Polyurethane Foam Support Research Articles

Identification of the adhesive domain of AtaA from Acinetobacter sp. Tol 5 and its application in immobilizing Escherichia coli.

Cell immobilization is an important technique for efficiently utilizing whole-cell biocatalysts. We previously invented a method for bacterial cell immobilization using AtaA, a trimeric autotransporter adhesin from the highly sticky bacterium Acinetobacter sp. Tol 5. However, except for Acinetobacter species, only one bacterium has been successfully immobilized using AtaA. This is probably because the heterologous expression of large AtaA (1MDa), that is a homotrimer of polypeptide chains composed of 3,630 amino acids, is difficult. In this study, we identified the adhesive domain of AtaA and constructed a miniaturized AtaA (mini-AtaA) to improve the heterologous expression of ataA. In-frame deletion mutants were used to perform functional mapping, revealing that the N-terminal head domain is essential for the adhesive feature of AtaA. The mini-AtaA, which contains a homotrimer of polypeptide chains from 775 amino acids and lacks the unnecessary part for its adhesion, was properly expressed in E. coli, and a larger amount of molecules was displayed on the cell surface than that of full-length AtaA (FL-AtaA). The immobilization ratio of E. coli cells expressing mini-AtaA on a polyurethane foam support was significantly higher compared to the cells with or without FL-AtaA expression, respectively. The expression of mini-AtaA in E. coli had little effect on the cell growth and the activity of another enzyme reflecting the production level, and the immobilized E. coli cells could be used for repetitive enzymatic reactions as a whole-cell catalyst.

Properties of vehicle support suspensions

The processes of damping of vibrations of sprung masses with polyurethane foam support cushions in the frequency range of vibrations with an optimal transfer function are investigated. The amplitude-phase-frequency characteristics of the masses are determined during vibrations with the subsequent presentation of transient processes, according to which the damping time of the vibrations of the sprung masses is determined. The used support cushions made of polyurethane foam reduce the minimum damping time of vibrations of the sprung masses on 1520 %, they are more wear-resistant and have greater damping properties than rubber support cushions. Keywords: spectral density, exposure frequency, transmission coefficient, deformation coefficient, vibration damping time, polyurethane foam. i.dyakov@ulstu.ru

Optimum interaction of light intensity and CO2 concentration in bioremediating N-rich real wastewater via assimilation into attached microalgal biomass as the feedstock for biodiesel production

Impoverishing nutrients from wastewater via assimilation into microalgal biomass has gained footprint in bioremediation technologies. To ease the harvesting of mature microalgal biomass from effluent, this study proposed the employment of fluidized bed bioreactor to grow attached microalgal biomass onto polyurethane foam support material while bioremediating the N-rich real wastewater from chemical fertilizer manufacturing industry. The complete removals of all nitrogen species (NH4+-N, NO2−-N and NO3−-N) together with COD and total phosphorus were achieved at the optimum light intensity and CO2 concentration of 216μmol/m2 s and 9.1 %, respectively, giving rise to the attached microalgal biomass productivity of 0.094g/L/day. These performances were also found maintaining for at least 4 cycles of reiterative uses of spent polyurethane foam support material in similar fluidized bed bioreactor setup condition with every cycle being introduced with fresh N-rich real wastewater. The mechanism of attachment formations study predicted that the polysaccharides and proteins from microalgal extracellular polymeric substances had bridged the cells onto polyurethane foam support material during the initial colonization prior to populating and growing to cover the surfaces of support material. For biodiesel production, the extracted neutral lipid content of attached microalgal biomass was found to be four times higher than the suspended growth culture. From the transesterification process, about 97 %–98 % of attached microalgal lipid could be converted into fatty acid methyl esters (FAMEs) mixture. Interestingly, the degree of saturated fatty acids (SFA) in FAMEs was recorded increasing with the increase of cycles of reusing spent polyurethane foam support material. The presence of more SFA in FAMEs could overall enhance the oxidative stability and contribute to higher cetane number of produced biodiesel from facilely harvested attached microalgal biomass.

