Recent advances in glycerol valorization via electrooxidation:Catalyst,mechanism and device

Glycerol is one of the most important biomass-based platform molecules,massively produced as a by-product in the biodiesel industry.Its high purification cost from the crude glycerol raw material limits its application and demands new strategies for valorization.Compared to the conventional thermocatalytic strategies,the electrocatalytic strategies can not only enable the selective conversion at mild conditions but also pair up the cathodic reactions for the co-production with higher efficiencies.In this review,we summarize the recent advances of catalyst designs and mechanistic understandings for the electrocatalytic glycerol oxidation(GOR),and aim to provide an overview of the GOR process and the intrinsic structural-activity correlation for inspiring future work in this field.The review is dissected into three sections.We will first introduce the recent efforts of designing more efficient and selective catalysts for GOR,especially toward the production of value-added products.Then,we will summarize the current understandings about the reaction network based on the ex-situ and in-situ spectroscopic studies as well as the theoretical works.Lastly,we will select some representative examples of creating real electrochemical devices for the valorization of glycerol.By summarizing these previous efforts,we will provide our vision of future directions in the field of GOR toward real applications.

Monoclonal antibody-based serological methods for detecting Citrus tristeza virus in citrus groves

Citrus tristeza virus （CTV） is one of the most economically important citrus viruses and harms the citrus industry worldwide. To develop reliable and effective serological detection assays of CTV, the major capsid protein （CP） gene of CTV was expressed in Escherichia coli BL21 （DE3） using the expression vector pET-28a and purified through Ni＊-NTA affinity chromatography. The recombinant protein was used to immunize BALB/c mice. Four hybridoma cell lines （14B10, 14Hll, 20D5, and 20G12） secreting monoclonal antibodies （MAbs） against CTV were obtained through conventional hybridoma technology. The titers of MAb-containing ascitic fluids secreted by the four hybridoma lines ranged from 10-6 to 10.7 in indirect enzyme-linked immunosorbent assay （ELISA）. Western blots showed that all four MAbs could specifically react with CTV CP. Using the prepared MAbs, dot-ELISA, Tissue print-ELISA, and triple antibody sandwich （TAS）-ELISA were developed to detect CTV in tree nurseries and epidemiological studies. The developed dot-ELISA and TAS-ELISA methods could detect CTV in crude extracts of infected citrus leaves with dilutions of 1：2560 and 1：10, 240 （w/v, g/mL）, respectively. Tissue print-ELISA was particularly useful for large-scale field sample detection, mainly owing to its simplicity and lack of sample preparation requirements. The field survey revealed that CTV is prevalent on citrus trees in the Chongqing Municipality, Jiangxi Province, and Zhejiang Province of China. The coincidence rate of serological and RT-PCR test results reached more than 99.5%. The prepared MAbs against CTV and established sensitive and specific serological assays have a significant role in the detection and prevention and control of CTV in our country.

Monoclonal Antibody-Based Serological Detection of Rice Stripe Mosaic Virus Infection in Rice Plants or Leafhoppers

Rice stripe mosaic virus(RSMV) is a rhabdovirus recently found in southern part of China and can cause severe reduction in rice production. To establish serological methods for RSMV epidemiological studies and to establish a control strategy for this virus, we first purified RSMV virions from infected rice plants and then used them as an immunogen to produce four RSMV-specific monoclonal antibodies(MAbs)(i.e.,1D4, 4A8, 8E4 and 11F11). With these MAbs, we have developed a highly specific and sensitive antigen-coated plate enzyme-linked immunosorbent assay(ACP-ELISA), a Dot-ELISA and a Tissue print-ELISA for rapid detections of RSMV infection in rice plants or in leafhoppers. Our results showed that RSMV can be readily detected in RSMV-infected rice plant tissue crude extracts diluted at 1:20,971,520(w/v, g/m L)through ACP-ELISA or diluted at 1:327,680(w/v, g/m L) through Dot-ELISA. Both ACP-ELISA and Dot-ELISA can also be used to detect RSMV infection in individual RSMV viruliferous leafhopper(Recilia dorsalis) homogenate diluted at 1:307,200 and 1:163,840(individual leafhopper/l L), respectively. Detection of RSMV infection in field-collected rice samples or in RSMV viruliferous leafhoppers indicated that the three serological methods can produce same results with that produced by RT-PCR(19 of the 33 rice samples and 5 of the 16 leafhoppers were RSMV-positive). We consider that the four MAbs produced in this study are very specific and sensitive, and the three new serological methods are very useful for detections of RSMV infection in rice plants or in leafhoppers and the establishment of the disease control strategies.

Monoclonal Antibody-Based Serological Detection Methods for Wheat Dwarf Virus

Wheat dwarf disease caused by wheat dwarf virus(WDV) is currently present in wheat growing regions in China and causes serious losses in wheat yield. To develop reliable and effective serological detection methods for WDV, the coat protein(CP) gene of WDV was cloned and expressed in Escherichia coli. The purified recombinant CP protein was immunized to BALB/c mice, and four hybridoma cell lines(i.e. 18G10, 9G4, 23F4 and 22A10) secreting anti-WDV monoclonal antibodies(MAbs) were obtained through the hybridoma technique. Using the prepared MAbs, an antigencoated-plate enzyme-linked immunosorbent assay(ACP-ELISA) and a dot-ELISA were established for detecting WDV in wheat samples. The most sensitive ACP-ELISA based on MAb 23F4 or 22A10 was able to detect WDV in 1:163,840(w/v,g/mL) diluted WDV-infected wheat plant crude extracts. The dot-ELISA based on MAb 23F4 was the most sensitive and able to detect the virus in 1:5,120(w/v, g/mL) diluted wheat plant crude extracts. A total of 128 wheat samples were collected from wheat growing regions in the Shaanxi and Qinghai provinces, China, and were screened for the presence of WDV using two developed serological assays. Results from the survey showed that approximately 62% of the samples were infected with WDV. PCR followed by DNA sequencing and sequence alignment validated the results from the two serological assays. Therefore, we consider that these two serological detection methods can be significantly useful for the control of WDV in China.

Designing specific bacterial 16S primers to sequence and quantitate plant endo-bacteriome

Plant endophytic bacteria colonize the internal tissues of plants and interact with plants closely.The past two decades have witnessed the increasing application of next-generation 16S r RNA gene sequencing in the investigation of bacterial communities.However,deciphering plant endo-bacterial communities by this method is difficult because of the co-amplification of massive plant organellar DNAs with bacterial 16S.Here,we designed polymerase chain reaction(PCR) primer sets,including799F/1107R,322F/796R,and 322F-Dr/796Rs(primer pair 322F/796R with a penultimate-base substitution in 322F),that can specifically amplify bacterial 16S from plant total DNAs.We computationally and experimentally evaluated the specificity,coverage,and accuracy of the newly designed primer sets.Both 799F/1107R and 322F-Dr/796Rs produced plant DNA-free 16S amplicon libraries or reduced plant DNA contamination to lower than 5% for the plant materials with extremely-low-abundance bacterial communities.The primer set 322F-A/796R was used through absolute quantitative PCR to quantitate the population size of rice leaf or root endo-bacteriome,which revealed 10^(6)–10^(7) and 10^(9)–10^(10) bacteria per gram fresh weight,respectively.These 16S primer sets and amplification methods enable the simple and inexpensive next-generation sequencing and quantification of plant endo-bacteriome,which will significantly advance studies on the plant-related microbiome.