Degradation of Cellulosic Materials by Trichoderma viride Cellulase

The extra-cellular filtrates of Trichoderma viride ITCC–1433 showed considerable cellulolytic activity against native celluloses, cellulose derivatives and raw materials. Newspaper-yellow and the rice straw were the prominent waste materials which were preferentially attacked by the enzyme. The alkali treatment of the latter doubled the sugar formation from it. As a result of cellulase action 80.4 per cent of the MN-Cellulose and 60.4 per cent of the alkali treated rice straw lost weight in 96 and 48 hr respectively. The weight loss was more or less equivalent to the reducing sugars formed.     

Biomass and Cellulosic Ethanol Production of Forage Sorghum Under Limited Water Conditions

This study presents results from a 2-year evaluation of biomass and cellulosic ethanol (EtOH) production potential of forage sorghum (Sorghum bicolor L. Moench) cultivars differing in brown midrib trait (i.e., bmr12) under dryland (no irrigation) and limited irrigation (2.88 mm?day^?1; subsurface drip) in the semiarid Southern High Plains of the USA. Commercial cultivar Sorghum Partners 1990 (SP 1990, conventional non-bmr) produced significantly more biomass (29–62 %) than a bmr12 cultivar PaceSetter bmr (PS bmr) under irrigated and dryland conditions during both years of this study. However, PS bmr biomass had higher cellulosic EtOH conversion efficiency than SP 1990 in both years according to simultaneous saccharification and fermentation analysis. Irrigation resulted in 26–49 % more biomass and 28–72 % more cellulosic EtOH production during both growing seasons, indicating that limited irrigation had favorable effects on both biomass and biofuel production. In the first year, when precipitation was below average, both cultivars produced similar amounts of cellulosic EtOH. During the second year, when precipitation was above average, higher biomass production of SP 1990 resulted in 28 % higher cellulosic EtOH production than PS bmr when averaged across both irrigated and dryland conditions. The large range of cellulosic EtOH production (1,600 to 3,380 L?ha^?1) during the 2 years of this study was primarily driven by differences in water availability that resulted from precipitation and irrigation. Our findings indicates that chemical composition and biomass yield potential of sorghum cultivars are critical factors that affect biomass and biofuel production under limited water conditions.     

A Visual Dual-Aptamer Logic Gate for Sensitive Discrimination of Prion Diseases-Associated Isoform with Reusable Magnetic Microparticles and Fluorescence Quantum Dots

Molecular logic gates, which have attracted increasing research interest and are crucial for the development of molecular-scale computers, simplify the results of measurements and detections, leaving the diagnosis of disease either “yes” or “no”. Prion diseases are a group of fatal neurodegenerative disorders that happen in human and animals. The main problem with a diagnosis of prion diseases is how to sensitively and selectively discriminate and detection of the minute amount of PrP^Res in biological samples. Our previous work had demonstrated that dual-aptamer strategy could achieve highly sensitive and selective discrimination and detection of prion protein (cellular prion protein, PrP^C, and the diseases associated isoform, PrP^Res) in serum and brain. Inspired by the advantages of molecular logic gate, we further conceived a new concept for dual-aptamer logic gate that responds to two chemical input signals (PrP^C or PrP^Res and Gdn-HCl) and generates a change in fluorescence intensity as the output signal. It was found that PrP^Res performs the “OR” logic operation while PrP^C performs “XOR” logic operation when they get through the gate consisted of aptamer modified reusable magnetic microparticles (MMPs-Apt1) and quantum dots (QDs-Apt2). The dual-aptamer logic gate simplifies the discrimination results of PrP^Res, leaving the detection of PrP^Res either “yes” or “no”. The development of OR logic gate based on dual-aptamer strategy and two chemical input signals (PrP^Res and Gdn-HCl) is an important step toward the design of prion diseases diagnosis and therapy systems.     

Efficient Plant Biomass Degradation by Thermophilic Fungus Myceliophthora heterothallica

