Biotechnology Commons^™

Mutation Of Aspergillus Sp. Using Ultraviolet Light And Nitrous Acid For Amylase Production From Banana Peels, Cyprian Erumiseli Oshoma, Johnson Oche Akor, Beckley Ikhajiagbe, Marcel James Ikenebomeh

Makara Journal of Science

Strain improvement through mutagenesis is important in the commercial development of microbial fermentation. This study aimed to produce amylase from banana (Musa sapientum) peels by using mutant Aspergillus sp. strains obtained via ultraviolet (UV) radiation and nitrous acid-based mutagenesis. Results revealed that banana peels pretreated with 0.8 N HCl had a biomass yield of 3.02 g/L and amylase activity of 2.81 U/L. Of the UV mutants, strain AUV1 had the highest biomass and amylase activity of 4.50 ± 0.21 g/L and 3.46 ± 0.14 U/L, respectively. Subsequently, HNO₂ mutants showed that strain ANA6 had 30.64% and …

Metabolic Feedback Inhibition Influences Metabolite Secretion By The Human Gut Symbiont Bacteroides Thetaiotaomicron, Jennie L. Catlett, Jonathan Catazaro, Mikaela Cashman, Sean Carr, Robert Powers, Myra B. Cohen, Nicole R. Buan

Department of Biochemistry: Faculty Publications

Microbial metabolism and trophic interactions between microbes give rise to complex multispecies communities in microbe-host systems. Bacteroides thetaiotaomicron (B. theta) is a human gut symbiont thought to play an important role in maintaining host health. Untargeted nuclear magnetic resonance metabolomics revealed B. theta secretes specific organic acids and amino acids in defined minimal medium. Physiological concentrations of acetate and formate found in the human intestinal tract were shown to cause dose-dependent changes in secretion of metabolites known to play roles in host nutrition and pathogenesis. While secretion fluxes varied, biomass yield was unchanged, suggesting feedback inhibition does not affect metabolic …

Autohydrolysis Pretreatment Of Mixed Lignocellulosic Biomass, Claudio Lira

Electronic Thesis and Dissertation Repository

Lignocellulosic biomass, such as agricultural and forestry residues, can be transformed into valuable fuels and chemicals. However, the high cost of feedstock handling and the complex nature of cellulosic biomass processing and conversion remain two major challenges in biorefineries. This thesis aims to tackle these challenges by assessing the transformation of multi-feedstock using autohydrolysis pretreatment.

Corn cobs and stover (residues from corn processing), poplar chips (forestry residue), bagasse and wheat straw (agricultural residues) are abundant and often under-utilized cellulosic residues. These feedstocks were used to investigate the effects of biomass characteristics on the composition of the autohydrolysis pretreatment products. Moreover, …

Examination Of Pseudomonas Fluorescence As A Recombinant Expression Host: Cloning, Expression, And Chromatography, Ahmed K.Ali Elmasheiti

Graduate Theses and Dissertations

In an effort to expand the pool of bacterium useful for biotechnology applications, Pseudomonas fluorescens, a common gram negative microbe, was examined for its ability to function in a recombinant setting. P. fluorescens is ubiquitous in nature and was initially identified as a soil bacterium found in dirt and is typically associated with plant material. Past literature indicates that it shared characteristics common to Escherichia coli and Bacillus subtilis, including simple growth conditions and potential cloning vectors, providing motivation to look into both the upstream and downstream characteristics of this bacterium. First, it was demonstrated that P. fluorescens could be …

Biological Lignocellulose Solubilization: Comparative Evaluation Of Biocatalysts And Enhancement Via Cotreatment, Julie M. D. Paye, Anna Guseva, Sarah K. Hammer, Erica Gjersing

Dartmouth Scholarship

Feedstock recalcitrance is the most important barrier impeding cost-effective production of cellulosic biofuels. Pioneer commercial cellulosic ethanol facilities employ thermochemical pretreatment and addition of fungal cellulase, reflecting the main research emphasis in the field. However, it has been suggested that it may be possible to process cellulosic biomass without thermochemical pretreatment using thermophilic, cellulolytic bacteria. To further explore this idea, we examine the ability of various biocatalysts to solubilize autoclaved but otherwise unpretreated cellulosic biomass under controlled but not industrial conditions.

