AI Insight
Researchers developed PACMAN, an automated platform for cultivating anaerobic bacteria, and used it to systematically study chain-elongating bacteria that produce medium-chain carboxylic acids. Testing nine bacterial strains with 20 different substrates revealed unexpected metabolic capabilities, discrepancies between genomic predictions and actual substrate use, and showed that lowering acetate-to-substrate ratios consistently produces longer carbon chains. The study also found that Gram-positive bacteria tolerate higher concentrations of their carboxylic acid products compared to Gram-negative strains.
Why it matters
This automated screening platform enables faster discovery of bacterial strains and conditions for producing valuable medium-chain carboxylic acids, which have applications in biofuels, bioplastics, and chemical manufacturing. The identified principles for controlling product chain length could improve the efficiency and economics of microbial biomanufacturing processes.
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⚠️ Preprint – Noch nicht peer-reviewed
Dieser Artikel wurde noch nicht von unabhängigen Experten begutachtet. Die Ergebnisse sind vorläufig und sollten mit Vorsicht interpretiert werden.
Anaerobic bacteria perform diverse metabolic functions with considerable biotechnological potential, yet their physiology remains poorly characterized because conventional anaerobic cultivation is low throughput. Here, we developed a Platform for Automated Cultivation of Microbial Anaerobes (PACMAN) and applied it to systematically characterize the physiology of diverse chain-elongating bacteria (CEB) that produce medium-chain carboxylic acids (MCCAs). High-throughput screening across nine CEB and 20 potential electron donors revealed extensive metabolic diversity, including previously unreported conversion of glycerol to octanoate by Pseudoramibacter alactolyticus and xylose to hexanoate by Caproiciproducens sp. 7D4C2. Comparison with genome-derived metabolic pathways further revealed widespread discrepancies between predicted and observed substrate utilization. Across diverse CEB and electron donors, decreasing the acetate-to-electron-donor ratio consistently shifted product distributions toward longer-chain carboxylates, revealing a general principle governing chain-length specificity, although maximum attainable chain length remained strain dependent. Finally, screening CEB across increasing carboxylate concentrations revealed substantial variation in MCCA tolerance, with Gram-positive MCCA producers exhibiting greater resilience than Gram-negative and butyrate-producing bacteria. Together, these findings reveal organizing principles underlying the metabolic versatility and product specificity of CEB and establish automated anaerobic phenotyping as a scalable approach for discovering microbial functions relevant to biomanufacturing.
Source: Automated anaerobic cultivation and phenotyping of diverse chain-elongating bacteria