Painting on polyurethane foam: “Composizione-Superficie Lunare” by Giulio Turcato

“Composizione-Superficie Lunare” (1965) is an artwork of the Italian artist Giulio Turcato (Mantua, 1912- Rome, 1995). This painting, inspired by moon travels, was created on a polyurethane foam support, material experimentalized by some other contemporary artists in the late 1960′s.In the present paper the organic and inorganic materials used as binders, fillers and pigments, as well as the support itself, have been investigated by means of a multi-analytical approach based on the application of Environmental Scanning Electron Microscopy Energy-Dispersive X-ray spectroscopy (ESEM–EDX), Micro-Attenuated Total Reflection Fourier Transform Infrared spectroscopy (µ-ATR–FTIR), High Performance Liquid Chromatography coupled with Diode Array Dectector and tandem Mass Spectrometry (HPLC–DAD, LC–MS/MS), Pyrolysis-Gas Chromatography and Evolved Gas Analysis coupled with Mass Spectrometry (Py-GC/MS, multi-shot Py-GC/MS and EGA–MS). The plethora of analytical techniques available allowed to provide for the first time a full characterization of the different materials used in “Composizione-Superficie Lunare” and of a Turcato's painting. The polyurethane foam artwork was painted using synthetic inorganic and organic pigments, such as methyl violet and manganese violet, dispersed in polyvinyl acetate as medium. The study was fundamental for establishing the original materials and aesthetics of the artwork as well as assessing the degradation state of the painting materials and of the polyurethane foam support. The results collected, crucial for planning an effective restoration campaign, highlight the importance of the contribution of analytical chemistry to cultural heritage.

Quantification of the Food Dye Indigo Carmine in Candies Using Digital Image Analysis in a Polyurethane Foam Support

The aim of this present work was to propose an alternative methodology to quantify the food dye indigo carmine in industrialized candies by the innovative technique of digital image analysis. To do so, the candy was solubilized in water and extracted to polyurethane foam, which is capable of selectively adsorbing the dye, removing interferents from the matrix. The foam was dried and glued on a sheet of paper. After that, digital images of the system were taken using a flatbed scanner. A free-access software was used to treat these images in order to obtain the color intensity of the foam, which was related to the concentration of the analyte. The linear range of this proposed method was 0.1 to 5.0 mg L−1. The limits of detection and quantification were respectively 0.20 μg g−1 and 0.68 μg g−1. These limits were adequate to determine indigo carmine in the studied candies. The precision of the method was estimated in 2.16% by the standard deviation of daily replicates and the accuracy in 113 ± 2% by recovery tests. The method was applied in the quantification of the analyte in real samples, and these results were compared with the ones obtained by a previously established chromatographic method, resulting in a statistical conformity at 95% confidence level.

Feasibility of the new method for orchid in vitro rooting using liquid and chemical sterilized culture medium under different sucrose concentration

Abstract The in vitro propagation of orchids is the only commercial large scale technique to obtain healthy and high quality plantlets with clonal origin. The use of new technologies in plant tissue culture systems could lead to efficiency increases and costs reduction of micropropagation systems. The main actual micropropagation system is based on semi-solid culture media solidified using agar, followed by sterilization using autoclaving, and cultivation under photomixotrophic conditions using sucrose as main source of energy to plant in vitro culture. We proposed in this study the use of new micropropagation system using chemical sterilized liquid medium using polyurethane foam as support and LED source of light in rooting stage of Miltassia ‘Shelobie Tolkien’. Thus, the objective of this research was to test different concentrations of sucrose, comparing the conventional semi-solid agar-based culture medium (control) and the use of liquid medium with polyurethane foam support. The following sucrose concentrations were used: 0, 7.5, 15, 22.5 and 30 g L-1. The experiment was conducted in a 2 × 5 factorial, in a completely randomized design with ten replications each over a total period of 105 days of cultivation. The chemical sterilization using ClO2 showed 100% of decontamination in all treatments. The use of liquid media with polyurethane foam showed better results than plants cultivated in agar medium, and can be used for replace agar-based for orchid in vitro rooting.

