Principles and practice of designing microbial biocatalysts for fuel and chemical production.

The finite nature of fossil fuels and the environmental impact of its use have raised interest in alternate renewable energy sources. Specifically, nonfood carbohydrates, such as lignocellulosic biomass, can be used to produce next generation biofuels, including cellulosic ethanol and other nonethanol fuels like butanol. However, currently there is no native microorganism that can ferment all lignocellulosic sugars to fuel molecules.

Kinetic characterization and structure analysis of an altered polyol dehydrogenase with d-lactate dehydrogenase activity.

During adaptive metabolic evolution a native glycerol dehydrogenase (GDH) acquired a d-lactate dehydrogenase (LDH) activity. Two active-site amino acid changes were detected in the altered protein. Biochemical studies along with comparative structure analysis using an X-ray crystallographic structure model of the protein with the two different amino acids allowed prediction of pyruvate binding into the active site.

Chromosomal mutations in Escherichia coli that improve tolerance to nonvolatile side-products from dilute acid treatment of sugarcane bagasse.

Lignocellulosic biomass provides attractive nonfood carbohydrates for the production of ethanol, and dilute acid pretreatment is a biomass-independent process for access to these carbohydrates. However, this pretreatment also releases volatile and nonvolatile inhibitors of fermenting microorganisms. To identify unique gene products contributing to sensitivity/tolerance to nonvolatile inhibitors, ethanologenic Escherichia coli strain LY180 was adapted for growth in vacuum-treated sugarcane bagasse acid hydrolysate (VBHz) lacking furfural and other volatile inhibitors.

Metabolic engineering of for the production of butyric acid at high titer and productivity.

Background: Several anaerobic bacteria produce butyric acid, a commodity chemical with use in chemical, pharmaceutical, food and feed industries, using complex media with acetate as a co-product. Butyrate titer of various recombinant did not exceed 10 g l in batch fermentations in any of the media tested.

Results: A recombinant (strain LW393) that produced butyrate as the major fermentation product was constructed with genes from , and .

Simultaneous fermentation of biomass-derived sugars to ethanol by a co-culture of an engineered Escherichia coli and Saccharomyces cerevisiae.

Microorganisms ferment xylose at high rate only when glucose concentration in the medium falls below a critical level. Since the specific productivity of product is highest during exponential to early stationary phase of growth, a glucose utilization negative ethanologenic E. coli (strain LW419a) was constructed for high rate of xylose fermentation in combination with Turbo yeast.

Fermentation of dihydroxyacetone by engineered and to products.

Methane can be converted to triose dihydroxyacetone (DHA) by chemical processes with formaldehyde as an intermediate. Carbon dioxide, a by-product of various industries including ethanol/butanol biorefineries, can also be converted to formaldehyde and then to DHA. DHA, upon entry into a cell and phosphorylation to DHA-3-phosphate, enters the glycolytic pathway and can be fermented to any one of several products.

Phosphoric acid based pretreatment of switchgrass and fermentation of entire slurry to ethanol using a simplified process.

Switchgrass (Alamo) was pretreated with phosphoric acid (0.75 and 1%, w/w) at three temperatures (160, 175 and 190 °C) and time (5, 7.5 and 10 min) using a steam gun.

Techno-economic analysis of ethanol production from sugarcane bagasse using a Liquefaction plus Simultaneous Saccharification and co-Fermentation process.

A techno-economic analysis was conducted for a simplified lignocellulosic ethanol production process developed and proven by the University of Florida at laboratory, pilot, and demonstration scales. Data obtained from all three scales of development were used with Aspen Plus to create models for an experimentally-proven base-case and 5 hypothetical scenarios. The model input parameters that differed among the hypothetical scenarios were fermentation time, enzyme loading, enzymatic conversion, solids loading, and overall process yield.

Plasmidic Expression of nemA and yafC* Increased Resistance of Ethanologenic Escherichia coli LY180 to Nonvolatile Side Products from Dilute Acid Treatment of Sugarcane Bagasse and Artificial Hydrolysate.

Hydrolysate-resistant Escherichia coli SL100 was previously isolated from ethanologenic LY180 after sequential transfers in AM1 medium containing a dilute acid hydrolysate of sugarcane bagasse and was used as a source of resistance genes. Many genes that affect tolerance to furfural, the most abundant inhibitor, have been described previously. To identify genes associated with inhibitors other than furfural, plasmid clones were selected in an artificial hydrolysate that had been treated with a vacuum to remove furfural.

Fermentation of sweet sorghum derived sugars to butyric acid at high titer and productivity by a moderate thermophile Clostridium thermobutyricum at 50°C.

In this study, a moderate thermophile Clostridium thermobutyricum is shown to ferment the sugars in sweet sorghum juice treated with invertase and supplemented with tryptone (10 g L(-1)) and yeast extract (10 g L(-1)) at 50°C to 44 g L(-1) butyrate at a calculated highest volumetric productivity of 1.45 g L(-1)h(-1) (molar butyrate yield of 0.85 based on sugars fermented).

Removing chiral contamination of lactate solutions by selective metabolism of the D-enantiomer.

Objective: A bio-based process is appealing for purification of L-lactic acid, the major enantiomer of polylactic acid syrup, generated by thermochemical processes at the end of life of PLA-based plastics, from its chiral impurity, D-lactic acid, before reuse.

