Thermophilic biocatalysts for one-step conversion of citrus waste into lactic acid

• DOI: 10.1007/s00253-023-12904-7
• Publication Date: 2024-01-20T07:02:41Z
• Authors: Martina Aulitto; Alberto Alfano; Emanuela Maresca; Roberto Avolio; Maria Emanuela Er...; Gennaro Gentile; Flora Cozzolino; Maria Monti; Annachiara Pirozzi; Francesco Donsì; Donatella Cimini; Chiara Schiraldi; Patrizia Contursi
• Keywords: 0301 basic medicine; Bacillus coagulans; Citrus waste; Fed-batch fermentation; Lactic acid; W. coagulans; Lactic acid; W. coagulans; Citrus waste; Fed-batch fermentation; 03 medical and health sciences; Environmental Biotechnology; Glucose; Food; Fermentation; Lactic Acid

Abstract Agri-food residues offer significant potential as a raw material for the production of L-lactic acid through microbial fermentation. Weizmannia coagulans, previously known as Bacillus coagulans, is a spore-forming, lactic acid-producing, gram-positive, with known probiotic and prebiotic properties. This study aimed to evaluate the feasibility of utilizing untreated citrus waste as a sustainable feedstock for the production of L-lactic acid in a one-step process, by using the strain W. coagulans MA-13. By employing a thermophilic enzymatic cocktail (Cellic CTec2) in conjunction with the hydrolytic capabilities of MA-13, biomass degradation was enhanced by up to 62%. Moreover, batch and fed-batch fermentation experiments demonstrated the complete fermentation of glucose into L-lactic acid, achieving a concentration of up to 44.8 g/L. These results point to MA-13 as a microbial cell factory for one-step production of L-lactic acid, by combining cost-effective saccharification with MA-13 fermentative performance, on agri-food wastes. Moreover, the potential of this approach for sustainable valorization of agricultural waste streams is successfully proven.

Key points • Valorization of citrus waste, an abundant residue in Mediterranean countries. • Sustainable production of the L-( +)-lactic acid in one-step process. • Enzymatic pretreatment is a valuable alternative to the use of chemical.

Graphical Abstract