Control of AtaA-mediated bacterial immobilization by casein hydrolysates

Acinetobacter sp. Tol 5 exhibits an autoagglutinating nature and high adhesiveness to various abiotic surfaces through its bacterionanofiber protein AtaA. We have developed new bacterial immobilization methods utilizing the high adhesiveness of AtaA. We previously reported that salt is essential for the adhesiveness of AtaA. In the current study, we unexpectedly found that Tol 5cells were not immobilized onto polyurethane foam support during growth in LB medium although AtaA was properly expressed and displayed onto the cell surface. The adhesion of Tol 5 resting cells was not affected by sugars but drastically inhibited by yeast extract and casein hydrolysates such as tryptone and casamino acids technical grade (CA-T). Some amino acids, which are major components of CA-T, partially inhibited the adhesion of Tol 5cells. Experimental results suggested that oligopeptides might effectively inhibit the cell adhesion. Immobilized cells onto the support through AtaA were detached in CA-T solution. Also, the detached cells could be re-immobilized onto the support without impairing of their adhesiveness by replacing CA-T solution to a basal salt medium. Microscopic observation revealed that breaking of AtaA-mediated cell-cell interaction is important for the detachment of Tol 5cells from the support. CA-T also inhibited AtaA-mediated autoagglutination and dispersed cell clumps through AtaA. This is the first report on adhesion inhibitors against AtaA and suggests that casein hydrolysates like CA-T would be a powerful tool for controlling AtaA-mediated bacterial immobilization.

Bacterial cellulose grows with a honeycomb geometry in a solid-state culture of Gluconacetobacter xylinus using polyurethane foam support

Abstract The polyurethane foam (PUF) allowed the growth of Gluconacetobacter xylinus for prompt production of bacterial cellulose (BC) due to high water storage capacity that let high water activity, as well as diffusion of oxygen through the PUF pores. PUF was studied in two sizes cut (0.13 cm3) and minced (0.08 cm3). Additionally, the study assessed the level of inoculum on the growth and the formation of BC. The highest yield of BC was 2.46 g L-1 of cellulose achieved with cut foam and 15% inoculum at 96 h. Fourier transform infrared spectroscopy (FT-IR), X-ray powder diffraction (XRD) and solid state 13C cross polarization and magic angle spinning nuclear magnetic resonance (CP/MAS NMR) analyses evidence crystalline structure type I for the produced microbial cellulose. According to scanning electron microscopy (SEM) analysis, the bacteria synthesized the biopolymer as a biofilm adhered to the solid support; thereby BC displays a honeycomb geometry.

Modeling to enhance attached microalgal biomass growth onto fluidized beds packed in nutrients-rich wastewater whilst simultaneously biofixing CO2 into lipid for biodiesel production

One way to reconcile an issue associating with the harvesting of microalgal biomass is via the application of attached growth cultivation mode, whereby the mature microalgal biomass can be facilely harvested from the support material. Accordingly, the objectives of present works were to model the attached growth of Chlorella vulgaris onto polyurethane foam support material in a fluidized bed bioreactor while simultaneously bioremediating real nutrients-rich wastewater and biofixing CO2 for biodiesel production. The mathematical models accounting the impact of various interactions between light intensities and CO2 concentrations in culture medium on growing attached microalgal biomass were initially improved. The successful practicality of models was confirmed from the analysis of statistical accuracy while predicting the growth of attached microalgal biomass in real nutrients-rich wastewater. When the microalgal growth reached the stationary growth phase, all the nutrients (nitrogen and phosphorous sources of compounds) were completed impoverished, accentuating the bioremediation potentiality in satisfying the effluent discharged requirements. Subsequently, the modeling of microalgal CO2 biofixation also unveiled that the highest CO2 biofixation rate was transpiring in parallel with the growth rate of attached microalgal biomass during the exponential growth phase. Upon the harvesting, the neutral lipid from mature attached microalgal biomass was found to contain 97.7% (by wt. of lipid) of fatty acid methyl esters (FAMEs) mixture, heralding the biodiesel purity. Assessment of biodiesel quality showed a balance composition among the saturated, monounsaturated and polyunsaturated FAMEs mixture with high in C16 and C18 FAME species for the materialization of efficient combustion.

Mechanistic kinetic models describing impact of early attachment between Chlorella vulgaris and polyurethane foam material in fluidized bed bioreactor on lipid for biodiesel production

