Wide pH Tolerance Research Articles

Evaluation of Inkjet Technologies for Digital Fabrication & Functional Printing

The report determined that the dispensing requirements for digital fabrication and functional printing applications vary widely. Inkjet printing for 3D fabrication requires the deposition of layers that are less than 40 μm along the build Z-axis. Deposit of 30-μm layers for opaque photo polymeric materials and 16-μm layers for transparent polymeric materials have demonstrated that evidence of the layering process is not discernable to the naked eye. The modified Xerox M-series PIJ bend mode head, which has 880 nozzles and ejects drops of 15 or 30 pl, produced even layers and smooth contours without evidence of process artifacts. Similarly, Objet printers using Ricoh Gen3PIJ piston mode printheads produce similarly smooth results, but the production process may require some layer shaving to yield the desired layer thickness. These dimensional targets will satisfy most visual, functional and radiation curing requirements for 3D fabrication applications. The ZPrinters, which use HP TIJ heads to fire polymer into tri-calcium phosphate powder coating, produce Z-layers over 100 μm thick. These typically require some post print curing and finishing.The reports from inkjet printers of electronics indicate that drop volumes of direct printing with metallic nano-particle silver require drops in the range of 1 to 10 pl depending on the refinement of the circuits lines. The Fujifilm Dimatix DMP inkjet print systems have become standard equipment in almost 700 research and development facilities for testing and producing printed circuits. Dimatix offer its 16-nozzle MEMS cartridge printheads in both 1 and 10 pl versions. Other companies have developed similar systems.PixDRO has developed production inkjet systems for fabricating solar cells using a variety of printheads to match process requirements. The Company offers Xaar 1001, Fujifilm Dimatix Spectra S-Class SE, SM, SL, (plus hot melt), SE3 and SX3, Konica Minolta KM 204, KM 256, KM 512 (plus hot melt), Trident ITW 256Jet-D.Acid etching and caustics deposit for some circuit printing approaches requires deposition devices with a wide pH tolerance range. We determined that heads that were stainless steel could provide the greatest pH range. The Trident ITW 256Jet-D head offers tolerances in the pH range of 2 to 13, and the ability for a trained end user to dissemble the head for maintenance.The chemical composition of inkjet printheads must have a surface energy that permits the flow of the print fluid with its surface tension through the head. The fluid must also have a surface tension that permits its adhesion with adjacent build layers. More viscose thermoplastic polymers will typically require heating to lower their viscosity to optimal levels for industrial inkjet printing. Heaters and thermistors are available for most industrial head. In addition to providing consistent temperature for jetting fluids, they can also provide hot melt capability. While Dimatix rates its DMC, D-series and most S-series heads at 70°C it also offers heads with ratings to 135°C. Xerox rates its M-series head as capable of handling fluid to 140°C. The MicroFab MJ-SF piezo dispenser and the Geiger SMLD 300G valve jet are rated to handle fluids up to 250°C. Canon Oce has applied for a patent for an inkjet type device that can tolerate fluid temperatures in excess of 1500°C. The ability to dispense liquids at high temperatures greatly extends the range of what is possible with inkjet fabrication and functional printing.

Cellulase Production by Pink Pigmented Facultative Methylotrophic Strains (PPFMs)

Pink pigmented facultative methylotrophs (PPFM) isolated from water samples of Cooum and Adyar rivers in Chennai and soil samples of forests located in various districts of Tamil Nadu, India were screened for cellulase production using carboxymethylcellulose agar (CMC agar) medium. The strains showed wide variations in the production of clearing zones around the colonies on CMC agar medium flooded with Congo red. CMCase and filter paper assays were used to quantitatively measure the cellulase activity of 13 PPFM strains. Among the strains, Methylobacterium gregans, MNW 60, MHW 109, MSF 34, and MSF 40 showed cellulolytic activity ranging from 0.73 to 1.16U mL(-1) with wide temperature (35-65°C) and pH (5 to 8) tolerance. SDS-PAGE analysis of the crude enzyme of PPFM strain MNW 60 exhibited several protein bands, and zymogram analysis revealed two dimeric cellulase bands with molecular mass of ~92 and 42kDa. Scanning electron microscopic studies revealed significant morphological differences between the cells grown in normal and CMC amended medium. The strain MNW 60 was identified as Methylobacterium sp. based on biochemical, physiological, and morphological analyses, and the methylotrophic nature was authenticated by the presence of mxaF gene, encoding methanol dehydrogenase as a key indicator enzyme of methylotrophs, with 99% similarity to Methylobacterium lusitanum. With the 16S ribosomal RNA sequence showing 97% similarity to M. lusitanum strain MP2, this can be proposed as a novel taxon of the genus Methylobacterium. The study forms the first detailed report on the extracellular cellulase production by pink pigmented Methylobacterium sp., and it is expected that this might be the basis for further studies on cellulase production by PPFMs to explore the molecular mechanism, strain improvement, and large-scale cellulase production for its application.

