Substrate-Induced Response in Biogas Process Performance and Microbial Community Relates Back to Inoculum Source

Area of Science:

• Biotechnology
• Environmental Science
• Microbiology

Background:

• Biogas production relies on microbial communities within anaerobic digesters.
• Understanding how microbial communities respond to substrate changes is crucial for optimizing biogas production.
• The source of the initial microbial inoculum can influence reactor performance and microbial community development.

Purpose of the Study:

• To investigate the influence of initial inoculum source on biogas reactor performance and microbial community dynamics.
• To assess the impact of substrate composition changes and feeding regimes on reactor performance.
• To test the hypothesis that process performance depends on initial inoculum source and microbial diversity.

Main Methods:

• Utilized continuously operated biogas reactors with two different initial inocula.
• Introduced a new substrate (milled feed wheat) via different feeding regimes (all at once or in two portions).
• Monitored volumetric and specific methane production, analyzed microbial community structure, and assessed cellulose degradation.

Main Results:

• Initial inoculum source significantly influenced specific methane yield and microbial community development, confirming the hypothesis.
• Despite initial differences, reactors eventually exhibited similar overall performance and microbial community structure.
• Different feeding regimes had minor effects on overall process performance and community structure but induced changes in the cellulose-degrading community.

Conclusions:

• The initial inoculum source plays a critical role in shaping biogas reactor performance and microbial community composition.
• While substrate changes impact performance, the inoculum's origin is a key determinant of the response.
• Feeding strategies have a limited effect on overall reactor function but can selectively influence specific microbial groups and functions like cellulose degradation.