Rapid and efficient enzymatic degradation of plant biomass into fermentable sugars is a major challenge for the sustainable production of biochemicals and biofuels. Enzymes that are more thermostable (up to 70°C) use shorter reaction times for the complete saccharification of plant polysaccharides compared to hydrolytic enzymes of mesophilic fungi such as Trichoderma and Aspergillus species. The genus Myceliophthora contains four thermophilic fungi producing industrially relevant thermostable enzymes. Within this genus, isolates belonging to M. heterothallica were recently separated from the well-described species M. thermophila. We evaluate here the potential of M. heterothallica isolates to produce efficient enzyme mixtures for biomass degradation. Compared to the other thermophilic Myceliophthora species, isolates belonging to M. heterothallica and M. thermophila grew faster on pretreated spruce, wheat straw, and giant reed. According to their protein profiles and in vitro assays after growth on wheat straw, (hemi-)cellulolytic activities differed strongly between M. thermophila and M. heterothallica isolates. Compared to M. thermophila, M. heterothallica isolates were better in releasing sugars from mildly pretreated wheat straw (with 5% HCl) with a high content of xylan. The high levels of residual xylobiose revealed that enzyme mixtures of Myceliophthora species lack sufficient β-xylosidase activity. Sexual crossing of two M. heterothallica showed that progenies had a large genetic and physiological diversity. In the future, this will allow further improvement of the plant biomass-degrading enzyme mixtures of M. heterothallica.     

The Economics of Biomass Collection and Transportation and Its Supply to Indiana Cellulosic and Electric Utility Facilities

With cellulosic energy production from biomass becoming popular in renewable energy research, agricultural producers may be called upon to plant and collect corn stover or harvest switchgrass to supply feedstocks to nearby facilities. Determining the production and transportation cost to the producer of corn stover or switchgrass and the amount available within a given distance from the plant will result in a per metric ton cost the plant will need to pay producers in order to receive sufficient quantities of biomass. This research computes up-to-date biomass production costs using recent prices for all important cost components including seed, fertilizer, herbicide, mowing/shredding, raking, baling, storage, handling, and transportation. The cost estimates also include nutrient replacement for corn stover. The total per metric ton cost is a combination of these cost components depending on whether equipment is owned or custom hired, what baling options are used, the size of the farm, and the transport distance. Total costs per dry metric ton for biomass with a transportation distance of 60 km ranges between $63 and $75 for corn stover and $80 and $96 for switchgrass. Using the county quantity data and this cost information, we then estimate biomass supply curves for three Indiana coal-fired electric utilities. This supply framework can be applied to plants of any size, location, and type, such as future cellulosic ethanol plants. Finally, greenhouse gas emissions reductions are estimated from using biomass instead of coal for part of the utility energy and also the carbon tax required to make the biomass and coal costs equivalent. Depending on the assumed CO₂ price, the use of biomass instead of coal is found to decrease overall costs in most cases.     

Economic Analysis of the Potential of Cellulosic Biomass Available in France from Agricultural Residue and Energy Crops

The objective of this research is to evaluate the feasibility and locations of using cellulosic biomass both from crop residues and from dedicated energy crops to supply 200-million-liter-biodiesel plants in France. The estimation of the potential amount of agricultural residue available in 2015 in each region of France is calculated. The residues considered in this study come from cereal straw and corn stover. Results show that eight out of the twenty one French regions have enough agricultural residues available to supply at least one 200 million liter biofuel plant. Region Centre has the largest potential, with enough residues to supply three to five plants. Finally, cost of supplying one biodiesel plant of 200 million liters in the region Centre is estimated. Results show that collection of biomass will be effective in an area with a radius of 58 Km to 168 Km depending of the raw material considered and its abundance. The cost of supplying a plant with miscanthus is much higher than with residues only. Thus, crop residues appear to offer a lower cost to produce biodiesel in the near term compared to a dedicated crop. Results show that production of biofuel from cellulosic biomass should not be limited by the supply of raw material, but costs of conversion to liquid fuels clearly will play a key role in the development of cellulosic biofuels. Energy prices and policies will have a significant impact on second generation biofuel development.     

A Biomimetic Spermatozoa Propulsion Method for Interventional Micro Robot

Nowadays, studies of the interventional micro robots have been hot topics in the field of medical device. The ultimate goal of medical micro robots is to reach currently inaccessible areas of the human body and carry out a host of complex operations such as minimally invasive surgery (MIS), highly localized drug delivery and opening up the blood vessels. Miniature, safe and energy efficient propulsion systems hold the key to mature this technology. In this paper, a prototype of endovascular micro robot based on the motion principle of spermatozoa is presented. The properties of this propulsive mechanism are estimated by modeling the dynamics of the swimming methods. In order to validate the theoretical results for spermatozoa propulsion, a scaled-up prototype of the swimming robot is fabricated and characterized in imitative bio-pipes full of silicone oil. Experimental results shown that the spermatozoa-like micro robot can be controlled to swim efficiently. And to adjust the rotation direction of the four flexible tails, the propulsion forces and the function of opening up the blood vessels will be generated.     

