A novel approach to study cellulose digestion kinetics in biogas fermentation applying feed-stop method and artificial medium to investigate effects of saccharides

Anaerobic cellulose digestion kinetics was studied using a novel artificial medium, which allowed cellulose mono-fermentation with a complex biogas biocenosis. Semi-continuous cellulose mono-fermentation was successfully performed with this medium for more than 18 months achieving high organic loading rates of 8.3 gl⁻¹d⁻¹ and short hydraulic residence times of 9.6 days. Cellulose hydrolysis kinetics was studied by monitoring the substrate depletion after short feed-stops using the data obtained to establish a 1st order reaction model. This method was used to assess the cellulose hydrolysis kinetics under the influence of selected carbohydrates, of which a mixture of cellooligosaccharides showed the highest potential. A qPCR-Method was established for quantitative monitoring of selected cellulolytic clostridia based on the extraction of metagenomic DNA and comparison to standards from single cultures. The monitoring indicated consistent growth of these clostridia in the novel cultivation approach.