Homoacetogens are a group of microorganisms with application potential to produce chemicals and biofuels by the bioconversion of synthesis gas. In this study, we collected waste activated sludge samples to screen homoacetogens by Hungate anaerobic technique, and studied the effect of pH on acetate and alcohol production from H2/CO2 gas. The mixed culture contained Clostridium ljungdahlii, Lysinibacillus fusiformis and Bacillus cereus. Acetate concentration achieved 31.69 mmol/L when the initial pH was 7. The mixed culture containing homoacetogen could converting H2/CO2 to acetate, which provides an efficient microbial resource for the bioconversion of synthesis gas.
Acetates ; chemistry ; Bacteria ; classification ; Biofuels ; Carbon Dioxide ; Hydrogen ; Sewage ; microbiology

Development of "liquid sunshine" could be a key technology to deal with the issue of fossil fuel depletion. β-caryophyllene is a terpene compound with high energy density and has attracted attention for its potential application as a jet fuel. The high temperature and high light-tolerant photosynthetic cyanobacterium Synechococcus elongatus UTEX 2973 (hereafter Synechococcus 2973), whose doubling time is as short as 1.5 h, has great potential for synthesizing β-caryophyllene using sunlight and CO₂. In this study, a production of ~121.22 μg/L β-caryophyllene was achieved at 96 h via a combined strategy of pathway construction, key enzyme optimization and precursor supply enhancement. In addition, a final production of ~212.37 μg/L at 96 h was realized in a high-density cultivation. To our knowledge, this is the highest production reported for β-caryophyllene using cyanobacterial chassis and our study provide important basis for high-density fuel synthesis in cyanobacteria.
Biofuels/microbiology* ; Carbon Dioxide/metabolism* ; Light ; Photosynthesis ; Synechococcus/radiation effects*

Bioenergy, as a renewable energy, is one of the best solutions to substitute part of fossil fuels. Based on the 6th World Bioenergy Symposium, this special issue includes latest reports and articles on the fields of bioethanol, biodiesel, microbial lipid, biofuel standard and aviation biofuels.
Bioelectric Energy Sources ; microbiology ; Biofuels ; microbiology ; Biotechnology ; instrumentation ; methods ; Ethanol ; isolation & purification ; metabolism

Dwindling supplies of conventional energy sources and the demand to increase the share of renewable energy for sustainability have increased the significance of biogas, the product of synergistic fermentation of biodegrable organic wastes from municipal, agricultural and industrial activities by microbial populations under anaerobic conditions. With extensive research and engineering practice, many technologies and modes have been developed for biogas production and application. Currently, the most widely used mode is the complete-mixing mesophilic fermentation. Europe, especially Germany, is leading the world in the combined heat and power production (CHP) from biogas. In this paper, updated progress in biogas technologies is reviewed, with focuses on anaerobic microorganisms, bioreactor configurations and process development, biogas production and applications, in which perspectives of biogas as a clean and renewable energy are projected.
Bacteria, Anaerobic ; metabolism ; physiology ; Biodegradation, Environmental ; Bioelectric Energy Sources ; microbiology ; trends ; Biofuels ; microbiology ; Fermentation ; Industrial Microbiology ; trends ; Refuse Disposal ; methods

To shorten the cultivation time and reduce the consumption of raw materials for microbial lipid production, oleaginous yeast Rhodosporidium toruloides AS 2.1389 was cultivated using a two-stage culture mode, in which the cell propagation and lipid accumulation were separated. The yeast cells recovered from the propagation culture were re-suspended in glucose solution for lipid accumulation, through which lipid content over 55% of the dry cell weight was achieved, the longer the propagation stage was, the higher the lipid content. Analysis of the lipid indicated that the long-chain fatty acids with 16 and 18 carbon atoms were major components, suggesting that the lipid can be an alternative feedstock for biodiesel production.
Basidiomycota ; growth & development ; metabolism ; Biofuels ; Cell Culture Techniques ; methods ; Fermentation ; Industrial Microbiology ; methods ; Lipids ; biosynthesis

Biofuels and bio-based chemicals from lignocellulosic biomass are sustainable, making them alternatives to petroleum-derived fuels and chemicals to address the challenges of the shortage of crude oil supply and climate change resulted from the overconsumption of petroleum-based products, particularly in China. However, high cost in liberating sugars from lignocellulosic biomass is still the bottleneck of the commercialization of biofuels and bio-based chemicals. In this article, the major components of cellulases and their synergistic role in the hydrolysis of pre-treated biomass is reviewed, followed by how to evaluate the enzymatic hydrolysis. With the elucidation of the underlying mechanism of the conformations of the enzyme molecules and their effectiveness in attacking cellulose substrate, more efficient enzymes are expected to be developed. Using the high production strain Penicillium decumbens, the on-site production of cellulases for cellulose ethanol production is discussed.
Biofuels ; Biomass ; Biotechnology ; methods ; trends ; Biotransformation ; Cellulase ; biosynthesis ; Hydrolysis ; Industrial Microbiology ; methods ; trends ; Lignin ; chemistry ; metabolism

