Enzymatic routes to hydrogen and organic acids production from banana waste fermentation by autochthonous bacteria: Optimization of pH and temperature

The Central Composite Rotational Design (CCRD) was employed to find the optimum pH (5.09–7.91) and temperature (27.1–46,9 °C) for hydrogen production in banana waste (BW) fermentation by autochthonous microbial biomass. The P and Rm ranged between 6.06 and 62.43 mL H2 and 1.13–12.56 mL H2.h−1, respectively. The temperature 37 °C and pH 7.0 were the optimum conditions for P (70.19 mL H2) and Rm (12.43 mL H2.h−1) as predicted by the mathematical model. Fructose and glucose are the primary alternative carbon sources in banana waste-fed batch reactors. The high concentration of lactic acid and H2 production was associated to Lactobacillus (52–81%) and Clostridium (14–35%). However, the most important finding was about butyric acid (HBu). This acid is the better indicator of hydrogen production than acetic acid (HAc). The pH effected carbohydrates fermentation and organic acids production. The genes encoding the enzymes related to galactose, sucrose, fructose, arabinose and xylose metabolism were predominant. •The optimization of H2 production from banana waste was achieved.•H2 production is positively related to the butyrate-type.•pH had influence on Clostridium and Lactobacillus abundance.•KO (KEGG Orthology) based elucidation of metabolic pathway.