The volatile fatty acids (VFAs) productions, as well as particulate organics decomposition, soluble chemical oxygen demand (SCOD) yield, and the VFAs production pathways, of mesophilic and thermophilic anaerobic fermentation were investigated. Batch experiments showed that the decomposition rate of volatile suspended solids (VSS), particulate carbohydrate (P-C) and particulate protein (P-P) followed the first-order kinetic model at different temperature. However, the intermediates， accumulated in the process of protein or carbohydrate digestion had a more significant inhibitory effect on the production of VFAs during the mesophilic anaerobic acidification process. Thermophilic fermentation led to more accumulation of VFAs compared to mesophilic fermentation. Then 13C stable isotope labeling experiment demonstrated that, acetic (HAc), propionic (HPr) and butyric (HBu) could be produced from carbohydrate and protein digestion, but valeric (HVa) was only generated from the degradation of protein. Finally, the possible pathway of HVa synthesis was proposed.

The microorganisms play crucial roles in the cycle of matter and damage the organic substances, sources of electrons, source of carbon, source of energy for their biosynthesis. While dying, the microorganisms contribute on their turn to enrich soil in different composed of the carbon. In this work, we studied the impact of the aerobic mesophiles microorganisms on the black sigatoka of banana in the old secondary forest. The objective was to count and to identify the microbial diversity of the forest ecosystems, as well as to study their impact on the development of the black sigatoka of banana around the forest reserve of Masako. The assessment of the microbial populations has been done in an experimental field according to a device in blocks of Fischer by the method of successive dilutions of coloration of Gram and by the discharge of ascospores. The results showed that the rain season was lower in total microbial biomass (700, 7 colonies) than the subdry season (840,3 colonies). The Bacillus genera have been more represented more than the Coccus genera. The impact of black sigatoka of banana was raised at the cultivar Libanga Likale (40%) and low at Yangambi 5 Km (14%). The distribution of microorganisms in depth in the sub-dry season to the level of surface with vegetation was considerable either 3819, 3. 103 UFC( UNIT FORMAT COLONY) by gram of soil between 0 and 5 cm against 2754,5.103 UFC by gram of soil between 15 and 20 cm. This suggests that the raised number of microorganisms could have positive impact on soil fertility by decreasing the illnesses in this ecosystem.

Upper mesophilic temperature acclimation of halophilic, hydrogen-producing bacteria from salt fields was investigated in this study, along with the changes in microbial abundance during an-aerobic digestion (AD) process. Genomic approaches such as PCR-denaturing gradient gel elec-trophoresis (DGGE) and next-generation sequencing (NGS) were performed to profile the mi-crobial communities. During AD, there was a significant abundance of Halanaerobacter lacunarum at 48°C followed by the increase in hydrogen yield, signifying potential contribution from the halophile in the hydrogen production. A decrease in the dominance of H. lacunarum and Halan-aerobium fermentans at 42°C, likely due to an increase in other bacterial species, was noted but their dominance significantly increased at temperatures of 45°C and 48°C. This investigation provides valuable insights in highlighting the potential of Halanaerobium sp. and the other halo-philic bacteria to adapt under upper mesophilic temperature conditions and synthesizing hy-drogen. The findings in the present study also underscore the importance of optimizing temper-ature and pH conditions to maximize hydrogen yield during high-salt anaerobic digestion.