Introduction.

Valorizing food waste is crucial in the bioeconomy, and anaerobic digestion has commercial potential for producing short-chain volatile fatty acids.

Objective.

This study aimed to analyze the effect of modifying the temperature of anaerobic digestion on the microbiome and the concentration of acetic and propionic acids in the medium.

Materials and methods.

In our work, after microbial communities were adapted to anaerobic conditions in a seed culture, we researched the effect of shifting the anaerobic medium temperature from 35 oC to 55 oC on microbiomes and the production of acetic and propionic acids. An experiment at ambient temperature was performed as the reference.

Results.

Bacteroidota, Firmicutes, and Proteobacteria were the phyla with the highest relative abundances in the anaerobic digestion. Many acidogenic bacterial genera were identified within these phyla. A significant decrease in Bacteroidota and an increase in Actinobacteriota abundances were found at 35 C and in the reference experiment. However, the composition of the identified bacterial communities at 55 C during the last stage of the cultivation was similar to that at the beginning of the cultivation at 35 C. Furthermore, no significant differences were found among the whole bacterial community, including identified and non-identified organisms. A notable increase in the concentration of iron was observed between 35 and 55 oC, although the metal concentration also increased in the experiment performed at ambient temperature.

Conclusion.

High acetic and propionic acid concentrations can be obtained in the culture medium at 55 oC and were higher than those observed at ambient temperature. These acids could be used for biotechnological applications.

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