Cell and Tissue Journal

Abstract Introduction: Concern over fossil energy costs and environmental deterioration, along with energy security, has created a strong motivation for research and development of routes to provide sustainable, renewable fuels. In recent years, the use of biomass to produce highly valued chemicals has attracted widespread attention. lignocellulosic biomass, as a promising renewable resource for biofuel production, has distinct advantages in terms of economic and environmental aspects. The conversion of renewable raw materials to hydrocarbon fuels is an attractive alternative to fossil fuels from an economic and environmental point of view. The production process of lignocellulosic biomass mainly consists of biomass accumulation, biomass decomposition, simple sugars, and conversion of sugars to biofuel. One of the crucial steps in the economic success of lignocellulosic biofuels depends on the inhibition of competitive metabolism in microorganisms to achieve high productivity. To date, a growing focus is on the use of S. cerevisiae and E. coli as cell lines. These two cellular factories have the benefits that are well known.

Aim: The organic compound D-1,2,4-Butanetriol is a valuable chemical with wide-ranging applications in various fields. The chemical synthesis routes for BT have many drawbacks. By genetically modifying microorganisms, the metabolic pathway for producing many substances, including BT, can be engineered. The organic compound D-1,2,4-butanediol (BT) is an important intermediate chemical widely used in fields such as pharmaceuticals, paper, polymer materials, and military applications. When D-xylose sugar is provided to the bacterium, it is first converted to an intermediate compound called xylonolactone. This compound itself slowly converts into xylonate through a non-enzymatic reaction. To produce xylonate, the engineered bacteria have received xylose and initially, by a dehydrogenase reaction by the xylose dehydrogenase enzyme, that converts it into an intermediate substance: xylonolactone. The xylonolactone is converted slowly and in a nonenzymatic reaction to xylonate. Xylonate is a five-carbon organic acid. Over the past few years, xylonate has been increasingly being considered as an important chemical due to its potential as an important chemical component. Xylonate has many applications that can be used in the food, chemical, and pharmaceutical industries. Specifically, xylonate can act as a precursor for the synthesis of D-1,2,4-Butanetriol and a decrease in concrete water. E.coli due to fast growth in cheap culture medium, having two enzymes for the bto synthesis and product production in lower 24 hours of fermentation was chosen as the target strain of genetic engineering and metabolism. This study aimed to clone and express xylose dehydrogenase from Caulobacter vibrioides in E.coli. Materials and Methods: At first, to access the bacterial gene sequence, the genome of the target bacterium was extracted. Then, to create a strain expressing the enzymes xylose dehydrogenase and xylonolactonase, the genes for these proteins were amplified from Caulobacter vibrioides CB1 and transferred to E. coli. For this purpose, the target genes were amplified using specifically designed primers via the Polymerase Chain Reaction (PCR) method and initially cloned into a pTZ57cloning vector and then subcloned into pET 26b expression vector. At the final step, the expression of the enzyme was assessed by SDS-PAGE, and the other confirmation was the reduction of NAD+ to NADH, which was used as an activity indicator of the enzyme, as investigated by a change in NADH absorbance at 340 nm. Results: Confirmatory tests were performed to ensure the presence of the gene in the vectors (using restriction enzymes and colony PCR for gene amplification). The expression and activity of the enzyme were analysed. The recombinant protein's presence was confirmed by SDS-PAGE for the xylose dehydrogenase gene, with a molecular weight of 52.2 kDa. The estimated recombinant protein expression levels were approximately 25%. Conclusion: The objective of this research was solely to establish the metabolic pathway for xylonate production in E. coli by surface expression of enzymes in this pathway (xylose dehydrogenase). The results obtained in this study confirm that half of the pathway is active at the cell surface, but further experiments are required to determine the precise production levels and complete the pathway. This study aimed to create a metabolic pathway for producing xylonate in E.coli.

Abstract Aim: Lignocellulosic biomass such as agricultural wastes (corn stover, sugar beet pulp and citrus peel) is a widely abundant and attractive source for the production of biofuels and chemicals.
biofuels are sources of clean and renewable energy that are considered as a potential substitute for non-renewable oil fuels. various methods and processes have been tested by scientists and researchers in this field and the most favorable conditions for producing biofuels from biomass. however, this biomass has not been fully exploited in many parts of the world for biofuel production, especially in developing countries, and there is little relation with crop residues and forest and waste in this area. so much work is still needed to replace fossil fuels with biofuels from biomass. lignocellulosic waste biomass such as cassava peels, sugar beet pulp, and Ulva lactuca are suitable materials for bioethanol synthesis.
D-xylose, is the second most abundant sugar in lignocellulosic hydrolysates. Nowadays, considerable efforts have been made to expand microbial cell factories to use D-xylose for the production of value-added chemicals. D-1,2,4-butanetriol (BT) is an extremely important intermediate chemical, is widely used in many fields, such as pharmaceuticals, paper, polymer materials, and military applications.A molecule 1,2,4-butanteriol (BT) is a polyol with unique chemical properties, which has a stereocenter and can be divided into D-BT (the S-enantiomer) and L-BT(the R-enantiomer). BT is widely used in the military industry, medicine, tobacco, polymer.  A synthetic pathway involving four enzymes—D-xylose dehydrogenase (XDH), D-xylonate dehydratase (XD), 2-keto acid decarboxylase (KDC), and aldehyde reductase (ALR)—has been proposed and implemented to produce BT from D-xylose, highlighting its significant role in bioproduction. And because in most studies, the xylonate dehydratase was used in the case of Caulobacter.crescentus, and given the very high genetic similarity between Caulobacter.crescentus and Caulobacter.vibrioides, the aim of this study is to clone and express xylonate dehydratase gene of C.vibrioides in the E.coli. For this purpose, the research was carried out with the aforementioned methods.
Material and methods:  The xylonate dehydratase gene was retrieved from the NCBI database and amplified using PCR with specific primers after extracting the C. vibrioides genome. The piece of the gene was cloned in the pET28 expression vector and then transferred to the E.coli prepared cells using chemical methods. After the induction of the cells, recombinant protein expression was examined using SDS-PAGE. Results: By using restriction enzymes, Colony PCR and sequencing, the cloning process and the entry of the gene into the pET28 expression vector was confirmed. The presence of the recombinant protein was tested by SDS-PAGE gel with a molecular weight of approximately 68 KDa and the expression rate of the recombinant protein, estimated by Image J software, was 54 percent.
Conclusion: The bioproduction of butanetriol requires the construction of a metabolic pathway consisting of several enzymes. The presence of the bacterium E.coli as the target strain and the use of cheap substrate such as xylose-containing biomass and the existence of the enzyme xylonate dehydratase are essential for the production of high-speed and high-volume D-1,2,4 butanetriol.