Anaerobic Detoxification Of Acetic Acid In A Thermophilic Ethanologen, A Joe Shaw, Bethany B. Miller, Stephen R. Rogers, William Robert Kenealy, Alex Meola, Ashwini Bhandiwad, W Ryan Sillers, Indraneel Shikhare, David Hogsett, Christopher Herring

Dartmouth Scholarship

The liberation of acetate from hemicellulose negatively impacts fermentations of cellulosic biomass, limiting the concentrations of substrate that can be effectively processed. Solvent-producing bacteria have the capacity to convert acetate to the less toxic product acetone, but to the best of our knowledge, this trait has not been transferred to an organism that produces ethanol at high yield. We have engineered a five-step metabolic pathway to convert acetic acid to acetone in the thermophilic anaerobe Thermoanaerobacterium saccharolyticum.

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The Exometabolome Of Clostridium Thermocellum Reveals Overflow Metabolism At High Cellulose Loading, Evert K. Holwerda, Philip G. Thorne, Daniel G. Olson, Daniel Amador-Noguez, Nancy L. Engle, Timothy J. Tschaplinski, Johannes P. Van Dijken, Lee R. Lynd

Dartmouth Scholarship

BackgroundClostridium thermocellum is a model thermophilic organism for the production of biofuels from lignocellulosic substrates. The majority of publications studying the physiology of this organism use substrate concentrations of ≤10 g/L. However, industrially relevant concentrations of substrate start at 100 g/L carbohydrate, which corresponds to approximately 150 g/L solids. To gain insight into the physiology of fermentation of high substrate concentrations, we studied the growth on, and utilization of high concentrations of crystalline cellulose varying from 50 to 100 g/L by C. thermocellum. .

Fungal Solid-State Fermentation And Various Methods Of Enhancement In Cellulase Production, Li Wan Yoon, Teck Nam Ang Dr., Gek Cheng Ngoh Dr, Adeline Seak May Chua Dr

Teck Nam Ang Dr.

Cellulase serves vast applications in the industries of biofuel, pulp and paper, detergent and textile. With the presence of its three components i.e. endoglucanase, exoglucanase and β-glucosidase, the enzyme can effectively depolymerize the cellulose chains in lignocellulosic substrate to produce smaller sugar units that consists of cellobiase and glucose. Fungi are the most suitable cellase producers attributing to its ability to produce a complete cellulase system. Solid state fermentation (SSF) by fungi is a preferable production route for cellulase as it imposes lower cost and enables the production of cellulase with higher titre. This article gives an overview on the …

Sweet Sorghum As A Bioenergy Crop: Literature Review, Teshome Regassa

Teshome H. Regassa

No abstract provided.

Development Of A Novel Inoculum Preparation Method For Solid-State Fermentation - Cellophane Film Culture (Cfc) Technique, Teck Nam Ang, Gek Cheng Ngoh, Adeline Seak May Chua

Teck Nam Ang Dr.

This study reports a user-friendly technique in the preparation of fungal inoculum intended for solid-state fermentation (SSF) – Cellophane Film Culture (CFC) technique. This technique uses cellophane film-overlaid agar plates to facilitate the separation of fungal biomass. The findings showed that inoculum of P. sajor-caju produced is viable, and it was confirmed by the presence of laccase enzyme activity in SSF of rice husk. The correlation between fungal dry and wet weights (r2 = 0.9329) provides an accurate estimation of fungal dry weight from its wet weight during inoculum preparation. Besides, this technique does not require a strict sterile handling …

Form And Function Of Clostridium Thermocellum Biofilms, Alexandru Dumitrache, Gideon Wolfaardt, Grant Allen, Steven N. Liss, Lee R. Lynd

