Entity

Time filter

Source Type


Tsibakhashvili N.Y.,Andronikashvili Institute of Physics | Tsibakhashvili N.Y.,Ilia State University | Kirkesali E.I.,Andronikashvili Institute of Physics | Pataraya D.T.,Durmishidze Institute of Biochemistry and Biotechnology | And 8 more authors.
Advanced Science Letters | Year: 2011

Microbial synthesis of nanoparticles has a potential to develop simple, cost-effective and eco-friendly methods for production of technologically important materials. In this study, for the first time a novel actinomycete strain Streptomyces glaucus 71 MD isolated from a soy rhizosphere in Georgia is for the first time extensively characterized and utilized for the synthesis of silver nanoparticles. Transmission Electron Microscopy (TEM) images revealed that most of the particles produced by this microorganism from AgNO 3 are spherical in shape with an average size of 13 nm. Scanning Electron Microscopy (SEM) allowed observing extracellular synthesis of nanoparticles, which has many advantages from the point of view of applications. Production of silver nanoparticles proceeded extracellularly with the participation of another microorganism, blue-green microalgae Spirulina platensis (S. platensis). In this study it is shown that the production rate of the nanoparticles depends not only on the initial concentration of AgNO 3 but also varies with time in a nonmonotonic way. SEM study of silver nanoparticles remaining on the surface of microalgae revealed that after 1 day of exposure to 1 mM AgNO 3 nanoparticles were arranged as long aggregates along S. platensis cells strongly damaged by silver ions. However, after 5 days of exposure to silver S. platensis cells looked completely recovered and the nanoparticles were distributed more uniformly on the surface of the cells. © 2011 American Scientific Publishers. Source


Partskhaladze G.,HIGH-TECH | Dudauri T.,HIGH-TECH | Berezhiani M.,HIGH-TECH | Berejiani A.,Durmishidze Institute of Biochemistry and Biotechnology | And 2 more authors.
Conference Proceeding - 4th International Conference, TAE 2010: Trends in Agricultural Engineering 2010 | Year: 2010

Production of fuels and chemicals by fermentation of renewable, low cost and plentiful cellulosic materials has received increasing attention due to several reasons including dwindling of fossil fuels. One of the key problems in the fermentation of lignocellulosic wastes to liquid fuel like ethanol or chemicals is the relatively low reactivity nature of cellulose. A number of factors are believed to influence cellulose reactivity, including particle size and surface area, lignin content, and cellulose crystallinity. Significant increase of cellulose hydrolysis by some economical and environmentally sound method is considered one of the important points to make cellulosics based fuel ethanol production cost competitive with gasoline. Cellulosic materials pretreatment method reported here has been developed to increase cellulose reactivity, in particular to increase the rate and extent of cellulose hydrolysis. Proposed method is based on the treatment of cellulosic material with a liquefied carbon dioxide under pressure followed by pressure release. It involves combination of the following processes: (i) saturation of cellulosic materials with water; (ii) contact of cellulosic materials with liquefied CO2 under pressure at temperature less than those which degrade sugars; (iii) pressure release that causes the evaporation of liquid CO 2. Temperature decrease associated with evaporation of the volatile liquid tends embrittle the fiber and enhances the effect of the pressure release on overall fiber disruption. Changes in cellulose polymerization degree and specific surface area have been determined when cellulosic wastes like wheat straw and corn stalks were frozen at -5°C, -10°C, -21°C and -31°C. Studies showed that cellulose polymerization degree was decreased about 2 times and cellulose specific reactionary surface area was increased around 10 times when above cellulosic wastes were frozen at -31°C and milled in 3-5 mm particles in the frozen state. © 2010 Czech University of Life Sciences Prague. Source


Pipia I.,Free University of Tbilisi | Pipia I.,Durmishidze Institute of Biochemistry and Biotechnology | Gogniashvili M.,Free University of Tbilisi | Gogniashvili M.,Durmishidze Institute of Biochemistry and Biotechnology | And 9 more authors.
Vitis - Journal of Grapevine Research | Year: 2012