Results: Polylactic acid (PLA), a renewable alternative to petroleum-derived plastics, contains a mixture of L- and D-lactic acid (LA) isomers with the L-isomer dominating (up to 95 %). A novel bio-based process was developed to produce chirally pure L-LA from syrup produced during recycling of PLA-plastics.

Pseudoepitheliomatous Hyperplasia: Relevance in Oral Pathology.

Pseudoepitheliomatous hyperplasia (PEH), a neglected entity by oral pathologist possesses utmost importance in the field of research. Of all the investigative challenges, PEH, a reactive epithelial proliferation is seen secondary to lesions with infectious, inflammatory, reactive, and degenerative origin. Small sized samples, incomplete excision, improper orientation, and dense inflammatory changes render diagnostic confront to the oral pathologist in exclusion of frankly invasive malignant lesions like squamous cell carcinoma from lesions exhibiting PEH.

Mutation in galP improved fermentation of mixed sugars to succinate using engineered Escherichia coli AS1600a and AM1 mineral salts medium.

Escherichia coli KJ122 was engineered to produce succinate from glucose using the wild type GalP for glucose uptake instead of the native phosphotransferase system (ptsI mutation). This strain now ferments 10% xylose poorly. Mutants were selected by serial transfers in AM1 mineral salts medium with 10% xylose.

DNA adducts-chemical addons.

DNA adduct is a piece of DNA covalently bond to a chemical (safrole, benzopyrenediol epoxide, acetaldehyde). This process could be the start of a cancerous cell. When a chemical binds to DNA, it gets damaged resulting in abnormal replication.

Combining treatments to improve the fermentation of sugarcane bagasse hydrolysates by ethanologenic Escherichia coli LY180.

Inhibitory side products from dilute acid pretreatment is a major challenge for conversion of lignocellulose into ethanol. Six strategies to detoxify sugarcane hydrolysates were investigated alone, and in combinations (vacuum evaporation of volatiles, high pH treatment with ammonia, laccase, bisulfite, microaeration, and inoculum size). High pH was the most beneficial single treatment, increasing the minimum inhibitory concentration (measured by ethanol production) from 15% (control) to 70% hydrolysate.

Immunology of oral candidiasis.

A successful pathogen is one that is able to effectively survive and evade detection by the host immune defense. Oral candidiasis has adopted strategies, which evade host defense and eventually cause disease in at-risk patients. Host defense against infections with Candida spp.

Polyamine transporters and polyamines increase furfural tolerance during xylose fermentation with ethanologenic Escherichia coli strain LY180.

Expression of genes encoding polyamine transporters from plasmids and polyamine supplements increased furfural tolerance (growth and ethanol production) in ethanologenic Escherichia coli LY180 (in AM1 mineral salts medium containing xylose). This represents a new approach to increase furfural tolerance and may be useful for other organisms. Microarray comparisons of two furfural-resistant mutants (EMFR9 and EMFR35) provided initial evidence for the importance of polyamine transporters.

Dental caries vaccine - a possible option?

Dental caries is an irreversible microbial disease of the calcified tissues of the teeth and it has a multifactorial origin. In India, the dental caries prevalence in 35-44 year olds was reported to be 80-95% in a DCI survey. Among the elderly in the 65-74 years age group, the DCI survey reported the caries prevalence to be about 70%, while the present survey reported it to be 51- 95% in various states.

Improving Escherichia coli FucO for furfural tolerance by saturation mutagenesis of individual amino acid positions.

Furfural is an inhibitory side product formed during the depolymerization of hemicellulose with mineral acids. In Escherichia coli, furfural tolerance can be increased by expressing the native fucO gene (encoding lactaldehyde oxidoreductase). This enzyme also catalyzes the NADH-dependent reduction of furfural to the less toxic alcohol.

Engineering furfural tolerance in Escherichia coli improves the fermentation of lignocellulosic sugars into renewable chemicals.

Pretreatments such as dilute acid at elevated temperature are effective for the hydrolysis of pentose polymers in hemicellulose and also increase the access of enzymes to cellulose fibers. However, the fermentation of resulting syrups is hindered by minor reaction products such as furfural from pentose dehydration. To mitigate this problem, four genetic traits have been identified that increase furfural tolerance in ethanol-producing Escherichia coli LY180 (strain W derivative): increased expression of fucO, ucpA, or pntAB and deletion of yqhD.

Seed train development for the fermentation of bagasse from sweet sorghum and sugarcane using a simplified fermentation process.

A process was developed for seed culture expansion (3.6 million-fold) using 5% of the hemicellulose hydrolysate from dilute acid pretreatment as the sole organic nutrient and source of sugar. Hydrolysate used for seed growth was neutralized with ammonia and combined with 1.

Complete genome sequence of Paenibacillus sp. strain JDR-2.

Paenibacillus sp. strain JDR-2, an aggressively xylanolytic bacterium isolated from sweetgum (Liquidambar styraciflua) wood, is able to efficiently depolymerize, assimilate and metabolize 4-O-methylglucuronoxylan, the predominant structural component of hardwood hemicelluloses. A basis for this capability was first supported by the identification of genes and characterization of encoded enzymes and has been further defined by the sequencing and annotation of the complete genome, which we describe.

Complete Genome Sequence of a thermotolerant sporogenic lactic acid bacterium, Bacillus coagulans strain 36D1.

Bacillus coagulans is a ubiquitous soil bacterium that grows at 50-55 °C and pH 5.0 and ferments various sugars that constitute plant biomass to L (+)-lactic acid. The ability of this sporogenic lactic acid bacterium to grow at 50-55 °C and pH 5.