown that these components are beneficial as food additives and potential therapeutics, a growing interest has appeared in the food industry to produce and market them. So far, 200 different structures of HMOs have been discovered. They are structure-specific which means the unique benefits of each HMO are bounded to their structures. However, only 6 simplest out of 200 structures are available outside breast milk, leaving many unique benefits unexploited. One reason lies in the limited capabilities of conventional microbial fermentation method in commercializing the more complex ones.