Microbiome of Fungus-Growing Termites: a New Reservoir for Lignocellulase Genes

Fungus-growing termites play an important role in lignocellulose degradation and carbon mineralization in tropical and subtropical regions, but the degradation potentiality of their gut microbiota has long been neglected. The high quality and quantity of intestinal microbial DNA are indispensable for exploring new cellulose genes from termites by function-based screening. Here, using a refined intestinal microbial DNA extraction method followed by multiple-displacement amplification (MDA), a fosmid library was constructed from the total microbial DNA isolated from the gut of a termite growing in fungi. Functional screening for endoglucanase, cellobiohydrolase, β-glucosidase, and xylanase resulted in 12 β-glucosidase-positive clones and one xylanase-positive clone. The sequencing result of the xylanase-positive clone revealed an 1,818-bp open reading frame (ORF) encoding a 64.5-kDa multidomain endo-1,4-β-xylanase, designated Xyl6E7, which consisted of an N-terminal GH11 family catalytic domain, a CBM_4_9 domain, and a Listeria-Bacteroides repeat domain. Xyl6E7 was a highly active, substrate-specific, and endo-acting alkaline xylanase with considerably wide pH tolerance and stability but extremely low thermostability.

Bacteriocin: safest approach to preserve food products.

Start of the 21st century with its universal call to feed the hungry is an appropriate time to refocus attention on food security and especially the impact of biopatenting on poor communities who are the primary victims of hunger in our world. Antibacterial metabolites of lactic acid bacteria and Bacillus spp have potential as natural preservatives to control the growth of spoilage and pathogenic bacteria in food. Among them, bacteriocin is used as a preservative in food due to its heat stability, wider pH tolerance and its proteolytic activity. Due to thermo stability and pH tolerance it can withstand heat and acidity/alkanity of food during storage condition. Bacteriocin are ribosomally synthesized peptides originally defined as proteinaceous compound affecting growth or viability of closely related organisms. Research is going on extensively to explore the nascent field of biopreservation. Scientists all over the world are showing their keen interest to isolate different types of bacteriocin producing strains and characterize bacteriocin produced by them for food preservation.

Effect of pH on growth, cell volume, and production of freshwater ciliates, and implications for their distribution

We investigated the effect of pH on growth, cell volume, and production of the freshwater ciliates Urotricha farcta, U. furcata, and U. castalia in laboratory cultures with Cryptomonas sp. as food. Overall, pH had a significant, species‐specific effect on all parameters investigated. The food alga, Cryptomonas sp., showed a wide pH tolerance, with positive growth rates between pH 4.4 and pH 9.65. Among the ciliates, U. farcta was the most pH‐tolerant and U. castalia was the most pH‐sensitive species, with positive growth being confined to pH 6.5‐8.2. The pH optimum was derived from cellular production rates. The pH optima of the three ciliate species were shifted; their production rates peaked at pH 4.4‐5.3 (U. farcta), pH 5.9‐7.3 (U. furcata), and pH 6.8‐7.9 (U. castalia). The pH effect on growth and survival of the ciliates was minor at circumneutral and moderately alkaline pH values, relative to the effect of temperature and food measured in earlier experiments. The widths of the pH tolerances of the ciliates were positively related to the widths of their temperature niches and to their natural distributions. U. farcta and U. furcata were characterized as euryoecious species, with broad pH and temperature tolerances and ubiquitous distribution; U. castalia is a rare, stenoecious species, requiring specific pH and temperature conditions.

