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

• DOI: 10.1016/j.biteb.2019.100256
• Publication Date: 2019-06-03T06:09:12Z
• Authors: Mohamed Ali Abdel...; Saad El-Din Hassan; Mohamed M. Roushdy; Mohamed Salah Azab; Mahmoud Ali Gaber
• Keywords: 11. Sustainability; 01 natural sciences; 12. Responsible consumption; 0105 earth and related environmental sciences

Abstract 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.