Lignocellulose-degrading enzymes from the gut of giraffe and zebra

In the present thesis the gut microbiome of large herbivores was targeted to identify the presence of active lignocellulose-degrading enzymes. As there are essentially no protocols for the cultivation of these microbiomes, which may differ from animal to animal, this study aimed at developing a reliable protocol for their cultivation, using the giraffe and zebra as target animals in order to compare a foregut and hindgut fermenter. Gut microbiome inocula were incubated with pure substrates (either cellulose, hemicellulose or lignin) or animal feed. Fermentation kinetics in terms of biogas and volatile fatty acids (VFAs) production, cell count, pH analysis and production of biosurfactants and bio-emulsifiers were performed. Giraffe gut microbiomes were more active on hemicellulose than on other portions of lignocellulose. This may be due to the fact that the retention time of the ingesta is just 40 hours. This may suffice to access and break down hemicellulose, that is, the external matrix in the complex lignocellulose structure. As for the zebra, the gut microbiome was particularly active on the feed to which it was adapted rather than the pure substrates. In the second part of the experiments, the characterization of the enzymatic activity of the samples obtained at the end of the fermentation was performed to detect the presence of enzymes in the gut of the two animals through an initial calorimetric and chromatographic investigation by HPLC, followed by anion exchange column fractionation and SDS-Page analysis. The results obtained from the enzymatic characterization do not clearly identify an enzymatic activity in the gut microbiome of both animals. Changes to the original protocol are needed, such as, for example, a change in the enzyme concentration to be analyzed and the sampling times.