Contribution of a Xylan-Binding Module to the Degradation of a Complex Cellulosic Substrate by Designer Cellulosomes

Conversion of components of the Thermobifida fusca free-enzyme system to the cellulosomal mode using the designer cellulosome approach can be employed to discover the properties and inherent advantages of the cellulosome system. In this article, we describe the conversion of the T. fusca xylanases Xyn11A and Xyn10B and their synergistic interaction in the free state or within designer cellulosome complexes in order to enhance specific degradation of hatched wheat straw as a model for a complex cellulosic substrate. Endoglucanase Cel5A from the same bacterium and its recombinant dockerin-containing chimera were also studied for their combined effect, together with the xylanases, on straw degradation. Synergism was demonstrated when Xyn11A was combined with Xyn10B and/or Cel5A, and ∼1.5-fold activity enhancements were achieved by the designer cellulosome complexes compared to the free wild-type enzymes. These improvements in activity were due to both substrate-targeting and proximity effects among the enzymes contained in the designer cellulosome complexes. The intrinsic cellulose/xylan-binding module (XBM) of Xyn11A appeared to be essential for efficient substrate degradation. Indeed, only designer cellulosomes in which the XBM was maintained as a component of Xyn11A achieved marked enhancement in activity compared to the combination of wild-type enzymes. Moreover, integration of the XBM in designer cellulosomes via a dockerin module (separate from the Xyn11A catalytic module) failed to enhance activity, suggesting a role in orienting the parent xylanase toward its preferred polysaccharide component of the complex wheat straw substrate. The results provide novel mechanistic insight into the synergistic activity of designer cellulosome components on natural plant cell wall substrates.Thermobifida fusca is an aerobic thermophilic soil bacterium with strong cellulolytic activity (52). The T. fusca enzyme system is an extensively studied free cellulase system in which nearly all of the cellulolytic enzymes have been fully characterized, from the individual enzyme sequences to the three-dimensional structures, as well as the biochemical activities of the native and recombinant proteins. The genome sequence has been published (36), and the number and types of carbohydrate-active enzymes produced by the organism are known. This actinomycete produces six different cellulases that have been well studied (29, 31, 32, 50, 52). T. fusca also has the ability to grow on xylan and produces several enzymes involved in xylan degradation, such as xylanases, β-xylosidase, α-l-arabinofuranosidase, and acetylesterases (1, 21).Previous research has suggested that the multienzyme cellulosome complex from Clostridium thermocellum is far more efficient than free cellulase systems that were tested in degrading polysaccharides (33). The cellulosome system is characterized by the strong bimodular interaction between the cohesin and dockerin modules that integrates the various enzymes into the complex (5, 35, 55). Scaffoldin subunits (nonenzymatic protein components) contain the cohesin modules that incorporate the enzymes into the complex via their resident dockerins. The primary scaffoldin subunit also includes a carbohydrate (cellulose)-binding module (CBM) through which the complex recognizes and binds to the cellulosic substrate (42, 46).In order to evaluate the reasons for the apparent advantage of cellulosomes over free enzymes, it is interesting to compare the properties of the best-characterized free-enzyme systems for degradation of polysaccharides with those of the best-studied cellulosome system. We have initiated a program to convert the free-enzyme system of T. fusca into an artificial designer cellulosome (11-13). The designer cellulosome concept is based on the very high affinity (20, 44) and specific interaction (37, 43, 55) between a cohesin and a dockerin module from the same species. Since the various scaffoldin-borne cohesins of a given species essentially show the same specificity of binding for the enzyme-borne dockerins, designer cellulosomes are constructed from recombinant chimeric scaffoldins containing divergent cohesins from different species, for which matching dockerin-containing enzyme hybrids are prepared, as a platform for promoting synergistic action among enzyme components (5). Free cellulases from the T. fusca system were converted to the cellulosomal mode by replacing their native CBM with a desired dockerin module, and in some cases, the resultant “designer cellulosomes” exhibited enhanced synergistic activity on crystalline cellulosic substrates compared to that of the mixture of wild-type enzymes (11).In this study, we incorporated xylanolytic enzymes into designer cellulosomes and investigated their hydrolytic effects on purified xylans and on a native, complex cellulosic substrate (hatched wheat straw). We focused on T. fusca xylanases 11A and 10B (Xyn11A and Xyn10B), which are the most abundant xylanases produced during growth on xylan (34). Xyn11A and Xyn10B function as endoxylanases (28, 34); Xyn11A contains a C-terminal family 2 CBM that binds both cellulose and xylan, whereas Xyn10B lacks a CBM. In some experiments, one of the previously converted (dockerin-containing) T. fusca endoglucanases, f-5A (11), was also introduced into the designer cellulosomes in order to evaluate cooperation between xylanases and cellulases in hydrolysis of a natural substrate. This study contributes primary information concerning a major feature of cellulosomes that had not been suitably addressed in earlier research: although xylanases are integral components of cellulosomes, their synergistic action in the cellulosome mode has yet to be examined experimentally. The xylan-binding CBM (termed XBM for the purposes of this report) was found to contribute to the activity of the parent Xyn11A enzyme.     

