Proizvodnja gelan gume fermentacijom, njezino izdvajanje, pročišćavanje i primjena

The microbial exopolysaccharides are water-soluble polymers secreted by microorganisms during fermentation. The biopolymer gellan gum is a relatively recent addition to the family of microbial polysaccharides that is gaining much importance in food, pharmaceutical and chemical industries due to its novel properties. It is commercially produced by C. P. Kelco in Japan and the USA. Further research and development in biopolymer technology is expected to expand its use. This article presents a critical review of the available information on the gellan gum synthesized by Sphingomonas paucimobilis with special emphasis on its fermentative production and downstream processing. Rheological behaviour of fermentation broth during fermentative production of gellan gum and problems associated with mass transfer have been addressed. Information on the biosynthetic pathway of gellan gum, enzymes and precursors involved in gellan gum production and application of metabolic engineering for enhancement of yield of gellan gum has been specified. Characteristics of gellan gum with respect to its structure, physicochemical properties, rheology of its solutions and gel formation behaviour are discussed. An attempt has also been made to review the current and potential applications of gellan gum in food, pharmaceutical and other industries.Tijekom fermentacije mikroorganizmi izlučuju egzopolisaharide, polimere topljive u vodi. Gelan guma je biopolimer odnedavno uvršten u skupinu mikrobnih polisaharida koji se zbog svojih novih svojstava sve više primjenjuje u industriji hrane te farmaceutskoj i kemijskoj industriji. Proizvodi ga tvrtka C.P. Kelco u Japanu i SAD-u. Dodatnim istraživanjem i razvojem tehnologije biopolimera proširit će se njegova primjena. U ovom je radu dan kritički osvrt na podatke o sintezi gelan gume s pomoću Sphingomonas paucimobilis, a osobito na proizvodnju fermentacijom te izdvajanje i pročišćavanje proizvoda. Opisana su i reološka svojstva medija tijekom proizvodnje te problemi vezani uz prijenos tvari. Navedeni su podaci o biosintetskom putu, enzimima i prekurzorima koji sudjeluju u njezinoj proizvodnji te primjena metaboličkog inženjeringa radi poboljšanja prinosa. Također se raspravljalo o značajkama gelan gume s obzirom na strukturu, fizičko-kemijska svojstva, reologiju otopina te ponašanje pri formiranju gela. Autori su prikazali sadašnju i buduću primjenu gelan gume u industriji hrane, farmaceutskoj industriji i ostalim industrijama

Skleroglukan: proizvodnja fermentacijom, izdvajanje, pročišćavanje i primjena

Exopolysaccharides produced by a variety of microorganisms find multifarious industrial applications in foods, pharmaceutical and other industries as emulsifiers, stabilizers, binders, gelling agents, lubricants, and thickening agents. One such exopolysaccharide is scleroglucan, produced by pure culture fermentation from filamentous fungi of genus Sclerotium. The review discusses the properties, fermentative production, downstream processing and applications of scleroglucan.Razni mikroorganizmi proizvode egzopolisaharide koji imaju višestruku primjenu u proizvodnji hrane, farmaceutskoj industriji i drugim industrijama, kao emulgatori, stabilizatori, učvršćivači, te sredstva za geliranje, podmazivanje i zgušnjavanje. Jedan takav polisaharid je skleroglukan proizveden fermentacijom s pomoću filamentoznih gljiva iz roda Sclerotium. U ovom se revijalnom prikazu raspravlja o svojstvima skleroglukana, njegovoj proizvodnji fermentacijom te izdvajanju i primjeni

Skleroglukan: proizvodnja fermentacijom, izdvajanje, pročišćavanje i primjena

Exopolysaccharides produced by a variety of microorganisms find multifarious industrial applications in foods, pharmaceutical and other industries as emulsifiers, stabilizers, binders, gelling agents, lubricants, and thickening agents. One such exopolysaccharide is scleroglucan, produced by pure culture fermentation from filamentous fungi of genus Sclerotium. The review discusses the properties, fermentative production, downstream processing and applications of scleroglucan.Razni mikroorganizmi proizvode egzopolisaharide koji imaju višestruku primjenu u proizvodnji hrane, farmaceutskoj industriji i drugim industrijama, kao emulgatori, stabilizatori, učvršćivači, te sredstva za geliranje, podmazivanje i zgušnjavanje. Jedan takav polisaharid je skleroglukan proizveden fermentacijom s pomoću filamentoznih gljiva iz roda Sclerotium. U ovom se revijalnom prikazu raspravlja o svojstvima skleroglukana, njegovoj proizvodnji fermentacijom te izdvajanju i primjeni

Evolution of changes in the computed tomography scans of the brain of a patient with left middle cerebral artery infarction: a case report