The fundamental mechanism of early attachment between Chlorella vulgaris microalgae cells and polyurethane foam support material was unveiled prior to the kinetic study and optimization of operational bed packing volume in fluidized bed bioreactor. All aiming to enhance the lipid accumulation for sustainable biodiesel production. The two-step early attachment mechanism was found starting with the short-range Lewis acid-base interaction before the cells migrating toward the surface of support material induced by the electrostatic attractive force. This mechanism was mainly propelled by the chemisorption stemming from the interactions of cell-to-cell repulsion and cell-to-support material attraction. The electrostatic attractive interaction transpired on the surface of support material was also maneuvering the kinetics of formation of early attachment as reflected by the zeta potential trend via the sequence of pH 9 < pH 7 < pH 5 > pH 3. The rapid early attachment formation in pH 5 culture medium in fluidized bed bioreactor had led to the highest weight of attached growth microalgae biomass attainability as opposed to the other pH mediums. By exploiting the pH 5 culture medium, the maximum yields of microalgae biomass, lipid and later biodiesel were harvested from the bioreactor packed with 6% (v/v) of polyurethane foam support material, confirming optimum packing volume. These yields were initially observed increasing with the increase of packing volume due to the increasing surface area of support material; and unfortunately, decreasing after 6% (v/v) of packing volume due to the congestion factor.

Enhanced oil recovery by hydrophobins from Lecanicillium lecanii

The hydrophobins (HFB)s are a class of proteins with high surface tension and thermostability which potential application in enhanced oil recovery (EOR). The entomopathogenic fungus Lecanicillium lecanii produced HFBs in an 8.8L-scale solid-state fermentation using polyurethane foams as inert support in three configurations. Additionally, crude enzyme with lipase activity was also produced and tested for EOR individually or in combination with HFBs. The polyurethane foam support in cubes attained the highest yield of class I HFB (17.3 ± 1%) and the highest lipase activity (3.6 ± 0.2 U/mg protein). These HFBs formed stable oil–water emulsions displaying an interfacial tension up to 7.6 ± 0.3 mN/m. The proteins were used in limestone cores under tertiary recovery oil well conditions to achieve up to 14% recovery.

Investigations in sonication-induced intensification of crude glycerol fermentation to dihydroxyacetone by free and immobilized Gluconobacter oxydans

This study reports crude glycerol fermentation by G. oxydans for dihydroxyacetone (DHA) production, and intensification of fermentation with sonication. Fermentation was carried out using both free and immobilized cells (on polyurethane foam support) for initial glycerol concentrations of 20, 30 and 50 g/L. Sonication at 20% duty cycle enhanced glycerol consumption by 60–84% with no significant change in cell morphology. Lesser DHA yield in crude glycerol fermentation was attributed to possible formation of inhibitory products. Slight reduction in DHA yield for initial glycerol concentration of 50 g/L was attributed to substrate inhibition. Higher DHA productivity was obtained for immobilized cells. Circular dichroism analysis of intracellular proteins obtained from ultrasound-treated G. oxydans revealed significant reduction in α-helix and β-sheet content. These conformational changes in protein structure could augment activity of intracellular glycerol dehydrogenase, which is manifested in terms of enhanced metabolism of glycerol by G. oxydans.

Mass production of Ajmalicine by bioreactor cultivation of hairy roots of Catharanthus roseus

Catharanthus roseus has been known to produce Ajmalicine which is used for treatment of circulatory disorders. Significantly low content of the drug in the natural plant necessitates development of alternative production protocols. Hairy root propagation was considered as a viable alternative. Mass cultivation of the hairy root culture was attempted in several bioreactor configurations; Bubble column, Rotating drum bioreactor, Modified Bubble column with polypropylene (PP) mesh support and Modified Bubble column with Polyurethane foam (PUF) support. Important factors like medium composition, inoculum density, illumination period and aeration rates were optimized before mass propagation of hairy roots. From the data gleaned, the cultivation in rotating drum bioreactor resulted in ajmalicine content of only 4.6±0.4mg/l. However, the ajmalicine concentration surpassed even that obtained in shake flask (with 34±2.3mg/l) in a customized bioreactor wherein the hairy roots were anchored onto a polyurethane foam, the highest reported in this scale of cultivation.

