Xiaoming Tan

Hubei University · College of Life Sciences

Due to its robustness to environmental stresses and fast growth, Synechococcus elongatus UTEX2973 is developed as a new model for researches on cyanobacterial molecular biology and biotechnology. However, systematic genetic modifications of S. elongatus UTEX2973 were hindered by the lack of effective genetic manipulation tools, especially available...

Sustainable production of biofuels and biochemicals has been broadly accepted as a solution to lower carbon dioxide emissions. Besides being used as lubricants or detergents, oleochemicals are also attractive biofuels as they are compatible with existing transport infrastructures. Cyanobacteria are autotrophic prokaryotes possessing photosynthetic...

Cyanobacteria have evolved various strategies to sense and adapt to biotic and abiotic stresses including active movement. Motility in cyanobacteria utilizing the type IV pili (TFP) is useful to cope with changing environmental conditions. The model cyanobacterium Synechocystis sp. PCC 6803 (hereafter named Synechocystis) exhibits motility via TFP...

Background In photosynthetic oleaginous microalgae, acyl-CoA molecules are used as substrates for the biosynthesis of membrane glycerolipids, triacylglycerol (TAG) and other acylated molecules. Acyl-CoA can also be directed to beta-oxidative catabolism. They can be utilized by a number of lipid metabolic enzymes including endogenous thioesterases,...

[Background] Cyanobacteria have shown promising potential for the production of various biofuels and chemical feedstocks. Synechococcus elongatus UTEX 2973 is a fast-growing strain with pronounced tolerance to high temperatures and illumination. Hence, this strain appears to be ideal for the development of photosynthetic biotechnology. However, mol...

In response to a broad range of habitats and environmental stresses, cyanobacteria have evolved various effective acclimation strategies, which will be helpful for improving the stress tolerances of photosynthetic organisms, including higher plants. Synechococcus elongatus UTEX 2973 and PCC 7942 possess genomes that are 99.8% identical but exhibit...

Most of the cyanobacteria accumulate osmolytes including sucrose, glucosylglycerol, in their cells in response to salt stress. Here we describe a protocol of our laboratory for extraction and quantification of cyanobacterial intracellular sucrose and glucosylglycerol. We have confirmed this protocol was applicable to at least four kinds of cyanobac...

Invertase can catalyze the hydrolysis of sucrose, and is widely distributed in cells of cyanobacteria and plants. Being responsible for the first step for sucrose metabolism, invertase plays important physiological roles and its enzymatic activity is frequently needed to be determined. All the methods for determination of the invertase activity are...

Cyanobacterial sucrose biosynthesis is stimulated under salt stress, which could be used for biotechnological sugar production. It has been shown that the response regulator Slr1588 negatively regulates the spsA gene encoding sucrose-phosphate synthase and mutation of the slr1588 gene also affected the salt tolerance of Synechocystis (Chen et al.,...

Bioethanol is one of the most promising and representative biofuel products. Photosynthetic production of ethanol using CO2 and solar energy based on cyanobacteria is of great significance for research and application, due to the potential to reduce CO2 emission and to provide renewable energy simultaneously. Here we review the history and updated...

Background Ethanol photosynthetic production based on cyanobacteria cell factories utilizing CO2 and solar energy provides an attractive solution for sustainable production of green fuels. However, the scaling up processes of cyanobacteria cell factories were usually threatened or even devastated by biocontaminations, which restricted biomass or pr...

It is important to obtain abundant sugar feedstocks economically and sustainably for bio-fermentation industry, especially for producing cheap biofuels and biochemicals. Besides plant biomass, photosynthetic cyanobacteria have also been considered to be potential microbe candidates for sustainable production of carbohydrate feedstocks. As the faste...

When subjected to mild salt stress, the cyanobacterium Synechocystis sp. PCC 6803 produces small amounts of glycerol through an as of yet unidentified pathway. Here, we show that this glycerol is a degradation product of the main osmolyte of this organism, glucosylglycerol (GG). Inactivation of ggpS, encoding the first step of GG-synthesis, abolish...

For more economical and efficient DNA clonging, pFL-XS-T, a Biobrick-T vector was constructed based on pMD18-T vector, carrying clonging regions of XbaI-XcmI-XcmI-SpeI. The results revealed that PCR products could be conveniently inserted into pFL-XS-T vevtor digested by XcmI by means of TA cloning. The positive frequency of recombination can meet...

Glucosylglycerols (GGs) are known as compatible solutes accumulated by some bacteria including cyanobacteria as well as higher plants for their adaptations to salt or desiccation stresses. Since being identified in Japanese sake, their physiological effects and potential applications on human health cares have been explored in the following 15 year...

Cyanobacterial blooms have occurred frequently in the surface waters of the world, posing a potential threat to humans and ecosystems due to their toxic secondary metabolite, microcystin. Genetic tools cannot easily explain the biosynthesis of MC in specific strains due to the iterative nature of MC production and environmental factors. In this stu...

Propane, a major component of liquid petroleum gas (LPG) derived from fossil fuels, has widespread applications in vehicles, cooking, and ambient heating. Given the concerns about fossil fuel depletion and carbon emission, exploiting alternative and renewable source of propane have become attractive. In this study, we report the construction of a n...

To study the roles of glucosylglycerol phosphate synthase (Ggps) in glucosylglycerol (GG) and glycerol biosynthesis, we over-expressed Ggps from either Synechocystis sp. PCC 6803 or Synechococcus sp. PCC 7002 in a Synechocystis strain with a high GG titer, and determined the GG and glycerol accumulation in the resultant mutants grown under differen...

