Bioconversion of Corn Crop Residues: Lactic Acid Production through Simultaneous Saccharification and Fermentation

Lactic acid (LA) is a chemical building block with wide applications in the food, cosmetics, and chemical industries. Its polymer polylactic acid further increases this range of applications as a green and biocompatible alternative to petrol-based plastics. Corn is the fourth largest crop in the world, and its residues represent a potentially renewable feedstock for industrial lactic acid production through simultaneous saccharification and fermentation (SSF). The main goal of this work is to summarize and compare the pretreatment methods, enzymatic formulations and microbial strains that have been combined in a SSF setup for bioconversion of corn crop residues into LA. Additionally, the main concerns of scaling-up and the innovation readiness level towards commercial implementation of this technology are also discussed. The analysis on commercial implementation renders the current state of SSF technology unsustainable, mainly due to high wastewater generation and saccharification costs. Nonetheless, there are promising strategies that are being tested and are focused on addressing these issues. The present work proves that the study and optimization of SSF as a biorefinery framework represents a step towards the adoption of potentially sustainable waste management practices.