Process optimization for tannase production by Bacillus gottheilii M2S2 on inert polyurethane foam support

Abstract Tannin acyl hydrolase (E.C. 3.1.1.20), commonly referred as “tannase”, breaks hydrolysable tannins into gallic acid and glucose. It finds commercial applications in food industry to reduce the level of tannins in fruit juices, preparation of instantaneous tea and production of gallic acid. In this work, a tannase producing Bacillus gottheilii M2S2 was isolated from the tannery effluent soil and a sequential optimization strategy was used to determine the effect of carbon source and inducer-tannic acid, nitrogen source NH 4 NO 3 , inoculum volume, initial pH, incubation time and mineral salts (KH 2 PO 4 , MgSO 4 , NaCl and CaCl 2 ·2H 2 O) in the production of tannase from Bacillus gottheilii M2S2 in solid state fermentation. Polyurethane foam was used as an inert support for growth of the microorganism. The microorganism was fermented at 32 °C in an optimized liquid medium composed of tannic acid (4%), NH 4 NO 3 (2%), KH 2 PO 4 (0.1%), MgSO 4 (0.2%), NaCl (0.1%) and CaCl 2 ·2H 2 O (0.05%) adjusted to initial media pH 4.74 then inoculated with 7.035% vv −1 inoculum and impregnated on polyurethane foam for 26.45 h under static condition . A final activity of 49.32±0.30 U L −1 was achieved, which represents an increase of 328% in relation to the initial unoptimized conditions.

The hydrophobicity of the support in solid state culture affected the production of hydrophobins from Lecanicillium lecanii

Lecanicillium lecanii has been successfully employed to produce hydrophobin-like proteins (HfbL) in solid state and submerged cultures varying the type of solid inert support. This study shows the results on the effect of hydrophilic Perlite and hydrophobic Polyurethane inert supports in solid state cultures for production of HfbLs by L. lecanii. The hydrophobicity of the support employed in solid state cultures influenced the yields and surface activities of the class I and class II HfbLs produced by L. lecanii. Class I HfbL was only produced using the hydrophobic polyurethane foam support, showing high surface activity that reduced ca. 50% hydrophobicity of Teflon, whereas class II HfbLs were produced on both polyurethane foam and perlite supports, and they reduced ca. 50% the surface tension of water and ca. 25% reduction of the hydrophobicity of Teflon.

Formation Mechanism of Cubic Mesoporous Carbon Monolith Synthesized by Evaporation-Induced Self-assembly

The formation mechanism of the cubic mesoporous carbon, FDU-16, synthesized by evaporation-induced self-assembly (EISA) was investigated at the molecular level by electron paramagnetic resonance (EPR) spectroscopic techniques. This material is synthesized using F127 pluronic block copolymer [poly(ethylene oxide)–poly(propylene oxide)–poly(ethylene oxide) (PEO106-PPO70-PEO106)] as a structure-directing agent (template) and phenolic resol as a carbon precursor. Using two spin probes derived from pluronics with PEO and PPO chains of different lengths that are designed to sense different regions of the system, we followed the evaporation and thermopolymerization stages of the synthesis in situ. To make such studies possible, we have used a polyurethane foam support, placed in the EPR tube, which allows for the efficient solvent evaporation as required for EISA. We focused on the evolution of the dynamics of the template and its interactions with the resol during the reaction. We observed that during the evaporation stage the resol is distributed throughout the entire PEO blocks, all the way to the PPO–PEO interface, interacting with them via H-bonds, thus hindering the local motion of the PEO chains. At the end of this stage there is no polarity gradient along the PEO blocks, as found for traditional F127 micelles in water or during the synthesis of silica materials, and the mesostructure is not well-defined. A polarity and a resol gradient developed during the thermopolymerization stage where the polymerizing resol is driven out to the outer region of the PEO corona. This produces a corona of resin-pluronic composite and a resol-free PPO core with high mobility of the PEO segments close to the PPO–PEO interface and restricted mobility in the composite corona. During this stage the final structure sets in.

Analysis of mechanical interaction between human gluteal soft tissue and body supports

Pressure sores are the most common complication associated with patient immobilization. They develop through sustained localized tissue strain and stress, primarily caused by body supports. Modifying support design can reduce the risk and extent of pressure sore development with computational simulations helping to provide insight into tissue stress-strain distribution. Appropriate material parameters for human soft tissue and support material, as well as precise anatomical modelling, are indispensable in this process. A finite element (FE) model of the human gluteal region based on magnetic resonance imaging (MRI) data has been developed. In vivo human gluteal skin/fat and muscle long-term material parameters as well as open-cell polyurethane foam support long-term material parameters have been characterised. The Ogden form for slightly compressible materials was employed to describe human gluteal soft tissue behaviour. Altering support geometries and support materials, effects on human gluteal soft tissue could be quantified. FE-analysis indicated maximal tissue stress at the muscle-bone interface, not at the skin. Shear strain maxima were found in the muscle layer near the fat-muscle interface. Maximum compressive stress magnitude at the sacral bone depended strongly on the behaviour of the pelvic diaphragm musculature. We hypothesize that the compliance of the muscles forming the pelvic diaphragm govern the relative motion of the buttock tissue to the adjacent bone structure under compression, thus influencing tissue stress magnitudes.