Photosynthetic production of chemicals and fuels by recycling CO 2 in cyanobacteria is a promising solution facing energy shortage and resource declination. Ethanol is an attractive and demonstrative biofuel product, and ethanol synthesis in cyanobacteria has been achieved by assembling of a pathway consisting of pyruvate decarboxylase (PDCzm) and...

Construction of highly efficient microbial cell factories producing drop-in biofuel alkanes is severely limited due to the lack of a fast detection method against alkanes. Here we first developed a sensitive fluorescent biosensor for rapid and in situ monitoring of intracellular alkane synthesis. Using GFP as reporter, the biosensor could actively...

Glucosylglycerol (GG) has a range of potential applications in health, pharmacy, and cosmetics due to its physiological, protein-stabilizing, and antioxidative properties. In addition to chemical synthesis and enzymatic catalysis, GG can be produced as a protective osmolyte in salt-stressed bacteria, such as the cyanobacterium Synechocystis sp. PCC...

Ethylene is widely used in the petrochemical industry and has traditionally been produced via the steam cracking of petroleum-based feedstock. The exploration of sustainable and carbon-neutral methods of producing ethylene from the renewable feedstock seems promising. The direct photosynthetic production of ethylene after the recycling of carbon di...

Background Fatty alcohols are widely used in industrial chemicals. The biosynthetic pathways for fatty alcohols are diverse and widely existing in nature. They display a high capacity to produce fatty alcohols by the metabolic engineering of different microbe hosts. Direct recycling of carbon dioxide to fatty alcohols can be achieved by introducing...

Free fatty acids are typically activated by thioesterification processes and catalyzed by the fatty acyl-CoA synthetase or fatty acyl-ACP synthetase. However, the routes for fatty acid activation in cyanobacteria are not well understood. In this investigation, the slr1609 gene, which encodes the fatty acid activation enzyme, was cloned from Synecho...

For metabolic engineering of cyanobacteria, there is an urgent need to construct a group of efficient heterologous gene expression platforms and to evaluate their expression efficiencies. Here we constructed three integrative vectors, the pKW1188-derived pFQ9F, pFQ9R and pFQ20, for integration of heterologous genes into the genome of the model cyan...

Although successful production of fatty alcohols in metabolically engineered Escherichia coli with heterologous expression of fatty acyl-CoA reductase has been reported, low biosynthetic efficiency is still a hurdle to be overcome. In this study, we examined the characteristics of two fatty acyl-CoA reductases encoded by Maqu_2220 and Maqu_2507 gen...

An integrative gene expression system has been constructed for the directional assembly of biological components in Synechocystis PCC6803. We have characterized 11 promoter parts with various expression efficiencies for genetic engineering of Synechocystis for the production of fatty alcohols. This was achieved by integrating several genetic modifi...

Because cyanobacteria are photosynthetic, fast-growing microorganisms that can accumulate sucrose under salt stress, they have a potential application as a sugar source for the biomass-derived production of renewable fuels and chemicals. In the present study, the production of sucrose by the cyanobacteriaSynechocystissp. PCC6803,Synechococcus elong...

Due to efficient photosynthetic capability, robust growth, and clear genetic background, cyanobacteria are recently used for production of different biofuel and biochemical molecules by genetic engineering and showed great potentials as the next-generation microbial cell factory. For improving the production of bio-products, a number of genetic mod...

Free fatty acid profiles of wild type and fatty acyl-ACP synthase deletion mutant strain of Synechocystis sp. PCC6803 indicated that one origin of these fatty acids is the process of lipid remodeling or lipid degradation. Lipase is the key enzyme involved in this process. The gene sll1969 is the sole gene encodes a putative lipase in Synechocystis...

The rapidly growing demand for energy and the environmental concerns about carbon dioxide emissions make the development of renewable biofuels more and more attractive. Tremendous academic and industrial efforts have been made to produce bioethanol, which is one major type of biofuel. The current production of bioethanol is limited for commercializ...

Cyanobacteria, photosynthetic bacteria with conversion capability to utilize solar energy and carbon dioxide and genetic engineering capacity to be easily modified to build non-native and improve native biosynthetic pathways, have displayed huge potential for biotechnology applications for direct production of biofuels by using solar energy as ener...

Strains and primers used in this study. (DOC)

FAEE production of E. coli mutant strain BL21 (ΔfadE)/pXT11/pMSD8/pMSD15 under varied fed-batch fermentation conditions: (a) varying initial culture medium; (b) varying feed glucose and feeding rate; (c) varying cultivation temperature; (d) varying induction time point. (TIF)

Biodiesel is a renewable alternative to petroleum diesel fuel that can contribute to carbon dioxide emission reduction and energy supply. Biodiesel is composed of fatty acid alkyl esters, including fatty acid methyl esters (FAMEs) and fatty acid ethyl esters (FAEEs), and is currently produced through the transesterification reaction of methanol (or...

Synechocystis sp. strain PCC 6803 cultured at 30°C losses viability quickly under chill (5°C)-light stress but becomes highly tolerant to the stress after conditioning at 15°C (Y. Yang, C. Yin, W. Li, and X. Xu, J. Bacteriol. 190:1554–1560, 2008). Hypothetically, certain factors induced during preconditioning are involved in acquisition of chill-li...

The production of high value biochemicals and high energy biofuels from sustainable resources through the use of microbial based, green conversion technologies could reduce the dependence on petrochemical resources. However, a sustainable source of carbon and a clean, cost effective method for its conversion to high quality biofuel products are obs...

In the cyanobacterium Synechocystis 6803, rbp3, a type-II RNA-binding protein gene, is slightly induced by temperature downshift. An rbp3 mutant shows significant reduction in total polyunsaturated fatty acids (PUFA) in membrane lipids. However, the reduction in PUFA has not attained the extent that would significantly affect the growth of the muta...