Culture Media Statistical Optimization for Biomass Production of a Ligninolytic Fungus for Future Rice Straw Degradation

The main objective of this study was to optimize a culture media for low scale biomass production of Pleurotus spp. Future applications of this optimization will be implemented for “in situ” rice straw degradation, increase soil nutrients availability, and lower residue and rice culture management costs. Soil samples were taken from different points in six important rice production cities in Colombia. For carbon and nitrogen source selection a factorial 4² design was carried out. The Plackett-Burman design permitted to detect carbon, nitrogen and inducer effects on fungus growth (response variable for all designs). This optimization was carried out by a Box-Behnken design. Finally a re-optimization assay for glucose concentration was performed by means of a One Factor design. Only 4/33 (12 %) isolates showed and important laccase or manganese peroxidase activity compared to Pleurotus ostreatus (HPB/P3). We obtained an increased biomass production in Pleurotus spp. (T1.1.) with glucose, followed by rice husk. Rice straw was considered an inducing agent for lignin degradation. Glucose was a significant component with positive effects, whereas Tween 80 and pH had negative effects. On the contrary, rice husk, yeast extract and CaCl₂ were not significant components for increase the biomass production. Final media composition consisted of glucose 25 g L^?1, yeast extract 5 g L^?1, Tween 80 0.38 % (v/v), Rice husk 10 g L^?1, CaCl₂ 1 g L^?1, and pH 4.88 ± 0.2. The Box-Behnken polynomial prediction resulted to be lower than the experimental validation of the model (6.59 vs. 6.91 Log₁₀ CFU ml^?1 respectively).     

Biomimetic polyene cyclizations: A review

It has been shown that certain polyenic substances, having trans olefinic bonds in the 1,5 relationship, can be induced to undergo stereospecific, nonenzymic, cationic cyclization to give polycyclic products with the all trans (“natural”) configuration. These transformations appear to mimic in principle the biogenetic conversion of squalene into polycyclic triterpenoids, e.g., lanosterol. Acetal as well as allylic alcohol functions have proved to be effective initiators for such cyclizations, many of which proceed to a remarkable degree of completion giving mainly totally cyclized products. Thus, it has been possible to convert, in a single step, an open chain tetraenic acetal having no chiral centers, into a tetracyclic product having seven such centers. The process is highly stereoselective giving only two of 64 possible racemates.Methylacetylenic and also styryl end groups are particularly useful cyclization terminators as they provide a means of realizing five-membered ring formation. Systems with these terminators have been developed for effecting the total synthesis of the steroid nucleus in a single step starting from a substrate containing only one ring.The mechanism of these biomimetic as well as of the enzymic cyclizations is open to question, but the balance of the evidence is somewhat in favor of a synchronous process.     

Biomimetic vibrissal sensing for robots

Active vibrissal touch can be used to replace or to supplement sensory systems such as computer vision and, therefore, improve the sensory capacity of mobile robots. This paper describes how arrays of whisker-like touch sensors have been incorporated onto mobile robot platforms taking inspiration from biology for their morphology and control. There were two motivations for this work: first, to build a physical platform on which to model, and therefore test, recent neuroethological hypotheses about vibrissal touch; second, to exploit the control strategies and morphology observed in the biological analogue to maximize the quality and quantity of tactile sensory information derived from the artificial whisker array. We describe the design of a new whiskered robot, Shrewbot, endowed with a biomimetic array of individually controlled whiskers and a neuroethologically inspired whisking pattern generation mechanism. We then present results showing how the morphology of the whisker array shapes the sensory surface surrounding the robot's head, and demonstrate the impact of active touch control on the sensory information that can be acquired by the robot. We show that adopting bio-inspired, low latency motor control of the rhythmic motion of the whiskers in response to contact-induced stimuli usefully constrains the sensory range, while also maximizing the number of whisker contacts. The robot experiments also demonstrate that the sensory consequences of active touch control can be usefully investigated in biomimetic robots.     

A Biomimetic Rotor-configuration Design for Optimal Aerodynamic Performance in Quadrotor Drone

Motivated by optimal combination of paired wings configuration and stroke-plane inclination in biological flapping flights that can achieve high aerodynamic per...     

