Integrating waste management with fuels and chemical production is considered to address the food waste problem and oil crisis. Approximately, 600 million tonnes crude glycerol is produced from the biodiesel industry annually, which is a top renewable feedstock for succinic acid production. To meet the increasing demand for succinic acid production, the development of more efficient and cost-effective production methods is urgently needed. Herein, we have proposed a new strategy for integration of both biodiesel and SA production in a biorefinery unit by construction of an aerobic yeast Yarrowia lipolytica with a deletion in the gene coding succinate dehydrogenase subunit 5. Robust succinic acid production by an engineered yeast Y. lipolytica from crude glycerol without pre-treatment was demonstrated. Diversion of metabolic flow from tricarboxylic acid cycle led to the success in generating a succinic acid producer Y. lipolytica PGC01003. The fermentation media and conditions were optimized, which resulted in 43 g L−1 succinic acid production from crude glycerol. Using the fed-batch strategy in 2.5 L fermenter, up to 160 g L−1 SA was yielded, indicating the great industrial potential. Inactivation of SDH5 in Y. lipolytica Po1f led to succinic acid accumulation and secretion significantly. To our best knowledge, this is the highest titer obtained in fermentation on succinic acid production. In addition, the performance of batch and fed-batch fermentation showed high tolerance and yield on biodiesel by-product crude glycerol. All these results indicated that PGC01003 is a promising microbial factorial cell for the highly efficient strategy solving the environmental problem in connection with the production of value-added product.

Zhengwu Lu, Zhiqun Chen, Yunguo Liu, Xuexue Hua, Cuijuan Gao, and Jingjing Liu. J. Microbiol. Biotechnol. 2024;34:1197-205. https://doi.org/10.4014/jmb.2402.02007

D-tagatose is a rare, naturally occurring low-calorie hexose, with a sweetness of 92% sucrose but only 1/3 of the calories. It has beneficial functions in lowering blood sugar, controlling obesity, preventing dental caries, and improving intestinal flora. In recent years, biotechnological routes to D-tagatose production from renewable raw materials have been regarded as very promising approaches. In this review, we provide an overview of the properties and applications of D-tagatose, with a focus on the current developments in the production of D-tagatose using enzymatic transformation and whole-cell catalytic synthesis. The biosynthetic pathways and the types and characteristics of the catalytic enzymes involved have been summarized, providing a reference for the design of D-tagatose synthesis pathways. We also expect that rapid developments in the fields of systems biology and synthetic biology will accelerate protein and metabolic engineering for microbial D-tagatose production in the future.

Garlic is famous for its unique flavor and health benefits. An effective means of authenticating garlic's origin is through the implementation of the Protected Geographical Indication (PGI) scheme. However, the prevalence of fraudulent behavior raises concerns regarding the reliability of this system. In this study, garlic samples from six distinct production areas (G1: Cangshan garlic, G2: Qixian garlic, G3: Dali single clove garlic, G4: Jinxiang garlic, G5: Yongnian garlic, and G6: Badong garlic) underwent analysis using HS-GC-IMS. A total of 26 VOCs were detected in the samples. The differences in VOCs among the different garlic samples were visually presented in a two-dimensional topographic map and fingerprint map. Principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA) were employed to demonstrate the capacity of the HS-GC-IMS method for effectively distinguishing garlic samples from different geographical sources. Further screening based on the p-value and VIP score threshold identified 12 different aroma substances, which can be utilized for the identification of garlic from different producing areas. The fusion of HS-GC-IMS with multivariate statistical analysis proved to be a rapid, intuitive, and efficient approach for identifying and categorizing garlic VOCs, offering a novel strategy for ascertaining garlic origin and ensuring quality control.

Lignin is an abundant and renewable aromatic polymer, but its structural heterogeneity hinders its efficient bioconversion. Unlike previous reviews that focused on isolated topics such as single enzymes, pathway engineering, or specific bioproducts, this paper comprehensively reviews the latest advances in the structural characteristics, microbial degradation mechanisms, and bioconversion of lignin. Particular emphasis is placed on the catalytic mechanisms of key lignin-degrading enzymes, including laccase, lignin peroxidase (LiP), and manganese peroxidase (MnP), as well as the applications of fungi, bacteria, and synthetic microbial consortia in lignin bioconversion. Metabolic pathways that channel heterogeneous lignin-derived aromatics into central carbon metabolism through sequential catalytic reactions are also covered. Furthermore, we evaluate the emerging applications of artificial intelligence and machine learning in enzyme design and bioprocess control. Finally, techno-economic and life-cycle considerations are integrated to guide large-scale deployment. This review provides in-depth insights into the cross-scale translation from laboratory biocatalysis to industrial biorefineries.