## 3 Results and Discussion
### Two-Stage Anaerobic Co-Digestion of CSL
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Day**} & **Biogas Yield,** & **Methane Yield,** & **Total Solids,** & **Volatile** & **Glucose,** & **Cellulose,** & **Protein,** \\  & **L/day** & **\%** & **\%** & **Solids, \%** & **g/L** & **g/L** & **g/L** \\ \hline
1 & 27.96 & 69.00 & 27.4 & 72.4 & 0.18 & 0.11 & 0.33 \\
2 & 25.56 & 73.23 & 30.2 & 73.0 & 0.12 & 0.15 & 0.31 \\
3 & 22.44 & 72.47 & 29.5 & 74.0 & 0.13 & 0.12 & 0.34 \\
4 & 25.24 & 71.30 & 31.5 & 74.6 & 0.20 & 0.16 & 0.36 \\
5 & 23.28 & 72.80 & 32.7 & 73.1 & 0.14 & 0.15 & 0.33 \\
6 & 34.70 & 69.45 & 31.3 & 72.7 & 0.12 & 0.16 & 0.27 \\
7 & 20.01 & 77.52 & 34.3 & 73.0 & 0.15 & 0.11 & 0.39 \\
8 & 21.32 & 71.19 & 39.4 & 74.0 & 0.14 & 0.11 & 0.37 \\
9 & 20.86 & 77.37 & 38.5 & 74.0 & 0.12 & 0.10 & 0.36 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Continuous process for biomethane production in the second bioreactor. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Day**} & **Biogas Yield,** & **Hydrogen Yield,** & **Total Solids,** & **Volatile** & **Glucose,** & **Cellulose,** & **Protein,** \\  & **L/day** & **\%** & **\%** & **Solids, \%** & **g/L** & **g/L** & **g/L** \\ \hline
1 & 0.00 & 0.00 & 46.1 & 75.4 & 0.27 & 0.19 & 0.12 \\
2 & 4.90 & 25.45 & 43.7 & 74.2 & 0.36 & 0.16 & 0.14 \\
3 & 5.28 & 19.29 & 43.7 & 75.0 & 0.31 & 0.16 & 0.11 \\
4 & 5.28 & 18.5 In Bioreactor 1, the predominant phyla were Bacillota (synonym Firmicutes) (46.78%) and Bacteroidetes (44.54%). In Bioreactor 2, the dominant phyla were Bacteroidetes (40.66%) and Bacillota (19.79%). Significantly, higher proportions in Bioreactor 2 were observed for Chloroflexota (8.08%), Verrucomicrobiota (3.49%), and Synergistota (3.18%), which were present at less than 1% in Bioreactor 1 (Figure 4). At the genus level, Bioreactor 1 was characterized by a high relative abundance of the genera Hallella (44.22%) and Limosiactobacillus (28.43%), while, in Bioreactor 2, these genera were represented at 11.01% and 0.03%, respectively. In Bioreactor 2, a significant proportion of other bacterial genera belonging to Bacteriota (18.78%), as well as Levilinea (7.05%) and Fontisphaera (2.39%), were observed, which were weakly represented or absent in Bioreactor 1 (Figure 5). Among the dominant species in Bioreactor 1 were _Hallella multiscacharivorax_ (44.22%), _Limosiactobacillus mucosae_ (28.43%), _Bifidobacterium pseudologum_ (7.27%), and _Caproicibacterium lactatiferentans_ (5%). Figure 3: Comparison between the biogas productions in continuous two-stage AD fed with solely corn steep liquor and fed with a mixture of corn steep liquor and cattle manure 1:1: hydrogen in BR\({}_{1}\) (**a**) and methane in BR\({}_{2}\) (**b**). _Hallella multisaccharivorax_ is the new name for _Prevotella multisaccharivorax_, a mesophilic Gram-negative bacterium [34; 35]. There is no direct evidence indicating that this species produces hydrogen. This species, is known for fermenting various sugars into acids such as acetic and succinic acids, but hydrogen production has not been reported in its metabolic profile. However, other species within the Prevotella genus have been associated with hydrogen production in anaerobic digestion processes. For instance, members of the Prevotella genus have been observed in hydrogen-producing granules, suggesting a role in hydrogen production within mixed microbial communities [36]. Recent research [37] demonstrated that supplementing anaerobic digestion (AD) systems with _Limosilactobacillus_ strains enhanced the co-production of hydrogen and methane. These bacteria facilitated the hydrolysis of lignocellulosic substrates, leading to increased volatile fatty acid (VFA) production and hydrogen accumulation. Notably, the upregulation of the hydrogenase gene _hydC_ was observed, indicating active hydrogen production pathways.