Metabolic engineering strategies for microbial utilization of methanol

The increasing shortage of fossil resources and environmental pollution has renewed interest in the synthesis of value-added biochemicals from methanol.However,most of native or synthetic methylotrophs are unable to assimilate methanol at a sufficient rate to produce biochemicals.Thus,the performance of methylotrophs still needs to be optimized to meet the demands of industrial applications.In this review,we provide an in-depth discussion on the properties of natural and synthetic methylotrophs,and summarize the natural and synthetic methanol assimilation pathways.Further,we discuss metabolic engineering strategies for enabling microbial utilization of methanol for the bioproduction of value-added chemicals.Finally,we highlight the potential of microbial engineering for methanol assimilation and offer guidance for achieving a low-carbon footprint for the biosynthesis of chemicals.

Metabolic engineering strategies for microbial utilization of C1 feedstocks

The use of abundant and cheap one carbon(C1)feedstocks to produce value-added chemicals is an important approach for achieving carbon neutrality and tackling environmental problems.The conversion of C1 feedstocks to high-value chemicals is dependent on efficient C1 assimilation pathways and microbial chassis adapted for efficient incorporation.Here,we opted to summarize the natural and synthetic C1 assimilation pathways and their key factors for metabolizing C1 feedstock.Accordingly,we discussed the metabolic engineering strategies for enabling the microbial utilization of C1 feedstocks for the bioproduction of value-added chemicals.In addition,we highlighted future perspectives of C1-based biomanufacturing for achieving a low-carbon footprint for the biosynthesis of chemicals.

OpNAC1 transcription factor regulates the biosynthesis of the anticancer drug camptothecin by targeting loganic acid O-methyltransferase in Ophiorrhiza pumila

Camptothecin(CPT) is an anticancer pentacyclic quinoline alkaloid widely used to treat cancer patients worldwide. However, the biosynthetic pathway and transcriptional regulation of camptothecin are largely unknown. Ophiorrhiza pumila, the herbaceous plant from the Rubiaceae family, has emerged as a model plant for studying camptothecin biosynthesis and regulation. In this study, a high-quality reference genome of O. pumila with estimated size of ~456.90Mb was reported, and the accumulation level of camptothecin in roots was higher than that in stems and leaves. Based on its spatial distribution in the plant, we examined gene functions and expression by combining genomics with transcriptomic analysis.Two loganic acid O-methyltransferase(OpLAMTs)were identified in strictosidine-producing plant O.pumila, and enzyme catalysis assays showed that OpLAMT1 and not OpLAMT2 could convert loganic acid into loganin. Further knock-out of OpL AMT1expression led to the elimination of loganin and camptothecin accumulation in O. pumila hairy roots.Four key residues were identified in OpLAMT1 protein crucial for the catalytic activity of loganic acid to loganin. By co-expression network, we identified a NAC transcription factor, OpNAC1, as a candidate gene for regulating camptothecin biosynthesis.Transgenic hairy roots and biochemical assays demonstrated that OpNAC1 suppressed OpLAMT1 expression. Here, we reported on two camptothecin metabolic engineering strategies paving the road for industrial-scale production of camptothecin in CPT-producing plants.

Recent advances on N-acetylneuraminic acid:Physiological roles,applications,and biosynthesis

N-Acetylneuraminic acid(Neu5Ac),the most common type of Sia,generally acts as the terminal sugar in cell surface glycans,glycoconjugates,oligosaccharides,lipo-oligosaccharides,and polysaccharides,thus exerting numerous physiological functions.The extensive applications of Neu5Ac in the food,cosmetic,and pharmaceutical industries make large-scale production of this chemical desirable.Biosynthesis which is associated with important application potential and environmental friendliness has become an indispensable approach for large-scale synthesis of Neu5Ac.In this review,the physiological roles of Neu5Ac was first summarized in detail.Second,the safety evaluation,regulatory status,and applications of Neu5Ac were discussed.Third,enzyme-catalyzed preparation,whole-cell biocatalysis,and microbial de novo synthesis of Neu5Ac were comprehensively reviewed.In addition,we discussed the main challenges of Neu5Ac de novo biosynthesis,such as screening and engineering of key enzymes,identifying exporters of intermediates and Neu5Ac,and balancing cell growth and biosynthesis.The corresponding strategies and systematic strategies were proposed to overcome these challenges and facilitate Neu5Ac industrial-scale production.