Lignocellulose is the most abundant renewable organic carbon resource on earth. However, due to its complex structure, it must undergo a series of pretreatment processes before it can be efficiently utilized by microorganisms. The pretreatment process inevitably generates typical inhibitors such as furan aldehydes that seriously hinder the growth of microorganisms and the subsequent fermentation process. It is an important research field for bio-refining to recognize and clarify the furan aldehydes metabolic pathway of microorganisms and further develop microbial strains with strong tolerance and transformation ability towards these inhibitors. This article reviews the sources of furan aldehyde inhibitors, the inhibition mechanism of furan aldehydes on microorganisms, the furan aldehydes degradation pathways in microorganisms, and particularly focuses on the research progress of using biotechnological strategies to degrade furan aldehyde inhibitors. The main technical methods include traditional adaptive evolution engineering and metabolic engineering, and the emerging microbial co-cultivation systems as well as functional materials assisted microorganisms to remove furan aldehydes.
Aldehydes ; Fermentation ; Furans ; Lignin/metabolism*

Mucic acid is a hexaric acid that can be biosynthesized by oxidation of D-galacturonic acid, which is the main constituent of pectin. The structure and properties of mucic acid are similar to that of glucaric acid, and can be widely applied in the preparation of important platform compounds, polymers and macromolecular materials. Pectin is a cheap and abundant renewable biomass resource, thus developing a process enabling production of mucic acid from pectin would be of important economic value and environmental significance. This review summarized the structure and hydrolysis of pectin, the catabolism and regulation of D-galacturonic acid in microorganisms, and the strategy for mucic acid production based on engineering of corresponding pathways. The future application of mucic acid are prospected, and future directions for the preparation of mucic acid by biological method are also proposed.
Hexuronic Acids/metabolism* ; Pectins/metabolism* ; Sugar Acids/metabolism*

Background and purpose:Colorectal cancer(CRC)is one of the major malignant tumors threatening human health worldwide,with long-term high incidence and mortality rate.Potassium channel modulatory factor 1(KCMF1)is a member of the E3 ubiquitin ligase family.It binds to target proteins through the RING domain and participates in the regulation of a variety of biological processes in vivo.However,the function of KCMF1 in CRC remains unclear.This study aimed to investigate the expression level of E3 ubiquitin ligase KCMF1 in colorectal tumor,and to explore the effects of KCMF1 on the proliferation of CRC cells and its underlying molecular mechanism.Methods:The The Cancer Genome Atlas(TCGA)and Genotype-Tissue Expression(GTEx)databases were used to analyze the expression level of KCMF1 in CRC tissues and adjacent tissues and the association between the KCMF1 expression and the prognosis of CRC patients.Furthermore,immunohistochemical staining was performed to detect the protein level of KCMF1 in 90 paired human CRC tissues and adjacent non-tumor tissues.Lentiviral shRNA delivery system was employed to specifically target the KCMF1 gene(shKCMF1)in HCT116 and HCT15 CRC cell lines.The effects of KCMF1 knockdown on cell proliferation,apoptosis and cell cycle distribution were assessed by methyl thiazoyl terazolium(MTT)assay,colony formation assay,Western blot and flow cytometry.Changes in the transcriptional profile in HCT116 cells upon KCMF1 knockdown were identified by RNA sequencing(RNA-Seq),and the affected signaling pathways were evaluated by bioinformatics analysis.Real-time fluorescence quantitative polymerase chain reaction(RTFQ-PCR),Western blot,luciferase reporter assay and cell immunofluorescence assay were utilized to validate the alteration of the affected signaling pathway.Results:The TCGA and GTEx databases and IHC results showed that the mRNA and protein expression levels of KCMF1 in CRC tissues were significantly upregulated compared with adjacent tissues(P＜0.01).KCMF1 expression level was negatively correlated with the survival time of patients with CRC(P＜0.01),and was positively associated with CRC clinical stage(P＜0.05).Compared with control cells,KCMF1 knockdown significantly inhibited the proliferation of HCT116 and HCT15 cells(P＜0.001),induced cell apoptosis(P＜0.001),and led to cell cycle arrest in G1 phase(P＜0.01).RNA-Seq analysis showed that KCMF1 was involved in the regulation of several signaling pathways,including nuclear factor-κB(NF-κB)signaling pathway.KCMF1 knockdown reduced the transcription levels of the target genes of NF-κB signaling pathway,including BCL-XL,XIAP and CIAP(P＜0.05),and suppressed the expression of phosphorylated p65 and nuclear translocation of p65(P＜0.01).Meanwhile,the activity of NF-κB reporter was reduced in tumor cells upon KCMF1 knockdown(P＜0.01).Conclusion:The expression of KCMF1 is significantly upregulated in human CRC tissues and positively associated with advanced clinical stage and poor prognosis.KCMF1 may promote the proliferation of CRC cells by activating the NF-κB signaling pathway.KCMF1 may be a potential new therapeutic target for CRC.