Dartmouth Scholarship

The importance of bacterial adherence has been acknowledged in microbial lignocellulose conversion studies; however, few reports have described the function and structure of biofilms supported by cellulosic substrates. We investigated the organization, dynamic formation, and carbon flow associated with biofilms of the obligately anaerobic cellulolytic bacterium Clostridium thermocellum 27405. Using noninvasive, in situ fluorescence imaging, we showed biofilms capable of near complete substrate conversion with a characteristic monolayered cell structure without an extracellular polymeric matrix typically seen in biofilms. Cell division at the interface and terminal endospores appeared throughout all stages of biofilm growth. Using continuous-flow reactors with a rate …

Regression Analysis On Ionic Liquid Pretreatment Of Sugarcane Bagasse And Assessment Of Structural Changes, Li Wan Yoon, Teck Nam Ang Dr., Gek Cheng Ngoh Dr, Adeline Seak May Chua Dr

Teck Nam Ang Dr.

This study aims to perform a regression analysis which leads to the optimization on the operating conditions of ionic liquid (IL), 1-ethyl-3-methylimidazolium acetate ([EMIM]oAc) pretreatment on sugarcane bagasse (SCB). The structural changes on SCB during pretreatment were also examined. The effects of temperature, time and solid loading on reducing sugar (RS) yield obtained from enzymatic hydrolysis of pretreated SCB were investigated by applying Central Composite Design (CCD) of Response Surface Methodology (RSM). Results from CCD were modeled into a second order polynomial equation and the model shows a good correlation between predicted and experimental values. The optimized condition for [EMIM]oAc …

A Quantitative Method For Fungal Ligninolytic Enzyme, Teck Nam Ang Dr., Gek Cheng Ngoh Dr, Adeline Seak May Chua Dr

Teck Nam Ang Dr.

Screening is conducted to select a fungus with desired characteristics intended for various applications, e.g. bioremediation and enzyme production. A qualitative method was used in this study for screening of fungal ligninolytic enzymes activities. The fungal ligninolytic activity was correlated with its growth from the screenings to identify a suitable fungus for solid substrate fermentation. Four strains of fungi, namely Phanerochaete chrysosporium, Pycnoporus sanguineus, Phlebia radiata and Pleurotus sajor-caju, were screened for their ligninolytic enzymes activities using guaiacol and Remazol Brilliant Blue-R (RBB-R) as screening reagents. The screenings were conducted at both the optimal growth temperature of each fungus and …

Process Characteristics And Microbiology Of Fura Produced In Ghana, James Owusu-Kwarteng, Kwaku Tano-Debra, Fortune Akabanda, Richard Glover

James Owusu-Kwarteng

Majority of traditional cereal-based foods consumed in Africa are processed by spontaneous fermentation and are important as weaning foods for infants and as dietary staples for adults. Detailed knowledge of traditional processing is a prerequisite for investigating ways to improve both the nutritional and microbiological qualities of the corresponding product. In this study, the traditional processing of millet into fura, a popular millet-based dumpling consumed throughout West Africa, particularly Nigeria, Burkina-Faso and Ghana was investigated in a range of production units in northern Ghana. Microbiology of the processing was also investigated. Processing steps included soaking or steeping the grains, washing, …

Metabolic Engineering Of A Thermophilic Bacterium To Produce Ethanol At High Yield, A. Joe Shaw, Kara K. Podkaminer, Sunil G. Desai, John S. Bardsley, Stephen R. Rogers, Philip G. Thorne, David A. Hogsett, Lee R. Lynd

Dartmouth Scholarship

We report engineering Thermoanaerobacterium saccharolyticum, a thermophilic anaerobic bacterium that ferments xylan and biomass-derived sugars, to produce ethanol at high yield. Knockout of genes involved in organic acid formation (acetate kinase, phosphate acetyltransferase, and L-lactate dehydrogenase) resulted in a strain able to produce ethanol as the only detectable organic product and substantial changes in electron flow relative to the wild type. Ethanol formation in the engineered strain (ALK2) utilizes pyruvate:ferredoxin oxidoreductase with electrons transferred from ferredoxin to NAD(P), a pathway different from that in previously described microbes with a homoethanol fermentation. The homoethanologenic phenotype was stable for >150 generations …