The optimum and tolerance pH range is correlated to colonial morphology in isolates of the entomopathogenic fungus Beauveria bassiana - a potential biopesticide

Beauveria bassiana is an insect pathogenic fungus used as a biopesticide in crop pest management. It exists saprophytically in the soil. The pH of the soil and the insect cuticle and its haemocoel may influence fungal survival and infection potential. Therefore the tolerance and optimum pH ranges were studied in 29 isolates of B. bassiana. Germination and growth bioassays in liquid culture medium adjusted to pH values in the range 3–14 at unit intervals were studied. A pH of 3 was found to be toxic to all isolates – conidia germinated at this pH but growth was totally inhibited. All isolates tolerated a pH of 5–13. Some isolates showed tolerance to a pH of 4 and/or 14 as well. Sixteen isolates showed a wide range of pH optimum of 5–13 while others had a narrower optimal range. The relation of the pH tolerance and optimum range of an isolate to its phenotypic characters (colonial morphology and growth-rate) was studied. All isolates with a ‘chalky’ type colonial morphology had an intermediate growth rate and showed a wide optimum range of pH 5–13 or 5–14. All isolates with ‘dusty’ type colonial morphology were found to have a high growth rate and a wide pH tolerance range of 4–14. Both chalky and dusty colonial morphology are due to a growth pattern characterized by iterated conidiation with a very brief hyphal stage. The correlation observed between these traits based on external phenotype would facilitate prediction of the pH tolerance characters of an isolate of B. bassiana.

Embryo tolerance and maternal control of the marsupial environment in Armadillidium vulgare (Isopoda: Oniscidea).

Marsupial development in terrestrial isopods subjects embryos to potential physiological stresses, including desiccation, osmotic variation, and high ammonia concentrations. In this study, we investigated tolerance of osmotic extremes, total ammonia, and pH in developmental stages of Armadillidium vulgare cultured in vitro. Marsupial stages were classified as stage 1 (chorionated eggs), stage 2 (having shed the chorion), and stage 3 (mancas). All stages showed wide but differing tolerance ranges. Stage 1 eggs possess the greatest ammonia tolerance, with high 7-d survival in 150 mM total ammonia, and a wide pH tolerance range. Mancas show the widest osmotic tolerance (100-1,400 mosm x kg(-1)) and display proficient hemolymph osmoregulation over this range. Stage 2 eggs reveal the narrowest tolerance ranges for all three parameters but still qualify as eurytopic. Silver staining revealed two distinct ion-transporting tissues in the developmental stages: a median band on the vitelline membrane of stage 1 and stage 2 eggs, corresponding in location to the embryonic dorsal organ, and the posterior three pairs of pleopodal endopodites in mancas. Gravid females do not downregulate ammonia but show efficient regulation of marsupial fluid pH and downregulation of osmolality during dehydration, both of which will provide additional protection to the marsupial young.

Occurrence of Clostridia in the Sediment of an Extremely Polluted Danube Reach

The species composition of clostridial communities of the sediment in a polluted area of the Danube (South of Budapest, Háros-Bay, Hungary) was investigated. The spore counts exceeded 700...800 CFU per gram (wet weight). 23 clostridial strains were identified by using API 20A anaerobe identification kits, another 20 physiological, biochemical, and ecological tests were also carried out. Results of numerical analysis showed that the clostridial community in the sediment of the Danube is composed of at least 4 different species. Members of C. perfringens, indicating to fecal contamination, C. subterminale and related bacteria were dominant in the examined area. All strains showed wide pH (5...9) and temperature (3...45°C) tolerance. They were able to grow on media containing significant amounts of lead (Pb2+), mercury (Hg2+), copper (Cu2+), and zinc (Zn2+). Strains of C. perfringens showed a wide range of degradative capacities (acid production from many different carbohydrates, gelatinase, lecithinase, lipase production, etc.). Vorkommen von Clostridien im Sediment eines extrem verunreinigten Abschnittes der Donau Untersucht wird die Zusammensetzung der Clostridien-Flora im Sediment eines stärker verunreinigten Bereiches der Donau (Háros-Bucht, südlich von Budapest). Die Sporendichte überschreitet 700 bis 800 koloniebildende Einheiten pro Gramm Frischsediment. Mit Hilfe des Identifizierungssystems API 20A für Anaerobier werden 23 Clostridienstämme identifiziert, wobei zusätzlich weitere 20 physiologische, biochemische und ökologische Tests durchgeführt werden. Das Ergebnis der numerischen Analyse zeigt, daß die Clostridiengemeinschaft des Donausediments aus wenigstens 4 verschiedenen Arten besteht. Dominant sind im Untersuchungsgebiet Clostridium perfringens, Indikator fäkaler Verunreinigung, C. subterminale und verwandte Arten. Alle isolierten Stämme zeigen hohe Toleranz im Bereich des pH-Wertes (pH = 5...9) sowie der Temperatur (3...45°C) und wachsen auf Medien mit erhöhten Konzentrationen an Pb2+, Hg2+, Cu2+ und Zn2+. Stämme von C. perfringens zeigen einen weiten Bereich an Abbaukapazitäten (Säureproduktion aus vielen verschiedenen Kohlenhydraten, Produktion von Gelatinase, Lecithinase, Lipase usw.).

