초록
<P><B>Abstract</B></P> <P>The objective of this study was to screen the factors that affect H<SUB>2</SUB>, organic acids and alcohols production from coffee waste pretreated in a hydrothermal reactor applying consortium of bacteria and fungi (indigenous from coffee waste) with hydrolytic and fermentative activity. The effects of pH (4.0–7.0), temperature (30–50 °C), agitation (0–180 rpm), headspace (50–70%), percentage of bioaugmentation (without microbial consortium to 20%), concentration of coffee pulp and husk (2–6 g/L), coffee processing wastewater (7-30 gCOD/L) and yeast extract (0–2 g/L) were evaluated using a Plackett-Burman design. The highest H<SUB>2</SUB> production potential (82 ml H<SUB>2</SUB>) was obtained under the following conditions: 30 °C, 180 rpm, 50% headspace, without bioaugmentation, 2 g/L pulp and husk coffee, 30 gCOD/L coffee processing wastewater and 2 g/L yeast extract. The main soluble products were acetic acid (1956 mg/L), lactic acid (786 mg/L) and ethanol (816 mg/L). <I>Lactobacillus</I> sp., <I>Clostridium</I> sp., <I>Saccharomyces</I> sp. and <I>Kazachstania</I> sp. were the main autochthonous microorganisms identified. Through metagenome functional analysis, enzymes related to lignin, phenol, cellulose, lignocellulose, and pectin degradation were identified, as well as acidogenesis, and H<SUB>2</SUB> production.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Coffee wastes (CW: wastewater, husk and pulp) for by-products obtainment. </LI> <LI> Temperature, pH, headspace and CW concentration affected H<SUB>2</SUB> production. </LI> <LI> Maximum values of H<SUB>2</SUB>, lactic acid and ethanol were 82 mL, 786 mg/L, 1816 mg/L. </LI> <LI> Microbial potential genes related to lignocellulose degradation were explored. </LI> <LI> <I>Lactobacillus, Clostridium</I> and <I>Saccharomyces</I> were identified in CW degradation. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>