<p>Abstract</p> <p>Introduction</p> <p>Stroke is a common and important condition in medicine. Effective early management of acute stroke can reduce morbidity and mortality.</p> <p>Case presentation</p> <p>A 63-year-old man presented to the Accident and Emergency department with a history of collapse and progressive right-sided weakness. Clinically this was a cerebrovascular accident affecting the left hemisphere of the brain causing right hemiplegia. Computed tomography scans, performed 3 days apart, showed the evolution of infarction in the brain caused by the thrombus in the left middle cerebral artery. This is one of the early signs for stroke seen on computed tomography imaging and it is called the hyperdense middle cerebral artery sign.</p> <p>Conclusion</p> <p>Patients admitted with a stroke, undergo CT brain within 24 hours. The scan usually takes place at admission into the hospital and is done to rule out a bleed or a space occupying lesion within the brain. A normal CT brain does not confirm a stroke has not taken place. When scanned early, the changes seen on the CT due to an infarction from a thrombus may not have taken place yet. This paper highlights the early changes that can be seen on the CT brain following a stroke caused by infarction due to a thrombus in the middle cerebral artery.</p

Microbial Monitoring of Common Opportunistic Pathogens by Comparing Multiple Real-Time PCR Platforms for Potential Space Applications

Because the International Space Station is a closed environment with rotations of astronauts and equipment that each introduce their own microbial flora, it is necessary to monitor the air, surfaces, and water for microbial contamination. Current microbial monitoring includes labor- and time-intensive methods to enumerate total bacterial and fungal cells, with limited characterization, during in-flight testing. Although this culture-based method is sufficient for monitoring the International Space Station, on future long-duration missions more detailed characterization will need to be performed during flight, as sample return and ground characterization may not be available. At a workshop held in 2011 at NASA's Johnson Space Center to discuss alternative methodologies and technologies suitable for microbial monitoring for these long-term exploration missions, molecular-based methodologies such as polymerase chain reaction (PCR) were recommended. In response, a multi-center (Marshall Space Flight Center, Johnson Space Center, Jet Propulsion Laboratory, and Kennedy Space Center) collaborative research effort was initiated to explore novel commercial-off-the-shelf hardware options for space flight environmental monitoring. The goal was to evaluate quantitative or semi-quantitative PCR approaches for low-cost in-flight rapid identification of microorganisms that could affect crew safety. The initial phase of this project identified commercially available platforms that could be minimally modified to perform nominally in microgravity. This phase was followed by proof-of-concept testing of the highest qualifying candidates with a universally available challenge organism, Salmonella enterica. The analysis identified two technologies that were able to perform sample-to-answer testing with initial cell sample concentrations between 50 and 400 cells. In addition, the commercial systems were evaluated for initial flight safety and readiness

Gellan Gum: Fermentative Production, Downstream Processing and Applications

The microbial exopolysaccharides are water-soluble polymers secreted by microorganisms during fermentation. The biopolymer gellan gum is a relatively recent addition to the family of microbial polysaccharides that is gaining much importance in food, pharmaceutical and chemical industries due to its novel properties. It is commercially produced by C. P. Kelco in Japan and the USA. Further research and development in biopolymer technology is expected to expand its use. This article presents a critical review of the available information on the gellan gum synthesized by Sphingomonas paucimobilis with special emphasis on its fermentative production and downstream processing. Rheological behaviour of fermentation broth during fermentative production of gellan gum and problems associated with mass transfer have been addressed. Information on the biosynthetic pathway of gellan gum, enzymes and precursors involved in gellan gum production and application of metabolic engineering for enhancement of yield of gellan gum has been specified. Characteristics of gellan gum with respect to its structure, physicochemical properties, rheology of its solutions and gel formation behaviour are discussed. An attempt has also been made to review the current and potential applications of gellan gum in food, pharmaceutical and other industries

Adsorption of C2 gases over CeO2-based catalysts: synergism of cationic sites and anionic vacancies

The synthesis of novel and efficient catalysts for acetylene hydrogenation exhibiting high selectivity towards ethylene is important due to the presence of selective acetylene hydrogenation reaction in petrochemical processing. Since adsorption of C2 gases constitutes the primary step in catalytic hydrogenation and governs the selectivity of the catalysts, we have explored the C2-adsorption potential of reducible CeO2-based systems. The adsorption of C2-gases over CeO2-based materials was assessed using experimental in situ spectroscopic techniques and in silico theoretical studies based on density functional theory. The effect of Pd2+ substitution on adsorption was studied. The addition of Pd2+-ions was found to enhance the adsorption of the gases. Theoretical calculations provided insights into the modes of adsorption, adsorption energetics and reactant–catalyst interactions. The role of the presence of cationic substitution and anionic vacancies in strengthening the adsorption of gases was established. Pd-substituted reduced CeO2 showed activity for the adsorption of all C2 gases. On the basis of the aforementioned experimental and theoretical observations, the catalysts were tested for acetylene hydrogenation, and Pd-substituted CeO2 was found to be a good catalyst for the reaction with complete acetylene conversion observed below 100 °C.by Manjusha C. Padole, Bhanu Pratap Gangwar, Aman Pandey, Aditi Singhal, Sudhanshu Sharma and Parag A. Deshpand