DNA sequence diversity was investigated in three plastid regions (the trnH-psbA intergenic spacer, accDpsaI intergenic spacer and the rp/16 intron) in a group of 40 wild grape (Vitis vinifera subsp. sylvestris) samples from the South Caucasus. This group included 22 samples from Georgia, 9 samples from Azerbaijan, 2 samples from Armenia and 7 samples from Turkey. The South Caucasus region is widely believed to be the area in which grape domestication began, and the study of genetic diversity in this region is viewed as key to understanding grape domestication in general. Four plastid haplotypes are evident in the 40 samples, and are designated by their character states at each of the 4 polymorphic positions: AAAT - 22 samples, ATTT - 6 samples, GTAC -1 sample, and ATAT -11 samples. The AAAT haplotype is restricted to Georgia and Azerbaijan, the ATAT haplotype is distributed across the entire study area, the ATTT haplotype is distributed in the southern part of the study area from the Black Sea to the Caspian Sea. The single GTAC haplotype was only found in southwestern Georgia. The AAAT haplotype is restricted to both wild (V. vinifera subsp. sylvestris) and cultivated (V. vinifera subsp. vinifera) grape samples from the Caucasus. This observation and the presence of all other plastid haplotypes observed in a previous study of worldwide grape cultivars highlight both unique and high levels of genetic variation in wild grape (V. vinifera subsp. sylvestris) from the greater Caucasus region. Source


Elisashvili V.,Durmishidze Institute of Biochemistry and Biotechnology | Kachlishvili E.,Durmishidze Institute of Biochemistry and Biotechnology | Khardziani T.,Durmishidze Institute of Biochemistry and Biotechnology | Agathos S.N.,Catholic University of Louvain
Journal of Industrial Microbiology and Biotechnology | Year: 2010

Three white-rot fungi displayed a wide diversity in their response to supplemented aromatic compounds. Pyrogallol stimulated Cerrena unicolor laccase and manganese peroxidase (MnP) synthesis in synthetic medium 2.5- and 2-fold, respectively, whereas 2,4,6-trinitrotoluene (TNT) brought about a 2.8-fold increase in laccase yield by Trametes versicolor in submerged fermentation of ethanol production residue. No eVect of the tested aromatic compounds on enzyme secretion by Ganoderma lucidum in mannitol-containing medium was detected. Nevertheless, G. lucidum is a potent producer of laccase in submerged fermentation of wheat bran and enzyme synthesis can be further increased by supplementation of medium with an appropriate inducer. The structure and the concentration of aromatic compounds play an important role in the regulation of enzyme synthesis. The supplementation of synthetic medium with 0.03-0.3 mM TNT or hydroquinone increased the diVerential rate of laccase synthesis by C. unicolor from 1,267 to 3,125-8,630 U mg biomass-1 day-1. Moreover, the same aromatic compound may function as either an inducer or a repressor, depending on the fungus and enzyme studied. Thus, hydroquinone increased 3-fold T. versicolor laccase activity decreasing 2- and 8-fold the yields of MnP and endoglucanase, respectively. © Society for Industrial Microbiology 2010. Source


Beridze T.,Ilia State University | Pipia I.,Ilia State University | Beck J.,Washington University in St. Louis | Hsu S.-C.,Washington University in St. Louis | And 8 more authors.
Acta Horticulturae | Year: 2014

DNA sequence diversity was investigated at two plastid regions (the trnH-psbA intergenic spacer and the rpl16 intron) in a geographically diverse group of 113 cultivated grape samples. This group included 40 samples from the Republic of Georgia, home to over 500 grape cultivars and the earliest archaeological evidence of grape domestication. The greater Caucasus region in which Georgia lies is widely believed to be the area in which grape domestication began, and the study of genetic diversity in this region is viewed as key to understanding grape domestication in general. Four plastid haplotypes are evident in the 113 samples, and are designated by their character-states at each of the 3 polymorphic positions: (AAA) - 23 samples, (ATT) - 29 samples, (GTA) - 26 samples, and (ATA) - 35 samples. The AAA haplotype was only observed in Georgian samples. The observation that the Georgian cultivars exhibited both unique plastid DNA variation (the AAA haplotype) and all other observed plastid haplotypes is consistent with previous studies that have observed both unique and high levels of genetic variation in wild grapes (V. vinifera subsp. sylvestris) in the greater Caucasus region. Source

Discover hidden collaborations