As a representative catabolic reaction that widely exists in nature, anaerobic digestion (AD) exhibits great value regarding the global carbon cycle, renewable energy development, and environmental protection. Such an important biochemical reaction was ignored before and should be introduced into the teaching and textbooks of undergraduate biochemistry courses. However, students may face obstructions when learning AD theories since the metabolic pathways in AD are very complex. To solve these problems, an instructive metabolic minimap of the AD reaction was designed, including its reaction stages, reaction pathways, substrates, and enzymes. Furthermore, the interrelationships between aerobic catabolism (AEC) and anaerobic catabolism (ANC) were also summarized by combining the catabolic pathways of typical biological macromolecules. In this paper, AD theories were first replenished into undergraduate biochemistry courses by metabolic minimap, which not only provided valuable supports for the practical teaching of AD in undergraduate biochemistry courses, but also acted as an important reference for students in biology‐related majors and biochemistry teachers.

A promising strategy to alleviate the plastic pollution from traditional petroleum‐based plastics is the application of biodegradable plastics, in which polyhydroxyalkanoates (PHAs) have received increasing interest owing to their considerable biodegradability. In the PHAs family, poly(3‐hydroxybutyrate‐co‐3‐hydroxvalerate) (PHBV) has better mechanical properties, which possesses broader application prospects. With this purpose, the present study adopted Cupriavidus necator to synthesize PHBV utilizing volatile fatty acids (VFAs) as sole carbon sources. Results showed that the concentration and composition of VFAs significantly influenced the production of PHAs. Especially, even carbon VFAs (acetate and butyrate) synthesized only poly(3‐hydroxybutyrate) (PHB), while the addition of odd carbon VFAs (propionate and valerate) resulted in PHBV production. The 3‐hydroxyvalerate (3HV) contents in PHBV were directly determined by the specific VFAs compositions, in which valerate was the preferred substrate for 3HV accumulation. After optimization by response surface methodology, the highest PHBV accumulation achieved 79.47% in dry cells, and the conversion efficiency of VFAs to PHBV reached 40%, with the PHBV production of 1.20 ± 0.05 g/L. This study revealed the metabolic rule of VFAs converting into PHAs by C. necator and figured out the optimal VFAs condition for PHBV accumulation, which provides a valuable reference for developing downstream strategies of PHBV production in industrial applications in future.

No abstract