Enhanced fermentative lactic acid production from source-sorted organic household waste: Focusing on low-pH microbial adaptation and bio-augmentation strategy

• Published in: The Science of the total environment Vol. 808; p. 152129
• Main Authors: Zhang, Zengshuai, Tsapekos, Panagiotis, Alvarado-Morales, Merlin, Zhu, Xinyu, Zervas, Athanasios, Jacobsen, Carsten S., Angelidaki, Irini
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 20.02.2022
• Subjects: Acidic fermentation; Adaptation process; Fermentation; Hydrogen-Ion Concentration; Lactic Acid; Source-sorted organic household waste; Sugars; Acidic fermentation; Lactic acid; Source-sorted organic household waste; Adaptation process
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2021.152129

Lactic acid (LA) production at low pH could significantly reduce the need for neutralizing agents, leading to reduction of operational costs. In the present study, LA production at acidic conditions was investigated using source-sorted organic household waste (SSOHW). Controlling the pH at low value (i.e. 5.0) and bio-augmenting with Pediococcus acidilactici led to a concentration of 39.3 ± 0.5 g-LA/L with a yield of 0.75 ± 0.02 g-LA/g-sugar. In contrast, secondary fermentation at higher pH level (i.e. 5.5 and 6.0) resulted in complete LA degradation. Subsequently, consecutive batch fermentations were conducted to adapt P. acidilactici to SSOHW and improve the LA production. Results showed that P. acidilactici could successively adapt in the SSOHW reaching a relative abundance above 2.8% at adaptation process. The added P. acidilactici ensured a high concentration of LA at three consecutive generations, achieving an increment above 18% compared to control test (abiotic augmentation). Moreover, adaptation processes (i.e. maintaining pH at 4.0 or stepwise decreasing the pH from 5.0 to 4.0) significantly improved LA concentration and productivity at the pH of 4.0. Overall, the results provide a promising method to reduce the LA production costs using residual resources. [Display omitted] •P. acidilactici could adapt in source-sorted organic household waste.•Bio-augmentation with P. acidilactici boosted lactic acid concentration by 18%.•Inhibitory effect of acid stress was relieved by adaptation process.•Adaptation of stepwise pH decrease was more efficient to increase LA production.