Biofilter Treatment of Volatile Organic Compound Emissions from Reformulated Paint: Complex Mixtures, Intermittent Operation, and Startup

Two biofilters were operated to treat a waste gas stream intended to simulate off-gases generated during the manufacture of reformulated paint. The model waste gas stream consisted of a five-component solvent mixture containing acetone (450 ppmv), methyl ethyl ketone (12 ppmv), toluene (29 ppmv), ethylbenzene (10 ppmv), and p-xylene (10 ppmv). The two biofilters, identical in construction and packed with a polyurethane foam support medium, were inoculated with an enrichment culture derived from compost and then subjected to different loading conditions during the startup phase of operation. One biofilter was subjected to intermittent loading conditions with contaminants supplied only 8 hr/day to simulate loading conditions expected at facilities where manufacturing operations are discontinuous. The other biofilter was subjected to continuous contaminant loading during the initial start period, and then was switched to intermittent loading conditions. Experimental results demonstrate that both startup strategies can ultimately achieve high contaminant removal efficiency (>99%) at a target contaminant mass loading rate of 80.3 g m−3 hr−1 and an empty bed residence time of 59 sec. The biofilter subjected to intermittent loading conditions at startup, however, took considerably longer to reach high performance. In both biofilters, ketone components (acetone and methyl ethyl ketone) were more rapidly degraded than aromatic hydrocarbons (toluene, ethylbenzene, and p-xylene). Scanning electron microscopy and plate count data revealed that fungi, as well as bacteria, populated the biofilters.

Caffeine degradation in solid state fermentation by Aspergillus tamarii: effects of additional nitrogen sources

The ability of Aspergillus tamarii V12A25 to use caffeine as sole nitrogen source was investigated in solid state fermentation (SSF) using two different supports, polyurethane foam (PUF) and sugarcane bagasse. Caffeine can be used in SSF as the sole nitrogen source, the carbon source being saccharose. If a simpler nitrogen source (ammonium sulphate, urea) is added to the medium containing caffeine, this source will be used first allowing fungal growth. If saccharose is still present when the simple nitrogen source has been degraded, caffeine will be used as the nitrogen source, together with saccharose. Caffeine at a concentration of 8 g/l has no effect on fungal growth when a simple nitrogen source is not limiting. The main difference between the two solid supports was the time required to complete the fermentation. With sugarcane bagasse as the support, substrates (caffeine, ammonium sulphate, urea) were degraded almost twice as fast as with PUF as the support. Theophylline and 3-methylxanthine, the major products from caffeine degradation, disappeared completely from the culture medium shortly after caffeine degradation stopped. The major advantage of using PUF support over sugar cane bagasse is that the former allows determination of fungal biomass which is not possible with the latter.

An in Vitro Potato Bioassay to Investigate Tuber Inductive Factors in Continuously Reused Hydroponic Nutrient Solutions

An experiment was conducted in the Biomass Production Chamber (BPC) at Kennedy Space Center to examine the effects of using continuously reused nutrient solution in an NFT system to support potato growth in batch and continuous planting scenarios. Tuberization was hastened and plant growth reduced on plants grown in the aged nutrient solution. We have previously reported that the effect is removed when the aged nutrient solution is filtered through activated charcoal. In order to investigate this apparent plant growth regulator response, an in vitro bioassay has been developed that allows for repeatable, small scale, and rapid testing of the tuber-inducing response. The bioassay is a liquid culture system that employs 600-mL Berzelius beakers capped with modified Sun transparent tissue culture bags, a light shield around the root zone, and a polyurethane foam support, which holds a micropropagated potato plantlet. With this bioassay, we have observed the same plant stunting and tuber initiation effects that were previously seen with the aged nutrient solution. The bioassay appears to be sensitive to environmental factors (PPF, photoperiod, and temperature) that influence tuberization. In addition, partially purified preparations of the apparent growth regulators have elicited the tuberization response. Currently, efforts are underway to examine the role of the microbial community associated with the BPC nutrient delivery system on the tuberization response.