Biomimetic systems for studying actin-based motility

Actin polymerization provides a major driving force for eukaryotic cell motility. Successive intercalation of monomeric actin subunits between the plasma membrane and the filamentous actin network results in protrusions of the membrane enabling the cell to move or to change shape. One of the challenges in understanding eukaryotic cell motility is to dissect the elementary biochemical and biophysical steps that link actin polymerization to mechanical force generation. Recently, significant progress was made using biomimetic, in vitro systems that are inspired by the actin-based motility of bacterial pathogens such as Listeria monocytogenes. Polystyrene microspheres and synthetic phospholipid vesicles coated with proteins that initiate actin polymerization display motile behavior similar to Listeria, mimicking the leading edge of lamellipodia and filopodia. A major advantage of these biomimetic systems is that both biochemical and physical parameters can be controlled precisely. These systems provide a test bed for validating theoretical models on force generation and polarity establishment resulting from actin polymerization. In this review, we discuss recent experimental progress using biomimetic systems propelled by actin polymerization and discuss these results in the light of recent theoretical models on actin-based motility.     

Differential Staining for Cellulosic and Modified Plant Cell Walls

A simple method to enhance the staining of cell wall components for fluorescence microscopy is described. In stems of Nicotiana tabacum and needles of Pinus eldarica lignin, the cuticle and unsaturated lipids are indicated by a purple-red fluorescence while pectocellulosic components fluorescc pale blue.     

A New Self-Loading Locomotion Mechanism for Wall Climbing Robots Employing Biomimetic Adhesives

A versatile locomotion mechanism is introduced and experimentally verified. This mechanism comprises four rectangular wheels (legs) with rotational phase difference which enables the application of pressure to each contacting surface for securing it to the surface using bio-inspired or pressure-sensitive adhesives. In this mechanism, the adhesives are applied to two rigid plates attached to each wheel via hinges incorporating torsional springs. The springs force the plates back to their original position after the contact with the surface is lost in the course of locomotion. The wheels are made of low-modulus elastomers, and the pressure applied during contact is controlled by the elastic modulus, geometry and phase difference of wheels. This reliable adhesion system does not rely upon gravity for adhering to surfaces, and provides the locomotion mechanism with the ability to climb walls and transition from horizontal to vertical surfaces.     

A Structurally and Functionally Biomimetic Biphasic Scaffold for Intervertebral Disc Tissue Engineering

Tissue engineering offers high hopes for the treatment of intervertebral disc (IVD) degeneration. Whereas scaffolds of the disc nucleus and annulus have been extensively studied, a truly biomimetic and mechanically functional biphasic scaffold using naturally occurring extracellular matrix is yet to be developed. Here, a biphasic scaffold was fabricated with collagen and glycosaminoglycans (GAGs), two of the most abundant extracellular matrix components in the IVD. Following fabrication, the scaffold was characterized and benchmarked against native disc. The biphasic scaffold was composed of a collagen-GAG co-precipitate making up the nucleus pulposus-like core, and this was encapsulated in multiple lamellae of photochemically crosslinked collagen membranes comprising the annulus fibrosus-like lamellae. On mechanical testing, the height of our engineered disc recovered by ~82-89% in an annulus-independent manner, when compared with the 99% recovery exhibited by native disc. The annulus-independent nature of disc height recovery suggests that the fluid replacement function of the engineered nucleus pulposus core might mimic this hitherto unique feature of native disc. Biphasic scaffolds comprised of 10 annulus fibrosus-like lamellae had the best overall mechanical performance among the various designs owing to their similarity to native disc in most aspects, including elastic compliance during creep and recovery, and viscous compliance during recovery. However, the dynamic mechanical performance (including dynamic stiffness and damping factor) of all the biphasic scaffolds was similar to that of the native discs. This study contributes to the rationalized design and development of a biomimetic and mechanically viable biphasic scaffold for IVD tissue engineering.     

Biomimetic platforms for human stem cell research

Stem cells are central to developing new treatment options for tissue regeneration and constructing controllable models for biological research. Bioengineered cell culture environments that combine microenvironmental control with tissue-specific transport and signaling are critical tools in our efforts to study tissue development, regeneration, and disease under conditions that predict the human in vivo context. We propose that experimentation at the interfaces of biology, engineering, and medical sciences is critical for unlocking the full potential of stem cells. Here, we focus on the design and utilization of in vitro platforms that recapitulate the environments associated with tissue development, disease, and regeneration.