End-product inhibition and acidification limit biowaste fermentation efficiency

• Published in: Bioresource technology Vol. 198; pp. 540 - 549
• Main Authors: Probst, Maraike, Walter, Andreas, Dreschke, Gilbert, Fornasier, Flavio, Pümpel, Thomas, Walde, Janette, Insam, Heribert
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.12.2015
• Subjects: Biotechnology - methods; Fermentation; Hydrogen-Ion Concentration; Lactate dehydrogenase; Lactic Acid - biosynthesis; Lactobacillus; Lactobacillus - metabolism; Methane - biosynthesis; Microbiome; Waste Management - methods; Waste treatment; Lactate dehydrogenase; Fermentation; Waste treatment; Lactobacillus; Microbiome
• ISSN: 0960-8524; 1873-2976
• DOI: 10.1016/j.biortech.2015.09.055

•Cascading approach of biowaste utilization offers optimized biowaste treatment.•Solid–liquid separation increases biomethane potential of fermentation residues.•Acid extraction counteracting end-product inhibition increases process efficiency.•pH control counteracting acidification increases process efficiency.•Bacterial community is influenced by treatment (and time) rather than by substrate. Converting waste to resource may mitigate environmental pollution and global resource limitation. The platform chemical lactic acid can be produced from biowaste and its liquid fraction after solid–liquid separation. A fermentation step for lactic acid production prior to the conversion of biowaste to methane and organic fertilizer would increase the biowaste’s value. Despite the huge potential and promising results of the treatment procedure, the reasons for efficiency loss observed previously need to be addressed in order to pave the way for an up-scaling of the fermentation process. Therefore, biowaste was fermented applying pH control, acid extraction and glucose addition in order to counteract reasons such as acidification, end-product inhibition and carbon limitation, respectively. The fermentation was competitive compared to other renewable lactic acid production substrates and reached a maximum productivity of >5gClactic acidg−1Ch−1 and a concentration exceeding 30gL−1. A combination of acidification and end-product inhibition was identified as major obstacle. Lactobacillus crispatus and its closest relatives were identified as key lactic acid producers within the process using Miseq Illumina sequencing.