**4. Conclusion**

The use of agro-industrial by-products with LAB, specifically *Lactobacillus* spp., and consequently the production of lactic acid, fits within the ideology and concept of circular economy, focusing on the pillars of economic, ecological, and social aspects. The use of material that is usually discarded represents a relief for the planet in terms of the reduction of polluting matter that thanks to innovation can be used, the reduction of costs for companies by substituting more expensive raw material for another more economically accessible, and the social contribution through the generation of employment and economic activation [51]. This favorable impact, sought by the United Nations with the fulfillment of the Sustainable Development goals proposed for the year 2030, can also be reflected in the valorization of agro-industrial by-products not only to produce lactic acid but also in other applications. Examples of these applications are nutraceutical formulations and pharmaceuticals through the use of fungal co-products [56], food packaging through the use of whey [57], valorization of lard through biotechnological tools employing fermentation in state solid of *Yarrowia lipolytica* and *Lacticaseibacillus paracasei* [58], biorefining of whey

*Use of* Lactobacillus *for Lactic Acid Production from Agro-Industrial By-Products DOI: http://dx.doi.org/10.5772/intechopen.106697*

from cheese in order to generate high-value products and eliminate environmental contamination by whey [59], revaluation of by-products of the wine industry through the application of LAB strains [60], use of fruit and vegetable by-products for the development of pharmaceutical products [61], etc.