Ecophysiological factors affecting growth, sporulation and survival of the biocontrol agent Penicillium oxalicum.

The effect of temperature, pH, water potential and sources of nitrogen and carbon on the biocontrol agent Penicillium oxalicum were studied in vitro. The fungus is xerotolerant, mesophillic and has a wide pH tolerance. The parameters evaluated (germination, germ tube length, growth rate and sporulation) showed different sensitivities to the environmental factors. Peptone and free amino acids gave the highest growth rates and high levels of sporulation. Xylose, mannose and fructose gave the highest growth rates and mannose induced strong sporulation. The effect of nutrients (mannose + arginine) and water potential was also studied in vivo. The xerotolerant character of the fungus was confirmed. From this study we consider Penicillium oxalicum ecologically competent to perform effectively as a biocontrol agent in the soil environment.

Stress tolerance of the tidal pool chlorophyte,Chlorococcum submarinum

Chlorococcum submarinum, isolated from a tidal rockpool, was shown to be highly resistant to environmental stress. The alga can grow in salinities from a few mmol m-3 to 2 kmol m-3, with optimum growth occurring between 0·1 and 0·5 kmol m-3. It has an extraordinarily wide pH tolerance, growing from pH 2 to at least 10·5. C. submarinum is also resistant to copper, growing (at 10–15% of optimum rates) in the presence of 10 ppm copper.

A variable stoichiometry model for pH homeostasis in bacteria

The composition of the proton-motive force of a hypothetical bacterial cell of wide pH tolerance is analyzed according to a model whereby the electron transport chain and various proton-linked sodium and potassium ion transporting modes are responsible for the development of the membrane potential and the chemical potentials of the three cations. Simultaneous use of two or more modes employing the same metal cation, but at a different stoichiometric ratio with respect to protons, produces nonintegral stoichiometry; the modes could represent either different devices or different states of a single device. Cycling of the cation, driven by proton-motive force, results. The relative conductances of the various modes are postulated to be pH-dependent. The pattern of potentials that results is qualitatively in accord with current knowledge and may reflect the mechanism of pH homeostasis in bacteria. The membrane potential is outwardly directed (positive inside) at extremely acid pH, becoming inwardly directed as the pH increases; the pH gradient across the membrane is large and inwardly directed (alkaline inside) at acid pH, becoming smaller and eventually inverting at alkaline pH values; the transmembrane potassium gradient is outwardly directed (high concentration inside) at all pH values; the transmembrane sodium gradient is inwardly directed at all pH values, following the pH gradient from acid through neutral pH, but then diverging at alkaline pH.

Protease inhibitors from broad bean isolation and purification

Four protease inhibitors were demonstrated and two, BBPI- 1 and BBPI- 2, were purified from broad bean seeds using a combination of (NH 4) 2SO 4 fractionation, ion-exchange chromatography on CM 52-cellulose and CM 50 Sephadex. BBPI- 1 and 2 had broad specificity and inhibited trypsin, chymotrypsin, thrombin, pronase and papain. Both inhibitors were heat stable, had a wide pH tolerance, a MW of approximately 11 000 and contained 14·5% N. BBPI- 1 and 2 had a pI of 8·5 and 7·5 respectively.