Kenaf stalk was pretreated by the white-rot fungus Pleurotus sajor-caju incubated in solid-state kenaf stalk cultivation medium. Delignification and subsequent enzymatic saccharification and fermentation of kenaf stalk were investigated in order to evaluate effects of microbial pretreatment on bioconversion of kenaf lignocellulose to fuel ethanol production. The highest delignification rate of 50.20% was obtained after 25-35 days cultivation by P. sajor-caju, which could improve subsequent enzymatic hydrolysis efficiency of kenaf cellulose. And the saccharification rate of pretreated kenaf stalk reached 69.33 to 78.64%, 4.5-5.1 times higher than the control. Simultaneous saccharification and fermentation (SSF) with microbial-pretreatment kenaf stalk as substrate was performed. The highest overall ethanol yield of 68.31% with 18.35 to 18.90 mg/mL was achieved after 72 h of SSF.
Biofuels ; Ethanol ; metabolism ; Fermentation ; Hibiscus ; metabolism ; microbiology ; Lignin ; metabolism ; Plant Stems ; metabolism ; Pleurotus ; metabolism

Lipase-mediated biodiesel production becomes increasingly important because of mild reaction conditions, pollution free during the process and easy product separation. Compared with traditional immobilized lipase, whole cell biocatalyst is promising for biodiesel production because it is easy to prepare and has higher enzyme activity recovery. Rhizopus oryzae IFO4697 can be used as the catalyst for biodiesel production. To further study the stability of the whole cell biocatalyst is extremely important for its further application on large scale. This paper focuses on the stability study of Rhizopus oryzae IFO4697 when used for the methanolysis of renewable oils for biodiesel production. The results showed that water content was important for achieving high catalytic activity and good stability of the biocatalyst. The optimum water content was found to be 5%-15%. Both particle size and desiccation methods showed no obvious effect on the stability of the biocatalyst. With GA cross-linking pretreatment, the stability of the biocatalyst could be improved significantly. When Rhizopus oryzae IFO4697 repeatedly used for next batch reaction, direct vacuum filtration was found to be a good way for the maintenance of good stability of the biocatalyst. Under the optimum reaction conditions, the methyl ester yield could keep over 80% during 20 repeated reaction batches.
Biocatalysis ; Bioelectric Energy Sources ; microbiology ; Biofuels ; Cells, Immobilized ; metabolism ; Lipase ; metabolism ; Rhizopus ; metabolism ; Soybean Oil ; metabolism

To evaluate the effectiveness of enzymatic assisted extraction (EAE) of lipid from the oleaginous yeast Rhodosporidium toruloides in the presence of beta-1,3-glucomannanase at a larger scale, we investigated the effects of enzymatic treatment and extraction conditions on lipid extraction yields at 10-L scale by using the broth of R. toruloides Y4 as the feed and ethyl acetate as the solvent. When it was treated for 0.5 h, the lipid extraction yield reached 71.1%, indicating that the enzymatic treatment process reached similar efficiency to that obtained at 10-mL scale. The inhibitory effect of emulsification was greatly reduced by repeated extraction. After extracted for three times, yields of lipid extraction, solvent recovery and total material recovery reached 92.9%, 87.0% and 94.2% respectively. As it can use the lipid production slurry with good extraction efficiency, EAE technology is promising for industrial production of microbial lipids.
Basidiomycota ; metabolism ; Biofuels ; Bioreactors ; Fermentation ; Industrial Microbiology ; Lipids ; biosynthesis ; isolation & purification ; beta-Mannosidase ; metabolism

In the present study, we developed a two-liquid phase fermentation system by adding 1% n-dodecane as oxygen-vector to enhance the microbial lipids productivity of Trichosporon fermentans using cassava starch hydrolysate. Results suggest that the oxygen-vector could alleviate the oxygen shortage in flask fermentation. The cell mass and lipids concentration were 101.2 g/L and 50.28 respectively in 2 L fermenter with the presence of 1% n-dodecane. Additionally, gas chromatography analysis also reveals that the microbial lipids produced by T. fermentans contained a higher percentage of saturated fatty acid in the oxygen-vector case.
Alkanes ; chemistry ; Biofuels ; Fermentation ; Industrial Microbiology ; methods ; Lipids ; biosynthesis ; Manihot ; metabolism ; Starch ; metabolism ; Trichosporon ; genetics ; metabolism