Free-nutrient supply and thermo-alkaline conditions for direct lactic acid production from mixed lignocellulosic and food waste materials

• Published in: Bioresource technology reports Vol. 7; p. 100256
• Main Authors: Abdel-Rahman, Mohamed Ali, Hassan, Saad El-Din, Roushdy, Mohamed M., Azab, Mohamed Salah, Gaber, Mahmoud Ali
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.09.2019
• Subjects: Banana peels; Food wastes; Lactic acid; Mixed waste fermentation; Thermo-alkaline fermentation; Thermo-alkaline fermentation; Lactic acid; Mixed waste fermentation; Food wastes; Banana peels
• ISSN: 2589-014X; 2589-014X
• DOI: 10.1016/j.biteb.2019.100256

This study aimed to achieve effective lactic acid (LA) production from waste materials. From natural sources on banana peels-containing media, 253 bacterial isolates were obtained. Isolate FW26 was selected for LA production from untreated banana peels (no pre-treatment) at pH 9.0 and 50 °C. It was identified as Enterococcus faecium strain FW26 using 16S rRNA sequencing. The optimal solid-to-liquid ratio was 1:10 (w/v) achieving LA at 15.9 g L−1 from direct utilization of banana peels. Utilization of co-substrates achieved positive synergistic effects on growth and LA production. Fermentation of banana peels and food wastes mixture (1:1.5, w/w) exhibited 22.2% improvements in LA concentration. Besides, exclusion of medium components achieved comparable LA fermentation parameters to that obtained with nutrient supplementation. Moreover, controlling of fermentation pH exhibited 81% improvements in LA concentration achieving 33.3 ± 2.6 g L−1 with yield of 0.84 g g−1-consumed sugars. This indicate the potentiality of strain FW26 for LA production by direct utilization of untreated mixed wastes without nutrient supplementation under thermo-alkaline conditions. •Thermo-alkaliphilic lactic acid bacterium, Enterococcus faecium FW26, was isolated.•Strain FW26 produced lactic acid (LA) by direct utilization of banana peels.•Co-utilization of food waste and banana peels depicted synergism.•LA was produced from untreated mixed wastes without nutrient supplementation.•Strain FW26 produces lactic acid from wastes with yield of 84% g/g-consumed sugars.