Quantifying Condition-Dependent Growth and Metabolic Behaviors inMicrobial Species

Anaerobic digestion (AD) is awidely adopted low-carbon technology for converting organic waste into valuable biobased products, such as volatile fatty acids (VFAs), and biogas. Despite its significance, optimizing the production of specific metabolic outputs remains challenging due to the complexity and variability of microbial interactions within AD communities. The primary objective of this study was to investigate the physiology and metabolic behavior of key strains within AD systems and to develop predictive models aimed at optimizing carboxylic acid production. Using Anaeromicropila populeti and Clostridium butyricum as representative primary fermenters, growth kinetics and metabolite production were analyzed across varying pH levels, carbon sources, and hydrogen availability. Growth parameters, including maximum growth rate and lag time, were estimated using multiple primary growth models. The results revealed strain-specific metabolic strategies: A. populeti achieved its highest growth rate ( 0.50±0.00 h−1) under cellobiose at pH 7.5, while C. butyricum reached its optimal growth rate (2.01±0.02 h−1) under glucose at pH 6.5 without hydrogen. A. populeti exhibited diverse VFAs profiles at lower pH, with the highest VFAs yield observed under cellobiose at pH 7.5, dominated by acetate, formate, and butyrate. In comparison, C. butyricum showed maximum VFAs yield under cellobiose at pH 7.5 with 10% H2, primarily producing acetate, formate, and butyrate. Hydrogen availability had minimal effects on overall VFAs yields in C. butyricum. These findings provided valuable insights into strain-specific responses to environmental conditions and offered a foundation for designing syntheticmicrobial community with optimized metabolic performance, enhancing the efficiency and scalability of AD processes.